Dynamic Finite Element Analysis For The Impact of An Engine Hood to A Radiator Support Frame
Date Issued
2006
Date
2006
Author(s)
Hung, Ting-Fang
DOI
zh-TW
Abstract
The structural strength of an automobile must pass through a series of tests due to safety concerns and regulations. However, it often takes a long time to manufacture a prototype and conduct a series tests. In order to save time and cost, the finite element simulations are usually performed to evaluate the strength of the designed car-body structure before the actual tests are conducted. However, the accuracy of finite element simulation for the strength analysis of a car-body structure, especially the dynamic impact analysis, is still being improved by researchers.
In this thesis, the strength of a radiator support frame impacted by a free-falling engine hood was examined with the use finite element code, LS-DYNA. The entire engine room of a recreational vehicle was modeled for the analysis. Key points of building a reliable model, such as connectivity of elements, modeling of spot welds and selection of material models, were determined first.
In the construction of a finite element model, disconnected elements were found due to poor quality of CAD files imported. An appropriate approach to remedy the CAD files was developed for the subsequent mesh generation. In order to model the hinge connecting the hood to the engine room, two different elements, such as revolute joints with rigid elements and revolute joints with rigid links, were thoroughly examined and the suitable element type was selected to represent the hinge in the finite element model.
In modeling spot welds, the efficiency in using the constrained spot weld approach and contact spot weld approach was compared. Constrained spot weld was found resulting in higher stress. In addition, the effects of different arrangements of constrained spot welds in the finite element model on the simulation accuracy were also examined. In order to further reduce the computation time, a theoretical model was also proposed in the present study to calculate the instantaneous angular velocity of the free-falling engine hood at the incipient impact to the radiator support frame, which was used to replace the simulation of the free falling of engine hood.
A series of experiments were also conducted in the present study to measure the strains and impact forces during the impact of the engine hood to the radiator support frame. The experimental data were found consistent with those obtained from the finite element simulation results. The accuracy of the finite element model built for the dynamic analysis for the impact of an engine hood to the radiator support was then validated. The approaches developed in the present study for the dynamic finite element model of impact analysis could be extended to the whole car-body structure.
Keywords: dynamic finite element analysis, impact analysis, engine hood, hinge and spot-weld models, experiments.
Subjects
動態有限元素法分析
撞擊分析
引擎蓋
旋轉機構與焊點模型
實驗
dynamic finite element analysis
impact analysis
engine hood
hinge and spot-weld models
experiments
Type
thesis
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