Comparison of some improved solutions for mixed-mode composite delamination coupons

Four different solutions for the energy release rate of orthotropic, beam-like fracture specimens were compared in the present work. Two beam theory-based approaches were utilized. The current authors developed one of them, the other one was previously published in the literature. A model based on refined plate theory was also considered. Finally equations based on a numerical calibration technique were utilized as a fourth solution. These solutions were extended for the case of composite double-cantilever beam, end-loaded split, single-leg bending and mixed-mode bending fracture specimens. Comparison between the different solutions shows somewhat distinct results, especially for the mode ratio. There are some explanations for the experienced discrepancies between the mentioned solutions.