A multi-domain Chebyshev collocation method for predicting ultrasonic field parameters in complex material geometries

• Published in: Ultrasonics Vol. 40; no. 1; pp. 177 - 180
• Main Authors: Nielsen, S.A., Hesthaven, J.S.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2002; Elsevier Science
• Subjects: Acoustical measurements and instrumentation; Acoustics; Complex geometries; Cross-disciplinary physics: materials science; rheology; Elastic scattering; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Materials science; Materials testing; Multi-domain; Nondestructive testing: ultrasonic testing, photoacoustic testing; Physics; Pseudospectral; Structural acoustics and vibration; Multi-domain; Pseudospectral; Complex geometries; Elastic scattering; Wave equation; Stress analysis; Spectral method; Acoustic measurement; Time domain method; Chebyshev polynomial; Material testing; Elastic wave; Collocation method; Non destructive test; Modeling
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/S0041-624X(02)00133-6

The use of ultrasound to measure elastic field parameters as well as to detect cracks in solid materials has received much attention, and new important applications have been developed recently, e.g., the use of laser generated ultrasound in non-destructive evaluation (NDE). To model such applications requires a realistic calculation of field parameters in complex geometries with discontinuous, layered materials. In this paper we present an approach for solving the elastic wave equation in complex geometries with discontinuous layered materials. The approach is based on a pseudospectral elastodynamic formulation, giving a direct solution of the time-domain elastodynamic equations. A typical calculation is performed by decomposing the global computational domain into a number of subdomains. Every subdomain is then mapped on a unit square using transfinite blending functions and spatial derivatives are calculated efficiently by a Chebyshev collocation scheme. This enables that the elastodynamic equations can be solved within spectral accuracy, and furthermore, complex interfaces can be approximated smoothly, hence avoiding staircasing. A global solution is constructed from the local solutions by means of characteristic variables. Finally, the global solution is advanced in time using a fourth order Runge–Kutta scheme. Examples of field prediction in discontinuous solids with complex geometries are given and related to ultrasonic NDE.