Investigation On The Dynamic Response And Deformation Mechanism Of Thin-walled Square Tube Subjected To Impact Loading

Thin-walled structure is widely used in automobiles, trains, aerospace and otherfields, depending on its advantages of good energy absorbing properties, light weight,simple techniques and low cost. As energy absorbing components, the thin-walledstructure can effectively absorb the impact kinetic energy and reduce the impactacceleration in the process of collision. However, stress wave propagation has anobvious effect on the initial deformation of thin-walled structure. It is impossible tocontrol the damage of the thin-walled structure effectively due to the lack of researchon the mechanism of stress wave. Therefore, it is of scientific research significanceand engineering application value to investigate the responses of thin-walledstructures under dynamic axial load and the effect of stress wave propagation isanalyzed. In this paper, thin-walled square tubes are the main research objects. Theaxial experiments and numerical simulation are conducted. The destructionmechanism of thin-walled square tubes is studied and the effects of stress wavepropagation, impact velocity and loading condition on the initial deformation isanalyzed. The relationship of the initial deformation and the final failure mode is alsodiscussed. Specific as follows:Firstly, the split Hopkinson pressure bar is used to carry out the dynamiccompression experiments of thin-walled square tubes under the action of stress wave.The buckling process and failure mode of square tubes in different conditions areobtained. The corresponding numerical simulation with the experiment is carried outand the results of experiment and simulation are compared. It is evident that the FEmodels are validated. Then the effect of stress wave propagation on the bucklingprocess is studied. The destruction mechanism of thin-walled square tubes under theaction of stress wave is revealed.Secondly, the dynamic compression experiments of square tubes constrained onrigid wall are carried out on the improved SHPB. The buckling process and failuremode of square tubes in different conditions are obtained. The numerical simulationmodel corresponding with experiment condition is established. The reliability of thenumerical simulation model is proved by comparing the results of experiment andnumerical simulation. The effect of impact velocity on the failure mode of thin-walledsquare tube is studied and the destruction mechanism of thin-walled square tubeconstrained on rigid wall is revealed. Finally, more numerical simulation of the axial dynamic compression ofthin-walled square tubes is conducted. The effect of impact velocity and loadingconditions on the dynamic buckling of thin-walled square tube is analyzed. Theresults show that, the impact velocity plays an important role in the initial damagelocation, and the compression quantity increases with the impact velocity increase;the effect of stress wave, which can affect the position of initial deformation, can beenhanced by using SHPB. The effect of initial deformation on the failure mode isdiscussed and it is found that the location of the initial deformation determines thefailure mode of thin-walled square tubes.