Response of a circular metallic hollow beam to an impulsive loading

A model of the dynamic response of a relatively long circular hollow section beam to a uniform blast modeled as an impulsive loading is developed in order to reveal the characteristic features of deformation and energy absorption of hollow section beams under such loading. A two-phase analytical model is proposed for a circular metallic hollow beam made of a strain-rate insensitive material. Both local and global deformations build up simultaneously during the first phase, and then only global bending occurs during the second phase. Because mainly large plastic deformations develop in the hollow section, the elastic deformations are neglected and a rigid-plastic method of analysis is applied. The responses of circular hollow beams with lengths between 600 and 1000 mm are analyzed for beam radii varying between 50 and 70 mm and wall thicknesses between 1.2 and 1.6 mm. The model predictions are verified by numerical simulations and reasonable agreement is observed with respect to the characteristic displacements and deformed section shape. The energy partitioning during the deformation process is briefly discussed.