Residual strength of composite laminates containing scarfed and straight-sided holes

This investigation is motivated by the needs to quantify the load-carrying capacity of composite laminates with scarfed holes, a damage cut-out shape employed to achieve flush repairs of composites. Both experimental testing and analytical modelling were carried out to investigate the damage progression behaviour of composite laminates containing either straight-sided or scarfed holes. Hoop strains were recorded by strain gauges located along the scarf surface and the results indicate a much greater extent of damage progression than specimens containing straight-sided holes. Three different strength-prediction models were employed to quantify the residual strength, including an analytical cohesive zone model developed in this work, an analytical inherent-flaw fracture mechanics method and a finite element-based continuum damage model. Comparisons of the experimental results with the model predictions reveal that the continuum damage model, calibrated using data from coupons with straight-sided holes, provides promising correlation with experimental results.