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Dimensioning and designing a testing rig for impact
loading on beams
Växjö 22-06-2010
15 ECTS
Mechanical Engineering / 2MT00E
Examiner : Samir Khoshaba
Supervisor: Samir Khoshaba
Thesis no: TEK 076/2010
Author: Erkan Candemir
Organisation/ Organization Författare/Author(s) Linnaeus University Erkan Candemir School of Engineering
Dokumenttyp/Type of Document Handledare/tutor Examinator/Examiner Examinator/examiner Examensarbete/Degree Project Samir Khoshaba Samir Khoshaba
Titel och undertitel/Title and subtitle Dimensioning and design of a testing rig for impact loading of beams
Abstract (in English)
This report is product of a degree project accomplishment at Linnaeus University
in Växjö, Sweden. It is about designing a testing rig for impact loading of beams
for laboratory use.
The project started with the idea of affecting the impact loads on the standard
steel construction beams. The aim of this project is to design an impact loading
testing rig which can be used for the purpose of laboratory experiments and
compare the real results from the experiments with the theoretical results from
the calculations.
The specimens to be used were 1 meter long 8 standard profiles given in the
project assignment. The first step in this project was to design and dimension a
testing rig which is suitable for laboratory use. The height and the maximum
mass were chosen according to laboratory use conditions and safety issues. The
second step was designing the fixation for the test sample to the testing rig
without any dislocation by the impact load. The third step was to measure the
falling height of the mass onto the test sample and measure the deflection of the
beam. In this case, the precision of falling height was not very important but
measuring the deflection of the beam with the highest possible precision was
most important. A measurement system is used considering this factor.
In the project, Solid Works and AutoCAD software are often used both in the
drawings and strength and stress analyses.
.
Key Words
Impact, load, testing rig, testing machine, beam, VKR, profile, bearing, laser displacement sensor,
fixation
Utgivningsår/Year of issue Språk/Language Antal sidor/Number of pages 2010 English 76
Internet/WWW
Preface
The thesis was written in Linnaeus University during the spring semester 2010. I would like to thank to following persons:
- Samir Khoshaba (Linnaeus University, Mechanical Engineering Department), for
supervision with his great experience and knowledge.
- Kordian Goetz (Linnaeus University, Mechanical Engineering Department), for helping
lot on the drawing and analysis software.
- Sevda Tsvetanova (Senior Lecturer in English at University of Ruse, Bulgaria), for helping
my report writing in English.
- Rafet Candemir (my uncle) for always supporting me.
Växjö on June 22, 2010
Erkan Candemir
Abstract
This report is product of a degree project accomplishment at Linnaeus University in
Växjö, Sweden. It is about designing a testing rig for impact loading of beams for
laboratory use.
The aim of this project is to design a ready to manufacture product which can be used
for the purpose of laboratory experiments and compare the real results from
experiments with the theoretical results from calculations.
Main designs are falling part and flexible fixations. Solid Works and AutoCAD software
were often used in the drawings.
Summary This report is product of a degree project accomplishment at Linnaeus University in
Växjö, Sweden. It is about designing a testing rig for impact loading of beams for
laboratory use.
The project started with the idea of affecting the impact loads on the standard steel
construction beams. The aim of this project is to design an impact loading testing rig
which can be used for the purpose of laboratory experiments and compare the real
results from the experiments with the theoretical results from the calculations.
The specimens to be used were 1 meter long 8 standard profiles given in the project
assignment. The first step in this project was to design and dimension a testing rig which
is suitable for laboratory use. The height and the maximum mass were chosen according
to laboratory use conditions and safety issues. The second step was designing the
fixation for the test sample to the testing rig without any dislocation by the impact load.
The third step was to measure the falling height of the mass onto the test sample and
measure the deflection of the beam. In this case, the precision of falling height was not
very important but measuring the deflection of the beam with the highest possible
precision was most important. A measurement system is used considering this factor.
In the project, Solid Works and AutoCAD software are often used both in the drawings
and strength and stress analyses.
Table of Contents 1. Introduction .............................................................................................................................................. 1
1.1 The Task .............................................................................................................................................. 1
1.2 The Objectives ..................................................................................................................................... 2
1.3 Limitations and Assumptions .............................................................................................................. 2
2. Impact Loading ......................................................................................................................................... 4
2.1 Impact loading in daily life .................................................................................................................. 4
2.2 Linear and bending impact .................................................................................................................. 6
2.2.1 Equations .................................................................................................................................... 7
2.2.2 Calculations ...................................................................................................................8 2.3 Excel Program.................................................................................................................................... 10
3. Design of the Testing Rig ........................................................................................................................ 12
3.1 Bottom Plate ..................................................................................................................................... 13
3.2 Columns............................................................................................................................................. 14
3.3 Falling Part......................................................................................................................................... 15
3.3.1 Connecting Plate ....................................................................................................................... 16
3.3.2 Impact Head .............................................................................................................................. 17
3.3.3 Side Holder ................................................................................................................................ 18
3.3.3.1 Pins ........................................................................................................................18 3.3.4 Fore Holder ............................................................................................................................... 19
3.3.5 Hinge ......................................................................................................................................... 19
3.3.6 Bearings ..................................................................................................................................... 20
3.3.7 Rope .......................................................................................................................................... 21
3.3.8 Weight Blocks ............................................................................................................................ 22
3.3.9 Rulers and Arrow ...................................................................................................................... 22
3.3.10 Fixations .................................................................................................................................. 24
3.3.10.1 Support Blocks ....................................................................................................24
3.3.10.2 Dimensioning of the Fixation Head ....................................................................25
3.3.10.3 Fixation Cap Plate ................................................................................................26
3.3.11 Cap Plate ................................................................................................................................. 27
3.3.11.1 Holder for Pulley..................................................................................................27
3.3.11.2 Pulley ...................................................................................................................28 3.3.12 Laser Displacement Sensor ..................................................................................................... 29
4. Conclusion ................................................................................................................................30
5. References .................................................................................................................................31
Appendixes Number of Pages
Appendix 1: Calculations 5
Appendix 2: Drawings 21
Appendix 3: FMECA 3
Appendix 4: Data Sheets 10
1
1. Introduction
This project was made for Linnaeus University Mechanical Engineering Department to design and
manufacture a laboratory device for impact loading.
One of the most important things in this project is to apply the theoretical background given in the
Machine Design courses about impact loading in reality. After taking the theory in the classes, it is
desired to see if the theoretical calculations match reality.
The main idea of this project is to design and dimension an impact loading testing rig which is
suitable for laboratory conditions. Since the testing machine will be used by students, it should be as
safe as possible and at the same time should be functional and easy to use.
1.1 The Task
The goal of this thesis is to design and dimension a testing rig for impact loads. The picture below
shows a sample design of the testing rig. Detailed drawings of all components and assemblies can be
found in Appendix Drawings.
Figure 1.1 Sketch of testing machine
Fixations
H Profiles Support
Blocks
Bottom
Plate
Rope
Testing
Beam
Falling Part
Rulers
Cap Plate
Laser displacement
sensor
2
The goal is to find solutions to the problems by providing answers to the following questions:
How shall a testing rig for impact loading be designed?
How can different loads apply to different sizes testing beams in different experiments?
How can the testing beam be fixed in a flexible way?
How can the movement of the plate be provided?
How can the beam deflection be measured?
Best alternatives for the problems above shall be chosen. And the testing machine will be designed
ready to manufacture. Since this is a real project, manufacturing of the testing machine should also
be affordable.
1.2 The Objectives
The objectives of this project are to design and dimension an impact loading testing machine for
laboratory use. The design of the impact loading testing machine shall contain the following sub-
designs:
Designing of the frame
Dimensioning of the frame
Calculating the minimum and maximum load that can be applied to the testing beam
Fixing of the testing beam. The testing beam should be steady, flexible and also this fixation
should not block the free bending of the beam
Measuring the deflection of the beam and falling height of the load precisely
Designing the testing rig to be safe
Making an FMECA analysis of the testing rig
1.3 Limitations and Assumptions
Some parts of this thesis are assumed and selected due to time limitation and the main purpose of
the thesis. The main goal is to design and dimension the impact loading testing rig. For this purpose
the focused fields are design and assembly. But since it is a real project it contains lots of other
factors (welds etc). To stay in the main field these factors are assumed.
3
The weld thickness between H profile column, bottom plate and cap plate is assumed to be
10 mm.
All other weld thicknesses in the design were assumed 5 mm.
All the material which used in the design chosen SS 1311 construction steel. Different
materials (bearings, plastic pulleys etc.) were indicated.
8 different standard testing beams are given. All the design and calculations were made
according to these 8 different beams. These beams can be seen in the figure below.
Figure 1.2 VKR profiles
Choosing the components cost effectiveness was took in consideration.
Lubrication of bearings was not calculated.
The theory of the laser displacement measuring device was not studied. It was selected
from the catalogue and replaced into the system appropriately. Related tables given
further.
4
2. Impact Loading
Impact loading is a type of dynamic loading. It is also called shock, sudden or impulsive loading. In
real life many examples of the impact loading may be seen. Some of them are as follows:
Driving a nail
Breaking up concrete with an air hammer
Automobile collisions
Dropping of cartoons by freight handlers
Razing of buildings with an impact ball
Automobile wheels dropping into potholes
Impact loads may be divided into three categories:
Rapidly moving loads of essential constant, as produced by vehicle crossing a bridge
Suddenly applied loads, such as those in an explosion, or from combustion in an engine
cylinder
Direct impact loads, as produced by a pile driver, drop forge or vehicle crash
Impact loads may be classified in some categories:
Compressive impact (Driving a nail)
Tensile impact (Starting a movement of a car which is pulling another car)
Torsional impact ( Jamming of a shaft for any reason)
Bending impact ( Falling of an object on a beam)
Combination of these listed above
2.1 Impact Loading in Daily Life
In daily life we inevitably deal with many impact loading applications. Sometimes we either notice
them or not. Impact loading applications in everyday life can sometimes be profitable and helpful
(e.g. Driving a nail, pneumatic nailing tool, etc), but usually it is an undesired situation (collision of
cars, dropping a mass from a height onto something, etc.)
5
(a) (b)
Fig 2.1 a) Collision of cars b) Driving a nail
Forklift accidents are an ideal illustration of our case. The operator misjudges the height and jarring
causes the load to fall. In this case FOPS protects the operator.
Figure 2.2 a) Forklift operator misjudges the height b) FOPS c) Simplified illustration of roof of a forklift
loaded by impact load
6
2.2 Linear and Bending Impact
When considering linear and bending impact, the structure
which the impact load is applied to can be assumed as a
spring because all materials have some elasticity.
When impact calculations are made, some assumptions are
made. These assumptions are:
The stiffness of the specimen is same for both static
and dynamic load.
The mass of the material is ignored. Figure 2.3 Sketch of impact loading
The damping of the specimen and friction are neglected. applied on a beam
Figure 2.4 Impact load applied to elastic component a) Original state b) Instant state when impact load
applied c) force-deflection-energy relation
7
2.2.1 Equations
Description Symbol Unit
Spring constant k N/mm
Static deflection mm
Maximum deflection mm
Weight W N
Mass m kg
Equivalent static force N
Height h mm Bending moment M Nmm
Section modulus Z
Table 2.1 Table for description of symbols
Static Deflection (
…………………………………………………………………………..………(Eqn.1)
Impact Factor (I.F.)
I.F. =
……………………………………………………………...……(Eqn. 2)
Maximum deflection caused by impact load ( )
……………………………….….….…(Eqn. 3)
Equivalent static force ( )
…………………………………………..(Eqn. 4)
Impact bending stress (σ)
……………………………………………………………………..….(Eqn. 5)
8
Table 2.2 Shear, Moment and Deflection Equations for simply supported beams (from Appendix D-2)
2.2.2 Calculations
The calculations are made to find out proper dimensions and quantities (applied mass, falling
height etc.) of testing beams for purpose. In this dimensioning process it was important that
deciding the impact load and falling height of the load be applied to the testing beam.
The maximum bending stress is sat to 500 MPa. Since there are 8 different standard sizes of VKR
profiles, 500 MPa stress can be reached with different loads and heights for different profiles.
Figure 2.5 VKR steel tube profile
In designing the testing machine, it was considered that for the weakest profile it shall be able
to generate deflections up to 500 MPa and shall also be able to reach 500 MPa for the strongest
testing beam. That means that the testing machine which will be designed shall be able to
produce impact in a range. But on the other hand the testing machine has some limitations
because of the size. It should not take big space and at the same time it should be handy.
9
The most important limitation is the deflection, equivalent static force and bending moment
produced by the falling part. Since this plate is designed specially and consists of many other
components which are designed to perform its special duty, its weight is calculated 5,5 kg
(including the coupler plate, the impact head, the hinge, 4 side holders, 2 fore holders and 12
bearings. See figure 2.6).
Figure 2.6 Falling part
It is not possible to produce a smaller impact which can be produced by 5,5 kg. The possible
lower limit for the deflection, equivalent static force and bending stress for testing beam is the
one produced by this 5,5 kg weight falling part.
The upper limit of the system could be stress and strength issues of the testing machine
components but it was kept under the impact effect produced by 10 kg falling from 1000 mm
height. In these maximum conditions we get 510 MPa on the strongest sample profile (VKR
50x50x5). Since 510 MPa is quite close to 500 MPa which is given as an upper limit, the load and
height which produce the 515 MPa bending stress can be kept.
It is possible to vary the load from 5,5 kg to 10 kg by adding weight blocks onto the falling part
and vary the height form 0 mm to 1000 mm. It is possible to obtain different values of
deflection, equivalent static force and bending stress depending on the variations of load and
height as mentioned above. The minimum and maximum values of these factors are shown in
the figure below both for the weakest sample profile VKR 30x30x2,5 as well as for the strongest
sample profile VKR 50x50x5.
10
(a) (b) (c)
Figure 2.7 Graphs for varying load and masses a) Deflections b)Equivalent static forces
c) Bending stresses
For the lower limits which are indicated by lower lines in the graphs above, the load is 5,5kg and
the height 0 mm, and for the upper limits which are indicated by upper lines in the graphs, the
load is 10kg and the height 1000mm. The factors vary in the hatched areas of the figure above.
Related calculations are given in Appendix Beam Calculations.
2.3 Excel Program
An excel program was programmed for the purpose of calculating static deflections, deflections due
to impact loads, equivalent static forces and bending stresses of 8 different VKR testing beams.
All the parameters of the materials (elasticity modulus, moment of inertias, section modulus etc)
were sat in the program. A mass to be applied as the load onto the material and falling height of
this mass shall be inserted by the user into the mass and falling height cells.
The program also draws the graphs of deflection due to impact and bending stress of all 8 VKR
profiles according to load and height.
The screen captures of the excel program for the inserted values of 5,5 kg, 0 mm and 10 kg, 1000
mm can be seen below.
11
Figure 2.8 Excel program (mass is 5.5 kg and falling height is 0mm)
Figure 2.9 Excel program (mass is 10 kg and falling height is 1000 mm)
12
3. Design of the Testing Rig
The intention of this thesis is to design an impact loading testing machine. Like all other design
processes, this design has many criteria, assumptions and limitations.
Some of the criteria are; safety reliability, cost-effectiveness, user-friendliness. Some of the
limitations are; total mass which is used to produce the impact load, dimensions of whole machine,
costs etc.
Assumptions are usually made about the load area on the testing beam both for contact area of
impact load and contact area of fixations. Since impact head and fixations have half cylindrical shape
the contact will occur in a line. These contact areas were assumed as rectangles with 2 mm thickness
and the same length as testing beam. A red hatched area of this rectangle can be seen in the figure
below
Figure 3.1 Contact areas on the testing beam
Many components were designed for the testing rig. These components are; falling part, columns,
fixation and cap plate with them sub-designs. These components are described henceforward.
The exact dimensions and detailed drawings were not given in this chapter. All the related drawings
and tables can be found in Appendix Drawings and Appendix Data Sheets
13
Figure 3.2 Picture of complete machine
14
3.1 Bottom Plate
The bottom plate is 10 mm thickness sheet steel. It is the component which holds whole rig
together. Its material is also suitable to be welded, so it keeps other components by welding.
Figure 3.3 Bottom plate
3.2 Columns
Columns are the body structures of the machine. They give the rigidity to the design. Since the
movable falling plate needs to move vertically and in a very balanced way, H profile columns
were selected. It keeps the falling part in the inner place at the same time the falling parts falls
with minimum friction loses.
Figure 3.4 Cross section of H profile
15
Some advantages of H profile columns are;
H Profile has grooved shape inside. Anything moving inside it can contact its fore surface
and side surfaces. Since an H profile limits the movement inside it with its 3 surfaces, it
results in a very stable movement. That is what is desired for the movable falling plate.
While it is moving only along a vertical axis, it should not flip, rotate or unbalance in any
direction. That is why the H profile was chosen as the most appropriate column for
constructing the main body of the machine.
H profile is stable on both sides. Since it has a symmetric structure, one of its sides can
be used as defined above, and its other side enables an upright position.
Since it is construction steel, it is very suitable for welding processes (especially welding
to the bottom plate).
The profile which was chosen is HE 300 A from the VKR catalogue. 1750 mm length was chosen
for the profiles which is appropriate for the rest of the design.
3.3 Falling Part
The falling part is one of the most important designs in this project since it produces the impact
load. It has to fall down from a selected height and give impact to the testing beam.
It consists of many different components. These components are as follows:
Name of Component Piece
Impact head 1
Coupler plate 1
Side holder 4
Fore holder 2
Bearings 12
Holder for pulley 1
Pulley 1
Hinge 1
Table 3.1 Components and pieces
16
Figure 3.5 Falling part
During the fall the plate has to sustain its parallel position to the testing beam surface but it can
flip, rotate or disposition in any direction and axis. If there wil be a friction, falling part will not
give true fall at the same time it will hit to wrong place on the beam.
(a) (b) (c)
Figure 3.5 a) Impact is to be applied in the middle of the testing beam b) Impact head hits the testing
beam in true position c) Impact head hits the testing beam in wrong position
17
The falling part has to fall exactly parallel to the testing beam and has to contact the beam in a
line (Figure 3.5.b) not at a point (Figure 3.5.c) so that it can provide an equal impact on the
contact line. For this purpose side and fore holders for bearings are designed and welded to
each edge of the falling part. Each one of the holders contains two bearings in a vertical position
so that it blocks any movement except linear movements in a vertical direction.
The mass of the falling part is m= 5576,83 grams ≈ 5,5kilograms. It has a rope connection on the
gravity center of the coupler plate by help of the hinge, so that it can be pulled up manually
using a rope.
The different parts which consist the falling part are described henceforward.
3.3.1 Connecting Plate
It is the plate which holds all the components together by welds. Since it comes as sheet steel it
is easy to be treated as needed.
Figure 3.6 Connecting plate
18
3.3.2 Impact Head
It is the component which hits the testing beam and produces the impact load. It is welded
symmetrically to the connecting plate on the bottom. It has a dimension of 50 mm. This
diameter was selected so that it contacts the testing beam and produces impact load.
Figure 3.7 Impact head
3.3.3 Side Holder
Side holder is the component which will be welded to the edges of both sides of the connecting
plate. It runs along the inner sides of the H profile and it holds two bearings which enable the
vertical movement of the falling part with minimum friction.
Side holder consists of 2 pins as the shafts for bearings. Pins are selected from standard pin
table they have narrowing edges. Pins will be placed into these holes by pressing and they keep
their position because of tolerances.
19
Figure 3.8 Side holder
3.3.3.1 Pins
Pins are selected according to Swedish standard table SMS.
Figure 3.9 Pin according to SMS
Parameter Value Unit Origin Comments
d 12 mm SMS Chosen according to bearing
inner diameter
L 40 mm SMS -
h 2,5 mm SMS -
Table 3.2 Data for selected pin
20
3.3.4 Fore Holder
Fore holder is pretty the same as a side holder. It has the same design but different dimensions.
The difference in dimensions comes from the shape of the H profile. Since side and fore holders
should run in the groove of an H profile, the length of the fore holder is decreased compared to
that of a side holder. Thus they both fit into the groove of the H shaped profile column.
3.3.5 Hinge
The hinge is to connect the falling plate to a lifting rope. Falling plate will be lifted with the help
of a rope. The hinge is welded exactly to the gravity center of the coupler plate of the falling
part. It should be at the centre point because the falling plate should fall down with as little
friction as possible. Otherwise some bearings will be subjected to bigger load.
Figure 3.10 Hinge
3.3.6 Bearings
Bearings are to balance the falling plate and prevent any movement except from exact vertical
movement.
When bearings were chosen, they were considered to be as light as possible. Since we use 12
bearings they give extra weight to the falling plate and this limits the load varying range. A direct
load does not act on the bearings in this case so any force was not calculated.
From the SKF catalogue, 6201-2Z/VA201 single row deep groove ball bearing was selected. The
information belongs to this bearing can be seen in the table below.
21
Figure 3.11 Bearing
Parameter Value Unit Origin Comments
d 12 mm SKF Catalogue -
D 32 mm SKF Catalogue Chosen according to the
shape of H profile
B 10 mm SKF Catalogue -
m 0,036 kg SKF Catalogue Quite light with respect
to falling plate
Table 3.3 Data table for bearing
3.3.7 Rope
The rope is to lift the falling plate up. It will be lashed to the hinge and pulled down from the
ground manually.
A plastic rope “kz-1“ with 6 mm diameter and 20 m length was selected from Taian Huifeng
Plastics Corporation catalogue. 3-4 m length rope is enough to lift up the falling plate so over
length rope can be cut.
22
Figure 3.12 Rope
Table 3.4 Data table for rope
3.3.8 Weight Blocks
Weight blocks were designed to add or remove load from the falling part. A groove was created
in the middle of all weight blocks so that they can swipe into the hinge and rope. To prevent any
possible bouncing right after the impact they were designed flat so that without any special
fixation mechanism, the weight blocks remain immobile.
23
All the weight blocks have made from SS 1311 and have a mass of 0,5 kg. 9 weight blocks can be
added onto the falling part. Falling part has 5,5 kg mass itself and 9 weight blocks have
9x0,5=4,5 kg mass. As maximum impact load 5,5+4,5=10 kg can be reached.
All individual weight blocks have 10 mm thickness. They reach 10x9=90 mm total thickness
when all the weight blocks has put onto each other. Considering this the length of the hinge was
decided 100 mm so an interruption does not occur between weight blocks and the link of the
hinge.
Figure 3.13 Weight blocks
3.3.9 Rulers and Arrow
Rulers which are 1 meter long were replaced onto the front face of one of the H profile columns.
They are to measure the falling height of the falling part.
Since 3 different outer sizes testing beams are given, 3 rulers starting from different levels
according to those testing beams were replaced. As can be seen from the figure below every
profile has its own ruler sat on the column, starting from the impact surface of the profile.
24
Figure 3.13 Rulers
Figure 3.14 Rulers from the top and arrow
As can be seen from the figure above, the red arrow was replaced to indicate the falling height.
It is on the same plane with the contact point of the impact head. So it can make accurate height
measurements.
Fixation
Head
VKR 30
Profile
Reference Line
Ruler for VKR
30 Profile
25
3.3.10 Fixations
One of the important designs in the project is fixations. Fixations were welded to the top surface
of the support blocks in a vertical position. They had to be designed according to some criteria.
These criteria are as follows:
The dimensions of the fixation head
The flexibility of the fixation
Figure 3.15 Fixation for testing beam
3.3.10.1 Support Blocks
Support blocks are designed to support the testing beam during the application of impact. They
shall be rigid to withstand the impact and high enough with respect to the maximum possible
deflection of the testing beams. It should be higher than 24,47 mm (the deflection of VKR
30x30x2,5 under 10,2 kg load falling from 1000 mm height).
Since the support blocks are to be welded to the bottom plate at the bottom sides and the
fixations are to be welded to the top plate, SS 1311 construction steel is appropriate both for
welding and rigidity.
They have two M16 holes on the top surface to keep the cap plate fixed during the application
of impact by the help of the two screws.
26
Figure 3.16 Support block
3.3.10.2 Dimensioning of the Fixation Head
The fixation head is the component where the testing beam stands on it. It will be welded onto
the top surface of the support blocks. Then the testing beam shall be replaced on it.
The contact between the testing beam and fixation heads shall be a line. For this purpose the
fixation head chosen half cylindrical shaped. Hereby it contacts the testing beam in a line and
also stands stable on the flat top surface of the support blocks.
The diameter of the cylinder was chosen 100 mm. Since it is a half cylindrical structure its height
is 50mm.
The width of the fixation head should be bigger than the width of the widest testing beam. That
means it should be wider than 50 mm. Hence 100 mm was chosen.
Figure 3.17 Fixation head
27
3.3.10.3 Fixation Cap Plate
To provide flexibility, a cap is designed for the fixation. While the cap prevents the testing beam
from bouncing off the fixation, it also prevents other types of dislocations of the testing beam
such as slipping in different directions. The cap can be tightened and loosened manually by wing
screws to the support block. Thus the testing beam can be fixed both in a reliable but also
flexible way.
Designing the fixation cap plate, same method was used as the holders for bearings. A 30 mm
diameter and 120 mm long pin chosen from the Swedish Standard Catalogue SMS connects two
L shaped steel plate.
Figure 3.18 Fixation cap plate
The fixation cap plate is fixed to the support blocks by two M16 screws. These screws give
flexibility to the fixation cap plate for different sized testing beams by tightening and loosening.
Figure 3.19 Flexible fixations for different sizes of testing beams
28
3.3.11 Cap Plate
The cap plate covers the H profiles overhead. It was dimensioned according to the width of the
H profiles and the distance between them. The thickness of the cap is 10 mm and it has a square
hole in the middle so that the rope for manual pulling goes through that hole.
It has a pulley upon that hole which changes the direction of the rope and enables the falling
part to be lifted up manually by the user standing on the ground.
(a) (b)
Figure 3.20 Cap Plate a) View from front b) View from back
3.3.11.1 Holder for Pulley
Holder for pulley is a rigid block to keep the pulley in position. Since the pulley is the component
which carries the most weight in the whole machine, rigid blocks were used to hold it. 45 mm
long and 8 mm thick pin was used to connect two blocks.
(a) (b)
Figure 3.21 Holders for pulley a) Without one of the blocks b) With two blocks and pin
29
3.3.11.2 Pulley
The pulley is used to change the direction of the robe. When the rope is released, it rubs with
the pulley and creates friction. This friction shall be as small as possible to make able to almost
free falling of the falling part. For this purpose plastic pulley was selected. Since the rope is also
made from plastic, the friction between plastic rope and plastic pulley is quite small.
The pulley is suitable for the ropes up to 14 mm diameter.
Figure 3.22 Pulley
The properties of this pulley can be seen in the table below:
Parameter Description Value Unit Origin
d Inner diameter 8 mm outdoorexperten.se
D Outer diameter 45 mm outdoorexperten.se
B thickness 17 mm outdoorexperten.se
Table 3.4 Data table for pulley
30
3.3.12 Laser Displacement Sensor
Laser displacement sensor was chosen to measure the deflection on the middle point of the
testing beam.
In the elastic area the deflection because of the impact load and it takes its original position
again occurs in a very short time interval. To observe and record this small displacement of a
point a fast laser displacement sensor “optoNCDT 1607” from Micro Epsilon Company catalogue
was chosen. The catalogue for this sensor can be found in the Appendix Data Sheets.
The point which the deflection will be measured shall be pointed by the sensor. After that the
sensor records and display on a display screen any displacement on the point. For our case this
reference point is the bottom middle of the testing beam. So the laser displacement sensor was
replaced into the design for this purpose. A rough picture of the situation can be seen below.
Figure 3.23 Laser displacement sensor
31
4. Conclusion
The idea of impact loading testing machine came with necessity of applying theoretical
information and calculation into reality. Most important point is finding the correct solution in
theory and matching it to the reality. For this purpose an impact load testing machine was
designed.
In the beginning 8 different VKR hole profile given. The testing rig was designed appropriate to
work with those 8 different size standard profiles. Since the necessity of changing the testing
beams in different experiments, a flexible fixation was designed. Flexible fixation was designed
with adjustable fixation cap so that it can be adjusted according to different testing beams.
One of the most important design was the falling part. A pure impact is desired to apply on the
testing beam. Hence the falling part was designed as less as frictionless so it is able to fall quite
to free falling movement. To provide the balance of the falling part, a design with bearings and
other sub-designs was made. For this purpose side and fore holders which are working together
bearings were designed.
The other important subject was to make the changing height and load applied onto the testing
beam possible. For this purpose weight blocks were used on the falling plate. 9 weight blocks
which every one of them has 0.5 kg mass. They were designed quite flat so any fixation is
unnecessary. The load can vary just putting the weight blocks onto the falling part.
Since some deflections will be very small (0.5 mm) an appropriate laser measurement device
was selected. By the help of laser displacement sensor minimum 0.5 mm deflection can be
measured.
Now at the end of the thesis I am happy because I designed my first real machine.
32
5. References
1. Juvinall, R.C. and Marshek, K.M. (2006) Fundamentals of Machine Component Design. John Wiley & Sons, Asia
2. Khoshaba S. (2010), Lecture notes in Machine Design M2 Course, Linnaeus University
3. Khoshaba S. (2010), Handbook fot Machine Design, Linnaeus University
4. SKF (2003), General Catalogue, School Edition
5. Larsson T. (2009) Fatigue assessment of riveted bridges, Lulea
6. Wright C. ( ) , Introduction to Impact Loading
7. Taavola K. (1998), Ritteknik Faktxbok, Athena lär
8. SMS 2374
9. Malmendahl S. and Nordergd K. (1997), Tabellsamling, ACTEC läromedel
[1] (Internet) Available from http://www.roymech.co.uk/Useful_Tables/Fatigue/Mechanics_Impact.html (03/05/2010) [2] (Internet) Available from http://www.profilex.com/english/steel_profiles.php (05/05/2010) [3] (Internet) Available from http://www.skf.com/skf/productcatalogue/jsp/viewers/productTableViewer.jsp?presentationType=3&lang=en&tableName=1_3_2 (05/05/2010) [4] (Internet) Available from http://www.zyxtek.se/steel_eng.htm (10/05/2010)
33
[5] (Internet) Available from
http://www.outdoorexperten.se/p-8684-blockskiva-fr-tgvirke-nylon-45-mm.aspx (15/05/2010) [6] (Internet) Available from http://www.micro-epsilon.com/download/products/cat--optoNCDT--en.pdf (17/05/2010) [7] (Internet) Available from http://www.engineering.com/Ask/tabid/3449/qactid/-1/qaqid/4133/Default.aspx (08/06/2010)
[8] (Internet) Available from http://www.micro-epsilon.com/download/products/cat--optoNCDT--en.pdf (08/09/2010)
[9] (Internet) Available from http://www.keyence.com/products/measure/laser/laser.php (09/09/2010)
[10] (Internet) Available from
Appendix 1, Page | 1 (5)
Calculations
The calculations are made for extreme conditions both for the weakest testing beam VKR 30x30x2,5
and the strongest testing beam VKR 50x50x5 for minimum and maximum. Other values between
these can vary from minimum to maximum as seen in the Figure 2.7. Formulas come from the
“Handbook for Machine Design”
Description Symbol Unit
Mass m kg
Height h mm
Load P N
Length L mm
Modulus of elasticity E MPa
Moment of inertia I Static deflection mm
Impact factor I.F. -
Deflection due to impact mm
Equivalent static force N
Impact bending stress σ MPa
Section modulus Z Table A-1 Table for descriptions of symbols
Table A-2 Material properties for VKR profiles
Appendix 1, Page | 2 (5)
For VKR 30x30x2,5 (m=5,5 kg, h=0 mm)
Static Deflection
Impact Factor I.F.
I.F.=
I.F. =
I.F. = 2
Maximum deflection caused by impact load
Equivalent static force
Impact bending stress σ
Appendix 1, Page | 3 (5)
For VKR 30x30x2,5 (m=10 kg, h=1000 mm)
Static Deflection
Impact Factor I.F.
I.F.=
I.F. =
I.F. = 84,55
Maximum deflection caused by impact load
Equivalent static force
Impact bending stress σ
Appendix 1, Page | 4 (5)
For VKR 50x50x5 (m=5,5 kg, h=0 mm)
Static Deflection
Impact Factor I.F.
I.F.=
I.F. =
I.F. = 2
Maximum deflection caused by impact load
Equivalent static force
Impact bending stress σ
Appendix 1, Page | 5 (5)
For VKR 50x50x5 (m=10 kg, h=1000 mm)
Static Deflection
Impact Factor I.F.
I.F.=
I.F. =
I.F. = 247,558
Maximum deflection caused by impact load
Equivalent static force
Impact bending stress σ
Appendix 2, Page | 1 (22)
Drawings
Appendix 2, Page | 2 (22)
Appendix 2, Page | 3 (22)
Appendix 2, Page | 4 (22)
Appendix 2, Page | 5 (22)
Appendix 2, Page | 6 (22)
Appendix 2, Page | 7 (22)
Appendix 2, Page | 8 (22)
Appendix 2, Page | 9 (22)
Appendix 2, Page | 10 (22)
Appendix 2, Page | 11 (22)
Appendix 2, Page | 12 (22)
Appendix 2, Page | 13 (22)
Appendix 2, Page | 14 (22)
Appendix 2, Page | 15 (22)
Appendix 2, Page | 16 (22)
Appendix 2, Page | 17 (22)
Appendix 2, Page | 18 (22)
Appendix 2, Page | 19 (22)
Appendix 2, Page | 20 (22)
Appendix 2, Page | 21 (22)
Appendix 3, Page | 1 (3)
FMECA Analyse
Customer
Issued by
Detail name
Detail nr. Design-FMECA
Project
Leader Date
Follow-up date Remarks Process-FMECA
Part nr
Component
Function
Possible failure
Failure effect
Failure reason
Probability of occurrence of failure
Severity of failure
Likelihood of detecting the failure
Risk Priority Number RPN
1
Bottom plate
Keep whole design together
Break, crack
All the design can displace
Bad welding
4
7
3
84
Material 2 7 8 112
Appendix 3, Page | 2 (3)
2
H Profile Columns
Body structure of the design
Non precisely replacement onto the bottom plate
Columns don’t stand perpendicular to the bottom plate
Welding mistakes
2
4
5
40
3
Falling plate
Moves vertically into the H profile groove
Non-precisely replacement of its components
Falling plate sticks and does not move
Measurement mistakes during jointing the components
3
8
5
120
Falling plate moves hard due to displacement of the components
Measurement mistakes during jointing the components
4 6 4 96
Problems on bearings (lubrication, manufacturing etc)
1 5 6 30
Appendix 3, Page | 3 (3)
4
Fixations
Keep the testing profile fixed and flexible
Displacement of the testing beam
The testing beam does not stay in position and impact can’t applied correctly
Over tightening the screws
7
2
6
84
Insufficient tightening the screws
5
3
3
45
5
Cap plate
Keeps the pulley on it changes the direction of the rope by help of the pulley
Pulley sticks and does not rotate accurate
Lifting and falling down of the plate gets harder
Material faults
2
6
3
36
The pin does not carry the load
Falling part collapses
Material fault or wrong material and diameter selection
1 10 6 60
6 Weight blocks
Creates load for impact
Spreading around because of the impact effect
Damages the objects standing around and the other components of the design
Absence of a fixation for weight blocks
3 9 1 27
Appendix 4, Page | 1 (10)
Data sheet 1 VKR hole profiles
Appendix 4, Page | 2 (10)
Data sheet 2.a Pins
Appendix 4, Page | 3 (10)
Data sheet 2.b Pins
Appendix 4, Page | 4 (10)
Data sheet 3 H Profiles
Appendix 4, Page | 5 (10)
Data sheet 4 Construction steels
Appendix 4, Page | 6 (10)
Data sheet 5 Physical properties of some metals
Appendix 4, Page | 7 (10)
Data sheet 6 Tensile properties of some metals
Appendix 4, Page | 8 (10)
Data sheet 7 Shear, moment and deflection equations for simply supported beams
Appendix 4, Page | 9 (10)
Data sheet 8.a Laser displacement sensor
Appendix 4, Page | 10 (10)
Data sheet 8.b Laser displacement sensor
Appendix 4, Page | 11 (10)
