Abstract

Several yield criteria for porous materials are compared with each other, defining the apparent yield stress as the yield stress of the porous material in simple compression. It was found that the plastic Poisson's ratio is the parameter needed to define the yield criterion, rather than the relative density. The plastic Poisson's ratio is regarded as a material characteristic that is obtained from a simple compression test. A new form of yield criterion was suggested, and it was applied to hydrostatic compression as well as uniaxial strain compression of sintered Al-2024 powder. The crossover point in the mean stress vs volume change curves of the processes was predicted. It is presented that the flow stress of the fully densed material can be obtained from that of the porous material using relations obtained from the yield criterion.

Keywords

• Sintered Powder;
• Yield Function;
• Relative Density;
• Plastic Poisson's Ratio;
• Uniaxial Strain Compression;
• Hydrostatic Compression

• 소결분말;
• 항복함수;
• 상대밀도;
• 소성푸아송비;
• 단축변형률 압축;
• 정수압 압축;