Quasi-static axial crush response of a thin-wall, stainless steel box component

Abstract

An experimental investigation was performed on the quasi-static, symmetric axial crush response mode of commercially-produced, welded AISI 304 stainless steel square box components. The first objective was to demonstrate that a specific configuration response consisting of a fold formation process and the corresponding load–displacement curve could be obtained using experimental control methods. Test specimens from a single length of tubing were examined in a progressive axial crush study, and the controls included removable grooved caps for end constraints, and shallow machined groove patterns on specimen sidewalls for collapse initiators. Consistent fold appearance and load–displacement curve shapes indicated that ten of the eleven test specimens exhibited the same symmetric, axial crush configuration response. During the first cycle of the secondary folding phase, observed differences on an average value basis were less than or equal to 3% for maximum loads, 6% for minimum loads, and 3% for energy absorption. The second objective of this investigation was to isolate the effect of alloy composition and microstructure on the axial crush configuration response. A higher concentration of carbon and smaller grain size resulted in an 18% increase in energy absorption in a secondary folding phase cycle. Overall, the results show that response can be restricted to a specific axial crush configuration response and therefore, a controlled and repeatable energy absorption process can be obtained and modifications to alloy composition and microstructure can be used to enhance energy absorption performance of the box component.