Numerical simulation and experimental study on toughening design of multilayer ceramic

Computer analysis was introduced as an auxiliary means for toughening design of biotechnological laminated ceramic composites. Based on a multilayer beam model, a finite element method has been used to simulate fracture behaviour, crack kink and its growing from basal sheet of hard layer to weak interface layer in the laminated ceramic structure. The post processing approach offers crack growing path, correlative load-displacement curve for three-point bending and shows toughening effect. The changes in the toughness and strength of laminated ceramics with the specimen's geometric parameters (thickness ratio, layer number) and materials properties parameters (fracture strain, Young's moduli, etc) were analyzed by FEA numerical simulation. The optimum-values of above parameters in toughening design were then determined. The effectiveness of this numerical simulation method is demonstrated by comparing the results of the numerical evaluation with the experimental measurement of fracture work for Si₃N₄/BN multilayer specimen in the three-point bending test. The rationality of the multilayer layer beam model is also affirmed. The primary mechanism of energy absorbing and toughening of the laminate ceramic composites was explained by the weak interface layers, which are capable of deflecting main cracks.