Analytical Method For Damping Capacity In Ceramic Matrix Composites

Ceramic Matrix Composites (CMC) exhibits excellent capabilities such as high temperature resistance. This material is considered as the perfect material for high temperature structures which are used in the aero and space aircrafts. In these fields, structural vibration may be the main cause which results in structure damage. On the other hand, increasing the damping capacity of material is one of the most effective methods to reduce vibration. Therefore, it will be important to understand the damping mechanism of CMC and develop a method to predict the damping coefficient of this material.The paper presents an analytical method for estimating damping capacity in unidirectional ceramic matrix composite. Based on the stress distribution in the bonded and de-bonded region of CMC with matrix cracks, we investigated the sliding mechanism of CMC, and then determined the length of the forward and reversed slip zone. Finally, we derived the expression of damping, and then, we analyze the influence of the main parameters through the numerical examples. Results show that: Decreasing the interfacial shear stress and fiber volume fraction can improve the damping capacity significantly.Because of the shear-lag models could not describe the influence between adjacent fibers, this paper estimated the damping capacity with FEM. The results show the analysis base on FEM is feasible. On this basis, we analyzed the effect of fiber array on damping behaviors of CMC. Results show that: Square diagonal packing has the best damping capacity.Combination of the method of estimating damping capacity and the response of longitudinal rod vibration, this paper presents the method for estimating the structural damping capaticy of CMC. On this basis, we analyzed the influence of loading frequency on structural damping behaviors of CMC.