A fracture control plan for composite structures

A fracture control plan for composite structures is proposed. Such a plan provides for a fail-safe approach to the design of composite primary structures. It integrates inspection techniques with proof testing to define the minimum flaw that can exist in a structure without failure. While crack propagation of a general flaw in composites is a complex problem, a specific flaw such as delamination is a common failure mode in typical engineering laminates. Using linear fracture mechanics, it is relatively straightforward to calculate the tendency for a delamination flaw to propagate. This approach, coupled with appropriate inspection techniques, constitutes the basis of the proposed plan. Currently, no fracture control plans exist for composite structures. The proposed plan is envisaged as a first step toward assuring the design of damage-tolerant composite structures.