인장 및 압축 등방 잔류응력 측정을 위한 누프 압입시험의 응력환산계수 결정 (Determination of Knoop Indentation Stress Conversion Factors for Measuring Equibiaxial Residual Stress)

서지정보

· 발행기관 : 한국부식방식학회
· 수록지 정보 : CORROSION SCIENCE AND TECHNOLOGY / 20권 / 6호 / 484 ~ 490페이지
· 저자명 : 정민재, 김영천

초록

Instrumented indentation testing has been widely used for residual stress measurement. The Knoop indentationis mainly selected for determining anisotropic mechanical properties and non-equibiaxial residualstress. However, the measurement of equibiaxial stress state and compressive residual stress on a specimensurface using Knoop indentation is neither fully comprehended nor unavailable. In this study, weinvestigated stress conversion factors for measuring Knoop indentation on equibiaxial stress state throughindentation depth using finite element analysis. Knoop indentation was conducted for specimens to determinetensile and compressive equibiaxial residual stress. Both were found to be increased proportionallyaccording to indentation depth. The stress field beneath the indenter during each indentation test was alsoanalyzed. Compressive residual stress suppressed the in-plane expansion of stress field during indentation.
In contrast, stress fields beneath the indenter developed diagonally downward for tensile residual stress.
Furthermore, differences between trends of stress fields at long and short axes of Knoop indenter wereobserved due to difference in indenting angles and the projected area of plastic zone that was exposed toresidual stress.

영어초록

Instrumented indentation testing has been widely used for residual stress measurement. The Knoop indentationis mainly selected for determining anisotropic mechanical properties and non-equibiaxial residualstress. However, the measurement of equibiaxial stress state and compressive residual stress on a specimensurface using Knoop indentation is neither fully comprehended nor unavailable. In this study, weinvestigated stress conversion factors for measuring Knoop indentation on equibiaxial stress state throughindentation depth using finite element analysis. Knoop indentation was conducted for specimens to determinetensile and compressive equibiaxial residual stress. Both were found to be increased proportionallyaccording to indentation depth. The stress field beneath the indenter during each indentation test was alsoanalyzed. Compressive residual stress suppressed the in-plane expansion of stress field during indentation.
In contrast, stress fields beneath the indenter developed diagonally downward for tensile residual stress.
Furthermore, differences between trends of stress fields at long and short axes of Knoop indenter wereobserved due to difference in indenting angles and the projected area of plastic zone that was exposed toresidual stress.

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