유한요소법을 이용한 중고속 변형률 속도에서의 박판 인장시편의 형상결정 = Determination of the Tensile Specimen for an Intermediate Strain Rate Test with Finite Element Method

다국어 초록 (Multilingual Abstract)

The strain-rate dependent mechanical properties of a sheet metal are indispensable for the reliability of the lightweight design and the crashworthiness of auto-body because the mechanical properties are remarkably changed by the level of the strain-rates. Since the level of the strain-rate in the crash analysis is between 10 /sec and 500 /sec, an appropriate experimental method has to be developed in order to acquire the material properties at the corresponding strain-rate. Design the specimen is important to perform the experiment because there is not standard tension specimen for the dynamic test. Numerical simulations are carried out in order to determine the dimensions and the shape of the specimen with an elasto-plastic explicit finite element method. In FE simulation and stress update, the plastic predictor - elastic corrector (PPEC) method is applied in order to integrate the stress tracking the JohnsonCook constitutive equation over a time step. The scheme adopts secant iteration in the plastic predictor - elastic corrector method in order to satisfy the plane stress condition. Finite element simulations are carried out to investigate the effect of the variation of geometric parameters in specimen such as the gauge length, the width and the fillet radius. Optimum dimensions are determined for standard specimens at the various strain- rates considering the effect of parametric variation and the crosshead speed of a press.<br/>

목차 (Table of Contents)

• ABSTRACT
  
• 1. 서론
  
• 2. 외연적 탄소성 유한요소 수식화
  
• 3. 유한요소을 이용한 인장시편의 결정
  
• 4. 결론
  
• 참고문헌