Influence of material strain hardening on energy absorption of axially loaded steel tubular members via first wrinkling mechanism

Experimental investigations have revealed that the crushing response of axially loaded tubular metallic members changes significantly depending on the strain-hardening capacity of the material. In this paper, the post-yield response of axially loaded stainless-steel and mild-steel tubes are examined under quasi-static loading from the perspective of deformation-controlled and force-controlled collapse mechanisms. The rotational instability of the plastic hinges developed along the tubes is traced numerically by considering an isolated plastic hinge model selected at the critical length of the tubes' shell. The characteristics of the hinges are probed using the moment-rotation diagrams. The stress profiles in the critical region of the tubes at various loading states are investigated. It is observed that the tubes' stability and energy absorption capacity are significantly dependent on the strain-hardening capacity of the material exploited during the formation of the plastic hinges.