Experimental and numerical study on static and dynamic axial crushing of square aluminum tubes: Effects of cutouts

The collapse of tubes under axial load is an important subject from the safety point of view, particularly in the design of energy absorbing devices used in many engineering applications. In this study, quasi-static and dynamic experiments were carried out on square thin-walled aluminum extrusions to investigate the effects of circular holes. Cutouts were introduced in the four corners of the square-section tube, not far from the end boundary of the tube, in order both to decrease the first peak load on the load-displacement characteristic and to control the collapse mode. Different aspects, such as the buckling modes and the energy absorption in quasi-static axial crushing tests, as well as dynamic effects and material rheology contributions in dynamic crushing tests, have been examined. For the dynamic tests, the parameters were the impacting mass and its velocity. The results showed a drop in the first peak function of the openings’ radius and the tube’s energy absorption capacity was kept. A comparison between static and dynamic tests results was carried out and the interpretation of the results in terms of deformation mechanism and energy absorption was discussed. Numerical simulations with the finite element code ABAQUS were conducted to confirm the experimental findings. The results of different numerical models, implicit and explicit calculations, that contribute to a basic understanding of the buckling and prediction of the crash behavior of the aluminum components without and with the cutouts are presented.

Energy Absorption Characteristics of a CFRP-Al Hybrid Thin-Walled Circular Tube under Axial Crushing

Thin-walled tubes have gained wide applications in aerospace, automobile and other engineering fields due to their excellent energy absorption and lightweight properties. In this study, a novel method of entropy-weighted TOPSIS was adopted to study the energy absorption characteristics of a thin-walled circular tube under axial crushing. Three types of thin-walled circular tubes, namely, aluminum (Al) tubes, carbon-fiber-reinforced plastics (CFRP) tubes and CFRP-Al hybrid thin-walled tubes, were fabricated. Quasi-static axial crushing tests were then carried out for these specimens, and their failure modes and energy absorption performance were analyzed. The CFRP material parameters were obtained through tensile, compression and in-plane shear tests of CFRP laminates. The finite element models for the quasi-static axial crushing of these three types of circular tubes were established. The accuracy of the finite element models was verified by comparing the simulation results with the test results. On this basis, the effects of the geometric dimension and ply parameters of a CFRP-Al hybrid thin-walled circular tube on the axial crushing energy absorption characteristics were studied based on an orthogonal design and entropy-weighted TOPSIS method. The results showed that Al tube thickness, CFRP ply thickness and orientation have great effect on the energy absorption performance of a CFRP-Al hybrid thin-walled circular tube, whereas the tube diameter and length have little effect. The energy absorption capability of a CFRP-Al hybrid tube can be improved by increasing the thickness of the Al tube and the CFRP tube as well as the number of ±45° plies.