Study On The Energy Absorption Of Lightweight Composite Thin-walled Structures

Thin-walled metal structures have very good energy absorbing performance and are widely used as an energy absorbing members in engineering fields.Lightweight composite thinwalled structures constituted by thin-walled metal structures enhanced by metal,fiber reinforced composites or cellular materials are expected to get much better energy absorption performance and efficiency.In this paper,the axial crush behaviors of three types of composite thin-walled structures,including multi-cell self-locking thin-walled structures,composite reinforced thin-walled structures,and foam-filled thin-walled structures,are studied.By using experimental,numerical and theoretical methods,the energy absorption characteristics,enhancement mechanisms and theoretical prediction methods of the related composite structures are obtained.Firstly,a type of multi-cell self-locking thin-walled structure composed of open sections is proposed.This type of structure has the advantages of easy preparation,low cost,flexible dimensions and cross-section.By performing axial quasi-static and dynamic loading tests,the energy absorption characteristics of the multi-cell self-locking structure were investigated,and the effects of various influencing factors were analyzed by using finite element method.The energy absorption capacity of the whole structure is effectively improved due to the interaction and self-locking of the components in the deformation process.Based on theoretical analysis,the theoretical formula of the static and dynamic mean crushing force is derived and is in good agreement with the simulation results.Secondly,carbon fiber reinforced plastic(CFRP)were used to enhance the aluminum alloy single-cell and multi-cell tubes.The static and dynamic experiments and numerical simulation were carried out to study the energy absorption characteristics of the specimens under axial loading conditions.On the basis of the experimental and numerical simulation methods,the effects of cross-section shapes,wall thickness,the number of carbon fiber layers and etc.on the energy absorption characteristics of the composite reinforced thin-walled structures are obtained.The results showed that the more layers of carbon fiber reinforced materials,the better the energy absorption enhancement effect.Due to the high energy absorption efficiency of the multi-cell tube itself,the enhancement effect of CFRP on the multi-cell structure is not as good as that on the empty tube.Finally,the energy absorption properties of aluminum alloy tubes filled with polyurethane foams and Expanded Polystyrene foams(EPS)were studied in both quasi-static and dynamic axial loading.Results showed that for such low-strength foam filling,the energy absorption offered by the interaction effect between foam and tube is about equal to that of the foam itself.In addition,polyurethane foams have a better filling effect than EPS foams.The same filling material has a higher energy absorption efficiency for the multi-cell tube than the single-cell tube.The research on these three types of lightweight composite thin-walled structures provides a good theoretical basis and novel design ideas for further improvement of lightweight and efficient thin-walled energy absorbing components.