HBS TriGrid V 1€¦ · When prompted to coarsen mesh, just press the No button. Drawing More Shapes Besides the above drawn rectangle, you may draw polygons and ellipses following

HBS TriGrid V 1.0

www.HBSNumerics.com

HBS TRIGRID V 1.0

www.HBSNumerics.com HBS TriGrid V 1.0

1 The HBS TriGrid | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Table of Contents

The HBS TriGrid .............................................................................................................................................................. 2

Drawing Shapes ................................................................................................................................................................ 2

Creating Triangular Meshes ............................................................................................................................................. 3

Drawing More Shapes ...................................................................................................................................................... 3

Transforming Shapes ........................................................................................................................................................ 3

Combining Shapes ............................................................................................................................................................ 4

Apply Transform and Combine Processes ....................................................................................................................... 5

Making a Gear ................................................................................................................................................................ 10

Including Interior Holes (Shapes) .................................................................................................................................. 19

Editing Shape Points (Nodes) ......................................................................................................................................... 21

Drawing Irregular Shapes ............................................................................................................................................... 21

Tracing Irregular Shapes ................................................................................................................................................ 26

Combining Exterior and Interior Shapes ........................................................................................................................ 27

Geometry Characteristics ............................................................................................................................................... 30

The View Toolbar .......................................................................................................................................................... 33

Examples from the World Wide Web ............................................................................................................................ 34

http://www.hbsnumerics.com/



2 The HBS TriGrid | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

The HBS TriGrid

The HBS (Hassan Bin Sulaiman) TriGrid is a software utility that enables you to divide any closed 2D area

into triangles for later finite element modeling processes. It requires a closed 2D area that runs in a

clockwise or a counter-clockwise direction. Here are some of the permissible shapes for HBS TriGrid: basic

shapes such as polylines, free-hand drawings, rectangles, polygons, ellipses, arcs, beziers, quadratic beziers,

curves, or a mixture of all basic shapes as shown in the following figure. You may create any number of

shapes (regions) which can be directly triangulated or after applying some transformations and/or

processing.

Drawing Shapes

Use the toolbar on the left side of the screen to draw shapes.

For example, to draw a rectangle, click on the rectangle icon on the toolbar. Once selected, click the left

mouse button on the drawing area to locate the first corner of the rectangle and drag the mouse to the

opposite corner and click the left mouse button again. You will be prompted to specify some parameters. As

a beginner, press the Enter key three times to accept the default parameters. You may draw polygons,

ellipses, polylines, arcs, beziers, curves, or free-hand drawings in a similar fashion. Note, however,

whenever you finish drawing a shape, press the Enter key three times to accept the default

parameters.




3 Creating Triangular Meshes | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Creating Triangular Meshes

To create a triangular mesh, click on the View → Generate menu item or the Generate button on the top left

corner of the screen. A triangular mesh with default parameters is created. When prompted to coarsen mesh,

just press the No button.

Drawing More Shapes

Besides the above drawn rectangle, you may draw polygons and ellipses following the exact same procedure

explained above. After drawing each single shape, you must press the Enter key three times to accept the

default parameters. While drawing a shape, if you want to cancel the drawing process, just press the right

mouse button (RMB). You may triangulate all shapes by clicking on the Generate button. See next figure.

Transforming Shapes

Transformations such as move, scale, rotate, and skew may be applied to any shape. To apply

transformation on a shape, click on the Transform button on the right hand side of the screen:




4 Combining Shapes | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

The outline of all shapes will be displayed. Once you click on a shape, it will be selected and eight adorners

will appear on the shape sides and corners. The mouse will change according to its position.

You may drag shapes by placing the mouse cursor on the shape's body. When the cursor changes to ,

start dragging it to the required position. To resize a shape, place the cursor on one of the eight adorners and

move outward or inward as desired. Similarly you may rotate shapes by clicking next to one of the four

corner adorners of the shape's bounding box and rotate either clockwise or counterclockwise. To skew a

shape, place the mouse cursor next to one of the side adorners, the cursor changes to north-south or east-

west directions. You may skew the shape accordingly.

Combining Shapes

You may combine any of the shapes by selecting the Combine button on the right hand side of the screen:

Click on the common area between two geometries, you will be prompted to select the combine method

(Union, Intersect, Exclude, and Xor). As a beginner, select Union. The two shapes will be merged as shown

next. You may triangulate shapes by clicking on the Generate button.




5 Apply Transform and Combine Processes | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Apply Transform and Combine Processes

1. Press the New button to start a new project. You will be prompted to save the old project. Save it if

needed.

2. Show the snap point grid or the snap line grid (whichever comfortable for you) by clicking on the

button on the left side of the screen:

3. Create a rectangle and a hexagon as shown next:

4. Click on the Transform button. Select the rectangle and resize it to make it a bit longer and drag it

inside the hexagon as shown next:





5. Click on the Combine button and click the common area between the two shapes (white area). When

prompted to select the combine mode, select Exclude.

6. Click on the Transform button and move the hexagon to the left end of the screen and move the

rectangle to the right of the screen as shown next:

7. Click on the Combine button again and select the common area between the rectangle and the

transformed hexagon and select Union. You are supposed to get a shape similar to the following

figure:

8. Click on the Show Strokes button:

The drawing changes as follows:





9. We need to remove the extra generated points as shown inside the red circles. First turn off the snap

point grid by clicking it. Next click on the Delete Point button and click every point to be removed.

You are supposed to get a similar shape as shown below.





10. Now generate the mesh by clicking on the Generate button and when prompted to coarsen the mesh,

simply press NO. See the following figure:

11. Let's insert two holes at the beginning and end of the wrench. Draw a small circle by clicking the

Ellipse button. Click on the drawing canvas to start drawing the circle. While holding the Ctrl key,

move the mouse to the required position and release the LMB when finished. Make a copy of the

circle by clicking on the Copy button on the right side of the screen. Click on the circle, select Yes.

Click on the Paste button and click anywhere on the screen and select Yes when prompted.

12. Move the circles to the required positions on the wrench as shown next:





13. Last but not least, we need to exclude the two circles by clicking on the Combine button. Click

inside each circle and select Exclude. When prompted, respond Yes.


simply press NO. See the following figure:

15. You can check the output via the Data menu. Click on the Data menu and select Mesh Nodes. If the

project is not saved yet, you will be prompted to save it. Save it in the right location. The table

appears as shown next. You may copy it and paste it in excel or any windows-based application.




10 Making a Gear | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Making a Gear

We will draw two gears like these ones:





1. Draw two concentric circles and a small square with the help of the snap point grid tool as shown

next.

2. Make eight copies of the small square. Copies will be stacked on each other. Move them one by one

and place them in their right position as shown next. You may need to turn off the Snap Point Grid

tool for smooth movement. Use the Transform – Rotate tool to rotate them and place them correctly.





3. Now you need to combine all squares by selecting the Combine button and clicking inside each

square and select Union.


simply press NO. See the following figure.





5. Make the inner circle smaller as shown next.

6. Generate the mesh by clicking on the Generate button and when prompted to coarsen the mesh,






7. Exclude the small circle by selecting the Combine button and clicking inside the circle and select

Exclude. Press Yes when prompted.

8. Generate the mesh by clicking on the Generate button and when prompted to coarsen the mesh,






9. You may make as many copies of the final region as you want as shown next.

1. Let's do the above example differently. Draw a circle with the help of the snap point grid tool as

shown:

2. Draw an elongate ellipse topped by a rectangle as follows:





3. Combine the elongate ellipse and rectangle via Exclude as follows:

4. Delete the top region using the Delete button on the right side of the screen:





5. Make eight copies of the small region. Copies will be stacked on each other. Move them one by one

and place them in their right position as shown next. You may need to turn off the Snap Point Grid

tool for smooth movement. Use the Transform – Rotate tool to rotate them and place them correctly.





Now you need to exclude all regions by selecting the Combine button and clicking inside each region and

select Exclude.

6. Move the gear to the right. Delete all small regions one by one. You will be left with one region only

as shown:




19 Including Interior Holes (Shapes) | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

7. We need to remove the extra generated points as before and generate the mesh as follows:

Including Interior Holes (Shapes)

You may include holes in your generated mesh as follows. For example, to include a hole in the left

combined shape, simply, select the ellipse icon on the left toolbar, and draw the ellipse anywhere on the

screen, you may drag it later. You may also draw it inside the figure as shown next:

As a starter, click the Generate menu item under View and have a look at the generated mesh. You are

supposed to get a similar figure.




20 Including Interior Holes (Shapes) | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Now to combine the interior shapes, you need to exclude them. Select Combine Geometries again and click

inside each of the shapes to be excluded. When prompted to select the combine method, select Exclude in

all cases. Click the Generate menu item under View and have a look at the generated mesh. You are

supposed to get a similar figure as shown next. In some cases, the mesh does not generate, in such a case,

you might need to enlarge the region size or do some minor transformation to get the generation process

started.




21 Editing Shape Points (Nodes) | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Editing Shape Points (Nodes)

Sometimes, you may need to edit (drag, insert, or delete) points or nodes on the shape. This is simply done

by selecting one of the editing methods under the Point menu item. For example, if the points are pretty

close to each other, you may delete the extra points. Similarly, if points are far apart from each other, you

may insert more points. In some odd cases, the Generate process may fail if nodes are not well placed, hence

you must edit those points.

Drawing Irregular Shapes

You have two icons to help you draw or trace highly irregular 2D shapes. The Line and Stroke icons. Click

the Line icon to start drawing a polyline shape. When finished, press the RMB. Press Enter once to use

default parameters. Now you have two options: 1. Close the polyline shape by pressing Enter twice. 2.

Connect to it any of the shapes on the toolbar by clicking the desired shape and drawing it. For example, we

may select the Stroke icon. The mouse cursor will display the No Draw case. Move the cursor pretty close

to the end of the drawn shape, the mouse cursor will change to cross which is a sign of drawing process. As

you move the mouse, it will draw a free hand drawing. Draw any highly irregular shape. When finished,

press the LMB to finish drawing this Stroke and press the RMB to finish using the Stroke. Click the Enter

key twice to close the shape using the default parameters. Click the Generate menu item under View and

have a look at the generated mesh. You are supposed to get a similar figure as shown next.

Now let's combine other shapes, say a Hexagon and an Ellipse as shown next:




22 Drawing Irregular Shapes | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Do Generate the mesh as shown next:

Now select the Combine Geometries menu item under Geometry and select Union as a starter.





You may need to do some point editing. For example, delete some of the extra points at the intersection of

the two shapes as shown above inside the red circles. Now generate the mesh to get the following figure.

You may include holes as before. Let's draw an irregular shape inside as shown next:





Again we may exclude the internal irregular shape as shown next.

To display the control volumes of the generated mesh, go to View and to Control Volumes. You get a

similar figure.





To display the circle packing of the generated mesh, go to View and to Circle Packing. You get a similar

figure.




26 Tracing Irregular Shapes | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Tracing Irregular Shapes

Let's assume you want to trace a highly irregular shape. You may retrieve an image using the Retrieve

Image icon, shown inside the red circle. The icon below is used to toggle display of the image. The other

one below is used to remove the image. The next figure shows the retrieved image.

You may use the Line or Stroke icons or both to trace the outline of the shape as shown next.

The generated mesh is shown next.




27 Combining Exterior and Interior Shapes | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Combining Exterior and Interior Shapes

We may union a rectangle at his tail and a hexagon at his top and exclude an ellipse inside as shown next.

The next figure shows the generated mesh of the combined shapes. The next five figures depict the

possibility of including interior shapes (hexagon, ellipse, and irregular shape) as holes inside a geometry.












30 Geometry Characteristics | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Geometry Characteristics

Characteristics of a certain geometry may be displayed via the Geometry toolbar located at the top right of

the screen:





For example, to change the fill of a geometry, click on the Fill icon, the Geometry Fill Window appears:

Select the requested color and preview it via Apply or approve it via OK or cancel it via Cancel.





The other properties including length, area, bounds, and coefficient matrix, are displayed by clicking on the

desired button and then click on the geometry whose properties are to be displayed.




33 The View Toolbar | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

The View Toolbar

The View toolbar:

is used to view almost all properties related to the generated mesh; e.g. nodes, numbers, boundary and path,

and control volumes and circle packing of the generated mesh as shown next. View buttons are toggles to

allow display/hide capabilities.




34 Examples from the World Wide Web | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com

Examples from the World Wide Web

Next are some examples that were taken from the World Wide Web and generated in no time.




35 Examples from the World Wide Web | HBS TriGrid V 1.0| © 2017 www.HBSNumerics.com



Documents

HBS TriGrid V 1€¦ · When prompted to coarsen mesh, just press the No button. Drawing More Shapes Besides the above drawn rectangle, you may draw polygons and ellipses following