Instabilities of Damage and Surface Degradation Mechanisms in Brittle Material Structural Systems.

摘要

A review of the theoretical and experimental information on surface degradation and related instabilities is presented, and the physical significance of surface or skin effects is identified. The research involves study of relation between surface degradation and scale or size as well as shape effects, and surface damage growth instabilities and related bursting in brittle materials. A theory is developed to trace growth of surface degradation and to-identify onset of relevant instabilities. Here e internal length is also estimated based on available experimental results. A comprehensive series of laboratory compression tests are performed on rectangular specimens with different dimensions of an artificial rock like material. Simultaneous nondestructive ultrasonic measurements are obtained at various locations on the -specimens. The damage and instability distributions obtained by using a finite element procedure and symbolic computation are related to the dissipated energy derived from ultrasonic measurements. Comparisons of theoretical predictions and nondestructive measurements correlate very well. Surface effects, Degradation, Energy dissipation, Brittle materials, Experiments, Numerical predictions, Verification.