The caughey absorbing layer method - Implementation and validation in ansys software

André F S Rodrigues, Zuzana Dimitrovová

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

The numerical analysis of the wave propagation problem, from elastic to electromagnetic waves, is often faced with the problem of dealing with unbounded media. Since the domain of finite-difference and finite element methods must be itself finite, various truncation techniques have been proposed over the last decades, such as absorbing boundary conditions (Lysmer and Kuhlemeyer[1]), infinite elements (Bettess [2]) and absorbing boundary layers (such as the Perfectly Matched Layer, or PML, introduced by Bérenger [3]). In this paper, the Caughey Absorbing Layer Method (CALM), proposed by Semblat et al. [4], is implemented in the commercial finite element software Ansys, using an implicit dynamics formulation. It is tested for one- and two-dimensional problems and its efficiency is compared with that of the Lysmer-Kuhlemeyer absorbing boundaries. The dependency on material parameters, loss factor and load frequency is also tested. To mitigate the problem of wave reflection at the interface between the medium of interest and the absorbing layer, different variations of damping along the layer's length are tested and their efficiency compared. By analysing the maximum displacement and the L2-norm of the displacement field, the implementation of the CALM in Ansys is shown to be effective at mitigating the problem of spurious wave reflection at the boundaries. Their performance is clearly superior to the Lysmer absorbing boundary conditions, but at a greater computational cost due to the additional degrees of freedom. The quadratic variation of the Rayleigh damping has proved to be the most effective, and an estimate of the optimum loss factor as a function of the length of the layer in relation to the wavelength to absorb was proposed. Although the optimal damping is frequency dependent, it was shown to work well even if the frequency is overestimated or greatly underestimated.

Original languageEnglish
Title of host publication11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014
PublisherInternational Center for Numerical Methods in Engineering
Pages557-568
Number of pages12
ISBN (Electronic)9788494284472
Publication statusPublished - 1 Jul 2014
EventJoint 11th World Congress on Computational Mechanics, WCCM 2014, the 5th European Conference on Computational Mechanics, ECCM 2014 and the 6th European Conference on Computational Fluid Dynamics, ECFD 2014 - Barcelona, Spain
Duration: 20 Jul 201425 Jul 2014

Conference

ConferenceJoint 11th World Congress on Computational Mechanics, WCCM 2014, the 5th European Conference on Computational Mechanics, ECCM 2014 and the 6th European Conference on Computational Fluid Dynamics, ECFD 2014
CountrySpain
CityBarcelona
Period20/07/1425/07/14

Keywords

  • Absorbing boundary layer
  • Elastic wave propagation
  • Finite element method
  • Spurious reflections
  • Unbounded domains

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  • Cite this

    Rodrigues, A. F. S., & Dimitrovová, Z. (2014). The caughey absorbing layer method - Implementation and validation in ansys software. In 11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014 (pp. 557-568). International Center for Numerical Methods in Engineering.