Micromechanical Characterisation Of Fatigue Damage Initiation And Propagation In Cfrp Using Synchrotron Radiation Computed Tomography

Micromechanisms of fatigue damage initiation and propagation in double-notch carbon/epoxy coupons have been investigated using synchrotron radiation computed tomography. The material system used is a particle-toughened system, and the role of the particles has been assessed. The use of in situ fatigue experiments and computed tomography allowed insights of the physical mechanisms to be obtained that are not possible to achieve using other methodologies. Observations have shown particles acting mainly to influence damage propagation, causing damage retardation within the resin rich regions. However, particles do not play a significant role in the process of early initiation, where the damage is localised at the fibre/matrix interface. Fibre breaks along 0 degrees ply splits occur due to local buckling or tension failure have been detected for various loads and cycle counts; while fibre breaks in the bulk composite are exclusively associated with high peak loads.