Study On Energy Absorption Characteristics Of Thin-walled Square Tube Of Composite Under Axial Compression Load

Due to their high specific strength,high specific stiffness and outstanding design-ability characteristic,the composite materials have been largely used in aerospace,transportation and architecture.However,as an automotive energy absorbing components,the application of composite thin-walled structures in aircraft is very limited,mainly due to the lack of accurate and reliable prediction models.With previous research on energy absorption characteristics of composite thin-walled structures under quasi-static axial compressive loads,few people can accurately simulate the failure morphology,energy absorption characteristics and load-displacement response.To study the energy absorption characteristics and mechanism under quasi-static axial compression load,the experiment and simulation of T700/3234 composite thin-walled square tube were done.Then study server factors of composite thin-walled square tube based on numerical simulation technology.The specific research contents are as follows:Firstly,composite thin-walled square tubes with three different layups([±45]_3s、[0/90]_3s、[±45/0/0/90/0]_s)were designed and fabricated,and quasi-static axial compression tests were carried out.The failure morphology,load-displacement curves and energy absorption mechanism during axial compression failure process were analyzed The relationship between stability and failure mode of composite thin-walled square tubes under axial compression was discussed.The effects of ply layup on the energy absorption characteristics of composite thin-walled square tubes were analyzed by investigating the initial peak load,average compression load,specific energy absorption and load efficiency.Secondly,the"single-layer shell","multi-layer shell"and"stacked shell"model of[±45]_3sspecimen were studied.The models were evaluated by comparing the failure morphology and load-displacement curve with the test.The"stacked shell"model has good consistency with the test in terms of failure morphology,average crushing load and specific energy absorption.And then the“stacked shell”model of[0/90]_3s、[±45/0/0/90/0]_s specimen were established and studied.Finally,the effect of the initiation method on the energy absorption characteristics of the composite thin-walled square tube was investigated.The"stacked shell"model of[0/90]_3ss specimen with different“concave-convex stages”as well as platen with different tips was established,and axial compression simulation analysis was carried out.The failure topography and load-displacement curves of the axial compression process were compared and analyzed.The result show that the platen with tips can reduce the initial peak load and lead the structure to a progressive and controllable crushing process by avoid the unstable buckling.It can also increase the specific energy absorption.