CTOD Evaluation of Surface Flaws Located in Highly Strain Concentration Zone of Stiffened Structural Components

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概要

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• Japan Welding Engineering Society (JWES) standard WES2805 established in 1976 aims to provide industry with guidance in crack assessment throughout a CTOD criterion. The recent revision of the WES2805 standard carried out by WR3 Committee of JWES makes use of a local strain parameter (ε) that is estimated from a local strain concentration factor (k_ε). The local strain concentration factor, which is estimated as a function of the elastic stress concentration k_t, so far has not been precisely defined. Furthermore, the WES2805 has shown some difficulties in crack assessment for complicated structural geometries. Hence, single and double stiffened specimens as used by the FTR Committee of JWES were computed in this work in order to investigate the problem. Three-dimensional elastic-plastic finite element analyses were carried out on wide stiffened plates containing surface cracks with different gemetric profiles. These FEM models were generated in order to investigate the local strain parameter and CTOD in a wide load range using three different strain concentration factor definitions. Analyses using the present WES2805 equation to estimate local strain were done, and the current difficulties in using this equation to estimate failure stresses are shown in this paper. Based on the FEM analysis, a new concept of σ_<net> evaluation, designated as "Net Section Stress Effect", is proposed to correct the general understimation trend of the local strain parameter, as well as failure stress, that is found in the present revised WES2805 document. Also a modified equation to estimate local strain was deduced in an effort to incorporate the newly proposed "Net Section Stress Effect" concept. The authors performed an evaluation of the new equation using the results obtained from finite element analysis as well as from experimental results of the wide stiffened plates research performed by the FTR Committee of JWES.

• 財団法人日本海事協会の論文

著者

• Machida Susumu

  Dept. Naval Architecture & Ocean Engineering University Of Tokyo

• Machida Susumu

  Dept. Naval Archit. & Ocean Eng. The University Of Tokyo.

• Morita Akiyasu

  Dept. Naval Architecture & Ocean Engineering University Of Tokyo

• YOSHINARI Hitoshi

  Dept. of Naval Archit. & Ocean Engg. Faculty of Engl, The Univ. of Tokyo

• Pereira Marcos

  Technical Investigation and Information Department, Research Center

• Pereira Marcos

  Technical Investigation And Information Department Research Center

• Yoshinari Hitoshi

  Dept. Naval Architecture & Ocean Engineering University Of Tokyo

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