Elastic-plastic stress distribution within reinforced plastics loaded normal to its internal filaments.

Two sets of equations have been derived which describe the internal stress distribution within reinforced plastics subjected to a force normal to the direction of its internal filaments. One set of equations is applicable to reinforced plastics with less than 68% filament by volume and the other to reinforced plastics with more than 68% filament. Each set is applicable over a complete range of loading which includes both elastic and plastic stresses. It is found that when reinforced plastics have less than 68% filament by volume only one plastic zone develops in a generic section before the cross section becomes entirely plastic. Additional plastic zones develop when reinforced plastics have more than 68% filament by volume. A simple expression for the elastic stress concentration factor was also found.