Energy absorption of sine wave beams subjected to axial impact loading

Structural impact is an area of research that has become very important in today's society, specifically in transportation systems. Use of energy absorbers as devices to absorb impact energy has been, and continues to be the focus of extensive research. The goal of energy absorber design is to create an absorber that will remove kinetic energy from the system in an efficient and reliable way while not imposing high force magnitudes on the moving body. Until now, the structural response of energy absorbers under an impact loading has concentrated on thin-walled prismatic structures, such as square and cylindrical tubes, as well as thin-walled tapered tubes. The sine wave beam has been previously investigated as an energy absorber under lateral impacting situations, however had yet to be studied under the axial impact loading condition. The aim of this thesis was to investigate the structural response and resulting energy absorbing performance of the sine wave beam subjected to axial impact and to compare this performance to that of previously considered thin-walled prismatic designs. Detailed finite element models were created and subsequently validated using existing theoretical and numerical models. These FE models were used to simulate the response of the sign wave beam and prismatic structures undergoing an axial impact. A parametric analysis was performed using the thickness of the upper and lower flange plates and the web, the amplitude of the sine wave web, and the number of sine wave periods along the length of the beam. The results show that the energy absorbing performance of the sine wave beam is affected greatly by the thickness of the structural components. Additionally, the web amplitude and period number play a vital role in the structural response and resulting energy absorption exhibited by the structure. Comparing the sine wave beam to typical prismatic tubes, advantages can be observed. The force felt by the impacting body is less for all of the sine wave beams than for any of the prismatic structures, when absorbing the same amount of kinetic energy. The sine wave beam also has greater stroke efficiency than the typical prismatic structures. The results indicate that larger number of design parameters in the sine wave beam therefore allows effective control over the crush deformation and resulting energy absorption compared to the prismatic absorber designs.