Theories and Capabilities of Intumescent Mat Numerical Modeling

Intumescent mat is widely used to support ceramic substrates in catalytic converters and is subjected to thermo-mechanical loading. As the substrate wall thickness becomes thinner to reduce backpressure and emission, exact prediction of mat pressure becomes more important in design stage to prevent future substrate failure during the canning and thermo-cyclic loading test. Experiment shows that the mat mechanical behavior is very much like highly nonlinear rate dependent hyper-foam material and it has permanent plastic deformation after either thermal or mechanical loading. Also, mechanical material property changes due to the temperature. This paper introduces some of the key features in developing constitutive model based on the hyperelastic theory by including viscous and plastic effects. To account for material property change at each temperature, material softening model will be introduced with respect to temperature and mechanical strain. The theory is coded as an implicit algorithm in ABAQUS™/STANDARD. Simulation and thermo-mechanical cyclic tests are compared to validate constitutive model.