Papers by Keyword: Complex Parameters

Abstract: Finite element method is widely used to simulate the behavior of piezoelectric ceramics; however, its application is limited by the knowledge of the material properties. The constitutive equations are well defined for low deformations (linear case) and for materials without energy losses. In the finite element formulation of piezoelectric equations, the energy losses are introduced in several ways. In this paper a methodology to adjust the damping parameters for the two most used models, Rayleigh parameters and complex constitutive equations, is presented. The simplest Rayleigh model uses only two damping constants to model the energy losses; one proportional to the mass matrix and the other proportional to the stiffness matrix. The other model uses complex values for all parameters in the constitutive equations; in this approach ten different damping constants must be determined.

Abstract: Loss characterization in magnetostrictors is one of the key issues for realizing reliable magnetomechanical transducers. Concerning with the hysteresis minor loop within a relatively linear area of magnetostrictive curve, there are three types of losses, elastic loss, magnetic loss and piezomagnetic coupling loss, similar to the loss mechanism of a piezoelectric (elastic, dielectric and piezoelectric losses) that our group has established recent years. By measuring accurately the mechanical quality factors QA for the resonance and QB for the anti-resonance in the admittance/impedance curve, we can derive these three physical losses. By introducing these losses factors we can characterize magnetostrictive losses using complex parameters.

Abstract: In this paper elastic stress field in an elliptic inhomogeneity embedded in orthotropic media due to non-elastic deformation is determined by the complex function method and the principle of minimum strain energy. Two complex parameters are expressed in a general form, which covers all characterizations of the degree of anisotropy for any ideal orthotropic elastic body. The stress acting on the long side of ellipse can be considered as a crack driving force and applied in failure and fatigue analysis of composites. For some special cases, the resulting solutions will reduce to the known results.