Coupled mechanical and thermal simulation of warm compaction
(1. College of Mechanical Engineering, South China University of Technology, Guangzhou 510640, China;
2. Department of Computer Science, Guangdong Police Officers College, Guangzhou 510232, China)
2. Department of Computer Science, Guangdong Police Officers College, Guangzhou 510232, China)
Abstract: Warm compaction process of pure iron powder was investigated. Due to the existence of elastic, plastic and thermal strains, a coupled mechanical and thermal model was applied. The elasto-plastic constitutive equations for powder material were developed based on ellipsoidal yield criterion and continuum theory. The constitutive equations were integrated into the constitutive integral arithmetic and solved employing incremental iterative solution strategy. The yield strength of iron powder was obtained according to the tensile experiments. When the compaction temperature was raised to 130 ℃, the yield strength of iron powder metal drops to 85% of room temperature value. Modified coulomb friction law is applied and the simulation results show that friction was an important factor resulting in the inhomogeneous relative density and reverse-density distribution phenomena in the regions near the die wall and the symmetrical axis.
Key words: powder metal; warm compaction; finite element method; friction; relative density