An experimental and numerical study of notch sensitivity of ARALL laminates

Abstract

The primary objective of this study was to investigate the notch sensitivity of ARALL 2 and ARALL 3 laminates subjected to uniaxial tensile loading. An experimental program was designed to test notched 0° and 90° ARALL specimens with three different hole diameters, 0.125 in, 0.250 in, and 0.500 inches. Unnotched specimens were tested to determine the elastic properties, including the shear modulus of of the ARALL laminates. Comparison of ARALL 2 and ARALL 3 laminates has shown that ARALL 3 laminates exhibit higher strength than the corresponding ARALL 2 specimens. Based on the experimental observations, a failure mechanism has been proposed for notched ARALL laminates. The failure of 0° ARALL laminates is governed by fiber failure in the aramid/epoxy layer.

Experimental results for the off-axis elastic properties are compared with the predictions from transformation equations. Finite element analysis of notched laminates was performed in order to gain a better understanding of the experimental results. A linear analysis was found to be unsuitable for predicting the complete response of ARALL laminates. A Successive Yielding Model was used for modelling the behavior of the ARALL laminates. Predictions of this Successive Yielding Model are in excellent agreement with experimental results. Finite element analysis was also used to study the end effects and for establishing the specimen geometry.