Transactions of Materials Processing (소성∙가공)

The Korean Society for Technology of Plasticity and materials processing (한국소성∙가공학회)
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Non-Quadratic Anisotropic Strain Rate Potential Defined in Plane Stress State

평면 응력 조건에서 정의된 비이차 비등방 변형률 속도 포텐셜

  • 김대용 (한국기계연구원 부설 재료연구소 변형제어연구그룹) ;
  • 김지훈 (한국기계연구원 부설 재료연구소 변형제어연구그룹) ;
  • 이영선 (한국기계연구원 부설 재료연구소 변형제어연구그룹) ;
  • ;
  • 정관수 (서울대학교 재료공학부)
  • Received : 2011.06.13
  • Accepted : 2011.07.19
  • Published : 2011.08.01
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Abstract

A non-quadratic anisotropic strain rate potential was introduced as a conjugate potential of the yield stress potential Yld2000-2d to describe anisotropic behavior of sheet metals, in particular, aluminum alloy sheets under plane stress state. This strain-rate potential takes into account the anisotropic yield stresses and R-values measured along the directions measured at 0, 45 and 90 degrees from the rolling direction, as well as the balanced biaxial yield stress and strain-rate ratio. The convexity of the strain-rate potential was completely proven. The strain-rate potential was applied for two anisotropic aluminum alloy sheets, AA6022-T4 and AA2090-T3. The results verified that the strain rate potential properly described the anisotropic behavior of aluminum alloy sheets and was closely conjugate of Yld2000-2d under the plane stress state.

본 연구를 통하여 비이차 비등방 항복 응력 포텐셜들의 근접 짝되는 변형률 속도 포텐셜들에 대해서 정리하고 Yld2000-2d의 근접 짝되는 Srp2003-2d에 대해서 상세 설명하였다. 제안된 비이차 비등방 변형률 속도 포텐셜 Srp2003-2d 식 형태가 소개 되었고, 볼록성이 증명되었다. 아울러 이방성 상수를 구하는 방법이 제시되었다. Srp2003-2d의 소성 거동을 살펴보기 위하여 자동차 용 알루미늄 합금 판재 AA6022-T4와 항공재료용 알루미늄 합금 AA2090-T3에 응용되었다. Srp2003-2d는 항복 응력 포텐셜 Yld2000-2d와 거의 흡사한 짝됨을 보여 주었으며, 알루미늄 판재의 비등방성을 적절히 묘사하였다. Srp2003-2d는 알루미늄 판재의 성형 공정의 모사를 위하여 이상 공정 이론을 비롯한 강소성체 재료에 대한 정식화에 적절히 응용될 수 있을 것이다.

Keywords

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