Automotive dynamics and safety

 

COURSEWORK ASSIGNMENT
Module Title: Automotive dynamics and safety	Module Code: 7AAD0054
Assignment Title: Quarter Car Vibration Model	Assignment type: Individual
Tutor:	Internal Moderator:

 

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Marks Awarded %:	Marks Awarded after Lateness Penalty applied %:
Penalties for Late Submissions ·         Late submission of any item of coursework will be capped at a minimum pass mark if received up to one week late. Any submission received more than one week late will be awarded a mark of zero. ·         Late submission of referred coursework will automatically be awarded a mark of zero. ·         Note: The School operates a strict policy on late submission. Canvas/Studynet marks all work submitted late, even by one second, as Late, in which case the above late penalties will be applied. Where genuine serious adverse circumstances apply, you may apply for an extension to the hand-in date, provided the extension is requested a reasonable period in advance of the deadline. However, you are warned that lateness due to network congestion (either at the University or on your local network), difficulty with filenames, poor time management and similar issues will not be considered as admissible circumstances. For this reason, you are advised to submit at least one hour before the deadline.
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ASSIGNMENT BRIEF Students, you should delete this section before submitting your work.
This Assignment assesses the following module Learning Outcomes (Take these from the module DMD): This assignment aims to enhance students’ knowledge on theoretical modelling or applied computer simulation or other practical methods to analyse vehicles dynamics and vibration.    The successful student will be able to: Ø  Apply analysis techniques to load the suspension model Ø  Use applicable method to model quarter car model with an aim to understand: ·     A method of characterizing the Newton laws for modelling oscillating behaviour ·     A theoretical approach to establish calculation of a 2 degree of freedom system ·     The impact of the modelling choices to the accuracy of results under different loading conditions ·     Understands subtle different approaches to model a vibrating system ·     How these findings can be used to improve the actual suspension system   Ø The assignment will reinforce a student to: ·       Analyse oscillating structural events such as amplitude, frequencies and shape modes. ·       Practice the structural behaviour under different modal assumptions (boundary conditions, load combinations) ·       Understand how loads can develop through an assembled suspension. ·       Be able to compare theoretical outputs to possible computer models. ·       Appreciate how the simulation approach can be used to predict the structural performance.
Assignment Brief: For the purposes of this assignment you have been tasked with simulating a simplified model of a quarter car suspension. You are encouraged to consider the identified loading scenarios and complete the tasks of this assignment. You may develop your own assumptions under your identified loading/displacement scenarios and provide a clear evaluation on the oscillating system when experiencing road conditions. Your defined assumptions should be based on a clear loading and boundary condition you may use to assess these solutions. These should lead you to develop your own model and validate it against other methods if applicable.   Please provide a report with your assumptions, calculations, solutions and observations as follows: •  Your assumptions in terms of design, requirements and measurables •  State clearly your requirements and limitations •  Justify your model choices and calculate their influence on its performance •  Explain the findings and discuss about possible weaknesses / strengths of the method •  Highlight design recommendations which can improve the function of the design. Important notes: •   All students must submit their individual report through Canvas/Studynet. •   The mark will be awarded to individual within the Canvas/Studynet.
Submission Requirements: •  Students must follow the requested tasks and report findings. •  Your submission may contain theoretical calculation, computer simulation or educational video/animation •  Applicable theoretical calculation or computer simulation must be reported using provided template. Please see blow document for detail information.
Marks awarded for: •     The assignment contains required tasks must be reported by all students. •    Report must be completed according the instruction provided on the template. •    The marking scheme has been specified on the template of the report. Please see blow document for detail of the tasks. A note to the Students: 1.         For undergraduate modules, a score above 40% represent a pass performance at honours level. 2.         For postgraduate modules, a score of 50% or above represents a pass mark. 3.         Modules may have several components of assessment and may require a pass in all elements. For further details, please consult the relevant Module Guide or ask the Module Leader.
Typical (hours) required by the student(s) to complete the assignment:   hours
Date Work handed out: Please check your assignment Available timing or your timetable for your UpToDate time slot.	Date Work to be handed in: Please check your assignment Due date or your timetable for your UpToDate time slot.	Target Date for the return of the marked assignment: 4 weeks after the deadline
Type of Feedback to be given for this assignment: Comments will be given on marked report through Canvas/Studynet. Generic feedback may be given in classroom.

 

 

7AAD0054 - Automotive dynamics and safety | Quarter car modelling | Assignment Brief

To improve the quality of the lab sheet please report any errors.

Please note: You must report all calculation modelling and computer simulations within the provided template. Any report outside the template structure will not be marked. 

 

Passive Suspension System

For road vehicle users, comfort is an important issue. To move from one place to another, road vehicles usually encounter various vibrations and shocks from ground, for instance, in traveling on a bumpy surface, or crossing over an obstacle. Prolonged exposures to vibrations cause some problems, such as pain and fatigue, for the passengers. To alleviate these problems, momentary loads from ground should be absorbed and damped out. Automotive suspension systems are intended to absorb and decrease the shocks and vibrations transferred from the ground to the passengers as well as the vehicle body. Passive suspension systems which consist of spring and damper components have been traditionally utilized on different types of vehicles, such as motorcycles, passenger cars, trucks and even bikes.

 

Quarter Car Modelling

Modelling of a passenger quarter car with passive suspension system has been proposed. The suspension system shown below represents the vehicle system at a single wheel. It consists of a spring, k_s, a damper, C_s. The tire stiffness and damping properties are also shown by k_t and C_t, respectively. The effective vehicle body mass is shown by M_s (sprung mass), and M_u (unsprung mass) represents the effective mass for the wheel and axle. The vertical displacements from the static equilibrium for M_u and M_s are shown by x_u and x_s, respectively. The road profile is represented by x_r. The suspension travel x_s - x_u is measured and compared to the set point (r = 0).

 

Ct Cs	Elements	Parameter	Value
	Effective mass for vehicle body	Ms [kg]	See your class list
	Effective mass for wheel system	Mu [kg]	See your class list
	Spring; vehicle suspension	ks [N/m]	See your class list
	Spring; wheel system	kt [N/m]	See your class list
	Damper; vehicle suspension	Cs [Ns/m]	See your class list
	Damper; wheel system	Ct [Ns/m]	See your class list
	Body vertical displacement	Xs [m]	See your class list
	Wheel vertical displacement	Xu [m]	See your class list
	Road profile	xr [m]	See your class list

Figure 1. Schematic of a simplified quarter car passive suspension and its specifications

 

Tasks

Please consider a passive suspension system with elements shown in Figure 1 and complete following tasks. Please answer any TWO Tasks out of THREE Tasks. If you submit answers to all questions, final marks will be determined using the best marks which satisfy the rubric. Applicable report must be completed within the provided Template.

 

Task 1: Theoretical modelling

1.       Perform free body diagram (FBD) for the system to satisfy the Newton’s 2^nd low. Make sure to draw all applied forces on the FBDs. Please develop your assumptions to address the applied forces onto the identified mases.

2.       Establish equation of motions (EOM) and solve the equations using appropriate parametric mathematical models. You may use your assumptions as used in the FBD of the system. Please make sure to address all loading scenarios applied to masses, springs, and damping elements.

3.       Fine Natural Frequencies (w) of the system and discuss about possible answers. You may consider a steady state free vibration and ignore the damping effects to simplify the EOM found in step 2 and complete the results using individual data.

4.       Drive Shape Modes and responses of the system. You may consider the assumption made in step 3. The general forms of responses need to be appropriately addressed based on individual data.

 

Task 2: MATLAB simulation

1.       Write a MATLAB program to simulate the system shown in Figure 1 considering all components of the system. You may develop the model using your individual data.

2.       Assess your MATLAB model against the mathematical model found in previous task. Comparison of the natural frequencies of the system, found using both models, is essential.

3.       Use the model created in step 1 to evaluate the function of the suspension against your individual road profile.

4.       Design a new suspension system by introducing new parameters which can provide smaller displacement (X_s) on the sprung mass.

Please note MATLAB software is available online upon registration on https://matlab.mathworks.com/.

 

Task 3: Educational video tutorial

1.       Students are requested individually to make a single educational video that practically shows the process of solving the theoretical model as requested in Task 1. The video muse address following criteria.

a.       Must show your individual data.

b.       Must show live hand calculation

c.       Must contain details of solution.

d.       Must contain live voice explanation.

e.       Must be less 5 minutes long.

f.        Must be in MP4 format.

g.       Must NOT contains any personal information.

2.       Here are some examples which can help to initiate an idea.

https://www.youtube.com/watch?v=TKbChGz4-mw

https://www.youtube.com/watch?v=lw5U4sLN5Qk

https://www.youtube.com/watch?v=D-Z7eDTjQpo

 

Useful references:

1.         Control Tutorials for MATLAB and Simulink, http://ctms.engin.umich.edu/CTMS/index.php?example=Introduction&section=SimulinkModeling, (last seen 11/02/2020)

2.         Duc Chung Tran, Quarter Car Modelling, https://uk.mathworks.com/matlabcentral/fileexchange/46316-quarter-car-modelling-zip, (last seen 11/02/2020)

3.         Jonathan Sprinkle, Quarter car suspension model, published on 30 Aug 2013, https://www.youtube.com/watch?v=TKbChGz4-mw, (last seen 11/02/2020)

4.         James Allison, Simulation and Animation of a Quarter-Car Automotive Suspension Model, https://uk.mathworks.com/matlabcentral/fileexchange/35478-simulation-and-animation-of-a-quarter-car-automotive-suspension-model, (last seen 11/02/2020)