Whilst a CDM approach uses damage variables to represent a typical crack density in a composite, damage initiation conditions will predominantly be controlled by material strength, and lay-up sequence. As a result, it was noted that, if the minimum stress levels required to achieve such conditions were not reached, damage initiation would not occur and, as a result, damage accumulation could not take place. In real materials, damage initiation usually nucleates from pre-existing flaws (e.g. manufacturing defects) within the laminate and, as a result, the stress level required to initiate damage can be much lower compared with that required in ideal laminates. This indicates that capturing the realistic distribution and morphology of pre-existing flaws is crucial for acceptable prediction of damage in composite parts. This challenge was addressed by identifying and implementing a phenomenological approach to damage modelling. This required the development of a modelling strategy able to include “inherent” manufacturing defects on the basis of relevant statistical data from experimental observations, i.e. void volume fraction, morphology, dimensions, location and orientation (Figure 3). Fracture mechanics based models, using the Virtual Crack Closure Technique (VCCT) or extended FEM (XFEM), were subsequently implemented. The validity of the approach was demonstrated against experimental data from flexural four-point bending fatigue testing generated during the HEGEL project (Figure 4). The use of the proposed phenomenological approach enabled a parametric study of damage behaviour in composites with respect to size and percentage of defects within the part.