Laminated Composite Plate Quasi-experimental Study And Numerical Analysis Of Static Indentation Damage

Nowadays the composite is used on aircraft structures more and more with high strength and low density, but the impact damage needs special attention. It is difficult to observe and survey the impact test for the impact process is moment. In this paper, an experimental investigation is performed on the characteristics damage of composite laminates with quasi-static indenting using Standard Test Method for Measuring the Damage Resistance of a Fiber-Reinforced Polymer-Matrix Composite to a Concentrated Quasi-Static Indentation Force (ASTM Standard).The damage process of composite plate under the quasi-static indent is very complicated. The mechanism of matrix crack, delamination and fiber rupture is analyzed. According to the quasi-static indenting force/displacement curve, displacement boundary condition is introduced and displacement load is put on step by step. Four damage criterions were adopted here to compute different impact damage modes. They were damage initiation criterion for matrix cracking and delamination propagation criterion for the laminate interfaces. The influence of local stiffness degression resulted from damage in the impact process is simulated by modifying the material constants of damaged layers. The results of the analysis are compared with the existing test data, and a good agreement are found.The process of composite laminates with quasi-static indenting damage under compress loads is simulated by using the stimulant result above. And the residual strength of the plate is evaluated. The results of the simulation proved that the simulate method is feasible. Factors which effect on the residual strength of the laminated plate with quasi-static indenting damage are discussed.The damage propagation of composite laminates with quasi-static indenting damage is studied by compress/compress fatigue test. Damage propagation under fatigue load is discussed by observing result of Ultrasonic C-scan. Finally, the residual strength after fatigue test is studied initially.