# Suspension Analysis based on Solidworks Modeling

Abstract— the paper covers a simulation of the front suspension system which obtained a better way to analyze the problem. With the help of theoretical study, the simulation was conducted by using composite elements mesh for the system, which leads to a more accurate solution comparing to the single solid mesh model. Keywords—Suspension, Stress, Solidworks, Simulation, FEM.

Introduction

A. Background

“The Formula SAE ® Series competitions challenge teams of university undergraduate and graduate students to conceive, design, fabricate and compete with small, formula style, autocross racing cars.”[1] Swansea University has been involved with this competition for almost 13 years. And the main design of this year’s car is optimized by the previous car model – S12 to obtain a better performance. Therefore, the target of the simulations was based on the front suspension system of S12 model. And the analyzing process was provided with the illustration of simple components so that the advantages and optimization of the simulation approach can be presented. B. Suspension System

The competition rules require the suspension system to ensure that the car should have good riding stability, appropriate vibration absorbing ability and competitive controlling level. Specifically, with the help of suspension system, the car should: (1) Keep stable when accelerating and braking; (2) Decrease the longitudinal incline of the main body; (3) Provide a proper camber angle when cornering; (4) Avoid movement interaction with compact connections between parts; (5) Has reliable load transfer between main body and the tires;(6) Be easy to assembly or maintain; (7) Has enough strength and working life to complete the race. The suspension system can be divided into two main types: dependent and independent. Comparing to the dependent type, the independent suspension system has many advantages: such as less unsprung mass, less space occupied and no riding interference between right and left side tires. Due to the design flexibility of unequal double A-arms suspension system, it was chose to be the targeting structure of the independent suspension system. Furthermore, It can fulfill the different space requirements of the pull rod connections arrangement to get appropriate dynamic features of the system. The main components of the front suspension system are: (1) Wishbones; (2) Pull rod; (3) Rocker; (4) Shocks & spring; (5) Brackets and bearings; (6) Upright. In this project, the simulations will focus on the first three components to perform an analysis of the load transfer for the front suspension system. Theory

In the analyzing part, many dynamic principles were used to evaluate the movement relationship of different components and decide the basic geometries. In fact, to satisfy the strength requirements of all structures, theoretical mechanics and material dynamics study was conducted to obtain the background knowledge of the calculations. 2-bar trusses with vertical load

Figure 32-bar trusses

Forces within each bar:

F_bar=F/(2 cosα )(1)

Displacement of the top point:

δ_point= Fh/(2EA cos^3α )= FL/(2EA cos^2α )(2)

Where E is the elastic modulus of the material and A is the cross-section area of the truss Bending Stresses of simple cantilever beam wih end load

Figure 2Cantilever beam

In bending, the maximum stress and amount of deflection can be calculated from the following equations:

σ=PL/Z (3)

∆ =(PL^3)/3EI(4)

Where σ=maximum stress along the beam (N/m^2)

∆ = deflection (mm)

P=force load (N)

L=length of the beam (mm)

Z=section modulus

E=elastic modulus (N/m^2)

I=moment of inertia about bending axis

Furthermore, for the cylindrical or tube beams, Z and I can be calculated as: (1) Cylindrical

I=〖πr〗^4/4(5)

Z=(πr^3)/4(6)

Where, r is the radius of the...

References: SAE International community, Formula SAE Lincoln Event Guide, 2013 edtion.

John C. Dixon. Suspension Geomytry and Computation. Wiley, PEP, SAE. The Open University, Great Britain..Tl.257.D59.2009

Bernd Heing and Metin Ersoy. Chasis Handbook. 3rd edtion. 978-3-8348-0994-0.2011..

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