Abstract
A theoretical model for dynamic failure of powder compacts is presented. The model is a modification of Chen's model for brittle materials to adapt with the special features of powder compacts. The model uses the damage mechanics to evaluate a linear isotropic damage parameter (
D) from initial damage state of compacts (
D
0) to one at the final failure. The initial damage state (
D
0) depends on the degree of compaction and the variables incorporated in the compaction process of a pure material with assumed zero damage state.
Series of cylindrical powder compacts made of di-pac sugar, sodium chloride, potassium bromide, and paracetamol d.c. powders are loaded dynamically according to the traditional known diametral compression (Brazilian) test. These materials are typical of the many powders used in the pharmaceutical industry. Thus, these experiments are utilized to obtain the fracture strain rate and the material constants involved in the model. The experimental results are found to be in a very good agreement with the suggested model.