Composites with high work of fracture

Abstract

Results obtained when investigating the fracture behaviour of wood have suggested the possibility of making composite materials with high work of fracture and low density, at the expense of moderate loss of stiffness. The reinforcing elements of the composite are made in the form of cylindrical tubes with helically wound walls of glass or carbon fibres, simulating, to a certain extent, the structure of wood cells. The hollow tubes, under tensile stress and in certain circumstances, are capable of deforming pseudo-plastically absorbing large amounts of energy in a manner which is effectively similar to that of ductile fibres Work of fracture in excess of 4 x 10 ⁵ J/m ² has been obtained, comparable to that of ductile metals. The dependence of the work of fracture on various parameters will be discussed together with some suggestions for compensating for the loss of stiffness without reducing the energy absorbing capacity of the system.