Study on Macro-Meso Coupled Problems in Material Failure

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This study had the first purpose of formulation of a technique having to do with computational mechanics at a meso-scale which can handle inclusively the fracture behavior of the material which has structure. The three-dimensional meso-analysis algorithm for single-phase solids by using computational disctontinuun mechanics model has been extended to deal with multi-phase materials containing fibers or inclusions and to consider in-and inter-granular fracture and transformation plasticity. It was the second purpose to grasp the influence which their meso-scale structure/behavior exert on the macro property such as constitutive equations and fracture toughness and to evaluate and improve the macro-scale modeling such as the homogenization method and the damage mechanics, based on the results.In 1997, first, we formulated the 3-dimensional meso-analysis algorithm considering in-and inter-granular fracture for single-phase solids (brittle polycrystalline solids) as an example of the mater … More ial which has structure. Next, we constructed the three-dimensional meso-analysis algorithm considering in-and inter-granular fracture and the transformation plasticity of the second-phase particles and so on for two-phase solids which contain microinclusions. Moreover, we made numerical simulations using these and considered about the validity of the computational technique.In 1998, first, analyzing at a meso-scale about the macro elasticity constants computation when single-phase solids and two-phase solids are beforehand accompanied by the microcrack damage, we evaluated and improved theoretical solutions given by the existing homogenization method and so on. Next, analyzing at an meso-scale about the nonstationary damage development in single-phase solids and two-phase solids, we evaluated and improved the existing macro continuum damage mechanics model. Lastly, conducting meso-analysis about the R curve (the crack developing resistance curve) behavior of single-phase solids and two-phase solids, we considered about the relation between the meso-scale structure and macro fracture toughness. The head investigator mainly took charge of the formulation of meso-analysis algorithm of three-dimensions and the assisting investigator mainly took charge of programming and the numerical computation. We established a method of the approach having to do with computational mechanics about the macro-meso interaction problem in case of material fracture. We got some knowledge about the phenomenon of the damage and the fracture of the solid. Less