Brittle Microcracking Solids Research Articles

Mesoscale Analysis of Solids Containing a Number of Microvoids by Using Natural Element Method (2nd Report, Ductile Fracture Analysis Considering Void Linking)

The two-dimensional meso-scale simulation method using the natural element method previously proposed by the authors for brittle microcracking solids has been applied to the analysis of the elastic deformation and fracture behavior of aluminum sheets containing random array of equi-sized holes under uniaxial and biaxial loading to study the ligament flow localization and void linking during ductile fracture. The calculated results for the load-displacement curve and the void linking have agreed well with the experimental results given by Geltmacher et al. The validity of the present method has been demonstrated through these numerical studies.

2-D Meso-Analysis of Material Damage by the Meshless Method. 1st Report, Overall Elastic Moduli of Solids Including Microcracks.

A meso-scale analysis method using the natural element method, which is a kind of meshless methods, is proposed for the analysis of material damage of brittle microcracking solids such as ceramic materials, concrete and rocks. The microcracking is assumed to occur along the Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The overall elastic moduli of anisotropic as well as isotropic solids containing a number of randomly distributed microcracks are calculated in order to demonstrate the validity of the proposed method.

2-D Mesoscopic Simulation of Two-Phase Materials Containing Short Fibers.

The two-dimensional mesoscopic simulation method previously proposed by one of the authors for brittle microcracking solids is applied to the analysis of two-phase materials containing short fibers. Numerical results are presented to demonstrate validity of the proposed method. The effect of elastic property, slenderness, volume fraction, fiber-end cracks and orientation-distribution function of short fibers on overall elastic properties of two-phase materials has been studied. The microcracking behavior under tensile, shear and bending stress conditions accompanied by crack deflection, crack bridging and fiber pull-out has also been analyzed by the proposed mesoscopic simulation method.

Two-Dimensional Mesomechanical Analysis of R-Curve Behavior in Brittle Microcracking Solids.

The two-dimensional mesomechanical simulation method previously proposed by the authors for brittle microcracking solids containing microinclusions is applied to the analysis of R-curve behaviors for a macrocrack under mode-I loading. Influences of grain size, residual stress, total volume fraction of microinclusions and critical microcracking stress at intergranular facets on the fracture toughness of single-as well as two-phase materials are discussed through the calculated results.

Damage mechanics models for brittle microcracking solids based on three-dimensional mesoscopic simulations

Fracture behaviors of brittle polycrystalline solids such as ceramic materials are deeply related to microcracking. Continuum damage mechanics is considered a powerful theoretical framework to deal with brittle microcracking solids. However, it is fairly difficult to obtain analytically, as well as experimentally, evolution equations for microcracking and reduced elastic compliances of microcracked solids. In the present study, a three-dimensional mesoscopic simulation method using a discontinuum mechanics model is employed to obtain this information. Based on the results of mesoscopic simulations, improved damage mechanics models assuming anisotropy as well as isotropy are proposed. Some numerical studies have been conducted to confirm their validities.

Three-Dimensional Mesomechanical Analysis of Brittle Solids Containing Microinclusions.

The three-dimensional mesomechanical simulation method previously proposed by the authors for brittle microcracking solids is extended to include the effects of microinclusions. The relationship between overall elastic moduli and total volume fraction of microinclusions as well as the influence of microinclusions on the microcracking behavior are studied in order to demonstrate the validity of the proposed method.

Mesoscopic Simulation of Microcracking Behaviors of Brittle Polycrystalline Solids : 1st Report, Study of Isotropic Theory in Continuum Damage Mechanics

Fracture behaviors of brittle polycrystalline solids such as ceramic materials are deeply related to microcracking. Continuum damage mechanics is considered a powerful theoretical framework to deal with brittle microcracking solids. However, it is fairly difficult to obtain analytically, as well as experimentally, evolution equations for microcracking and reduced elastic compliances of microcracked solids. In the present study, a mesoscopic simulation method at grain scale using a discontinuum mechanics model is employed to obtain such information. The validity and limitations of the isotropic theory of continuum damage mechanics are studied here.

Computational damage mechanics models for brittle microcracking solids based on mesoscopic simulations

Fracture behavior of brittle polycrystalline solids such as ceramic materials is closely related to microcracking. Continuum damage mechanics is considered as a powerful theoretical framework within which to deal with brittle microcracking solids. However, it is fairly difficult to obtain analytically as well as experimentally evolution equations for microcracking and reduced elastic compliances of microcracked solids. In the present study, a mesoscopic simulation method using a discontinuum mechanics model is employed to obtain this information. Based on the results of mesoscopic simulations, improved damage mechanics models assuming anisotropy as well as isotropy are proposed and applied to the finite element analysis of microcracking near the macrocrack-tip in a compressive stress field.

Enhanced Computational Damage Mechanics Models for Brittle Microcracking Solids.

The existing computational damage mechanics models for brittle microcracking solids are improved, based on the results of mesoscopic simulations previously presented by the authors. The relations between the elastic compliances and the microcrack density, especially in the compressive stress state, are modified for the isotropic theory. For the anisotropic model, the damage evolution equations are modified so as to give positive values of the damage rates in an arbitrary stress state. These enhanced damage mechanics models are applied to the two-dimensional finite element analysis of brittle microcracking solids in order to test their validities.

3-D Mesomechanical Analysis of Brittle Microcracking Solids and Improvement of Damage Mechanics Models. 2nd Report, Anisotropic Damage Mechanics Model.

The three-dimensional mesomechanical simulation method proposed in the first report of the present study has been applied to the analysis of a brittle microcracking solid under various loading conditions. The validity and the limitation of the existing anisotropic damage mechanics model have been studied by comparing its predictions with the results of mesoanalysis. Based on these results, the evolution equation for the microcrack density in the existing damage mechanics model has been improved. The validity of the improved damage mechanics model has been verified against the results of mesoanalysis.

3-D Mesomechanical Analysis of Brittle Microcracking Solids and Improvement of Damage Mechanics Models. 1st Report, Isotropic Damage Mechanics Model.

A three-dimensional mesomechanical simulation method using a discontinuum mechanics model (the rigid bodies-spring model)has been proposed and applied to the numerical analysis of brittle polycrystalline solids containing microcracks. The relationship between microcrack density and elastic modulus under the influence of microcrack closure and surface friction as well as the evolution equation for microcrack density are discussed. The isotropic model in continuum damage mechanics has been improved, based on the results of these mesomechanical simulations.

Finite element analysis of static and dynamic fracture of brittle microcracking solids. Part 1: formulation and simple numerical examples : Toi, Y; Atluri, S N Int J PlasticityV6, N2, 1990, P169–188

Finite element analysis of static and dynamic fracture of brittle microcracking solids. Part 1: formulation and simple numerical examples : Toi, Y; Atluri, S N Int J PlasticityV6, N2, 1990, P169–188

Finite element analysis of static and dynamic fracture of brittle microcracking solids: Part 1: Formulation and simple numerical examples

The continuum constitutive modeling for rate-dependent fracture of brittle microcracking solids is discussed. The rate-type constitutive equation that is proposed takes into account the rate effect on microcracking and plastic deformation. In order to best the validity of the proposed modeling, numerical studies are conducted on a barunder uniaxial tension, a beam under pure bending, and on the phenomenon of microcracking around the tip of a macro-crack under mode-I loading.

Finite element analysis of static and dynamic fracture of brittle microcracking solids. Part 3: Stationary and rapidly propagating cracks under dynamic loading

Abstract The continuum constitutive modeling for rate-dependent fracture of brittle microcracking solids, which was described in Part 1 of this paper, is applied to the finite element analysis of stationary and rapidly propagating macrocracks under dynamic loading. The microcrack toughening effect is discussed, along with the influence on it of the size of the microcracked process zone and the various parameters in the microcrack density evolution equation, through the observation of the behavior of the general crack-tip energy-relase parameter, the T integral.

Finite element analysis of static and dynamic fracture of brittle microcracking solids

Abstract The continuum constitutive modeling for rate-dependent fracture of brittle microcracking solids, which was described in Part 1 of this paper, is applied to the finite element analysis of stationary and nonstationary macrocracks in a single-edge-notched three-point bend specimen under a static loading. The microcrack damage zones near the macro-crack-tip can be classified as being “large-scale.” The microcrack toughening effect in stationary cracks is observed through the behavior of the crack tip energy-flux parameter, the T ∗ -integral. The numerical results of the nonstationary crack analysis are compared with the available experimental results for a silicon carbide specimen.