Development of a Prediction Tool for Strength and Life of Composites Structures

Abstract

An advanced strength and life prediction tool, MAE, was developed for the analysis and design of composite structures and components. The MAE integrates three theories and methods: micromechanics of failure (MMF), an accelerated testing method (ATM) and an evolution of damage (EOD). The MAE can serve as a useful tool to predict damage initiation, progression and life under various durability loading and environmental conditions. It can handle the inhomogeneous complex geometries and structural components such as open-hole, filled-hole, bonded/bolted joint, stiffened panel, textile, etc. Therefore, it can help select not only the material and laminates but also optimal geometrical configurations. The MAE modules were implemented and integrated with a commercial finite element software, Abaqus, for better reliability and maintainability. Several examples of strength and life predictions of open-hole and double-edge notched specimens demonstrated the capability of the MAE as an advanced tool for the composite durability design. Nomenclature i t = time at the i-th step i t ∆ = subtime segment f E = stiffness of fiber constituent m E = stiffness of matrix constituent f v = volume fraction of fiber T ∆ = difference between operation and cure temperatures c = moisture content f t = time to failure ) (e f t = time to failure for an element (e) i D = damage fraction at time i t ) ( ) ( i e t D = partial damage fractions at time for an element (e) i t 1 I = first invariant of microstress vM σ = von Mises microstress σ