by Yang, Jiashi

Electromechanical fields around an anti-plane, semi-infinite crack in piezoelectric semiconductors of 6mm symmetry are obtained. The effects of semiconduction on fields near the crack tip are examined.

DOI: 10.1007/s10704-006-6943-2
Print publication date: 11/1/2005
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by He, Q. -C.; Pensée, V.

The microstructure model proposed in this work is an assemblage of hollow spheres saturated by a fluid. The solid phase of each sphere is linearly elastic and spherically anisotropic. On the basis of this microstructure model, the effective bulk modulus, Biot’s coefficient and porosity variation are determined. It is shown that local anisotropy has important effects on the macroscopic isotropic poroelastic properties via a dimensionless material parameter which characterizes the degree of anisotropy and exponentially affects the porosity.

DOI: 10.1007/s10704-006-6784-z
Print publication date: 11/1/2005
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by Kotousov, Andrei

DOI: 10.1007/s10704-006-6783-0
Print publication date: 11/1/2005
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by

DOI: 10.1007/s10704-006-6694-0
Print publication date: 11/1/2005
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by Tian, Changlu; Cui, Weicheng

A ligament field ahead of a crack tip for Model-I plane strain problem in a power-law hardening material is developed. Based on this solution, a formula for the critical value of J-integral in terms of T-stress for an elastic-plastic material is derived. T-stress effects on fracture toughness are discussed.

DOI: 10.1007/s10704-006-6693-1
Print publication date: 11/1/2005
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by Lazopoulos, K.; Papadopoulos, G. A.

The experimental method of caustics is applied to buckling behaviour of straight cracked columns. Two major parameters of the problem may be defined through the caustics method: the SIF and the high strain internal region. The knowledge of these parameters may be used to improve predictions of the buckling behaviour of cracked columns.

DOI: 10.1007/s10704-006-6692-2
Print publication date: 11/1/2005
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by Zhou, Bin; Thouless, M. D.; Ward, S. M.

Ultrasonic spot welds have been used as a model system to investigate how to determine the mode-I cohesive parameters associated with interfacial fracture of a spot weld. Numerical analyses indicated that, while multiple combinations of the two cohesive parameters (characteristic strength, , and toughness, Γ I) could result in virtually indistinguishable behaviors for individual geometries, only a single pair of parameters can provide a unique set of behaviors for different test geometries. This provides the basis for determining the cohesive parameters by comparing numerical predictions to experimental observations. In particular, a direct uniaxial tensile test was found to be particularly useful for measuring the characteristic strength of an ultrasonic weld. With the characteristic strength known, the toughness of the weld was determined by fitting numerical predictions to experimental observations of the load–displacement curves obtained from T-peel specimens bonded with the ultrasonic weld. These two parameters were then used without modification to predict the performance of welded U-peel specimens. The numerical predictions for this third configuration were in excellent agreement with the experimental results, verifying that it may be possible to use cohesive-zone parameters to predict the behavior of different geometries of spot welds formed under nominally similar conditions.

DOI: 10.1007/s10704-005-6036-7
Print publication date: 11/1/2005
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by Li, Xue; Marasteanu, Mihai O.

Low temperature cracking is the major distress observed in asphalt pavements in the northern US and Canada. In the past years fracture mechanics concepts were introduced to investigate the fracture properties of asphalt mixtures at low temperatures. In this paper the cohesive zone model (CZM) is used to describe the fracture behavior of asphalt mixtures at low temperatures and the interface element is used to numerically simulate the material response under monotonic loading. The simulation is calibrated with the experimental results from a newly proposed semi circular bend (SCB) test. A parametric analysis of the input material properties indicates that the tensile strength has a significant effect on the peak load in the SCB configuration, the modulus has a strong effect on the calculated stiffness of the SCB specimen, and the fracture energy influences the post-peak behavior of the asphalt mixtures. The calibrated numerical model was applied to simulate the low temperature cracking in a simplified asphalt pavement and to study the influence of these material parameters on the performance of asphalt pavements.

DOI: 10.1007/s10704-005-6035-8
Print publication date: 11/1/2005
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by Morris, Dylan J.; Cook, Robert F.

Extension of the indentation fracture toughness estimation method to very small length scales often requires the use of an indenting punch much more acute than the oft-used Vickers probe. Experimental results for very acute, sharp probes have motivated a new approach to the indentation fracture mechanics of radial crack development. An extension of the standard two-component (residual elastic–plastic+elastic contact) stress-field model of radial fracture is proposed, based on the concept that a sufficiently acute indenter can also act as a ‘wedge,’ prying open the surface-located radial cracks. In this, the first of a two-part series, a three-component wedging indentation model is constructed, and some general characteristics of the model are explored. In particular, the implications of the three-component stress field of the model for the description of radial crack development during load-unload indentation cycles of acute probes are considered. Explicit predictions of crack development are compared with the qualitative features of experimental observations, providing a basis for the quantitative comparisons in Part II.

DOI: 10.1007/s10704-005-6034-9
Print publication date: 11/1/2005
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by Morris, Dylan J.; Vodnick, Aaron M.; Cook, Robert F.

The companion article proposed a model for radial crack development at sharp contacts. The major extension of this model from previous works is the inclusion of a ‘wedging’ mechanism, to form a three-stress-field description of indentation crack evolution. Here, the amplitude terms of the three stress-intensity factors comprising the model are calibrated from experimental in situ and post situ inert-environment radial crack measurements on soda-lime glass. These values are scaled to predict radial crack evolution during cube corner and Vickers indentation of fused silica and soda lime glass in inert and ambient air environments. Both the conventional two-field and the proposed three-field model predictions are compared with radial crack lengths measured during indentation load-unload cycles (through the transparent materials with an in-situ apparatus). The three-field model is shown to be a great improvement over the two-field model in the description of crack evolution at cube-corner indentations, particularly with respect to the significant crack extension during loading and the attainment of a maximum crack length during unloading. The three-field model is consistent with observations of Vickers fracture in soda-lime glass and is able to reproduce the features of radial fracture evolution on the ‘anomalous’ glass, fused silica.

DOI: 10.1007/s10704-005-6033-x
Print publication date: 11/1/2005
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