Studies Of FEM Impact Simulation And Its Deformation Resistance Analysis Against Shock On CFRP Strengthening Beams

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.