基于ls-dyna的汽车前纵梁碰撞.doc
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基于ls-dyna的汽车前纵梁碰撞,摘 要近年来由交通事故引起的伤亡人数不断增加使得汽车厂家和消费者对汽车安全问题的重视程度越来越高。随着消费者的安全观念日益增强，汽车厂家在汽车的设计和研发方面也将安全放在了非常重要的位置。因此，汽车安全已成为当今汽车工程领域亟待完善的研究领域,并且得到了社会的高度关注。由于实车碰撞试验受到时间长和费用高等限制，一般只做...
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摘 要
近年来由交通事故引起的伤亡人数不断增加使得汽车厂家和消费者对汽车安全问题的重视程度越来越高。随着消费者的安全观念日益增强，汽车厂家在汽车的设计和研发方面也将安全放在了非常重要的位置。因此，汽车安全已成为当今汽车工程领域亟待完善的研究领域,并且得到了社会的高度关注。
由于实车碰撞试验受到时间长和费用高等限制，一般只做少量的验证性试验。在实际产品设计中，大量采用有限元分析的方法来代替碰撞试验，并且有研究结果表明，利用非线性动力学分析软件LA-DYNA进行碰撞模拟仿真与实车碰撞试验的结果吻合良好，可以有效地替代实车碰撞试验进行碰撞分析。
汽车发生正面碰撞时,主要由车身前部的塑性变形来吸收碰撞能量,其中起重要作用的是前纵梁，70 %以上的汽车碰撞能量由前纵梁吸收才能保证驾驶室尽可能完整。 理想的前纵梁设计应该能够充分利用前纵梁的塑性变形来吸收汽车碰撞中的大部分能量。汽车前纵梁通常可以简化为薄壁结构, 因此，研究薄壁结构的碰撞变形吸能特性在汽车前纵梁设计中具有重要的意义。
为了使汽车前纵梁在碰撞过程中能够吸收更多的能量， 本文主要研究不同焊点间距、板厚和材料特性等偏差的汽车前纵梁的碰撞吸能特性，综合考虑了全面碰撞和偏置40%碰撞前纵梁的综合吸能特性，并且针对前纵梁的不同截面形状、板厚、焊点间距、焊点直径和偏转角度等设计变量，建立了前纵梁碰撞的有限元分析模型，并利用有限元软件LS-DYNA和响应曲面优化算法，进行了碰撞模拟仿真和优化设计，从而得出了碰撞吸能特性最优的汽车前纵梁。
关键词 汽车设计；前纵梁；碰撞分析；优化设计；响应曲面法
Abstract
In recent years, the rising number of people caused by traffic accident makes car’s manufacturers and consumers pay much attention to safety problem. With the growing of consumer’s security concept, automobile manufacturers will also put the security in an important position during design. Therefore, automobile safety has become an important research field of automotive engineering, and has gotten the much attention of the society.
Because the real crash test takes longer time and higher cost, generally only a little confirmatory test. In the practical product design, using a large number of finite element analysis method to replace the crash test, and the results show that, by using the nonlinear dynamic analysis software LA-DYNA collision simulation and real crash test results are agreement, it can effectively substitute the real car test collision analysis.
When the car has a frontal crash, the plastic deformation of the front body will absorb most of collision energy, and the front side member play an important role in the process. In order to ensure the cab as complete as possible, more than 70% of collision energy must be absorbed by front side member. The ideal front side member design should make the front side member absorb most of the energy in the vehicle collision, reducing its impact on the human body injury. To study the relationship between the structure and deformation, the front side member can be simplified into a thin shell element, so as to finish the security design of front side member. Therefore, the study of thin wall front side member energy absorbing characteristics has important significance to design of front side member.
In order to make the car front side member absorb more energy in colliding process, this paper have studied energy absorption characteristics base on different spot spacing deviation, plate thickness, material characteristics and so on, considering the overall and offset 40% collision energy absorbing characteristics of the front side member, and finished optimum design of the front side member base on the design parameters of the front side member, such as different cross-section shapes, thickness, spot weld pitch, spot diameter and collision direction deviation by using LS-DYNA and the response surface optimization, thus obtains the front side member being the best energy absorbing characteristics.
Key words vehicle design; front side member; impact analysis; optimization; response surface method
目 录
摘 要 I
ABSTRACT II
第1章 绪论 1
1.1 课题来源和背景 1
1.2 汽车碰撞研究方法 3
1.2.1 试验法 ………………………………………………………………………3
1.2.2 有限元法 ……………………………………………………………………3
1.3 汽车碰撞国内外研究现状 4
1.3.1 国外研究现状 ……………………………………………………………….4
1.3.2 国内研究现状 5
1.4 本课题的研究目的和内容 7
1.4.1 本课题的研究目的 7
1.4.2 本课题的研究内容 7
1.4.3 本文结构 8
1.5 本章小结 9
第2章 基于不同焊点间距及各类误差的汽车前纵梁碰撞仿真分析 10
2.1 汽车前纵梁碰撞模型的建立 10
2.1.1 建立网格模型 10
2.1.2 添加载荷和约束 12
2.2 碰撞过程 14
2.3 结果分析 15
2.4 本章小结 19
第3章 基于不同截面汽车前纵梁碰撞性能比较 20
3.1 不同截面汽车前纵梁简化模型 20
3.2 结果分析 23
3.3 本章小结 31
第4章 保险杠和前纵梁组合部件的碰撞仿真分析 32
4.1 全面碰撞仿真模型的建立 32
4.2 各种截面前纵梁薄壁机构有限元模型的全面碰撞过程仿真 34
4.3 全面碰撞结果分析 37
4.4 汽车偏置40%碰撞前纵梁仿真分析 37
4.4.1 不同截面前纵梁偏置4..
近年来由交通事故引起的伤亡人数不断增加使得汽车厂家和消费者对汽车安全问题的重视程度越来越高。随着消费者的安全观念日益增强，汽车厂家在汽车的设计和研发方面也将安全放在了非常重要的位置。因此，汽车安全已成为当今汽车工程领域亟待完善的研究领域,并且得到了社会的高度关注。
由于实车碰撞试验受到时间长和费用高等限制，一般只做少量的验证性试验。在实际产品设计中，大量采用有限元分析的方法来代替碰撞试验，并且有研究结果表明，利用非线性动力学分析软件LA-DYNA进行碰撞模拟仿真与实车碰撞试验的结果吻合良好，可以有效地替代实车碰撞试验进行碰撞分析。
汽车发生正面碰撞时,主要由车身前部的塑性变形来吸收碰撞能量,其中起重要作用的是前纵梁，70 %以上的汽车碰撞能量由前纵梁吸收才能保证驾驶室尽可能完整。 理想的前纵梁设计应该能够充分利用前纵梁的塑性变形来吸收汽车碰撞中的大部分能量。汽车前纵梁通常可以简化为薄壁结构, 因此，研究薄壁结构的碰撞变形吸能特性在汽车前纵梁设计中具有重要的意义。
为了使汽车前纵梁在碰撞过程中能够吸收更多的能量， 本文主要研究不同焊点间距、板厚和材料特性等偏差的汽车前纵梁的碰撞吸能特性，综合考虑了全面碰撞和偏置40%碰撞前纵梁的综合吸能特性，并且针对前纵梁的不同截面形状、板厚、焊点间距、焊点直径和偏转角度等设计变量，建立了前纵梁碰撞的有限元分析模型，并利用有限元软件LS-DYNA和响应曲面优化算法，进行了碰撞模拟仿真和优化设计，从而得出了碰撞吸能特性最优的汽车前纵梁。
关键词 汽车设计；前纵梁；碰撞分析；优化设计；响应曲面法
Abstract
In recent years, the rising number of people caused by traffic accident makes car’s manufacturers and consumers pay much attention to safety problem. With the growing of consumer’s security concept, automobile manufacturers will also put the security in an important position during design. Therefore, automobile safety has become an important research field of automotive engineering, and has gotten the much attention of the society.
Because the real crash test takes longer time and higher cost, generally only a little confirmatory test. In the practical product design, using a large number of finite element analysis method to replace the crash test, and the results show that, by using the nonlinear dynamic analysis software LA-DYNA collision simulation and real crash test results are agreement, it can effectively substitute the real car test collision analysis.
When the car has a frontal crash, the plastic deformation of the front body will absorb most of collision energy, and the front side member play an important role in the process. In order to ensure the cab as complete as possible, more than 70% of collision energy must be absorbed by front side member. The ideal front side member design should make the front side member absorb most of the energy in the vehicle collision, reducing its impact on the human body injury. To study the relationship between the structure and deformation, the front side member can be simplified into a thin shell element, so as to finish the security design of front side member. Therefore, the study of thin wall front side member energy absorbing characteristics has important significance to design of front side member.
In order to make the car front side member absorb more energy in colliding process, this paper have studied energy absorption characteristics base on different spot spacing deviation, plate thickness, material characteristics and so on, considering the overall and offset 40% collision energy absorbing characteristics of the front side member, and finished optimum design of the front side member base on the design parameters of the front side member, such as different cross-section shapes, thickness, spot weld pitch, spot diameter and collision direction deviation by using LS-DYNA and the response surface optimization, thus obtains the front side member being the best energy absorbing characteristics.
Key words vehicle design; front side member; impact analysis; optimization; response surface method
目 录
摘 要 I
ABSTRACT II
第1章 绪论 1
1.1 课题来源和背景 1
1.2 汽车碰撞研究方法 3
1.2.1 试验法 ………………………………………………………………………3
1.2.2 有限元法 ……………………………………………………………………3
1.3 汽车碰撞国内外研究现状 4
1.3.1 国外研究现状 ……………………………………………………………….4
1.3.2 国内研究现状 5
1.4 本课题的研究目的和内容 7
1.4.1 本课题的研究目的 7
1.4.2 本课题的研究内容 7
1.4.3 本文结构 8
1.5 本章小结 9
第2章 基于不同焊点间距及各类误差的汽车前纵梁碰撞仿真分析 10
2.1 汽车前纵梁碰撞模型的建立 10
2.1.1 建立网格模型 10
2.1.2 添加载荷和约束 12
2.2 碰撞过程 14
2.3 结果分析 15
2.4 本章小结 19
第3章 基于不同截面汽车前纵梁碰撞性能比较 20
3.1 不同截面汽车前纵梁简化模型 20
3.2 结果分析 23
3.3 本章小结 31
第4章 保险杠和前纵梁组合部件的碰撞仿真分析 32
4.1 全面碰撞仿真模型的建立 32
4.2 各种截面前纵梁薄壁机构有限元模型的全面碰撞过程仿真 34
4.3 全面碰撞结果分析 37
4.4 汽车偏置40%碰撞前纵梁仿真分析 37
4.4.1 不同截面前纵梁偏置4..
