STUDIES ON THE EFFECT OF AN EXTERNAL FLAW ON THE TENSILE-STRENGTH OF SHORT KEVLAR FIBER THERMOPLASTIC POLYURETHANE COMPOSITES

The effect of an external flaw on the tensile strength of short kevlar fiber-thermoplastic polyurethane (TPU) composites has been studied with respect to fiber content, fiber orientation, location of the external flaw, and the temperature of test. The composites showed a three-step reduction in tensile strength with increasing flaw size. The critical flaw-length region was shifted to higher flaw-size levels with increasing fiber content. With increasing temperature, the critical flaw length was increased in the case of unfilled TPU, whereas it remained more or less constant in the case of short kevlar fiber-filled-TPU composite.