Axial Crushing Experiment Study And Theoretical Analysis Of Foam-filled Thin-walled Structures Under Quasi-static Compression

Thin-walled aluminum alloy(A1 alloy)structure,carbon fiber reinforced plastics(CFRP)tube,aluminum foam(Al foam)and polyurethane foam(PU foam)all can be used as good energy absorbers in automobile,aviation and other industries for their light weight and high energy absorption capacity.Many experts and scholars have studied many aspects of PU foam,CFRP,Al foam and Aluminum Alloy,found foam-filled thin-walled structure is capable of absorbing structure potential in the car collision.First of all,different fiber materials,light alloy materials,the aluminum foam of different density,polyurethane foam of different density and other lightweight materials have been made extensive investigation,choosing CFRP,hard Aluminum Alloy,functional density gradient Aluminum foam and rigid polyurethane foam as the research category.Based on the national standard,the mechanical properties of these materials were tested,and the mechanical properties of the materials were obtained.Secondly,according to the collision energy absorption index,this paper designed tapered structures.In order to clarify the advantages of the design modes,this article studies the crushing behaviors of CFRP,Al alloy tapered tube and their foam-filled structures subjected to quasi-static axial compression.Analyzes and compares the collapse modes and force-displacement curves of these investigated structures.Calculates the energy absorption(EA)and the specific energy absorption(SEA)of these investigated structures.Experimental results show that the CFRP tapered tubes have higher SEA than that of the Al-alloy tapered tubes and the circular CFRP tubes filled with PU foam have better energy absorption capacity than that of the square and hexagonal structures.Then,the study find that the total energy absorption of foam-filled thin-walled structure is higher than that of the corresponding separate thin-walled structure and foam alone structure combined.As a result,the energy absorbing effect between the hollow A1 alloy tubes and Al foam-filled structures are compared in detail.Finally,based on the deformation mode of the PU foam-filled the CFRP structures,the mechanical model of the structure are established.For CFRP,the main energies may assumed to be:energy required to bend the fiber layers outside the shell radius(Wb),energy required to strain the material in the circumferential direction(Wh),energy required to crack the matrix in the vertical direction of the shell wall(Wm)and the energy dissipated due to friction between crushing platen and petals(Wf).The stress-strain curves of PU foam under quasi-static compression is fitted,and the formula of the energy absorption of the circular section foam is deduced.