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Structural Engineering and Mechanics
  Volume 76, Number 4, November25 2020 , pages 505-512
DOI: https://doi.org/10.12989/sem.2020.76.4.505
 


Error estimation for 2-D crack analysis by utilizing an enriched natural element method
J.R. Cho

 
Abstract
    This paper presents an error estimation technique for 2-D crack analysis by an enriched natural element (more exactly, enriched Petrov-Galerkin NEM). A bare solution was approximated by PG-NEM using Laplace interpolation functions. Meanwhile, an accurate quasi-exact solution was obtained by a combined use of enriched PG-NEM and the global patch recovery. The Laplace interpolation functions are enriched with the near-tip singular fields, and the approximate solution obtained by enriched PG-NEM was enhanced by the global patch recovery. The quantitative error amount is measured in terms of the energy norm, and the accuracy (i.e., the effective index) of the proposed method was evaluated using the errors which obtained by FEM using a very fine mesh. The error distribution was investigated by calculating the local element-wise errors, from which it has been found that the relative high errors occurs in the vicinity of crack tip. The differences between the enriched and non-enriched PG-NEMs have been investigated from the effective index, the error distribution, and the convergence rate. From the comparison, it has been justified that the enriched PG-NEM provides much more accurate error information than the non-enriched PG-NEM.
 
Key Words
    crack analysis; error estimation; natural element method; interpolation enrichment; stress recovery; global and local errors
 
Address
Department of Naval Architecture and Ocean Engineering, Hongik University, Sejong 30016, Korea
 

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