Characterization of static failure in laminates containing transverse preform transitions by image processing

Preform laminates are introduced to reduce costs when manufacturing large composite structures such as wind turbine blades. A preform is defined as a stack of unidirectional and biaxial dry non-crimp fabric glass fibre plies weakly bonded using a polymeric binder material. In using preforms, potentially weak interfaces are created between preforms in the cured laminate, called preform transitions. The failure of transverse preform transitions subject to static tension is characterized in terms of crack density by a novel automated image processing method for crack quantification. It is found that for static tension, the transverse preform transition geometry has equal or lower crack density compared to the equivalent continuous laminate.