The crush behavior of glass fiber reinforced plastic sections

Abstract

The crush response of glass fiber reinforced plastic tubes, of cylindrical, square and rectangular section, made from unidirectional tape with various alternating 0° and 90° lay-ups, and also of small samples cut from these tubes, was studied with particular reference to the effects of the geometry of the crush trigger initiator. It was found that the propagation of delamination cracks contributed little to the energy absorption capacity, most of the crush resistance being derived from the development of kink bands in the fiber structure. The crush resistance of square tubes with thinner walls was largely provided by the corners. As the wall thickness increased, the planar portions contributed more to the crush resistance. Approximate estimates of the specific energy may be made from crush tests of simple flat sections. The trigger geometry alters the energy absorption capacity by the extent to which it generates deformation flaws which can then propagate within the wall structure. Softer crush anvils reduce the effectiveness of the trigger crush initiator and can lead to global failure of the section, rather than to stable, progressive crush.