The role of "thickness effect" on the damage progression and crack growth inside the plain-woven carbon fiber composites

This study addresses the role of the “thickness effect” on damage propagation and cracks growth inside the plain-woven carbon fiber composites under Iosipescu shear loading. Specimens of three different thicknesses are tested at 60%, 80%, and 100% of their respective maximum stress values. Acoustic Emission (A.E.), Infrared Thermography (I.R.T.), and ex-situ Micro-CT analyses are performed on the representative specimens at each applied load step. The A.E. analysis indicates that the extent of matrix cracking decreases with the increase in the thickness of the laminate. The significance of the Felicity ratio is also observed when specimens are reloaded at different stress levels. The I.R.T. analysis shows that the thermoelastic effect causes a temperature drop in the elastic range. Micro-CT analysis observed only matrix bruises due to shear deformation in the elastic range, whereas the kink band formation, crack diversion, crack arrest, and delamination are observed through the C.T. scans when performed at elevated stress levels. The quantitative analysis shows the extent of crack growth in 3D space at 0% and 100% stress levels. The manufacturing defects adversely affect crack propagation, and the density of the cracks rises with the increase in thickness of the specimen. A material-degradation-based progressive damage analysis was performed through Ansys using maximum stress failure criteria. The numerical and experimental results indicate that the increase in thickness of the sample increases the crack growth near the top and bottom V-notched section due to the tension-compression configuration of applied loading