Determination of Cap Model Parameters using Numerical Optimization Method for Powder Compaction
Abstract
Many advantages are inherent to the successful powder metallurgy (P/M) process especially in high volume manufacturing. The strength/density distribution of the compacted product is crucial to overall success. The finite element analysis (FEA) method has become an effective way to numerically simulate strength/density distribution in a P/M compact. The modified Drucker-Prager cap (DPC) model has been shown to be a suitable constitutive relationship for metal powder compaction simulation. The calibration of the modified DPC model involves a procedure known as a triaxial compression test. Equipment for completing a triaxial compression test on metal powders is neither readily available nor standardized in the P/M industry. A robust calibration procedure that requires only simple experimental tests would increase the usability of the simulation procedure. This research created a universal cost/time-effective calibration method to accurately determine all parameters of a modified DPC model by using a combination of numerical simulation methods, numerical optimization methods and common material testing techniques. The use of the triaxial compression test is eliminated and the new method relies only upon conventional compaction equipment, standard geometry and readily available metallographic techniques. The DPC parameters were determined by applying the proposed method on ferrous powders. The predicted DPC parameters were verified on a compressed product with complex geometry.