Random glass mat reinforced thermoplastic composites. Part II: Analysis of model materials

The mechanical properties of random continuous glass mat reinforced composites, as determined by standard tensile tests, are known to have a very large scatter. New test procedures have shown that the tensile modulus in these materials can vary by a factor of two over a 12.7‐mm (½‐in) distance. The elastic modulus in a 150 × 305‐mm (6 × 12‐in) plaque can vary by a factor of three. In order to understand the effects of the gauge length on the properties of such materials measured in tensile and flexural tests, a simple model, in which the tensile elastic modulus is modulated by a spacewise sinusoidal variation, has been analyzed. The effect of the functional form of the modulus variation has been assessed by analyzing a square‐wave variation.