Experimental Analysis of Residual Stresses in CFRPs through Hole-Drilling Method: The Role of Stacking Sequence, Thickness, and Defects

Carbon fiber reinforced plastics (CFRPs) gained high interest in industrial applications because of their excellent strength and low specific weight. The stacking sequence the unidirectional plies forming a CFRP laminate, thicknesses, primarily determine mechanical performance. However, during manufacturing, defects, e.g., pores residual stresses, are induced, both affecting properties. objective present work is to accurately measure stresses CFRPs as well investigate effects sequence, overall laminate thickness, presence on stress state. Residual were measured through incremental hole-drilling method (HDM). Adequate procedures have been applied evaluate for orthotropic materials, including calculating calibration coefficients finite element analysis (FEA) based thickness Using optical microscopy (OM) computed tomography (CT), profound insights into cross-sectional three-dimensional microstructure, location shape process-induced pores, obtained. This microstructural information allowed comprehensive understanding experimentally determined strain results, particularly at transition zone between individual plies. effect was investigated by considering calculate depth 0.06 mm 0.12 model utilizing these results evaluation. A maximum difference 46% defect-free porous material sample conditions observed hole 0.65 mm. significance employing correctly calculated evaluation highlighted validation tests.