Macro- and Micro-Mechanics of Mixed-Mode Dynamic Fracture of Concrete. Part 1. Micro-Mechanic Analysis
Final rept. 15 Dec 1990-14 Dec 1992
WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING
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A hybrid experimental-numerical procedure was used to analyze the micro-mechanics of the mixed-mode, static and dynamic fracture of a concrete three-point bend specimen with an offset precrack. Fourtwo beam moire interferometry was used to record simultaneously separating horizontal and vertical displacements associated with stablerapid growth. An elasto-static elasto-dynamic finite element code was execute in its propagation mode with assumed crack closure stress CCS versus crack opening displacement COD and crack shearing stress CSS versus crack sliding displacement CSD relations which were adjusted to match the computed and measured CODs and CSDs. The resultant CCS versus COD and the CSS versus CSD relations were then used to compute the dissipated energy in the FPZ. This energy dissipation rate in the FPZ accounted for about 80 of the total energy release rate throughout the dynamic fracture process. This study also showed that the strain energy released at the crack tip and the dissipated energy in the fracture process zone after crack kinking are due mainly to mode I crack tip deformation.
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