Abstract
Composite materials inherently exhibit scatter in their basic characteristics such as the mechanical properties of constituent materials, fibers orientations, ply thicknesses, and applied loads. The uncertainties present in the basic parameters are available, in most cases, in the form of ranges or intervals. The use of the existing deterministic failure theories, which do not consider the observed variabilities in the input parameters, leads to poor failure assessment of composite materials. Several probabilistic failure models have been proposed in the past few decades. However, the probabilistic methods require a knowledge of the probability distributions of the basic variables which are not available in most practical systems. This work, for the first time, presents an interval-based failure analysis of composite materials using the truncation-based interval analysis and the universal gray system theory. These methods require only the lower and upper bounds of the uncertain parameters which are available in most practical systems. The application of the proposed interval-based failure models is demonstrated by considering two types of graphite/epoxy laminates: [0/±45/90]
S
and [0/90]
2
. This work shows that more realistic and meaningful failure assessment can be made using the universal gray system theory and the truncation-based interval analysis compared to the deterministic failure analysis.