blocksim training guide.pdf

8/11/2019 blocksim training guide.pdf

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BlockSim 1.0

Born of ReliaSoft ingenuity,Bred to set new standards


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No part of this training guide may be reproduced or transmitted in any form or by any means, forany purpose, without the expressed written consent of ReliaSoft Corporation, Tucson, AZ, USA.

ReliaSoft and BlockSim are trademarks of the ReliaSoft Corporation.

1999 ReliaSoft Corporation. ALL RIGHTS RESERVED

115 South Sherwood Village Drive, Suite 103Tucson, AZ 85710

USA520-886-0366

[email protected]

http://www.ReliaSoft.com/BlockSim

Printed in the United States of America10 9 8 7 6 5 4 3 2


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1 BlockSim 1.0 Training Guide

About this Training Guide

This training guide is intended to provide you with many examples of the application's use. This training

guide begins with step-by-step examples and then proceeds into more advanced examples and questions. At

any time during the training, please feel free to ask the instructor(s) any questions you might have.

Contacting ReliaSoft

ReliaSoft can be reached at:

CORPORATIONReliaSoft Plaza, Suite 103

115 South Sherwood Village Drive

Tucson, AZ 85710

USA

Phone: (520) 886-0366

Fax: (520) 886-0399

E-mail: [email protected]

For up-to-date product information, visit our Web site at:

http://www.ReliaSoft.com/BlockSim


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2 First Steps

BlockSim 1.0 is a 32-bit application that has been designed to work with Windows 95/98 and Windows NT.

Regardless of which operating system you are using, BlockSims internal screens and commands are

identical in all systems and this training guide is equally applicable.

2.1 Starting BlockSim 1.0

There are two ways to start BlockSim, from the Startbutton or from the BlockSim shortcut icon on the

desktop. First, from the Startbutton, select Programs, ReliaSoft BlockSimand thenBlockSim Version

1.0as shown next.


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First Steps BlockSim 1.0

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You can also start BlockSim 1.0 from the shortcut icon located on the desktop. Double-click the BlockSim

icon to start the application.

2.2 BlockSim 1.0: A Familiarization

BlockSim's work environment has been designed around the Multiple Document Interface and the Project

Explorer. These tools display and manage the Diagram Sheets, Spreadsheets, Plot Sheets, and Templates

you will create and use in BlockSim. Each tool is described next.

2.2.1 Initial Screen

When you begin a new session in BlockSim, the first window you will encounter is the Initial Screen,

shown next.1

This screen will prompt you to either create a new Project or open an existing Project. You can open an

existing Project by double-clicking one of the Project names shown in the recent files list box or you can

click Open an Existing Projectand browse for the desired Project in the Open Projectwindow that will

appear.

For the purposes of this overview, you will create a new Project. Click the Create a New Projectbutton.

1If the Do not show this againoption is selected, the Initial Screen will not be displayed at startup. This selection can

be reset on the Otherpage of the User Setup.


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BlockSim 1.0 First Steps

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2.2.2 Template Preview

When you create a new Project, the Template Previewwindow appears. The Template Preview window is

shown next with its components identified.2

This window allows you to preview and select from the existing BlockSim Templates in the current

directory. BlockSim's Templates contain sets of re-usable pre-defined Blocks, Template Blocks, that you

can drag into the Diagram Sheets to create Reliability Block Diagrams (RBDs). Click a Template name to

display the Blocks it contains in the preview area on the left. Select a name and click OKor double-click a

Template name to close the Template Preview window and open the selected Template in the Project. Click

Browseto open a Browse For Folder window in which you can locate other previously saved Templates in

other directories. Click New Templateto close the Template Preview window and open a new Template in

the Project.

Click New Templateto close the Template Preview window and open a new Template in the Project.

When you are prompted to enter a name for the new Template that will be created in the Project, click OK

to accept the default name. When you are prompted to enter a name for the new Diagram Sheet that will

also be created in the new Project, click OKto accept the default name.

2If the Do not show when creating new Projectsbox is checked, the Template Preview window will not be displayed

when a new Project is created. This selection can be reset on the Otherpage of the User Setup.


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2.2.3 Multiple Document Interface

Once you have opened or created a Project, you will encounter BlockSim's Multiple Document Interface

(MDI). The MDI serves as the container and manager for all the windows you will use in BlockSim. The

menu and toolbar options available within BlockSims MDI will vary depending on the windows that are

currently open. In addition, BlockSims flexible MDI allows the user to configure the work space to meetindividual needs by hiding or moving the Menu Bar, Toolbars, Project Explorer, and Template Panel. The

next figure displays the MDI and its components so that you can familiarize yourself with the options

available within the MDI. Your screen may look slightly different than the one shown next. For example,

the Project Explorer is sometimes displayed in a panel (as in the next figure) and sometimes as a window

(as in Section 2.2.4) depending on your "Docking" selection.


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2.2.4 Project Explorer

To perform your system analyses with BlockSim, you will create Diagrams, Spreadsheets, Plots, and

Templates. BlockSim allows you to store and organize the Diagrams, Spreadsheets, Plots, and Templates

related to a particular Project together in a single file, a BlockSim Project file (*.rsw). The Project Explorer

allows you to manage the files included in a single BlockSim Project. The appearance of the ProjectExplorer will vary depending on whether the Docking option is selected. If Dock Project Explorer is

selected from either the Project Explorershortcut menu3or from the Viewmenu, the Project Explorer will

be displayed as a fixed panel on the right side of the MDI. If Dock Project Exploreris not selected, the

Project Explorer will be displayed as a window like the one shown next. From within the Project Explorer,

you can add, import, export, rename, and delete files within the current Project.

2.2.5 Diagram Sheet

The Diagram Sheet is the workspace in which you will create simple or complex RBDs. You can configure

Blocks and relationship lines in the Diagram Workspace. At the bottom of the Diagram Sheet, the Status

Boxdisplays the analysis status (EDIT or Analyzed) of the diagram, the Command Buttonsallow you to

initiate analyses based on the diagram. Block Countdisplays the number of Blocks in the Diagram

Workspace and Path Countdisplays the quantity of Paths that have been defined in the Diagram Sheet.

3 Right-click inside the Project Explorer to display a shortcut menu with the commands that pertain to BlockSim

Projects.


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Now close the Project by selecting Close Projectfrom the Filemenu or Project Explorershortcut menu.

A Save Changes window will appear to prompt you to save changes Project Files. Click No to close the

Project without saving changes. With the MDI displayed and no Projects open, you are now ready to work

through some examples.

2.3 A Quick Overview Example

This simple example has been designed to familiarize you with BlockSim's interface and tools.

A simple system consists of three resistors configured reliability-wise in series. The failure characteristics

of each component are presented in the table shown next. Create a Reliability Block Diagram (RBD) to

represent the system, plot system Reliability vs. Time, and calculate the Reliability of the system at 50 days

of operation.

Component Failure Distribution Parameters

Resistor 1 Exponential Mean Time = 1000

Gamma = 0

Resistor 2 Exponential Mean Time = 500

Gamma = 0

Resistor 3 Exponential Mean Time = 333.33

Gamma = 0

2.3.1 Create a New BlockSim Project

The first step is to create a new Project by selecting New Projectfrom the Filemenu or by clicking theNew Projecticon.

The Template Preview window will be displayed to allow you to select an existing Template or create a

new Template in the new Project. For this example, you will create a new Template within the Project.

Click New Templateto open a new Template in the Project. When you are prompted to enter a name

for the new Template, click OKto accept the default name. When you are prompted to enter a name

for the new Diagram Sheet (the workspace in which you will create simple or complex RBDs) that will

also be created in the new Project, click OKto accept the default name.

Your screen will look like the figure shown next.


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The new Template is displayed in the Template Panel located at the left side of the MDI. Notice that

the Template Name Bar located at the top of the Template Panel displays the name of the new

Template, Template 1, and that the Template Name Bar is yellow to indicate that the Template is

currently active. Multiple Templates can be open at the same time within BlockSim. For each open

Template, a Template Name Bar will be displayed in the Template Panel. When you click a Template

Name Bar, the Template becomes active, the Template Name Bar becomes yellow, and the Blocks

associated with the Template are displayed in the Template Panel.


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2.3.2 Creating a Template Block

BlockSim Blocks, defined with the reliability characteristics of system components, are the building blocks

you will use to create your Diagrams. The next step is to create a new Template Block that will be used as

the pattern for the resistor Blocks you will use in your RBD.

To add a Block to the active Template, click the Add New Blockicon in the Templatetoolbar,

or select Add New Blockfrom the Templatemenu. The Block Propertieswindow, in which you can

define the new Block with the life characteristics of the component, will appear as shown next.

On the Failurepage of the Block Properties window, you will define the Block to represent the failurecharacteristics of the Resistor 1 component. Type Resistor 1in the Block Namebox. Verify that the

Block Can Failoption is selected (i.e., the check box is checked).4Verify that the Static Blockoption

is not selected.5 Select Exponentialunder Failure Distributionand notice that the Parameter Input

Boxes to the right change to represent the parameter requirements of the selected distribution. Type

1000for the value of Mean Time6and 0for the value of Gamma. Click Graphto update thepdfPlot

in the Graphics Screen to the right. ThepdfPlot will now represent the current Failure page selections.

4The Block Can Fail option is selected to indicate that the component can fail. If the Block Can Failoption is not

selected, the Reliability of the Block at all times is considered to be 1 or 100% and the other options on the Failure

page will be unavailable.5The Static Block option is not selected to indicate that a time-dependent failure distribution will be defined for the

component. If the Static Blockoption is selected, an input box will appear in which you can type the Reliability of the

component at a fixed point in time and the other options on the Failure page will be unavailable.6By default in BlockSim, the exponential parameter is defined as "Mean Time." Although the "Mean Time" definition

is appropriate for this example, you can also define the exponential parameter as "Lambda" from the Calculationspage

of the User Setup.


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The Block Properties window will look like the picture shown next. Click OK to close the BlockProperties window and create a new Block in the active Template.

The Template now holds a new Block. You can modify the appearance of the new Block by clickingthe Block Graphicicon in the Templatetoolbar,

or by selecting the Block (by clicking once on it) and then selecting Block Graphic from the Template

menu. The Graph File Manager will open to allow you to select a bitmap graphic (*.bmp) for display

on the Block.


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Display the bitmap graphics stored in the BLOCKSIM\Pictures\General\Electronics directory by

clicking Browse, selecting the directory from the Browse for Folder window that appears and clicking

OK. Browse through the available bitmap graphics by clicking the buttons

located near the top left corner of the Graph File Manager. When you move the mouse over a graphic,

the file name will be highlighted in the File Name Box to the left of the graphics. Click once on a

graphic to highlight its name in the File Name Box.

Locate the resistor.bmp graphic shown next by clicking the graphic or by scrolling through the File

Name Box and selecting the file name. Double-click the graphic to select it for display on the currentBlock.

The appearance of the Resistor 1 Block in the Template will change to display the selected bitmap

graphic and your screen will look like the figure shown next.


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You will now create two more Template Blocks to represent the Resistor 2 and Resistor 3 components.On the Failurepage of the Resistor 2 Block, make the following selections:

Block Name: Resistor 2

Block Can Fail: Selected

Static Block: Not Selected

Failure Distribution: Exponential

Mean Time: 500

Gamma: 0

Click OK to close the Block Properties window. Repeat the procedure to define the properties of theResistor 3 Block with the failure characteristics of the Resistor 3 component.

Block Name: Resistor 3

Block Can Fail: Selected



Mean Time: 333.33

Gamma: 0


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2.3.3 Build a Simple Diagram

Now you are ready to build a simple Reliability Block Diagram (RBD) by placing the Template Blocks you

have created into the Diagram Sheet. You will do this by dragging the Blocks from the active Template into

the Diagram Sheet.

Drag the Resistor 1Template Block into the Diagram Sheet by clicking the Block in the TemplatePanel to select it, holding down the left mouse button, dragging the cursor into the desired position on

the Diagram Sheet and releasing the mouse button. Your screen will look like the figure shown next.

Notice that a copy of the Block is placed in the Diagram Sheet and the Template Block remains in the

Template Panel. Template Blocks are like re-usable patterns that you can use to save time and effort.

When you drag a Template Block into a Diagram Sheet, a separate (independent) Block is created in

the Diagram Sheet that you can modify to meet the needs of the particular diagram.

Now drag the Resistor 2 Block and Resistor 3 Block into the Diagram Sheet as well.

2.3.4 Arrange and Connect the Blocks

You are now ready to arrange and connect the Blocks in the Diagram Sheet to create a Reliability Block

Diagram (RBD) that will represent the reliability-wise configuration of the system.

Place the Blocks in a horizontal row with Resistor 1on the left, Resistor 2in the center, andResistor3 on the right. Drag the Blocks as before by clicking the object to select it, holding down the left mouse

button, moving the cursor into the desired position and releasing the mouse button. Your Diagram

Sheet will look like the next figure.


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Now you are ready to connect the Blocks to represent the relationships between components of thesystem. Select the Resistor 1component by clicking once on the Block. When a Block is selected, a

blue outline will appear around the Block and object handles will appear at each corner and on all four

sides of the Block as shown next.

When you move the cursor over the object handles in the selected Block, a circular target symbol

appears. This target symbol is the anchor for the relationship lines you will draw between Blocks.

Move the mouse over the object handles on the Resistor 1Block. When a target symbol appears, holddown the left mouse button and drag a line from the Resistor 1 Block to the Resistor 2Block withwhich it will be connected. When the target symbol is located above the second object, release the

mouse button. A relationship line will now connect the two Blocks.

You can also use the Join Blocks tool to connect Blocks in the Diagram Sheet. Connect the Resistor 2Block with the Resistor 3Block by clicking the Join Blocksicon,

or by selecting Join Blocksfrom the Diagrammenu. The cursor will change to display a target symbol

at the tip of the arrow. Click the source Block (Resistor 2), hold down the left mouse button and drag a

line to the destination Block (Resistor 3). When the target symbol is located above the second object,

release the mouse button. The Blocks will be connected with a relationship line as before. Yourdiagram will now look like the next figure.

7 Note that when using the Join Blocks tool to create

relationship lines, you must right-click the Diagram Sheet to stop adding relationships and return to

BlockSim's normal mode.8

7Notice that the connecting line arrows point from the source Blocks to the destination Blocks to represent the flow of

the system. The specification of source and destination Blocks is relevant to BlockSim's analysis of the system

configuration.8If you do not right-click the Diagram Sheet to return the cursor to its normal mode, you will not be able to perform

other activities in BlockSim. If you are experiencing difficulties with the program, make sure that the cursor is in its


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2.3.5 Analyze the Diagram

Now that you have defined the reliability characteristics of each component Block and arranged and

connected the Blocks to represent the system, you are ready to analyze the Diagram.

Select Analyzefrom the Toolsmenu or click the Analyzeicon,

located in the Analyzetoolbar or at the bottom of the Diagram Sheet. ReliaSoft's Results Panel will

appear to display the results of the analysis as shown next.9

normal mode. A dialogue balloon reminder appears in the upper right of the MDI while the Join Blocks tool is

activated.9Note that the first time you analyze a Diagram in BlockSim, you will be prompted to indicate whether you would like

to display the Results Panel each time a Diagram Sheet is analyzed. You can reset this preference on the Other page of

the User Setup.


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With the Analyze tool, BlockSim analyzes the relationships of the components in the system and

presents the reliability-wise configuration mathematically in ReliaSoft's Results Panel. Click OKto

close the Result Panel and return to the Diagram Sheet.10

2.3.6 Plot System Reliability

Now you can generate Plots based on the reliability characteristics of the entire system. Select Plotfrom the Toolsmenu or click the Ploticon,

located in the Analyze toolbar or at the bottom of the Diagram Sheet. The Plot Sheet will appear,

displaying the Probability of Failure vs. Time Plot as shown next.11

10At this time, you may have noticed that the status in the Status Box in the bottom left corner of the Diagram Sheet

has changed from EDITto Analyzedto indicate that system relationships have been analyzed.11 If you have previously opened a Plot Sheet in BlockSim, the Plot Type selected in the last Plot Sheet opened will

appear. If a Plot Type other than the Probability of Failure vs. Time Plot appears, you can select the Probability of

Failure vs. Time Plot from the Plot Type menu.


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Additional Plots are also available in BlockSims Plot Sheet, including Reliability vs. Time, pdfPlot,

Failure Rate vs. Time, Static Reliability Importance, and Reliability Importance vs. Time. In thePlot

Typebox, click the arrow to select a Plot type from the menu.

Now close the Plot by clicking the Close button in the top right corner of the Plot Sheet,

and click Yeswhen asked if you want to insert the Plot into the Project. A Plot Namewindow will

appear, as shown next. Type a Plot name and click OKor click OKto accept the default name.


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Click the Project Explorericon,

to place the focus on the Project Explorer window. You can see that a Plot file has been added to the

Project in the Plotsdirectory. Now return the focus to the Diagram Sheet by double-clicking its name

in the Project Explorer, Diagram 1.

2.3.7 Calculate System Reliability

In addition to generating system reliability plots, BlockSim is also capable of calculating standard system

reliability metrics based on the exact system reliability function.

To calculate the Reliability of the system at a specified time, select Quick Calculation Padfrom theToolsmenu or click the QCPicon,

located in the Analyzetoolbar or at the bottom of the Diagram Sheet. The Quick Calculation Pad

(QCP) will appear. Standard reliability calculations can be obtained using the first page of the QCP, the

Generalpage.

To determine the Reliability of the system at 50 days, select Std. Probability Calculationsunder

System Calculations. Under Required Input from Userenter a Mission End Timeof 50. Finally,

click Calculateand the results of the calculation will appear under Resultsas shown next.

You can see that the Reliability of the system at 50 days is 0.7408 or about 74.08%. Click Closeto

close the Quick Calculation Pad and return to the Diagram Sheet.


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2.3.8 Save and Close the Project

Now save the Project as 1stStep.rsw. To do this, click the Save Projecticon,

or select Save Projectfrom the Filemenu. In the Save Project Aswindow, enter 1stStepas the file

name and click Save. If you are working with an evaluation copy of BlockSim, you will be unable to

save. In this case, leave the Project open and proceed with the rest of the Training Guide.

After saving the file, close the Project by selecting Close Projectfrom the Filemenu. You will now belooking at the MDI without any Projects open.


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3 Step by Step Examples

3.1 Detailed Examples

3.1.1 Example 1

A computer consists of two hard drives and a circuit board. The two hard drives operate reliability-wise in

parallel within the system. The reliability and optimization characteristics of each component are presented

in the table shown next.

Component Failure

Distribution

Parameters Max

Achievable

Reliability

Feasibility of

Increasing

Reliability

Hard Drive 1 Weibull Beta = 2.5

Eta = 3000 days

Gamma = 0

.999 Moderate

Hard Drive 2 Exponential Mean Time = 10000

Gamma = 0

.999 Easy

Circuit Board Weibull Beta = 1.5

Eta = 5000 days

Gamma = 0

.999 Hard

Do the following:

1. Create a Reliability Block Diagram (RBD) of the system.

2. Calculate the Reliability of the system at 730 days (2 years) of operation.

3. Calculate the Reliability of the system at 730 days if the Hard Drive 1 component is removed from thesystem.

4. Determine the optimum scenario for increasing the Reliability of each component in order to achieve asystem Reliability of 0.98 (or 98%) at 730 days of operation.


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Step by Step Examples BlockSim 1.0

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Solution

Create a new Project by selecting New Project from the File menu or by clicking the New Projecticon.

Select the Example1.rst Template from the Template Preview window and click OK. The selectedTemplate will open in the new Project. The Project Explorer and a blank Diagram Sheet will also

appear and you will be prompted to enter names for the new Diagram Sheet. Accept the default name.

Your screen will look like the picture shown next.

The Diagram Sheet is the workspace in which you will create simple or complex diagrams that

represent the reliability characteristics of systems or processes. The Project Explorer appears behind

the Diagram Sheet. View the Project Explorer by clicking on it behind Diagram 1, by selecting View

ProjectExplorerfrom the Viewmenu, or by clicking its icon,

located on the Standardtoolbar. The Template, Example1, appears in the Template Panel at the left

side of the MDI.


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BlockSim 1.0 Step by Step Examples

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You are now ready to build a simple Reliability Block Diagram (RBD) by dragging Blocks from the

Example1.rst Template into the Diagram Sheet.

Place the focus on Diagram 1again by double-clicking its name in the Project Explorer or by clickingthe Diagram itself located behind the Project Explorer. Drag the Starting BlockTemplate Block into

the Diagram Sheet by clicking the Block in the Template Panel to select it, holding down on the left

mouse button, dragging the cursor into the desired position on the Diagram Sheet and releasing themouse button. The Starting Block will represent the starting point of the computer system in this

example. Every diagram in BlockSim must have exactly one starting point and one ending point.12

Your screen will look like the figure shown next.

12Although every Diagram must have a single starting point and a single ending point, these points do not necessarily

have to be Starting and Ending Blocks. For example, if a Diagram represents a series system, the first Block will be the

starting point and the last Block will be the ending point. For this Detailed Example, however, a Starting Block that

possesses no failure characteristics must be used.


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Now drag the Hard Drive and Circuit BoardBlocks from the Template into the Diagram Sheet. Draga second Hard DriveBlock into the Diagram to represent the second hard drive component in the

system. The Diagram Sheet will now contain four Blocks and the Example1.rst Template will be

unchanged, as shown next.

Double-click the Starting Blockin the Diagram Sheet to open the Block Properties window, shownnext.


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In this window, you can define the reliability characteristics of the component. Because this Block

does not represent a component of the system with failure characteristics to be taken into account, the

Block Can Failoption has been unchecked to indicate that the component cannot fail. Because the

component cannot fail, the other options on the Failurepage are unavailable. Click OKto close the

Block Properties window.

The Starting Block is defined as a Block that cannot fail. The system in this example contains onlythree components; two hard drives and a circuit board. The hard drives are connected in parallel. So theoriginal system would look like the figure shown next.

However, this original system contains two starting points (Hard Drive 1 and Hard Drive 2). A

BlockSim diagram must have exactly one starting point and one ending point. Therefore, a single

starting point (StartingBlock) that does not possess failure characteristics was introduced to close the

system without impacting reliability calculations.

The Circuit Board Block has also already been defined with the failure characteristics of thatcomponent. The failure distribution properties have already been set in the Template Block. Move the

mouse over each Block within the Template to view the Tool Tip Text. The Tool Tip Text displays

the failure distribution properties of the Block over which the cursor is positioned. You can change the

properties of the Block within the Diagram Sheet or within the Template. If you change the properties

of a Block within the Template, then each time the Block is dragged into the Diagram Sheet the Block's

properties will reflect the values specified in the Template.

Now double-click the Hard DriveBlock at the top of the Diagram Sheet to define the characteristics ofthe Hard Drive 1 Block. Be sure that the following options and properties have been defined:

Block Name: Hard Drive 1

Block Can Fail:Selected


Failure Distribution: Weibull

Beta: 2.5 Eta:3000 days

Gamma:0

Then click OKto close the Block Properties window.


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Double-click the other Hard DriveBlock to define the Hard Drive 2 Block. Be sure that the followingoptions and properties have been defined:

Block Name: Hard Drive 2

Can It Fail: Selected



Mean Time: 10000

Gamma: 0

Click Graph to update the pdf Plot to graphically represent the current failure distribution. Thewindow will look like the next figure.


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Now you are ready to connect the Blocks to represent the relationships between the components of thesystem. Use either connection method to connect the Starting Blockto the Hard Drive 1Block, the

Starting Blockto the Hard Drive 2Block, the Hard Drive 1Block to the Circuit BoardBlock, and

the Hard Drive 2 Block to the Circuit Board Block. If you use the Join Blocks tool to add

relationship lines, be sure to right-click on the Diagram once the relationships have been made, in order

to return to BlockSim's normal mode. Your screen will look like the next figure.

Notice that the Hard Drive Blocks are diagrammed in parallel to show that if one hard drive componentfails, the system will continue to operate with the other hard drive component. Now that you have

defined the reliability characteristics of each component Block and arranged and connected the Blocks

to represent the system, you are ready to analyze the system.


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To analyze the system, select Analyzefrom the Toolsmenu or click the Analyzeicon,

located in the Analyzetoolbar or at the bottom of the Diagram Sheet. ReliaSoft's Results Panel will

appear, displaying the results of the analysis as shown next. Click OKto close the Result Panel.


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Now you can generate Plots based on the reliability characteristics of the entire system. Select Plotfrom the Toolsmenu or click the Ploticon,

located in the Analyze toolbar or at the bottom of the Diagram Sheet. The Plot Sheet will appear,

displaying the Probability of Failure vs. Time Plot as shown next.

Click the Add to Projecticon,

to add the Plot to the Project. A Plot Namewindow will appear, in which you can name the Plot. Click

OKto accept the default name, Probability of Failure vs. Time (Diagram 1). Now view the Project

Explorer by selecting ViewProjectExplorer from the Viewmenu, or by clicking the View Project

Explorer icon,

located in the Standard toolbar. You will notice that Probability of Failure vs. Time (Diagram 1)

has been added to the Project under Plots. Now return the focus to the Plot Sheet. Close the Plot by

clicking the Close(X) buttonin the top right corner of the Plot Sheet. You will now be looking at theDiagram Sheet.


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BlockSim also allows you to obtain standard reliability results based on the exact system reliabilityfunction. To calculate the Reliability of the system at 730 days, the Quick Calculation Pad (QCP) will

be used. Select Quick Calculation Padfrom the Toolsmenu or click the QCPicon,

located in the Analyzetoolbar or at the bottom of the Diagram Sheet. The QCP will appear as shownnext.

The QCP contains two page index tabs, Generaland Optimization. To determine the Reliability ofthe system at 730 days, select Std. Probability Calculations under System Calculations on the

General page. Under Required Input from User, type a Mission End Time of 730. Finally, click

Calculateand the results of the calculation will appear under Resultsas shown next.


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You can see that the Reliability of the system at 730 days is 0.9438 or 94.38%. Click Closeto close

the Quick Calculation Pad and return to the Diagram Sheet.

Next, you will determine the Reliability of the system if Hard Drive1is turned off or absent from thesystem. BlockSim allows you to perform what-if calculations based on the RBDs you create. You

can toggle the status of individual Blocks on or off to indicate if the component is active or inactive and

then obtain reliability results for the system under those hypothetical conditions.

To toggle the status of Hard Drive 1 to off, right-click the Block and select Toggle Block On/Offfrom the shortcut menu that appears.

13 A red Xwill appear on the Block to indicate that the component

is inactive, as shown next.

Now re-open the QCP. Std. Probability Calculations will already be selected and 730 will be

specified as the Mission End Time. Click Calculateand the results will be displayed under Results.

You can see that with Hard Drive 1 inactive, the Reliability of the system at 730 days decreases from

0.9438 (94.38%) to 0.8792 (87.92%). Close the QCP.

Now toggle the status of the Hard Drive 1Block back to on by selecting the Toggle Block On/Offmenu item again from the shortcut menu. The red Xwill disappear, indicating that the component isactive.

13You can also click the Block to select it and then choose Toggle Block On/Offfrom the Diagrammenu.


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BlockSim also provides the capability of performing optimization calculations to determine the bestway to achieve a system Reliability goal by improving the Reliability of individual components.

Double-click the Hard Drive 1Block to open the Block Properties window. Click the Optimization

tab to display the Optimizationpage. On this page, you can define the optimization characteristics of

the selected component. Enter 0.999(default) into the Max Achievable Reliabilitybox to indicate the

highest Reliability value that can reasonably be achieved for the component. Drag the marker on the

Feasibility scale to Moderate to indicate that it is moderately difficult (or costly) to increase theReliability of the component. Click Graph to update the Cost vs. Reliability Plot in the Graphics

Screen to the right. The window will look like the next figure.

Click OK to return to the Diagram Sheet. Now, right-click the Hard Drive 1Block and select Toggle

Optimize Status from the Diagram Block shortcut menu.14 A green box will appear at the bottom

right corner of the Block, as shown next, to indicate that the Reliability of this component is to be

considered in the optimization algorithm.

Now define the optimization characteristics of the Hard Drive 2 and Circuit Board Blocks. For theHard Drive 2 Block, the Max Achievable Reliability is 0.999 and the Feasibility is Easy. For the

Circuit Board Block, the Max Achievable Reliabilityis 0.999 and the Feasibilityis Hard. Be sure to

select the Toggle Optimize Statusoption for both Blocks.

14You can also select the Block and then choose Toggle Optimize Statusfrom the Diagrammenu.


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Re-open the QCP and click the Optimizationtab. The Optimizationpage allows you to set up andconduct the optimization algorithm for the system. For Mission End Timetype 730; for Reliability

Goal type 0.98; for Iterations,15

accept the default value of 50. Select the Show Results

Automaticallyoption as shown next.

Click Calculate to begin the optimization. Because the Show Results Automatically16 option isselected, when the optimization calculations are complete, the results will appear in ReliaSoft's Results

Panel as shown next.

15The Iterationsinput box allows you to enter the maximum number of iterations of the optimization algorithm to be

calculated in order to obtain a solution. As the complexity and number of units in the system increases, a greater

number of iterations may be required.16 If the Show Results Automatically option is not selected, click the Report button to display the results in

ReliaSoft's Results Panel.


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The Reliability goals for each optimized component, displayed in the R_goal(730)column, represent

the optimum scenario for increasing component Reliability in order to achieve the system Reliability

goal of 0.98 (or 98%) while minimizing the system cost. The number of equivalent units that would

have to be placed in parallel to achieve this Reliability is shown in the N.E.P.U. column, which stands

for Number of Equivalent Parallel Units. Click OKto close the Result Panel and click Closeto close

the Quick Calculation Pad.

At this time, save the Project as Example1.rsw. To do this, click theSave Projecticon,

or select Save Projectfrom the Filemenu. In the Save Project Aswindow, enter Example1as the file

name and click Save. After saving the file, leave the Project open, as it will be used in the next

example.


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3.1.2 Example 2

The circuit board of the previous example was examined further to determine the major failure modes so

that its reliability could be improved. It was found that most of the failures were due to the failure of the

processor and the fan. The properties for the processor and fan are shown in the table below.

Component Failure

Distribution

Parameters Max

Achievable

Reliability

Feasibility of

Increasing

Reliability

Processor Weibull Beta = 2.3

Eta = 7655.19 days

Gamma = 0

.999 Moderate

Fan Exponential Mean Time = 14231.83

Gamma = 0

.999 Easy

The processor and fan are connected reliability-wise in series.

Do the following:

1. Create an RBD for this subsystem.

2. In the previous example, it was found that the Reliability of the circuit board should be increased from0.9457 to 0.9806 for the system to reach a reliability goal of 0.98. Find the optimized Reliabilities for

the processor and fan in order to achieve this goal of 0.9806.

Solution

First you need to insert another Diagram into the Project. To do this, select Add New File then AddNew Diagramfrom the Filemenu or right-click inside the Project Explorer and select Add New File

then AddNew Diagram from the shortcut menu. A new, blank Diagram sheet will be placed into the

Project under Diagrams(in the Project Explorer) and it will also appear in the MDI.

Next, you will open an existing Template called Example2.rst. Open this Template by selecting

Import Filethen Template from the Filemenu or by right-clicking inside the Project Explorer and

selecting Import File then Template. A Template Preview window will open. Select the

Example2.rst file from the list of files (in the BlockSim\Templates directory) and click OK. Your

screen will look like the next figure.


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You can now see that you have two Templates open at the same time. The active Template is indicated

by a yellow Template Name Bar in the Template Panel. You can switch between Templates by

clicking the Template Name Bar with the Template's name.

Double-click the ProcessorBlock in the Example2Template to view the Block Propertieswindow.Be sure that Block Can Fail is selected on the Failure page. Next, select Weibull as the failure

distribution and enter the known parameter values (see table on page 35). Click Graphto view thepdf

Plot for the current parameter values based on the selected distribution. Your screen will look like thefigure shown next.


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Now click the Optimization tab to display the Optimizationpage of the Block Properties window.Type the proper values for the Max Achievable Reliabilityand select the correct Feasibilityoption as

shown next. Be sure to click Graphso that the Cost vs. Reliability Plot reflects the current settings.

Click OKto accept the current Block Properties and close the window.


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Double-click the Fan Block in the Template to open the Block Properties window and enter theappropriate Block Properties for the Fanusing the same process described for the Processor. After

you have entered all of the properties, click OK.

Now drag one ProcessorBlock and one FanBlock from the Template into Diagram 2. To connect theProcessorto the Fan, click once on the ProcessorBlock to select it. When the Block is selected, a

blue outline will appear around the Block and object handles will appear at each corner and on all foursides of the Block. When you move the cursor over the edge of the selected Block, a circular target

symbol appears. This target symbol is the anchor for the relationship lines you will draw between

Blocks. Move the mouse over the edge of the ProcessorBlock. When a target symbol appears, hold

down the left mouse button and drag a line from the ProcessorBlock to the FanBlock. When the

target symbol is located above the second object, release the mouse button. A relationship line will

now connect the two Blocks.17

Now right-click the ProcessorBlock and select ToggleOptimize Status from the shortcut menu. Agreen box will appear at the bottom right corner of the Block to indicate that the reliability of this

component is to be optimized. Do the same for the FanBlock. Your screen will look like the figure

shown next.

17You can also use the Join Blocks tool to connect Blocks in the Diagram Sheet. Click the Join Blocksicon or select

Join Blocksfrom the Diagrammenu. The cursor will change to an arrow with a target symbol to indicate that it is in

Connection Mode. Place the target symbol over the source Block and, while holding the left mouse button down, drag

the cursor from the source Block to the destination Block and release. A relationship line will now connect the two

Blocks. Then, right-click on the Diagram to return to BlockSim's normal mode.


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Analyze the system by selecting Analyzefrom the Toolsmenu or clicking the Analyzeicon,

located in the Analyzetoolbar or at the bottom of the Diagram Sheet. ReliaSofts Results Panel will

appear, displaying the results of the analysis. Click OKto close the Results Panel.

Next, you will optimize the Reliabilities of the processor and fan so that the system Reliability meetsthe Reliability goal of 0.9806. Open the Quick Calculation Pad (QCP) and click the Optimizationtab.

Make sure that 730is entered for the Mission End Time, the ReliabilityGoal is set at 0.9806, and

leave the number of Iterations at 50 (default). In addition, Show Results Automaticallyshould be

selected. The QCP will look like the next figure.

Click Calculateto conduct the optimization calculations. The results are shown next.


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Notice that although you entered a Reliability Goalof .9806, the optimization algorithm has returned

results for a System Reliability R_goal(730)value of .9807. This occurred because the Mathematical

Tolerance for convergence criteria in BlockSim has been set to .001 by default. You can change the

Mathematical Tolerance for convergence criteria on the Calculationspage of the User Setup.

Click OKto close the Results Panel and click Closeto close the QCP. Select User Setupfrom the Filemenu and click the Calculationstab to display the Calculations page. Under Precision to be used for

convergence criteria, type .0001in the Mathematical Tolerancebox as shown next.


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Click OKto close the User Setup. You have now increased the precision to be used for convergencecriteria in BlockSim calculations that are solved numerically. Because this value represents a range in

which the calculated solution can vary from the target, decreasing this value will increase the time

required for calculations because more iterations will be required.

No re-open the QCP and perform the optimization calculation again. The results are displayed in thefigure shown next.

You can see that the results have now been returned for a System Reliability R_goal(730) value of

.9806. As the results indicate, to achieve a Reliability goal of 0.9806, the Reliability of the Processor

must be at least 0.9955 and the Reliability of the Fanmust be at least 0.985.

Click OK to close the Results Panel and click Close to close the QCP. Save the Project asExample2.rswand leave the Project open, as it will be used in the next example.


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3.1.3 Example 3

In BlockSim, you have the ability to include subsystems within selected Blocks. This allows you to drill

down or view the subsystems within a particular component. This example will demonstrate this aspect of

BlockSim. At this point, you will still be working with the data and diagrams used in Examples 1 and 2.

Do the following:

1. Include the fan and processor as a subsystem within the circuit board.

2. Calculate the Reliability of the system at 730 days.

Solution

To begin, make sure that Diagram 1 is the current control. This is the Diagram with two hard drivesand a circuit board. Double-click the CircuitBoardto open the Block Propertieswindow.

In the Block Propertieswindow click the Othertab. On the Otherpage click to select the Block AsDiagram option. Then click the arrow in the box below the Block As Diagramoption. A menu will

appear that contains a list of all available Diagrams in the current Project. Select Diagram 2from thislist. This is the file with the processor and the fan that you were working with in Example 2. The

selected Diagram will be displayed in the Graphics Screen on the right side of the Block Properties

window. Your screen will look like the figure shown next.

You can zoom in on the Diagram displayed in the Graphics Screen by left-clicking on the display, and

you can zoom out by right-clicking. Click OKto apply the current settings to the Circuit Board Block

and close the Block Properties window.


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The CircuitBoardBlock has now been modified. It still contains the original picture, but it is now inthe shape of a folder. Subdiagram Blocks (Blocks that contain subsystems, or diagrams) are identified

in BlockSim in this way.

The CircuitBoardis now defined by the subsystem containing the fan and processor. In other words,

the Block definition indicates that the circuit board is composed of one fan and one processor. In

reality this is obviously not the case. However, this example simply shows you how one Block can

represent another subsystem.

To calculate the Reliability of the system at 730 days, the QCP will be used. Select Quick CalculationPadfrom the Toolsmenu or click the QCPicon,

located in the Analyze toolbar or at the bottom of the Diagram Sheet. Select Std. Probability

Calculationsunder SystemCalculations if it is not already selected. Type 730 for the Mission End

Time and click Calculate. The results are shown next.


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The Reliability of the system at 730 days is 0.9438 (94.38%) which is the same as the result returned in

Example 1.

Save and close the Project. You can close the Project by selecting Close Projectfrom the Filemenuor by right-clicking in the Project Explorer and selecting Close Project.


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3.1.4 Example 4

ACME Company manufactures subsystems for oil refinery plants. One of the subsystems that ACME

manufactures consists of two power generators, three pumps, and one valve. The two generators are

identical to each other, as are the pumps. The pumps are in a 2-out-of-3 configuration. The system

configuration is shown next.

Generator

Generator

Pump

ValvePump

Pump

The following table presents the failure data for the generators.

Number in Group State Time-to-failure, hr

1 F 1150

1 F 1660

1 S 1660

5 S 1850

2 F 3000

4 S 3000

1 S 3200

4 S 4150

1 F 4330

1 F 4800

4 S 4850

1 F 5600

1 F 6100

1 F 7800

3 S 8500

1 F 8750

2 S 8750

3 S 10100

1 S 11500

3 S 12000

The table shown next presents the failure distribution data and parameter values for the pumps and thevalve.

Component Failure Distribution Parameter Values

Pumps Mixed Weibull

(2 Subpopulations) 1 = 0.589, 1 = 6343.390 hrs, Portion[1] = 0.2695

2 = 2.394, 1 = 20301.856 hrs, Portion[2] = 0.7305

Valve Exponential Mean Time = 830288.94


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Do the following:

1. Using Weibull++, determine an appropriate failure distribution for the generators based on the givendata.

2. Estimate the parameters of the selected distribution using Maximum Likelihood Estimation (MLE).

3. Generate a table of system Reliabilities given a start time of 1000 hours and an end time of 5000 hourswith a time increment of 1000 hours.

Solution


Select the Example4.rst Template from the Template Preview window and click OK. The selected

Template will open in the new Project. The Project Explorer and a blank Diagram Sheet will also



Double-click the Generator Block inside the Template. The Block Properties window will appear.The properties for the Generator Block have not been set. The parameter values are currently

unknown, however life data was given at the beginning of this example based on life tests conducted on

the generator. This data can be used to calculate the parameters of the failure distribution for the

Generator Block.


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Be sure that you are on the Failurepage of the Block Properties window. Click Compute Distributionin the bottom left corner. This will launch ReliaSoft's Weibull++ 5.0.

18Weibull++ 5.0 is a software

application designed to analyze life data. The Weibull++ Data Type Expert will appear. You will use

the Data Type Expert to create the appropriate data sheet for the Generator component's life data.19

Under Grouped Data Entryselect Times-to-Failure withSuspensions (Right Censored)and click

OK. A new data sheet will be created for you based on your selection.

Enter the data given for the Generator into the data sheet as shown next.

Maximum Likelihood Estimation (MLE) will be used for parameter estimation. You can specify thisby clicking the OtherToolstab. Click MaximumLikelihood(MLE)to select it. Return to the Main

Controls page by clicking the Main Controlstab.

Weibull++ comes with a utility called the Distribution Wizard. The Distribution Wizard conducts avariety of goodness-of-fit tests designed to suggest the best distribution for your data. Select

Distribution Wizardfrom the Datamenu, or click the Distribution Wizardicon.

18 Weibull++ 5.0 must be installed on your computer system in order for you to utilize the Compute Distribution

option.19If the Data Sheet Wizard appears, click the Data Type Expertbutton located in the bottom right corner to display

the Data Type Expert window.


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The Distribution Wizard will appear. Click Begin Auto Runso that the Distribution Wizard can go

through the process of suggesting a distribution. After the Distribution Wizard has finished conducting

the tests, the 2-parameter Exponential distribution will be suggested as indicated by the 1 in the

Rankingfield next to Exponential 2as shown next.

Click Implement Suggestion to indicate that you would like the parameters calculated using the 2-parameter Exponential distribution. The Distribution Wizard will close and you will now be viewing

the Folio with the entered data and the parameters calculated as shown next.


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Close Weibull++ by clicking Closelocated in the Main toolbar. A message box will appear to ask ifyou would like to save the changes made to the Folio. Click Yes and save the Folio as Example4.wdf.

The next message box asks if you would like to update the Block's distribution information. Click Yes.

A third message box appears to inform you that the failure distribution pdfPlot cannot be displayed in

the Graphics Screen on the right side of the Block Properties window because of insufficient resolution

in the Y direction. Click OK. The parameter values calculated using Weibull++ will be inserted as the

parameter values of the failure distribution of the GeneratorBlock as shown next. Click OKto accept

the current Block Properties.

Note that because the exponential parameter in BlockSim is defined by default as "Mean Time," the

"Lambda" parameter calculated in Weibull++ was converted to "Mean Time" when you updated the

Block's distribution information. If "Lambda" had been defined as the exponential parameter, the

Block Properties would have been updated with the calculated Lambda value. You can change the

exponential parameter definition from the Calculationspage of the User Setup.


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Now you will arrange the Blocks in the Diagram. Because BlockSim's Diagrams must have only onestarting point, you will use the Starting Block as the starting point of the Diagram. Place the Starting

Blockon the left side of the Diagram. Drag one GeneratorBlock into the Diagram and place it above

and to the right of the Starting Block. Drag another GeneratorBlock into the Diagram and place it

below and to the right of the Starting Block. Drag the Pump Block into the Diagram three times,

placing them in a vertical line to the right of the Generator Blocks. Drag the ValveBlock into the

Diagram and place it on the far right side. Your Diagram will look like the figure shown next.


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Now you will connect the Blocks by dragging relationship lines between them. Connect the StartingBlockto each of the GeneratorBlocks. The Generator Blocks will be connected to each of the Pump

Blocks through a Node. A Node is a different type of Block that can be defined to indicate the number

of paths that must successfully pass through the Block in order for the system to succeed (k-out-of-n).

To place a Node into the Diagram, select Add Nodefrom the Diagrammenu or click the Add Node

icon,

located in the Diagramtoolbar. The cursor will turn into a pointing hand holding a circle.

Place the cursor in the Diagram between the Generator Blocks and the Pump Blocks and click to place

the Node. Your screen will look like the figure shown next.


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operate. Make sure the Node Can Fail box is not selected. Then click OK to close the Node

Properties window.

Now connect each Pump Block to the Pump Node and connect the Pump Node to the Valve Block.Your Diagram will look like the figure shown next.

Analyze the system by selecting Analyzefrom the Toolsmenu or click the Analyze icon,


appear to display the results of the analysis as shown next. Close the Results Panel by clicking OK.


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Insert a Spreadsheet into the Project by selecting Add NewFilefrom the Filemenu and then selectingAdd New Spreadsheet. A Spreadsheet will open in the MDI. You can also see that the Spreadsheet

has been added to the Project by viewing the Project Explorer.

Now return the focus to Spreadsheet 1. The Function Wizard will be used to generate a table ofsystem Reliabilities. Open the Function Wizard by selecting FunctionWizardfrom the Toolsmenu or

by clicking the Function Wizardicon,

located in the Analyze toolbar. The Diagram Sheet to which the Function Wizard is linked (in this

case, Diagram 1) is displayed in the box in the bottom left corner. The Function Wizard is linked to the

Diagram Sheet that is active when the Function Wizard is activated.

Scroll down through the list of available functions and select Table of Reliabilities given a timerange. Type 1000for the Iter. Start Time, 5000for the Iter. End Time, and 1000for the IterationIncr.in the input boxes as shown next.


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Click OKto generate the table in the Spreadsheet. The generated table is shown in the next figure.

Save the Project as Example4.rswand close the Project.


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3.1.5 Example 5

Consider the following telecommunications network:

1

2

3

4

5

6

7

8

A

B C

ED

F

The letters A-E represent the communication centers, where A is the main center. F is a city to which

service is being supplied. The numbers 1-8 represent the communication lines. Communication lines 3and

6can operate in two directions, i.e., from Bto Dand from Dto B. The communication centers cannot fail,while the failure rate ( ) for the communication lines is 1.3E-6 failures/hour. The repair distribution for the

communication lines is Normal with a Mean of 101.35 hours and a Standard Deviation of 62.1 hours.

Do the following:

1. Find the Reliability of the system at 17,520 hours.

2. Find the estimated time at which 25% of the communication systems that are in operation will havefailed.

3. Using the Simulation tool, estimate the total downtime for the system for one year (8766 hours).

4. Add this system to a Template so that the entire system can be added to a national communications

system.


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Solution


Select the Example5.rst Template from the Template Preview window and click OK. The selectedTemplate will open in the new Project. The Project Explorer and a blank Diagram Sheet will also



For this example, the exponential parameter should be defined as "Lambda" instead of "Mean Time."To define the exponential parameter as Lambda, select User Setup from the File menu to open the

User Setup window. Click the Calculationstab to display the Calculations page of the User Setup and

click to de-select the Use Mean Time for the Exponential distributionoption as shown next.


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When the Use Mean Time for the Exponential distribution option is not selected, you will be prompted

to enter a value for Lambda each time you define a Block with the Exponential distribution.

Double-click the Com CenterBlock in the Template to open the Block Propertieswindow. The ComCenters designated by the letters A-Ecannot fail. Therefore, make sure the Block Can Failoption is

not selected and click OK. Now double-click the ComLineBlock. The failure distribution associated

with each communication line is the Exponential distribution. Select Exponential under Failure

Distributionand enter 1.3E-6for the value of Lambda. Then click the Repairtab to open the Repair

page. Click to select the Block Can Be Repaired option. The Repair Distribution options will

become available. Select Normalas the Repair Distribution and enter 101.35for the Meanvalue and

62.1for the Stdvalue, as shown in the next picture.


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Click OKto accept the Block Properties and close the window. Finally, double-click the CityBlock.As is the case for the Com Centers, the City cannot fail. Click to de-select the Can It Failoption and

click OK.

The communication lines are the most important Blocks in this example. The communication centerscannot fail and will be used as nodes within the RBD. They will be used to direct the communication

lines. In addition, because lines 3and 6flow in two directions, multiple representations of lines 3and 6and communication centers B-Emust be included. A relationship line within BlockSim cannot flow in

two directions at the same time. In other words, there can be no circular paths. When constructing the

RBD, be sure to change the name of each ComLineand ComCenterBlock within the Diagram to

represent the proper communication line. You can change the name of the Block by double-clicking it

to open the Block Properties window. In the upper right corner you will see Block Name. Designate

each communication line as Com Line 1, Com Line 2, etc. Designate each communication center as

Com Center A, Com Center B, etc. A representation of the RBD to be constructed is shown next.

Center A

Center B Center C

Center D Center E

Com 1

Com 2

Com 3

Com 4

Com 5

Com 6

Com 7

Com 8

Com 3 Com 6 City

The RBD constructed using BlockSim is shown next.


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Analyze the system by selecting Analyzefrom the Toolsmenu or click the Analyzeicon,


appear, displaying the results of the analysis.

The Quick Calculation Pad (QCP) will be used to calculate the Reliability of the system. To access theQCP, select Quick Calculation Padfrom the Toolsmenu or click the QCPicon,

located in the Analyze toolbar or at the bottom of the Diagram Sheet. Select Std. Probability

Calculationsunder System Calculations if it is not already selected. Type 17520 for the Mission

EndTimeand click Calculateto return the system Reliability as shown next.

The Reliability of the system at 17,520 hours is 0.9984 (99.84%).


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The second question asks at what time will 25% of the communication systems in operation havefailed. The BX Information calculation will be used to calculate the time at which 25% of systems will

be down. Select BXInformationunder SystemCalculations. Type 25for the BX% Information At

input box and click Calculateto return the result as shown next.

The time at which 25% of the communication systems will fail is approximately 24.5817E+4 hours.

Close the QCP by clicking Close.

You will now use BlockSim's Simulation tool to analyze the system for one year of operation. 21 SelectSimulatefrom the Toolsmenu or click the Simulateicon,

located in the Analyzetoolbar or at the bottom of the Diagram sheet. The Reliability/Maintainability

Simulationwindow will open. Click the Maintainabilitytab to open the Maintainabilitypage.

On the Maintainabilitypage, type 8766 in the End Timefield. In the Incrementsfield, type 1000.Make sure the Use Seedoption is selected with a Seed Value of 1 in order to replicate these results.

The window will look like the figure shown next.

21The calculations performed in the QCP are based on the components' Failure information only. The Maintainability

Simulation uses the components' Repair information in order to obtain such results as point availability, mean

availability, etc.


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Click the Setuptab to access the Simulation Setuppage. For Number of Outer Loops, type 1. ForNumber of Inner Loops, type 10000. The Total Number of Simulations will be calculated

automatically. Return to the Maintainability page and click Simulate to begin the simulation. The

results will be displayed in ReliaSoft's Results Panel, as shown next.


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As you can see, the Down Time for the system is 0 hours of the 8766 total hours. These results can be

sent to a Spreadsheet by clicking the Transfer to Spreadsheeticon,

located in the Result Paneltoolbar. After clicking the Transfer to Spreadsheeticon, click OKon the

Result Panel to close it. Click Closeon the Reliability/Maintainability Simulationwindow to closeit. You can see that the Spreadsheet has been added to the Project by viewing the Project Explorer.

BlockSim also allows you to add entire diagrams to Templates. This makes it possible to represent anentire system with one Block. To add the current system to the Example5 Template, first save the

Project as Example5.rsw. Then right-click on the Diagram Sheet and select Add Diagram to

Template from the shortcut menu. BlockSim will automatically save the Diagram and a Subdiagram

Block will appear within the Example5Template, identified by the folder graphic shown next.

Double-click the newly created Subdiagram Block to open the Block Properties window. The Otherpage will be displayed, Block As Diagramwill be selected, and the system will be displayed in the

Graphics Screen on the right. Type TeleCommin the Block Name box as shown in the next figure.

Click OK to close the Block Properties window. As you can see, the Block Name TeleComm has

been inserted below the Block within the Template as shown next.


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Finally, the Block can be represented with a picture. Select the TeleCommBlock and click the BlockGraphicicon,

located in the Templatetoolbar. ReliaSoft's Graph File Managerwill appear. Select a picture from

the list to represent the system within the Block. You can move through the pages of pictures by

clicking Forward>and


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4 Practice Questions

Practice Question 1

Consider the following circuit bridge system:

All components are identical, following an Exponential life distribution with = 8.126E-4 failures/day.

1. Create a Template to create the RBD and customize the Template to your liking.

2. Create the Reliability Block Diagram for this system.

3. Estimate the Reliability at 200 days using the QCP.4. Plot the Reliability vs. Time Plot.5. Insert the Reliability vs. Time Plot into the Project.

6. Rename the Diagram as Bridge.

7. Add the Diagram to the Template.

8. Export the Template as Bridge.rst.

9. Save your file as QUEST1.RSWand leave it open.

C

E

D

B

A


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Practice Questions BlockSim 1.0

68

Practice Question 2

The reliability predictions of the previous problem can also be performed using Simulation. However, the

results are dependent on the number of simulations. This example will take you through such a scenario.

1. QUEST1.RSWshould already be open.

2. Open the Reliability/Maintainability Simulation by clicking on its icon located on the Analyzetoolbar.

3. In the Reliability tab, enter an End Time of 200and a Increment value of 100.

4. On the Setup page, type 1for the Number of Outer Loops and 100for the Number of Inner Loops.What is the reliability of the system at 200 days? How does this value compare with the reliability

obtained in Practice Question 1?

5. Repeat item 4 with 1000, 5000, and 10000Inner Loops. When is the reliability estimate closer to the

analytical value obtained in Practice Question 1?

6. Save and close the Project.


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BlockSim 1.0 Practice Questions

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Practice Question 3

Consider the following Disk Array subsystem:

The failure distributions and parameters for each component are:

Distribution Parameters

Array Controllers Weibull = 1.2,

= 1953 days.

Power Supply Lognormal = 7.0102 (log-mean),

= 1.2124 (log-std).

Fan Exponential = 0.000070265 failures/day.

Hard Drive Weibull

= 2.5, = 3000 days.

The Power supply subsystem is in a 2-out-of-4 configuration. The Fans are in a 2-out-of-3 configuration.

The Hard Drives are also in a 2-out-of-3 configuration.

Do the following:

1. Create a Block for each type of component within a Template and customize the Template to yourliking.

2. Create the RBD.3. Obtain the Reliability vs. Time Plot.

4. From the Plot, determine:

i. The Reliability of these units for a mission of 182 days, R(182days).ii. The mission duration for the system if a 90% Reliability is required.

iii. Add the Plot to the project.

Array

Controllers

Array

Controllers

Power

Supply

Power

Supply

Power

Supply

Fan

Fan

Fan

Hard Drive

Hard Drive

Hard Drive

Power

Supply


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5. Using the Quick Calculation Pad, determine:

i. The Reliability of this system for a mission of 182 days, R(182days).

ii. The Reliability for each subsystem/component.

iii. The mission duration for the system if a 90% Reliability is required.

iv. Knowing that the system has successfully operated for 182 days, what is the probability it willoperate successfully for another 182 days?

v. What is the MTTF for this system?6. Obtain thepdfPlot for this system.7. Obtain the Failure Rate vs. Time Plot for these units. From the plot, what is the Failure Rate of this

system at 182 days?

8. Add a Spreadsheet into the Project. Using the Function Wizard obtain:

i. The Failure Rate at 182 days.

ii. A table of times given Reliability, starting from 0.9 to 0.99 with a 0.01 increment.

9. Add the Diagram to the Template.

10. Export the Template as Disk Array.rst.

11. Break the system into 4 subsystems: an Array Controllers subsystem, a Power Supplies subsystem, aFans subsystem, and a Hard Drives Subsystem (i.e., create 4 new diagrams).

i. Add a new Template to the Project.

ii. Add each of the 4 new Diagrams to the new Template.

iii. Create the RBD for the system using the subdiagrams.

iv. Using the QCP obtain the Reliability of this system for a mission of 730 days, R(730days).

v. A Reliability goal of 85% is required at 730 days (2 years). Is the Reliability goal met? If not,optimize the system if it is known that there is only room for improvement for the two Array

Controllers and the Power Supplies. In addition, it is known that it is hard to improve the

Array controllers and much easier to improve the Power Supplies. The Maximum Achievable

Reliability is 0.999 for both subsystems.

vi. Using the optimum Reliability values obtained for the Array Controllers subsystem and for thePower Supplies subsystem, determine the optimum Reliability values at the component levelfor these two subsystems. (Hint: Use the subdiagrams).

12. Save your file as QUEST3.RSW.13. Close the Project.


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Practice Question 4

The advantage of adding a Diagram into a Template is that it can be used repeatedly in other diagrams.

Consider the following system in which the Disk Array of Practice Question 3 is connected with the Bridge

System of Practice Question 1 as shown next:

1. Create a new Project, and import the previously saved Templates Bridge System.rst, and DiskArray.rst.

2. Create the RBD for the above system.

3. Estimate the Reliability of the system at 200 days.

4. Save the Project as QUEST4.RSWand close it.

Bridge

System

Bridge

System

Disk Array Bridge

System


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Practice Question 5

A four-engine airplane has two engines on each wing. It requires at least one engine to be operating on each

wing for a successful mission. Assume that the Reliability of each engine is 90% for a specified mission

duration.

1. Create the RBD.2. Obtain the Reliability of the system.3. Add a new Diagram and repeat the example, but this time consider a 2-out-of-4 engine configuration.

4. When is the Reliability of the system higher? Why?

5. What should the Reliability of each engine be in the first design in order to achieve the systemReliability of the second design? Since the units are identical you can assume the same feasibility of

increasing the Reliability and maximum achievable reliability for each engine.

6. Save the project as QUEST5.RSWand close it.


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Practice Question 6

A subsystem of a machine is composed of a Ball-Bearing subsystem and a Shaft, as shown below:

The inspection times (in hours) for the Ball-Bearing subsystem are given in the table below.

Number in State Last Inspected State State End Time

5 0 F 600

16 600 F 1900

12 1900 F 2900

18 2900 F 3500

18 3500 F 3900

2 3900 F 4500

6 4500 F 5200

17 5200 F 6300

73 6300 S 6300

The life data for the Shaft are given in the table below.

Number in State State State End Time1 F 1226

1 F 1943

1 F 2362

1 F 2518

1 F 5462

1 F 6404

1 F 10388

5 S 11772

1. Using the 2-parameter Weibull distribution for the ball-bearing data and the Lognormal distribution forthe shaft data, estimate the Reliability of the system at 1,000 hrs.

2. What is the Reliability of each component at 1,000 hrs?

Shaft

Ball-BearingSubsystem


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5 Answers to Practice Questions

The purpose of this section is to provide answers to the Section 4 Practice Questions.

Practice Question 1

2.

3. R(200days) = 0.950628763015724

Practice Question 2

4. Not very accurate.

5. The Reliability estimated using 100,000 Inner Loops is closer to the analytical value.


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Answers to Practice Questions BlockSim 1.0

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Practice Question 3

2.

4. From the Reliability vs. Time plot:

i. R(182days) 0.99

ii. T 530 days

5. Using the QCP:i. R(182days) = 0.995149ii. Array Controller 0.943673

Power Supply 0.931857

Fan 0.987293

Hard Drive 0.999094

iii. T = 527.689625iv. R(182,182) = 0.967608v. MTTF = 1316.101351 days

7. 0.00008 failures/day

8. Using the Function Wizard:

i. = 0.000077 failures/day

ii.

Reliability Time

0.9 527.689625

0.91 505.928557

0.92 483.106413

0.93 458.962751

0.94 433.129516

0.95 405.058397

0.96 373.872274

0.97 338.009927

0.98 294.1977970.99 232.943628


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BlockSim 1.0 Answers to Practice Questions

77

11.

iii.

iv. R(730days) = 0.7906

v. Array Controller: 0.9301 (no change)Power Supplies: 0.9228

vi. Array Controller: No changePower Supplies: 0.7088

Practice Question 4

3. R(200days) = 0.9423


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Answers to Practice Questions BlockSim 1.0

Practice Question 5

1.

Or

2. R = 0.9801

3. For the 2-out-of-4 engine configuration: R = 0.9963

4. The second design, because there is more redundancy in the 2-out-of-4 configuration.

Documents

blocksim training guide.pdf