Publications de nos chercheuses et chercheurs

Currently, mechanisms used for the chemical kinetic modeling of solid degradation during thermal exposure are based on a kinetic law which is an adaptation of the Arrhenius principal equation. Moreover, to simulate the rate of each reaction of the mechanism of thermal degradation, four parameters have to be determined (A, E, n and νν). But, the estimation process is made by algorithm and this process is not controlled whereas it is primordial to find a physical sense of the parameter values and to criticize the parameter values found, in order to guaranty the validity of the model. In order to control and to critic the estimation process knowledge are necessary. Then, this work proposes to analyze the kinetic model with a new statistical methodology based on a global and local sensitivity analysis. For the global sensitivity analysis, the Sobol's technic is used. This methodology permits to deal with the different aspects of the kinetic law together whereas these aspects are treated independently in the literature. Then, a global view of the model behavior, its advantages and limits is obtained. Sensitivity analysis permits firstly to understand the role and the influence of the parameters in the differential equation used to model the mass loss rate of a solid fuel as function of the temperature and the time. It highlights the specific role of A and E, known in the literature as “the compensation effect”. Secondly, this work considers the uncertainty determination of each parameters and the uniqueness of the solution found.