Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Development of Test Method for Simple Shear and Prediction of Hardening Behavior Considering the Bauschinger Effect

단순전단 시험법 구축 및 바우싱거효과를 고려한 경화거동 예측

  • Kim, Dongwook (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Bang, Sungsik (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Kim, Minsoo (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Lee, Hyungyil (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Kim, Naksoo (Dept. of Mechanical Engineering, Sogang Univ.)
  • Received : 2013.03.12
  • Accepted : 2013.07.14
  • Published : 2013.10.01
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Abstract

In this study we establish a process to predict hardening behavior considering the Bauschinger effect for zircaloy-4 sheets. When a metal is compressed after tension in forming, the yield strength decreases. For this reason, the Bauschinger effect should be considered in FE simulations of spring-back. We suggested a suitable specimen size and a method for determining the optimum tightening torque for simple shear tests. Shear stress-strain curves are obtained for five materials. We developed a method to convert the shear load-displacement curve to the effective stress-strain curve with FEA. We simulated the simple shear forward/reverse test using the combined isotropic/kinematic hardening model. We also investigated the change of the load-displacement curve by varying the hardening coefficients. We determined the hardening coefficients so that they follow the hardening behavior of zircaloy-4 in experiments.

본 연구에서는 zircaloy-4 판재에 대해 바우싱거 효과를 고려한 경화거동 예측모델을 구축했다. 금속소재 가공에서 인장 후 압축 시 항복응력이 감소한다. 이에 스프링백 해석 시 바우싱거 효과를 반드시 고려해야 한다. Simple shear 시험에서 적정 시편크기 및 적정 조임토크에 대한 결정법을 제시했다. 5 가지 재료에 대한 simple shear 시험을 통해 응력-변형률 곡선을 구했다. 또한 유한요소해석을 활용해 simple shear 하중-변위 곡선으로부터 유효응력-변형률 곡선으로 변환과정을 소개했다. 등방/운동성 경화 조합모델을 활용해 simple shear 순/역방향 시험을 모사했다. 이때 각 경화계수에 따른 하중-변위 곡선 변화를 관찰하고, zircaloy-4에 대한 경화계수를 결정했다.

Keywords

References

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