Elastic Wavefield Modeling for Arbitrarily Oriented Orthotropic Media

Composite materials have gained a considerable importance, being widely applied e.g. in aerospace industries as unidirectional, layered or woven structures. Through their complex build-up these materials exhibit anisotropic elastic behavior, raising considerable difficulties for ultrasonic nondestuctive testing techniques. For materials exhibiting orthotropic elastic symmetry, fundamental plane wave characteristics are presented. These relationships ar further applied for transducer-field modeling using the Generalized Point Source Synthesis method. Since for complex-shaped components the material's natural symmetry planes are in general not identical with the components's surfaces, a respective transformation has been applied to yield a compact elastic tensor representation for such configurations. Based on this formulation, all analytical results are obtained in a coordinate-free form, where the material's spatial orientation appears as an additional parameter. Since orthotropy inclu des the higher symmetries tetragonal, transversely isotropic, cubic and isotropic, the results presented cover most of the materials of today's industrial interest. Numerical results cover slowness and group velocities diagrams as well as field pattern calculations for commerical transducers including time-dependent rf-impulse modeling.