Spinning Process And Energy Absorption Characteristics Of CFRP/aluminum Hybrid Tubes

Fiber composites/metal hybrid tubes combine lightweight and high-strength of fiber composites with low-cost and ductile of metal,which not only improve the energy absorption performance of the whole structure,but also have significant lightweight effect.However,the hybrid tubes suffer difficulty in forming.The current process could not solve the problem of interlayer bonding,resulting in single hybrid structure configuration.Meanwhile,the energy absorption characteristics and mechanisms of the hybrid structure are complicated.In this work,the 2/1 structure carbon fibre reinforced plastics(CFRP)/aluminum hybrid tube was prepared by power spinning process.Then the effect of the process on the interlayer bonding performance was explored.The energy absorption characteristics of the hybrid tube were studied by quasi-static axial crushing test.Also,finite element simulation was employed to predict the energy absorption characteristics of the hybrid tubes under quasi-static axial crushing and multi-angle impact facing the actual collision environment and the energy absorption mechanisms were revealed by combining experiment and simulation.Firstly,the 2/1 structure CFRP/aluminum hybrid tube was successfully prepared using power spinning process.The corresponding forming and processing method were established by the parameter optimization during the surface treatment,spinning and processing..The CFRP/aluminum hybrid tube showed good forming quality under 3-pass power spinning process with spindle speed of500r/min,rotary feed of 0.3mm/r and thinning rate of 30%.The power spinning process effectively improved the interlayer bonding performance of the hybrid tube.The interlayer lamination defects were reduced and the interlayer bonding performance was distributed stably along the axial and radial directions of the tube.The average interlayer shear strength was up to 31.0Mpa,which was nearly 75%higher than that of the assembling hybrid tube without spinning forming.Secondly,the energy absorption characteristics of the 2/1 structure CFRP/aluminum hybrid tube based on power spinning were studied by quasi-static axial crushing test.The assembling 2/1 structure CFRP/aluminum hybrid tube without spinning forming and 1/1 structure hybrid tube were also involved to explore the energy absorption characteristics of the hybrid structure under different interlayer bonding performance and structure configuration.Results indicated that the hybrid structure based on spinning forming outperformed all hybrid structures in specific energy absorption capacity(39.2 k J/kg)and crushing force efficiency(0.64).The inner aluminum layer showed diamond mode while the outer one showed concertina mode.The CFRP layer showed progressive failure mode with sufficient fragmentation.The mean crushing force of the 2/1 structure hybrid tube was calculated by the axial crushing analytical model,and the error between the calculated value and the test value was about 13%.Thirdly,the finite element models of the CFRP/aluminum hybrid tubes were established through ABAQUS/Explicit and VUMAT subroutines based on multi-layer solid element and 3d-Hashin failure criterion.The prediction of energy absorption characteristics of the hybrid tubes under quasi-static axial crushing and multi-angle impact facing the actual collision environment were realized.The predicted results under quasi-static axial crushing involving force displacement curves,deformation failure modes and energy absorption indicators agreed well with the experiments.The predicted results under multi-angle impact showed that the increase of axial loading rate and impact loading angle(0?20°)would lead to the transformation of the hybrid tube from concertina mode to irregular diamond mode and the energy absorption performance would decrease.However,the hybrid tube had a minimum reduction in specific energy absorption capacity and could maintain relatively stable crushing force efficiency compared with corresponding single tubes.The effect of impact loading angle on energy absorption performance weakened.Finally,the energy absorption mechanisms of the CFRP/aluminum hybrid tubes under quasi-static axial crushing and multi-angle impact were revealed by experiments and simulations.It was found that the development of delamination failure between layers of the hybrid structure during crushing was bound to dissipate energy.The more adequate damaged CFRP layer was identified in the hybrid structure under the effect of inner and outer aluminum layers and interlayer bonding.The CFRP and aluminum layers contributed more internal energy in the hybrid structure during crushing than the corresponding single structures.The combination of these conditions made the hybrid tube possessed the most excellent energy absorption characteristics and 21% higher energy absorption than the sum of corresponding indicidual parts.With the increase of axial loading rate and impact loading angle,the damage degree of the CFRP layer in the hybrid structure decreased,resulting in the energy absorption performance of the hybrid tube decreased.However,the configuration advantage of the hybrid structure avoided unstable Euler mode,and was more favorable for the CFRP layer to play a bearing and energy absorption role in multi-angle impact than single structures.Consequently,the effect of impact loading angle on energy absorption performance weakened.