Modeling the Effect of Damage in Composite Structures: Simplified Approaches

Chapter 5Impact

Impact damage (see Figure 5.1) combines all the individual forms of damage discussed in previous chapters: holes, cracks, delaminations and fibre breakage. The hope is, therefore, that once the individual types of damage are understood, it would be relatively straightforward to combine the best models of the previous chapters to create a reliable model for impact damage in composites. Unfortunately, nothing is further from the truth. The individual models, as discussed already, are not accurate enough or general enough. In addition, the interaction of the different damage types is not covered in any of the previous chapters, but it turns out it is critical in understanding and modelling impact damage. More elaborate models are necessary for the individual damage types which may then form the stepping stones for a reliable model for impact damage. Until such models are available and readily usable, approximate models for impact damage will form the basis of a design environment.

Figure 5.1 Section cut showing the damage created in a quasi-isotropic laminate after 25 J impact

The impacts considered in this chapter will focus on such combinations of impactor mass and energy, which are typically referred to as low speed–high mass impacts. Unlike higher energy impacts where significant amounts of damage are readily visible on the impacted surface, low-speed impact ...