Progressive failure analysis of laminated composite plate with open hole under fatigue loads

In this study, progressive failure analysis was performed by creating a finite element model in the numerical environment of glass fiber reinforced circular hole and pin joint composite materials under cyclic loads. Additionally, experimentally, flat, circular perforated and pin-joint plates were subjected to fatigue tests. S-N curve was created for samples without holes. Residual strength and residual stiffness curves obtained from experimental fatigue tests depending on the number of cycles were used in progressive failure analysis. In the numerical study, a program that can perform progressive failure analysis under cyclic loads was created using APDL (ANSYS Parametric Design Language) codes. Hashin and Puck FailureCriteria are used in this program. A flow chart was used in fatigue progressive failure analysis. Material properties are reduced suddenly if the material is damaged, based on the flow diagram, and gradually if there is no damage, using appropriate stiffness and strength reduction formulas. Glass fiber reinforced polymer composite sheets have 8 layers and a total thickness of 2.5 mm. The plate dimensions are 250x25 mm and the hole diameters of the specimens with circular holes and pin joints are determined as 6 mm. Dynamic tests were performed on the specimens using different loading rate ranges, starting from 80% of the average static tensile load obtained. A loading rate of 30% was used only in specimens without holes, and at this loading rate the cycle went to infinity (106≥). In the last stage, final damage images obtained from numerical and experimental studies were compared and damage cycle number graphs depending on loading rates were obtained. A parametric study was also carried out for the finite element model with holes and pin joints. In the parametric study, thickness and hole diameters were changed. As a result, progressive failure analysis program codes that work under repeated loads, can be applied to different physical problems, and are suitable for different failure damage theories have been written and verified through experiments.