Dynamic plastic deformation of hexagonal frames

Abstract

The dynamic plastic response of a hexagonal frame to an internal pressure pulse of arbitrary shape is analyzed, including large-deformation geometric effects that result in redistribution of the bending and membrane reactions. Peak pressures of several multiples of the static yield load are considered, and the frame material is assumed to be rigid perfectly plastic. The effect of pulse shape on final plastic deformation is determined by numerically solving the governing sets of differential equations for a variety of parameter combinations. In the small deformation range, the permanent plastic deformation is shown to be dependent on an effective pressure, defined in terms of the first moment of the pressure pulse; the response duration is proportional to the pulse duration. In the large deformation range, the permanent plastic deformation is a function of the average pressure applied during the response, and the response duration depends on a characteristic time constant which is a function of material properties and hexagon size.