Modeling the Effect of Damage in Composite Structures: Simplified Approaches

Chapter 1Damage in Composite Structures: Notch Sensitivity

1.1 Introduction

Owing to its construction, where two basic constituents, fibres and matrix, are combined, a composite structure shows a wide variety of types of damage. Damage may be specific to one or both of the constituents or involve interaction of the two. Furthermore, depending on the scale over which phenomena are described, damage may have different forms ranging from micro-voids or inconsistencies and cracks of the fibre/matrix interphase to large-scale delaminations, holes and laminate failures.

Here, the emphasis is placed on damage that is no smaller than a few fibre diameters with the understanding that this damage most likely is the result of creation and coalescence of damage at smaller scales, which are beyond the scope of this book. Within this framework, the most common forms of damage are matrix cracks, fibre/matrix interface failures, fibre failures, through-thickness failures (holes and cracks) and inter-ply failures such as delaminations. Of course any combination of these may also occur as in cases of impact damage. Representative forms of damage and their corresponding scales are shown in Figure 1.1.

Figure 1.1 Typical damage at various scales of a composite structure

In advanced composites typical of aerospace structures, the matrix has much lower strength than the fibres. Failure then typically ...