The thermomechanical behavior of casting sands is discussed from an experimental and a theoretical point of view. Uniaxial compression tests at temperatures ranging from 20 degrees C to 950 degrees C and at different values of strain rate (epsilon over dot = 10(-2)s(-1), epsilon over dot = 10(-3)s(-1) and epsilon over dot = 10(-4)s(-1)) have been performed. They show that casting sands exhibit no strain rate effect in the temperature range 20-600 degrees C, and that an elastoplastic model is well suited to describe the experimental results. Three thermoelastoplastic models, derived from Cam Clay and Hujeux models have been developed. These new models take into account the cohesion of the material. The physical parameters needed for these models have been obtained in the temperature range 20-300 degrees C by using triaxial tests, uniaxial compression tests, isotropic compression tests and die pressing tests. An original triaxial apparatus has been built allowing a temperature of 800 degrees C and a pressure of 4 MPa to be reached. In the temperature at which the parameters have been obtained (20-300 degrees C), two additional triaxial compression tests at different confining pressures are used to check the validity of the thermoelastoplastic models used. The best quantitative results are obtained with the revised modified Cam Clay model. [References: 24]
展开▼
