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Objective Fracture Parameters and a Paradox for Interface Cracks

Due to the oscillatory singular stress field around a crack tip, interface fracture has some peculiar features. This paper is focused on two of them. One can be reflected by a proposed paradox that geometrically similar structures with interface cracks under similar loadings may have different failure behaviors. The other one is that the existing fracture parameters of the oscillatory singular stress field, such as a complex stress intensity factor, exhibit some nonobjectivity because their phase angle depends on an arbitrarily chosen length.

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The widely used tensile stiffness ratio is not a correct measure of anisotropy degree

In our recent paper, some interesting conclusions are found when we attempt to establish a standardized compliance matrices for general anisotropic materials. The abstract is as follows.

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The surface-forming energy release rate based fracture criterion for elastic-plastic crack propagation and interpretation on paradox of Rice

The J-integral based criterion is widely used in elastic-plastic fracture mechanics. However, it is not rigorously applicable when plastic unloading appears during crack propagation. One difficulty is that the energy density with plastic unloading in the J-integral cannot be defined unambiguously.

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Adaptive periodical representative volume element for simulating periodical postbuckling behavior

Finite element method (FEM) with fixed representative volume element (RVE) encounters some difficulties in simulating the periodical postbuckling behaviors of infinite long beam or infinite large film on soft substrate under compression, because the wavelength and pattern of buckling are not known before simulation and will change with the increase of compression strain.

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The theoretical ultimate magnetoelectric coefficients of magnetoelectric composites by optimization design

This paper investigates what is the largest magnetoelectric (ME) coefficient of ME composites, and how to realize it. From the standpoint of energy conservation, a theoretical analysis is carried out on an imaginary lever structure consisting of a magnetostrictive phase, a piezoelectric phase, and a rigid lever. This structure is a generalization of various composite layouts for optimization on ME effect.

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Direct influence of residual stress on the bending stiffness of cantilever beams

Although the cantilever beam has been widely used as a sensor to measure various physical quantities, important issues such as how residual stress affects its bending stiffness and what are the underlying physical origins have not been fully understood. We perform both theoretical analyses and finite-element simulations to demonstrate for the first time that without changing the material tangent stiffness, residual stress within the beam can directly influence the bending stiffness of the beam.

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An effective bead-spring model for polymer simulation

An effective bead-spring model combining the advantages of large time steps of traditional bead-rod models and computational rigor of traditional bead-spring models is proposed to simulate the dynamic behaviors of flexible polymer chains with arbitrary longitudinal stiffness. The proposed model can be used to simulate many types of polymer chains or networks with different chain elasticity via a unified integration scheme with reasonably large time steps. The paper can be found at http://dx.doi.org/10.1016/j.jcp.2007.11.012

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