Energy release rates of degrading composite structures

Energy release rates during progressive damage and fracture of laminated composite structures subjected to loading are evaluated via computational simulation. A computer model is utilized for the assessment of structural response, progressive fracture, and defect/damage tolerance characteristics. Constituent material properties, stress and strain limits are scaled up from the fiber and matrix subregions to the structure level to evaluate the overall damage and fracture propagation for composites. Damage initiation, growth, accumulation, and propagation to fracture are included in simulations. Results show the damage progression sequence and the changes in the structural response characteristics during different degradation stages. The fundamental premise of computational simulation is that the complete evaluation of laminated composite fracture requires an assessment of ply and subply level damage/fracture processes. Local computation and quantification of damage energies are used to monitor the composite damage mechanisms in the requisite detail. The relationship between local damage and associated energy releases are established within the computational simulation procedure.