kinematic analysis performance between short long...

The Turkish Online Journal of Design, Art and Communication - TOJDAC ISSN: 2146-5193, September 2018 Special Edition, p.2697-2709

KINEMATIC ANALYSIS PERFORMANCE BETWEEN SHORT LONG ARM AND PARALLEL SUSPENSION FOR RACING CAR

Mohd Khairul Nizam Bin Suhaimin Advanced Manufacturing Center, Fakulti Kejuruteraan Pembuatan, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia. *Corresponding Author, Email: [email protected]

Zuhriah Binti Ebrahim Advanced Manufacturing Center, Fakulti Kejuruteraan Pembuatan, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia.

Mohd Razali Bin Muhammad Advanced Manufacturing Center, Fakulti Kejuruteraan Pembuatan, Universiti Teknikal Malaysia Melaka,

Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia.

Muhammad Zaidan Bin Abdul Manaf Fakulti Teknologi Kejuruteraan, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian

Tunggal, Melaka, Malaysia

ABSTRACT Presently, the implementation of a suitable suspension system plays an important role in the handling of the vehicle especially when it involves the racing car. Kinematic analysis of suspension especially for race car suspension is very essential to provide optimum performance and stability. However, there is still limited study on identifying the kinematic analysis performance between two types of Double Wishbone Suspensions which are Short Long Arm (SLA) and Parallel Arm Suspension. Hence, the objective of this paper is to determine the best suspension’s kinematic performance of students’ racing car between both of these suspensions system. The process of choosing the best suspension design is based on step by step engineering design module. The step started with a rough sketch, detailed design in CAD and lastly analyzed using A ltair Motion View Software on static ride analysis that gives more accurate comparison data for both left and right wheel displacement . By obtaining the data of several basic suspension geometry parameters such as the values of toe, camber, caster, and tread change from front suspension and rear suspension, the experimental results conclude that the better kinematic performance for suspension development of student racing car is SLA suspension. Thus, the result of this study provides a detailed analysis of the two types of double wishbone suspens ion which are SLA and Parallel that provide a better understanding of parameter geometry for suspension system analysis performance.

Keywords: Parallel Suspension; SLA Suspensions; Suspension Kinematic Analysis.

I. Introduction Presently, one of the most popular automotive events among students in the world is racing "Formula-1". It is a competition of where students applied their capabilities in designing and developing a simplified version of Formula One race car, for example, the event of FV Malaysia [1]. When involve of a racing car, [2] claimed that the implementation of a good suspension system is crucial as it represents major act during race car racing. According to [3], the compatibility of a suspension system is important in order to ensure that under various conditions, the wheel contact to the road maintained and also the road shocks towards driver is minimized. [4] defined the suspension as isolation of two masses hence while designing suspension, a balanced design should be provided in order to carry out functions like road holding, load carrying, and passenger comfort. In a simple way, the purpose of the suspension system is to isolate the vehicle body from road bumps and vibrations, while keeping the wheels in contact. Basically, there are different types of suspension system adapted in car racing. Double wishbone suspension is favorable suspension system that is applied used in order to facilitate the development of the suspension design with

Submit Date: 05.07. 2018, Acceptance Date: 22.08.2018, DOI NO: 10.7456/1080SSE/346 Research Article - This article was checked by Turnitin

Copyright © The Turkish Online Journal of Design, Art and Communication


a suitable weight of the component [5]. However, for double wishbone, there is no comparative study on performance between same length upper and lower arm suspension called Parallel Arm and unequal length of lower and upper arm suspension which is called Short Long Arm (SLA). Of course, the suggested design should be excellence in diminishing the aero-dynamical obstacle as the system would help all the components such as spring, damper, and wheels aligned in perfect position.[6]. [7] stated that for SLA, the upper arm is usually shorter to induce negative camber as the suspension jounces (rises). It is the type of independent non-parallel, non-equal, double wishbone design [8]. For SLA, the shape of the wishbone, by having different length, it can uniformly circulate the stresses over the members effectively which lead a higher stability for the vehicle as negative camber is induced during cornering [9]. As for the parallel suspension, it involves the arrangement of equal A-arms and parallel arm design and the equal A-arms are widely accepted as camber changes can be easily eliminated [9]. [10] claimed that this type of suspension where the components work mechanically in parallel fixed make it is as a more conventional system. The parallel mechanical suspension also can balance the suspension rate that leads to vehicle stability [11]. In addition, [12] viewed that the parallel wishbone (equal-length parallel arms eliminate the unfavorable condition on the inside wheel is probably the most widely used racing suspension design and also makes up a significant proportion in the domestic market.

As [13] explains that a good suspension integrated with a good kinematics design to keep the tire as perpendicular to the pavement as possible, optimal damping and spring rates to keep the tire on the ground at all times, and strong components that do not deflect under the loads induced upon them Thus, study of kinematic suspension for the system is essential for racing car competition as, during cornering of the vehicle, there are forces lead to instability and roll of the car which depends on the kinematics of the suspension [14]. [15] claimed that by having suspension kinematic analysis running in simulation software, the stability of the suspension geometry is attained by providing an optimum base for designing the frame. There are some considered parameter factors need to be understood by the researchers such as tread change, camber, caster, and toe in order to design a geometry and running the kinematic analysis [16]. [17] in his paper have tried to optimize student formula car suspension parameters and conduct kinematic analysis to the wishbones locally and globally. [15] and [1] has applied kinematic analysis using multi-body dynamics (MBD) software, Altair MotionView.

The objective of the paper is to study the kinematic performance of the racing car suspension system between SLA and Parallel suspension. This paper is organized in the following manner: Section 2 gives the detailed methodology of the design and analysis tool. Section 3 discusses the simulation results obtained from the software used. Conclusions are drawn in section 4.

II. Methodology The study begins with defining the configuration, location, and geometry of the suspension system. Then after the setting been settled, the suspension design is conducted by using CAD through CATIA software for 3D design. The analysis process continued This data is then used to model the car in the multibody dynamics (MBD) environment. The software used in this simulation is Altair Motion View.

A. Define Configuration In order to conduct the analysis the open wheeled racing car suspension system, the first and foremost thing is to know the tire data according to manufacturer’s specification along with the vehicle parameters respectively. The weight of the car is only 200kg and the parameter configuration of the car is shown as in figure 1.




Figure 1

B. Suspension Design A “double-wishbone” suspensions, Parallel and Short-Long Arm suspension were designed using two wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckle. The geometry designs for the Parallel and Short-Long Arm suspension are shown in Figure 1 and Figure 2, respectively. First, in this design, the suspension is supported by a triangulated A-arm at the top and bottom of the knuckle. The earliest designs of the A-arm suspension included equal length upper and lower arms mounted parallel to the ground. This design has many advantages over any of the previous independent front suspensions. Short-Long Arm suspension was designed when there was a suggestion to make the double A-arm front suspension satisfactory for high-performance use was to determine a way for the suspension to gain negative camber as it was compressed after designing, implementing, and experimenting with the equal length (Parallel) double A-arm suspension had been done.

In figure 2 and figure 3, the "A" label is the upper arm and the "B" label is for lower arm. The design is not greatly different as both of the suspensions are double wishbone type. The different is in term of the upper and lower arm length.



Figure 1: The Parameter Configuration of the Car


Figure 2

Figure 3

C. Kinematic Analysis by Altair Motion View For suspension design, it is compulsory to undergo motion analysis. The best specification for carefully control the motion of the wheel throughout suspension travel should be understood such the factor geometry that involve in the analysis such as camber, caster, angle, toe, and tread change. These analyses were carried using Altair Motion View under static ride condition. From the analyzed results, the graph of parameters factor will be compared for SLA and Parallel Suspension and best on was taken out. It involves both front suspension and rear suspension system. Figure 4 and figure 5 show the analysis involve the front suspension and rear suspension



Figure 2: The Geometry Design of Short Long Arm (SLA) Suspension


! Figure 4: Front Suspension Analysis

.

! Figure 5: Rear Suspension Analysis

III. Result and Discussion

Front Suspension Result of the literature analysis shows that the critical requirements can be classified into three categories as follows;




a) Toe analysis

Based on graph 1, at static, the wheel vertical displacement of SLA suspension is in 0mm and the value of toe is at -0.1 degree. Meanwhile, the wheel vertical displacement of parallel suspension is 0mm and the value of toe is 0.22 degree. For rebound, when the wheel moves downward -80mm, the kingpin inclination for SLA suspension will be changed to -3.3 degree. Meanwhile, the Parallel arm suspension becomes 0.67 degree at the same displacement. For jounce, when the wheel moves upward 80mm, the SLA suspension shows that its value of toe will be changed to -4 degree whether the kingpin inclination for Parallel suspension become decreased to -1.75 degree at the same displacement.

As this is a front wheel drive vehicle, the tires were in a toe-out position during jounce. This is due to the moment created to straighten the tires while cornering for better vehicle handling [1]. So by the comparison for both suspensions, SLA suspension is preferable as the toe out condition is more optimum compared to parallel suspension.



Graph 1: Toe Analysis for front for SLA and Parallel Suspension


b) Chamber analysis

From the graph 2, both the Wheel Vertical Displacement versus Camber Angle graph for left wheel and right wheel are identical. For SLA suspension, when the wheel vertical displacement is 0mm, the camber angle is -0.1˚. When the wheel vertical displacement is -80mm, the camber angle becomes -3.3˚. When the wheel vertical displacement is 80mm, the camber angle becomes -4˚. Meanwhile, for parallel suspension, the chamber angle at static condition is -0.22˚. When the wheel vertical displacement is -80mm, the camber angle becomes -0.67˚. When the wheel vertical displacement is 80mm, the camber angle becomes -1.75˚.

The length of upper control arms will determine the curvature of the camber curve. If upper and lower arms were the same length, the camber curve will be a straight vertical line and if upper arm is shorter than the lower, the curve will be concave towards negative camber which is preferred while cornering [16]. Hence SLA suspension is chosen.



Graph 2: Chamber Analysis for Front SLA & Parallel Suspension


c) Caster analysis

Refer to the graph 3, for an SLA suspension it is noticed that at the static condition, which is at 0mm wheel vertical displacement, the caster angle obtained is 8.8⁰. Then, for rebound condition which is at -80mm displacement, the caster is 6.4⁰. As for jounce condition at 80mm displacement, caster angel obtained is 10.1⁰. Meanwhile, it can be compared to a parallel suspension which at the static condition, which is at 0mm wheel vertical displacement, the caster angle obtained is 8.6⁰. Then, for rebound condition which is at -80mm displacement, the caster is 7.4⁰. As for jounce condition at 80mm displacement, caster angel obtained is 10.75⁰.

The value of caster angle should be near 0 degree which in order for front suspension equal and achieves stability. [9] However, based on the observation obtained, the angle of the caster only changes a little due to steering axis that does not compensate much during jounce and rebound. Positive caster is maintained to ensure the axis of rotation is in front of the tire patch on the ground to keep the tire straight every time the wheel is turned. Without positive caster, the wheel will not rotate steadily

Rear Suspension Result of the literature analysis shows that the critical requirements can be classified into three categories as follows;



Graph 3: Caster Analysis for Front SLA and Parallel Suspension


d) Toe analysis

!

Refer to graph 4, at static, the wheel vertical displacement of SLA suspension is in 0mm and the value of toe is at 0.1 degree. Meanwhile, the wheel vertical displacement of parallel suspension is 0mm and the value of toe is also 0.1 degree. For rebound, when the wheel moves downward -80mm, the toe value for SLA suspension will be changed to 5.3 degree. Meanwhile, the Parallel suspension becomes 5.6 degree at the same displacement. For jounce, when the wheel m oves upward 80mm, the SLA suspension shows that its value of toe will be changed to 3 degree whether the toe value for Parallel suspension become decreased to 3.5 degree at the same displacement.

[4] claimed that in consideration of front steering condition, the rear suspension should have high toe value. From the analysis, it can be suggested that the parallel suspension better than SLA suspension in term of rear toe analysis.



Graph 4: Toe Analysis for Rear SLA and Paralell Suspension


e) Caster Analysis

From the graph 5, for a SLA suspension, it is noticed that the caster angle changes slightly which rises from 10.5⁰ to 13.75⁰, giving a total of 3.25⁰ increments. The same result is obtained for both left and right wheel. Meanwhile, parallel suspension shows that there is no difference in term of increment which is also rose up to 13.75⁰ from 10.5⁰, which also equal to 3.25 increments.

From the observation obtained the angle of the caster only changes a little due to steering axis that does not compensate much during jounce and rebound. At rear side caster value should zero so it can connect a zero toe rod. Since there is no difference between SLA and Parallel Arm Suspension, so they are both compactible.



Graph 4: Toe Analysis for Rear SLA and Paralell SuspensionGraph 5: Caster Analysis for Rear SLA and Parallel Suspension


f) Tread Change

.

From the graph 6, a comparison was done between a rear wheel drive setup from a different type of suspension which is SLA and Parallel Suspension. Based on the graph obtained, when the vertical wheel displacement for SLA suspension is at 80mm, the vehicle achieves a tread change of 70mm/m. The tread change stays at 155 mm/m when the vertical displacement is at 0mm. As the wheel displacement falls to -80mm, the tread change of the vehicle obtains 206mm/m. As for the parallel suspension, when the vertical wheel displacement is at 80mm, the tread change achieves 25 mm/m. The tread change stays at 155mm/m when the vertical displacement is at 0mm. As the displacement falls to -80mm, the tread change of the vehicle obtains 290mm/m.

Even though both wheels produce different results, it is obvious that such minimal tread change is caused by SLA Suspension because the body roll and yaw can be minimized and there will be minimum tread change during jounce and rebound of the driven wheel [18]. Therefore, the tread change will be minimized which in terms increase the traction and handling of a vehicle



Graph 6: Tread Change Analysis for Rear SLA and Parallel Suspension


IV.Conclusion As a conclusion, this paper discussed how the process of choosing the best suspension design is based on step by step engineering design module. The step started with a rough sketch, detailed design in CAD and lastly analysed using Altair Motion View Software. In addition, the analysis is undergoing on static ride analysis that gives more accurate comparison data for both left and right wheel displacement. By obtaining the data of several basic suspension geometry parameters such as the values of toe, camber, caster, and tread change from front suspension and rear suspension, it will make easier to studied and analysed. Based on author findings from the experimental results, the better final design for suspension development of student racing car is short-long arm (SLA) suspension. However, for the future research, the study perhaps should be more focus on the different type of racing cars in order to compare the effectiveness of another suspension system with more detail analysis. The findings in this article should contribute to a comprehensive understanding of both types of double wishbone suspension system.

Acknowledgment The authors gratefully acknowledge UTeM Zamalah Scheme for sponsoring the publication of this article and indirect contributions from the research group, Sustainable and Responsive Manufacturing (SUSREM)

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