Research On Energy Absorption Characteristics Of CFRP Aluminum Alloy Hybrid Tubes

The rapid development of the automobile industry and the frequent occurrence of traffic accidents have made automobile safety a focus of people’s attention.With the increase of car ownership,social problems such as energy and environment are becoming more and more prominent,and automobile lightweight has become the development trend of automobile in the future.In recent years,Carbon Fibre Reinforced Plastic(CFRP)has been gradually applied in the automotive field to meet the requirements of lightweight and crashworthiness of automobiles by virtue of its advantages of light weight,high strength,high designability and strong specific energy absorption ability.However,CFRP also has many problems,such as high brittleness,failure instability and high cost.More and more research is turning to the hybrid structure of CFRP and metal,which can meet the higher and higher energy absorption demand of automobiles in the future,and also can greatly reduce the weight of energy absorption components.Therefore,the study of energy absorption characteristics of this new structure has important engineering application value.In this dissertation,the axial energy absorption characteristics of CFRP aluminium alloy hybrid tube are studied by theoretical simulation and experimental method,and the effects of different factors on its energy absorption characteristics are discussed,which provides a reference for the structural design of hybrid energy absorption structure.The main research contents are as follows:Based on the mechanics of composite materials and damage mechanics,combined with the mechanical properties and failure modes of composite materials,the corresponding failure criteria and performance degradation criteria for intralaminar and interlaminar damage of composite materials were determined,and the progressive damage model of composite materials for axial crushing of CFRP aluminium alloy hybrid tubes was established.The finite element model of axial crushing of CFRP aluminum alloy hybrid tubes was established in ABAQUS.The axial crushing process and energy absorption characteristics of CFRP aluminum alloy hybrid tubes with rectangular,square,hexagonal,octagonal and circular cross-section shapes were compared and analyzed.The results show that the Fmax,CFE and SEA of the hybrid tubes increase gradually with the increase of the number of sides.While the SEA and CFE of the circular section are the largest,and the octagonal section is the closest to the circular section.Based on the finite element model of axial crushing,the effects of the thickness ratio of aluminum alloy to CFRP(tm/tc),the number of layers,the angle of layers and the ratio of axial fibers to circumferential fibers on the energy absorption performance of CFRP aluminum alloy hybrid tubes with circular cross section were studied.Research shows:(1)When the thickness ratio of aluminium alloy to CFRP is close,it will bring higher SEA.(2)The increase of the number of layers can effectively improve the energy absorption and crushing efficiency,but the SEA will decrease if the number of layers is too large.(3)Small angle layers near the axial direction will bring larger initial load peak,while large angle layers near the circumference will help to improve SEA and CFE.(4)Tubes with cross-laminations of large and small angles can absorb more energy than single-angle ply.CFRP aluminium alloy hybrid circular tube specimens with different geometric parameters and stacking schemes were designed and manufactured,and quasi-static axial compression tests were carried out respectively.The process of axial compression,failure mode and energy absorption mechanism were analyzed.The experimental results are compared with the simulation results.The results show that: the simulation deformation mode is similar to the test,and the error of Crashworthiness evaluation index is less than 10%.,thus proving that the effects of different factors on energy absorption characteristics of CFRP aluminum alloy hybrid tubes obtained from simulation are reliable.