Numerical simulation of extruded clay paste compression

The manufacturing process of clay tiles includes a pressing step in which the material undergoes stresses, that may result in the appearance of defects. To understand the phenomena involved, a numerical model of the pressing step was developed. Different tests were performed to determine the different behaviour laws necessary to the numerical simulation (rheological, tribological, damage). A rheological study, based on free compression tests, allowed to charaterize the elasto-visco-plastic behaviour of the extruded clay paste. The constitutive parameters were estimated by inverse analysis of the experimental force displacement curves using a Strategic evolution algorithm coupled with a metamodel. Two damage models, the Latham and Crockoft criterion and the Oyane criterion, were compared to model the cracking. To simulate the crack's propagation, an element deletion algorithm was used. The friction models of Coulomb and Tresca were investigated to model the global friction between the clay and the tools. The different parameters of the friction law were identified by inverse analysis of an experimental pressing force obtained during a shaping test. The identified model is valided on the case study of an instrumented forming of a tile lug and allows to simulate the shaping of an industrial tile.