ИСТИНА

Last decades, an increased attention has been paid to the deep understanding of the processes caused by residual stresses in laminated composites, specifically, shape distortion and possible damage of the product at the stage of manufacturing. The presence of residual stresses in the composite material affects the occurrence of such defects as delamination, warping, as well as the appearance of microcracks in the matrix of the material, which has a significant impact on the static and fatigue strength of the final product made of composite material. In this paper, we consider the change of the distribution of the residual stress field caused by manufacturing process in the specimen with initial delamination defect (crack) due to appearance of free edge cut. Different length of initial crack has been analyzed with well-known composite material AS4/8552-1. The curing model is numerically implemented using ABAQUS finite element modeling package with special user subroutines. The coupled thermal and stress problem under plane strain conditions is solved for the modelling of curing. The history of energy release rates under mode I, II (GI, GII) were analyzed over time during process of polymerization and free edge cut appearance using seam crack technique. A slight increase in the GI and GII values at the crack tip during polymerization and a multiple excess of these values after a mechanical cut is shown. On the contrary obtained by modelling levels of stress components are essential and cannot be ignored in consequent structural analysis. The results of the study can be applied for prediction of residual stresses in composite structure by means of simulation and further understanding the nature of fracture of composites.