고강도강판에서의 전단파단

다국어 초록 (Multilingual Abstract)

Substituting advanced high strength steels (AHSS) for existing mild steels to enhance crashworthiness and fuel efficiency gives rise to new types of fracture so-called ‘shear fracture’ during forming process due to their reduced ductility. However, the term, ‘shear fracture’, is used in various cases because there is no specific definition of it. Shear fracture in AHSS can be classified into two types. The first type is observed at die radius when sheets are stamped with small R / t ratio (ratio of die radius to sheet thickness). The second type is in-plane shear fracture where the main fracture mechanism is in-plane shear deformation. In this paper, before everything, the term, ‘shear fracture’, is defined for four cases. The stretch-bending test at quasi-static state is simulated with Abaqus/Explicit based on the experimental conditions1) for various R / t values to identify the first type. Deformation process is analyzed to explain the transition of fracture type and load-displacement curves obtained from the simulation are compared with that of the experiment to secure validity of the simulation. Furthermore, strain paths of various material points are investigated in the square-cup-drawing process to identify the second type of shear fracture.

목차 (Table of Contents)

• Abstract
• 1. 서론
• 2. 전단파단
• 3. Stretch-bending 시험
• 4. 사각컵드로잉 시험
• 5. 결론
• References