Part 2: Model Evaluation Rate-Dependent Elasto-Viscoplastic Constitutive Model for Industrial Powders.

摘要

The PSU-EVP model's constitutive parameters for alumina powder are presented.The PSU-EVP model was also used to back-predict the triaxial test data obtained for MZF and alumina powders using constitutive parameters such as the initial voids ratio (e_0),compression index (lambda),and spring-back index (kappa).In the case of MZF powder,8 out of 12 back-prediction cases had average relative difference (ARD) values below 20%.In the case of alumina powder,7 out of 11 back-prediction cases had ARD values below 20%.Based on the back-prediction results,it was concluded that the PSU-EVP model gave fairly good results for most triaxial test data collected at 0.62 MPa/minute and 6.21 MPa/minute.However,the back-prediction results obtained at 20.7MPa/minute had high ARD values.A sensitivity analysis was done to study the effect of changes in parameter values on the hydrostatic triaxial compression (HTC) and conventional triaxial compression (CTC) back-prediction results.From the sensitivity analysis,+-10% (standard deviation variation from +- 0.8sigma to +- 2.3sigma) changes in lambda and e_0 mean values had marked effect on the HTC results.However,changes in the lambda,kappa,and e_0 mean values do not produce any noticeable effect on the CTC prediction results.Overall,the PSU-EVP model can be considered to be the first step towards the development of a more robust and accurate model for prediction of stresses and strains in a dry powder compression process.