Engineering Life Prediction of Composite Materials: Elements of a Mechanistic Model

Abstract

It is the practice in engineering to attempt to avoid problems that we do not understand; such is frequently the case for damage development in composite materials. The prudent designer prescribes design strain levels low enough so that damage development is thought to be precluded. However, something should be known of damage development if it is to be avoided, and the basic question of how long a particular structure will last cannot be answered without some understanding of damage development in composite materials. As new material systems and applications are developed and as old ones are further exploited, a more and more precise understanding of damage development will be required. What is needed is a rational analysis that can be used to describe and explain damage development in composite laminates so that we can anticipate their residual strength, stiffness, and life under engineering conditions. In general, this requires a replacement for the single-crack problem (and fracture mechanics) in homogeneous isotropic materials.