Impact strength of thin-walled composite structures under combined bending and torsion

Abstract

The effect of bending and torsional stresses on the fracture characteristics of thin-walled square, rectangular and circular cylindrical structures has been investigated under static and impact loadings by use of the apparatus capable of applying bending and torsional moments in various proportions. The thin-walled structures were fabricated from glass-fiber strand, chopped strand mat and unsaturated polyester resin. Comparisons between experimentally determined strength and theoretical predictions using the failure criteria are presented. As a result of this investigation, the existence of the relation between the fracture mode and the strength was recognized and the failure criteria examined could be used successfully to predict the combined impact bending and torsional strength of thin-walled composite structures.