Damage and failure analysis of bolted joints in composite laminates

Abstract

Composite materials have gained popularity in high-performance products that need to be lightweight, yet strong enough to take high loads. Their adoption as a major contribution to aircraft structures followed on from the discovery of carbon fibre at the Royal Aircraft Establishment at Farnborough, UK, in 1964. Bolted joints are needed to fasten highly loaded composite components to other composite or metallic parts. They are easy to assemble and can be disassembled when required for inspection and/or maintenance purposes without imparting damage. Generally, the determination of local stress distribution in a bolted joint is a three-dimensional problem due to bending effects and clamping of the fastener. The stress state in the vicinity of a bolted hole depends on many complex factors such as friction properties of the members, contact problem, geometry and stiffness of the joined members, joint configuration, clamping force and loading conditions. To precisely include all these factors in a stress analysis of a joint based on conventional analytical methods is extremely cumbersome. Analytical and numerical models developed during the last 50 years to describe damage accumulation and final failure are discussed in this chapter.