The Influence of Nonlinear Elasticity on the Accuracy of Thermal Shock Damage Evaluation by the Impulse Excitation Technique

摘要

This work quantifies the influence of nonlinear elasticity on the accuracy of the thermal shock damage evaluation of high-alumina refractory castables based on dynamic Young's modulus and damping characterization data obtained via the impulse excitation technique (IET).The nonlinear elasticity leads to shifts in the Young's modulus and damping values in dependence of the impulse intensity. An IET apparatus was employed according to the ASTM E1876-07 standard; the method was improved by nonlinear analysis based on the excitation control. Two arbitrary coefficients were defined to evaluate the nonlinearity with respect to the im-pulse intensity. Three high-alumina refractory castables were submitted to progressive thermal shock damage and evaluated. The results show that the influence of nonlinear elasticity on the Young's modulus is significant and that nonlinear elasticity is a determining factor for the accuracy of the damping characterization (up to -0.93 % and +114 %, respectively, depending on the damage level).