扭力樑式懸吊系統衝擊試驗之有限元素分析

Finite Element Analysis for The Impact Test of a Torsion Beam Suspension System

孫嘉珮(Chia-Pei Sun)

指導教授 ： 陳復國

國立臺灣大學/工學院/機械工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.02860

摘要

汽車後懸吊系統對於車輛的安全性、操縱性及適乘性均有關鍵性的影響，因此必須通過一連串的實車試驗來檢測。然而實車衝擊試驗所需之成本較高且時程亦長，故目前在進行實際測試前，多會採用有限元素法模擬測試流程，來預測實車衝擊試驗的結果，以加速研發及優化設計等過程，減少所需成本的耗費。
本論文採用小客車之扭力樑式懸吊系統作為研究載具，首先利用簡化之整車模型進行動態有限元素法分析，模擬車輛以高速通過高斜率突起路面之實車衝擊試驗過程及結果。在整車模型簡化之過程中，本論文探討必須考慮的要點，如結構體簡化、功能件運動模式、搭接件間之連接方式及參數選用等。然後再將實車衝擊試驗簡化為扭力樑式懸吊系統局部之靜態變形分析，以靜態有限元素法分析之方式，重現實車衝擊試驗後扭力樑之結構變形狀態，藉以建立汽車後懸吊系統衝擊試驗之等效靜態局部分析模式，大幅縮短有限元素法分析之模擬時間。
本論文利用動態有限元素法分析模擬實車試驗過程，以及採用等效靜態局部分析模式，均可重現實車試驗後挖孔扭力樑產生之挫曲變形狀態，證明本論文所建立之兩種有限元素法分析模式都能有效預
測實車突起乘越衝擊試驗過程中扭力樑之變形狀態。
在進行實車衝擊試驗前，若能以局部之台架試驗先進行測試，以預測扭力樑之結構強度設計是否合乎規範要求，便能節省許多人力、物力及開發時程。因此本論文亦藉由前述所建立之有限元素分析模式，模擬所設計及規劃之台架試驗方法的可行性，模擬結果顯示，該台架試驗方法可得到與實車試驗相同之扭力樑變形模式，證明可用此台架試驗方式來預測扭力樑式懸吊系統實車撞擊結果。
本論文之研究成果可供未來設計人員進行後懸吊系統及台架試驗設計及研究之依據。

關鍵字

實車衝擊試驗 ； 動態有限元素法分析 ； 靜態有限元素法分析 ； 扭力樑式懸吊系統 ； 台架試驗

並列摘要

Rear suspension system is a crucial factor determining a vehicle's reliability and controllability. It is thus important to carry out series of practical vehicle examinations testing the performance of a rear suspension system. However, time and cost are the main concerns on the design and test of a rear suspension system. Therefore the finite element method is often utilized to simulate the real vehicle collision tests before the actual vehicle examinations are carried out. The finite element simulations have been proven to be the most effective way to speed up the design and development relating to this field, in the same time minimizing costs.
This thesis took a torsion beam suspension system mounted in a sedan as a carrier to study the deformation of the twist beam in the impact test of a vehicle running over a road bump with the use of the finite element analysis. A simplified full car model was constructed to simulate the impact test using the 3D dynamic/explicit code LS-DYNA. In the model construction, the influences of model simplification, special element function, connecting parts linkage methods and parameter selection are explored and evaluated. The validity of the simplified model was confirmed by the presence of the buckled deformation of the twist beam obtained from the simulation that is consistent with the actual impact test result. A 3D finite element model of a real suspension system
was then established taking the impact forces obtained from the full car dynamic analysis as the corresponding boundary conditions. The local analysis of the real suspension system was performed using the static code ABAQUS/Standard. The buckled deformation of the twist beam was also presented in the static simulation results. It is inferred that the deformation of the twist beam occurred in the impact test of a vehicle running over a road bump can also be predicted by a local analysis of a rear suspension system using an equivalent static local model if the corresponding boundary conditions are available. The developed equivalent static local model in this thesis can save significant computing time in simulating the impact test.
With the developed 3D dynamic and static models, the feasibility of a bench test design that simulates the actual impact test of a vehicle running over a road bump was examined by the finite element analysis. The simulation results reveal that the buckled deformation can also be reproduced in the test with the designed bench test apparatus. It therefore indicates that the designed bench test could be applied to predict if the twist beam would succeed in the impact test of a vehicle running over a road bump.
The research results achieved in this thesis provide valuable references for the future design of a rear suspension system and corresponding bench tests for predicting the strength of the twist beam in
the impact test of a vehicle running over a road bump.

並列關鍵字

torsion beam rear suspension system ； vehicle impact test ； 3D finite element analysis ； bench test design

參考文獻

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