Analysis of Creep in a Si-SiC C-Ring by Finite Element Method

The long-term creep deformation of a siliconized silicon carbide ceramic C-ring subjected to a compression load at 1300°C in air is studied by the finite element method. Based on asymmetric creep responses observed under uniaxial creep tests, multidirectional constitutive equations in power-law form are derived using the parameters of effective stress/strain. The elastic solutions are first solved and used as a guide to reach the final mesh design and as initial conditions. Solving the initial value problem in which equilibrium and constitutive equations are satisfied at all times, this model gives time-history of stresses and displacements. Fair agreements were obtained in load-point displacement rate, damage zone, neutral axis locations, stress relaxation and redistribution when compared with simple curved beam theory and experimental data. As common with other nonlinear problems, the convergence of the finite element solutions strongly depends on the time step as well as the finess of the element size, particularly at the regions where principal stresses are close to the threshold stress for creep damage.