Fracture Analysis Of Interface Crack In Functional Material Double Plates

With the development of science and technology, convectional material double-layer plates composed by bonding different materials are widely used in more and more modern science and technology fields. It is very fragile to be made and used for material structure and mechanical parts. With the confluence of the certain load, convectional eateries will inevitably be material defects the material will have some defects inevitably. Because of defects(cracks,inclusions, voids, etc.), the material structure will lose efficacy or damaged in advance. The damages will influence the performance of double-layer plates. As a result, it is significance to study the fracture problem of functional materials double-layer plates.Complex function method is one of the effective methods to study the fracture problem. The complex function method can be used to study the crack tip of laminated mechanics of composite material with the interface crack,for example, the linear crack,the star crack, the parallel crack, the arrayed-crack periodically, etc. In the meantime, complex function method can be applied to solve the fracture problems with the interface crack in functional materials double-layer plates.In this paper, by means of complex function method and the method of undetermined coefficients, an anti-plane fracture problems of the piezoelectric composite material double-layer plates with interface crack and the bending fracture problems of the orthotropic composite double-layer plates with interface crack are studied respectively. For the former problem, an anti-plane fracture problem of the Piezoelectric composite material double-layer plates, first of all,we change the interface fracture problem into a system of partial differential equations with the boundary value problem. Further more, with the complex variable function method, we select the special stress function and special electric displacement function, which contain solid parameters and match the control equations. Using the method of undetermined coefficients and the boundary conditions, the non-homogeneous linear equations containing eightunknown numbers are established with the aid of boundary conditions.Undetermined coefficients are obtained by solving the equations. Then, we will be able to solve the boundary value problems of the partial differential equations. Based on the stress function and the electric displacement function in the crack tip of the piezoelectric composite double-layer plates, we define the stress intensity factor and electric displacement intensity factor near the interface crack tip. After that, near the interface crack tip for mode ? of transverse isotropic dual piezoelectric materials, the computational formulas of stress intensity factor, electric displacement factor, stress field, and electric displacement are further deduced. For the bending fracture problems of orthotropic composite double-layer plates, we can convert the mechanical problems to the boundary value problems of partial differential equations. First of all, by introducing the stress singularity index, the boundary value problems of partial differential equations are changed into algebraic problems by the complex variable function method and the method of undetermined coefficients.Further more, by setting up non-homogeneous linear equations with eight solutions, we get the deflection function. After that, near the interface crack tip for bending fracture of the orthotropic composite material double-layer plates,the computational formulas of stress intensity field, the displacement field, the bending moment, the torque, the strain, and the stress intensity factor with the fracture parameters are further deduced. In the end, with the pole diameter changing, the variation of the stress, the electric displacement, and the bending moment of the functional material double-layer plates are numerically analyst on the fixed direction.