Investigation of residual strength of composite laminates subjected to oblique indentation

Abstract

The primary objective of this research work is to study the oblique indentation damage resistance in composite laminates, since indentations or impact taking place in actual in-flight scenarios may not necessarily be normal to the plane of the structural elements. In order to achieve this, the effect of fiber orientation, indentation depth and filler material on delamination behaviour of GFRP laminates and hybrid laminates subjected to oblique indendation are investigated. Cyclic indentation response of GFRP laminates in oblique plane are studied with AE monitoring. The post-impact residual properties of the composites laminates have been evaluated by compression after indentation tests. In order to evaluate the in-service behaviour of the impact-damaged composites, acoustic emission activity was monitored during indentation tests and Compression tests. In this Thesis, a short introduction on Composite materials, QSI testing, AE techniques, indentation damage resistance characterization methods are summarised. The most relevant published literature on all aspects of AE technique to characterize the failure modes and indentation damage resistance in laminated composites are reviewed. Novel inclined indentation testing fixture has been designed and developed exclusively for this research work has been explained. newline