AN INTEGRATED APPROACH TO DESIGN AND MONITOR COMPOSITE STRUCTURES UNDER IN-SERVICE FATIGUE LOADINGS

摘要

Fatigue failure and in-service loss of stiffness of composite parts are due to a multi-mechanism damage evolution which mainly includes cracks, delamination and fibre failures. This works presents an innovative, comprehensive framework for the fatigue design of composite parts, based on the actual physics of damage evolution. The initiation and growth of each mechanism, its interaction with the others and the effects on the strength and stiffness of the parts are described by suitable models and experimentally validated. The combination of all these models into a single design framework provides a highly innovative design tool as well as an enormous increase in the safeness and reliability of the structural applications in composites. The in-service reliability and safety of these parts can be further improved by using a new structural health monitoring methodology. This methodology, based on the exploitation of the self-sensing capabilities of conductive nano-modified laminates, allows the continuous assessment of the damage state and the correlation of its evolution with the residual elastic properties of the composite parts. Damage induced by unexpected events can be also monitored.