【作者】 董立新；

【导师】 戴光泽；

【作者基本信息】 西南交通大学 ， 材料学， 2006， 硕士

【摘要】 随着汽车轻量化的发展,铝合金材料在车体中大量应用,为提高铝合金框架结构中梁的抗冲击性能,研究人员进行了大量的尝试,其中CFRP增强铝合金梁就是探索其抗冲击性能的一种结构形式。但是,目前对这种复合结构形式在横向冲击载荷下的动态响应及结构的抗冲击性能的认识还处于探索之中。 本研究利用有限元数值仿真技术及工程软件,对CFRP增强铝合金梁结构在冲击载荷作用下的动力学响应问题进行了探讨,应用弹塑性动态仿真方法,获得了模拟冲击过程的实践经验和模拟冲击过程的计算结果,主要体现在以下方面: 1.在对冲击动力学的基础理论、冲击动力学问题的一般分析方法概述基础上,将冲击动力学的基本方程和有限元分析相结合,详细地阐述了解决冲击问题的数值模拟法—非线性有限元法的基本原理及求解过程,提出用显式中心差分法求解非线性有限元动力学方程组,用对称罚函数法解决接触碰撞问题; 2.应用大型有限元显式动载荷分析软件ANSYS/LS-DYNA,建立了CFRP增强铝合金梁和单纯铝合金梁的有限元冲击模型,对在横向冲击过程进行了动态模拟仿真,分别获得了CFRP增强铝合金梁和单纯铝合金梁在冲击过程中的应力分布、应变及变形分布、吸收冲击功能力等特性进行了对比分析。分析结果表明采用CFRP增强铝合金梁,能够有效地提冲击功吸收能力,减少冲击变形,模拟结果与有关文献[18]的实验结果基本吻合; 3.利用APDL程序命令,通过修改铝合金梁壁厚参数的方法,对不同壁厚参数的CFRP增强铝合金梁和单纯铝合金梁的抗冲击性进行了分析比较,获得了铝合金梁壁厚对梁的抗冲击性能的影响关系。 本研究的数值仿真法,对于CFRP增强铝合金梁的结构设计有更多还原

【Abstract】 As the lightweight design applications of aluminum alloy beams to vehicles body-frame development recently, many efforts are made intending to increase the impact resistance against shocking. Aluminum beam reinforced with CFRP (carbon fiber reinforced plastics), namely, ABC, is one of these applications. However, many unknowns are remained on the response of ABC structure under the impact loading. It seems necessary to simulate this impact process through finite element method (FEM) in order to predict its responses on both the stress and strain distributions during impact process.In the present research, the impact process is simulated by means of finite element method (FEM) through a common commercial software, called, ANASY-DYNA, where the elastic-plastic elements are used to investigate the response of the impact dynamic loading on a CFRP reinforced aluminum beam. The whole simulation processes are discussed in details, which includes the modeling preprocing, the parameters selecting and/or calculation process and the post processing. The final results and the influence factors are mainly discussed as well and the whole thesis is oriented as follows:Firstly, based on the fundamental theory and the general solving process of impact dynamic problems, the author combines the constitutive equations of impact process with FEM, expound detailedly the basic theory and solving process of nonlinear finite-element-method which has better performance at solving impact problem. It is suggested that nonlinear finite element mechanical equations set could be solved by explicit difference method and the contact under impact loading is treated with penalty function method.Secondly, by means of large-scale computational and commercial software, namely, ANSYS/LS-DYNA, two FEM impact models ofthe aluminum beams both with CFRP strengthened structures and without under the transverse impact loading have been established. And then, the internal stress, the strain and deformation, and impact energy absorption at every moment during impact process are obtained by FEM solutions. The results show that the impact absorption energy of the aluminum alloy beams reinforced with CFRP could be more effectively increased so that the corresponding displacement could be decreased effectively than that of the aluminum beams without CFRP. Comparing the current results to the experimental research in [18], it shows that the impacted deformation and corresponding dynamic characters of the aluminum alloy beams strengthened with CFRP are in good agreement with that of the experimental data.Finally, the influences of wall thickness are investigated. By means of setting different wall thickness of ABC and that without CFRP through APDL command parameter, the relations between the impacted deformation and wall thickness are obtained as well.In summary, FEM based numerical simulation is an effective way not only in design of ABC structures but also in analyzing the impact response of other FRP strengthened structures. Furthermore, the current study is expected to provide an actural significance and common guideline in structure design problems under impact loading, such as lightweight vehicle frame design.更多还原