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M39MAE ADAMS Coursework

What needs to be Considered

By Dr. Gary Wood

Content

• Coursework load case and data • Some things to consider

• Example: Buckling • Some ADAMS points

Load Cases to Consider

• Understanding how load cases can be developed is important as well as defining the typical loads expected for certain scenarios

• These loadings do not necessarily cause a failure

• Nor do they mean that if passed there will be no failure (as this would indicate that the element has been over designed)

Images from (Blundell & Harty (2004))

Load Cases to Consider (continued)

• For an automotive application load cases for “sign off” procedures will have been determined

• These can be used to design the system components to ensure that they can sustain the loads

• Each company will have a different set of data like the one shown in the table

• These will be based on previous experiences with their vehicle Images from

(Blundell & Harty (2004))

Load Cases to Consider (continued)

• The acceleration figures are used to give imaginary inertial force • These values do not account for the effects of gravity • The vehicles properties need to be considered (such as mass, CoG

height, wheel base, unspring mass etc.) • These values can be applied to the wheel centre (be careful about

where the data may be resolved to)

Images from (Blundell & Harty (2004))

Please Note: The loads shown in the previous two slides are

examples, do not use for the coursework.

How the Loads Are Applied • The loads can be applied

to the wheel centre to replicate the loading condition for the particular event

• Once the simulation is run then the resultant forces can be examined at the various joints

• This is a static analysis Vertical Force (Fz)

Lateral Force (Fy) Longitudinal Force (Fx)

How the Loads Are Applied (continued)

• The simulation is run over a short period to ensure no transient are created

• The loads can be applied such that they ramp on over the designated time period

• The end results is the system in equilibrium so that the loads can be examined Vertical Force (Fz)

Lateral Force (Fy) Longitudinal Force (Fx)

Some Example Simulation Results

The results show different loads and moments

Suspension Data

• Below is the suspension geometry that will be used for the coursework

• Note there is data for the bump stops

Front Suspension Main Parts (passenger side)

The suspension spring stiffness is 132 N/mm

Vehicle Mass (m) 1300 kg CG Height (CG) 480 mm

Weight Distribution (WD) 53% Front Wheelbase (W) 2550 mm

Track (t) 1700 mm SLR (SLR) 300 mm

Unsprung (m_u) 45 kg Acceleration due to gravity (g) 9.81 m/s2

Vehicle Data for the CW

• The overall vehicle parameters are shown in the table below

• These are used to determine the static values used for the analysis

• After this the loads are applied to the suspension for the various scenarios

Load Case Fx (N) Fy (N) Fz (N) Mx (Nmm) My (Nmm) Mz (Nmm) 1g_Static Front Right 0 0 2912 0 0 0

Front Left 0 0 2912 0 0 0 Rear Right 0 0 2582 0 0 0 Rear Left 0 0 2582 0 0 0

7g_Bump Front Right 15529 0 23293 0 0 0 Front Left 0 0 2912 0 0 0

Rear Right 13771 0 20656 0 0 0 Rear Left 0 0 2582 0 0 0

1.10g_Brake Front Right 4454 0 4049 0 -1336205 0 Front Left 4454 0 4049 0 -1336205 0 Rear Right 1589 0 1444 0 -476683 0 Rear Left 1589 0 1444 0 -476683 0

Brake_and_Bump Front Right 16287 0 24430 0 -1336205 0 Front Left 4454 0 4049 0 -1336205 0

Rear Right 13012 0 19518 0 -476683 0 Rear Left 1589 0 1444 0 -476683 0

1.30g_Cornering Front Right 0 -6564 5049 -1969138 0 0 Front Left 0 -1006 774 -301917 0 0 Rear Right 0 -4925 4477 -1477568 0 0 Rear Left 0 -755 687 -226547 0 0

Cornering_and_Bump Front Right 16954 -6564 25430 -1969138 0 0 Front Left 0 -1006 774 -301917 0 0

Rear Right 15034 -4925 22551 -1477568 0 0 Rear Left 0 -755 687 -226547 0 0

Load Case Scenarios

Load Case Scenarios (continued) Load Case Fx (N) Fy (N) Fz (N) Mx (Nmm) My (Nmm) Mz (Nmm) 3g_Berm Front Right 0 -22711 7570 -3406581 0 0

Front Left 0 0 0 0 0 0 Rear Right 0 -20140 6713 -3020931 0 0 Rear Left 0 0 0 0 0 0

1.20g_Acceleration Front Right -2005 0 1671 0 0 0 Front Left -2005 0 1671 0 0 0

Rear Right -4587 0 3823 0 0 0 Rear Left -4587 0 3823 0 0 0

Acceleration_and_Bump Front Right 12696 0 22052 0 0 0 Front Left -2005 0 1671 0 0 0 Rear Right 10010 0 21897 0 0 0 Rear Left -2005 0 3823 0 0 0

1.00g_Reverse_Brake Front Right -1878 0 1878 0 563256 0 Front Left -1878 0 1878 0 563256 0

Rear Right -3616 0 3616 0 1084824 0 Rear Left -3616 0 3616 0 1084824 0

Reverse_Brake_and_Bump Front Right -16717 0 22259 0 563256 0 Front Left -1878 0 1878 0 563256 0 Rear Right -18076 0 21690 0 1084824 0 Rear Left -3616 0 3616 0 1084824 0

4g_Ditch_Hook Front Right 0 27036 774 8110908 0 0 Front Left 0 6564 5049 1969138 0 0

Rear Right 0 23976 687 7192692 0 0 Rear Left 0 4925 4477 1477568 0 0

Please note that only the front right wheel needs to be modelled in terms of loads, the rest are given for information

CW Analysis

• All of the scenarios in the previous slides need to be evaluated

• These will allow for the general loading condition that the tie rod will be subjected to

• The design of the tie rod needs to be such that it can support these loads

• Above these values however a failure needs to be introduced such that it protects the other components of the suspension

• The solution needs to be in a form such as a “mechanical fuse”, this is down to the groups to consider and design

Aim of the Coursework

• The main idea of the second coursework is to develop a design that can be proven to fail in a specific way

• Remember the aim of the design is to be a sacrificial element to protect more vital components (such as the wheel knuckle and steering rack)

• There are a number of areas that need to be considered to accomplish this

Aim of the Coursework (continued)

• There have been some ideas highlighted that can and should be considered but there are a wide variety of alternatives that can be used

• The design needs to consider what might happen during its use and how these can be mitigated through the design

• Further consideration needs to be given for the application such as cost and weight

Buckling – One Area to Consider

“Buckling can be defined as the sudden large

deformation of structure due to a slight increase of an existing load under which the structure

had exhibited little, if any, deformation before the load was increased”

From Assakkaf (2013)

Buckling

• Some notes and examples on Buckling have been added onto Moodle

• These can be used to form a base for the investigation

• The loads that the tie rod will experience can be determined from ADAMS

Buckling – (continued)

• A simple example would be a hinge-hinge joint, free to rotate at each end

• The critical buckling load can be given by:

Images from (Clifford et al 2010)

2

2

CR L I Eπ

P =

Buckling – (continued)

• The areas to consider here are E (Young's modulus) and I (second moment of area)

• This means material and shape considerations

Images from (Clifford et al 2010)

2

2

CR L I Eπ

P =

Buckling – (continued)

• The areas to consider here are E (Young's modulus) and I (second moment of area)

• This means material and shape considerations

Images from (Clifford et al 2010)

Buckling – (continued)

• Potential for other more interesting designs could be an eccentrically loaded strut

• More complicated but closer to the actual design needed……. you decide

Images from (Clifford et al 2010)

Images from (Pascarella & Vogler 2008)

Consider the Design

• You should consider what has been designed before • Learn from the ideas and think about why they have

been designed in that manner • Build up your own hypothesis and use these to build

your design • Remember to consider the

application and the impact that this can have on the design considerations

Aston Martin Control Arm

• Here it can be clearly seen that there is a distinct “kink” in the control arm

• What do you think this is?

• Could a similar principle help your design?

Images from (Pascarella & Vogler 2008)

Control of the Failure • The failure mode is very important • You do not want a brittle failure • This will cause the vehicle to have an

uncontrollable response to the failure

Images from (IH8MUD 2013)

Control of the Failure • The failure mode is very important • A ductal failure yields a more controlled failure

that allows the car to still respond

Images from (IH8MUD 2013)

Control of the Failure • The failure mode is very important • Be careful of the failure type and consider the

yield characterises of the material that are being considered for the design

Final Design

• The final design is in your groups hands • Make sure to justify and evaluate all avenues

for the design • Use any tool at your disposal to help with this

study • Think about all the lectures and apply the

knowledge learnt to this design application

References Assakkaf, Ibrahim (2013) Columns: Buckling (Different Ends) [online], available from

http://www.assakkaf.com/courses/enes220/lectures/lecture27.pdf [21st April 2013]

Clifford, Michael et al (2010) An Introduction to Mechanical Engineering Part 2. Hodder Education.

Formula Student Germany (2013) Formula Student Germany [online], available from http://www.formulastudent.de/fsg/pr/news/details/article/pats-seven-deadly- sins-of-fs-design/ [21st April 2013]

IH8MUD (2013) Online Forum [online], available from http://forum.ih8mud.com/80- series-tech/168221-drag-link-bent-locked-steering.html [21st April 2013]

Pascarella, Robert & Vogler, Michelle (2008) Analysis of Tie Rod Separations in Motor Vehicle Crashes. SAE Technical Paper. 2008-01-0177.

M39MAE ADAMS

We will continue to look at this in the tutorials, these are just some guiding

note to help navigate around the model

Importing the Model

• The model required for the coursework along with the loads that need to be applied can be found on Moodle

• This file should be used for the simulations • A further file which maps the displacement of

the tie rod can also be found

Running the Simulation

• To run the simulation you must put the following simulation detailed in

• The solver needs to be changed from “default” to “static”

• End Time = 1.0 • Steps = 200 • Once you are ready to run you need

to press the static equilibrium button and then the play button

Changing the Wheel Loads • To change the wheel loads for each

load case you need to go to the menu and open the design variable modify option

• This can be found in the menu through “Build/Design_Varaible_Modify

• You will then be presented with a Database Navigation Window

• Only modify the variables that are highlighted on the next page

Changing the Wheel Loads (continued)

• The following variable can be changed in accordance with the wheel loads given:

f_lateral_force f_longitudinal_force

f_vertical_force m_lateral_moment

m_longitudinal_moment m_vertical_moment

Changing the Wheel Loads (continued) • Once one of the variables have

been selected press “OK” • You will be present with

another dialog box • Only change the “Standard

Value” to what is required for the load case

• Then press “OK” • You can then run the simulation

as described before to see the effects of the loads on the tie rod

Changing the Wheel Loads (continued) • To change variable quickly you can right click in the

“Name” box and this will bring up browse which will then bring up the database navigation page again

• Select the appropriate force / moment you want to modify and press OK

Reviewing the Results

• Once the simulation has been run you should see red lines or curves that represent the force or moment that you have applied

• Check the right load has been applied

Reviewing the Results

• To view the detailed results entre the postprocessor

Reviewing the Results

• To view the displacements results use the “Request” elements to see the x, y and z displacements for each end of the tie rod

Reviewing the Results

• To view the forces in the joints change “Source” to “Result Sets” and look at the joints called j_toe_link_inner and j_toe_link_outer

Reviewing the Results • Then the forces and moments can be selected to

see there response to the wheel loads • These results are given in the ground reference

system

coursework attached.docx

Assignment – Durability and Reliability of a car tie rod

The assignment involves evaluating a particular scenario (a car tie rod) to design a component that can withstand particular load conditions expected of the vehicle and to create a design that will sustain the loads but also fail when intended to protect other key parts. Overall, this coursework aims to assess a broad spectrum of the subject as well as looking at a detailed study of a particular scenario to evaluate the durability and reliability theories.

For this assignment the students should work to evaluate a particular scenario using the ideas and theories (and beyond where appropriate). The aim of this study is to evaluate and design a tie rod for a rally car steering mechanism. The tie rod needs to be designed in such a way that it can sustain the desired load case expected during “normal” operation of the vehicle. Consideration then needs to be made such that if the “normal” scenarios are exceeded, how the loads are managed within the suspension system. This means looking to design the tie rod to be a sacrificial element that will fail protecting the more important / costly components of the suspension system.

Work details:

This coursework needs to be submitted in the form of a technical report through plagiarism. The word limit for this report is 5,500 words in the main body of the report.

-Some writing about What is a function, the purpose and design of a car tie rod.

-What is reality force or loads and the problems come up in a car tie rod part when the car working in different places and different cases by technical analysis

-Coursework should contain case study, graphs, tables with their references.

-All references must be a CU Harvard style with 15 references.

-Good structure with heading (list of contains, list abbreviation list, graphs and tables list, Introduction,…,….,…., Counclosion)

- Priorety to be using ADAMS software if No you can use any computer programing to draw or make any calculation to make it a good and clear work.

Use the following information to assist you