Effect of combined loading on cracks in graphite/epoxy composites

Moire Interferometry technique has been used to study the effect of combine d loading on crack displacement in graphite epoxy plates. Specimens with ce ntral cracks of various-orientations were subjected: to uniaxial tensile lo ads. Thus, the cracks were under biaxial-stress fields, mode I (tension str ess) and mode II (sliding stress). The: obtained fringe patterns represente d contours of. constant-in-plane displacements. Based on these fringe patte rns, two types of displacements were determined at the crack center, crack opening displacement (COD) and crack shearing displacement (CSD). The effec t of combined loading on COD and CSD as well as the behavior of the materia l under these conditions was investigated in more detail. Experimental data were compared with the linear elastic fracture mechanics (LEFM) solution. (C) 2001 Elsevier Science Ltd. All rights reserved.