A very important problem in the research of layer structures is the modeling of cracks on the material interface. Due to the complex physical and mechanical properties of this structure, the simulation of discontinuities such as cracks and material interface by traditional finite element methods requires a very fine mesh density. Furthermore, mesh smoothing requires a really large amount of computational resources. Therefore, the extended algorithm which does not require the remeshing technique was born to solve the crack problems. In this paper, the extended consecutive-interpolation finite element method (XCFEM) is employed to modeling the mix-mode interface cracks between two dissimilar isotropic materials. The XCFEM using 4-node consecutive-interpolation quadrilateral element (XCQ4) provides continuity of nodal gradient due to the concept of “consecutive-interpolation” so that the stress and strain fields derived from XCQ4 is smoother than that obtained by the classical FEM element. The accuracy and effectiveness of the method are demonstrated via various numerical examples and compared with other researches.
Analysis of mechanical behavior of a structure containing defects such as holes and inclusions is essential in many engineering applications. In many structures, the discontinuities may have a significant influence on the reduction of the structural stiffness. In this work, we consider the effect of multiple random holes and inclusions in functionally graded material (FGM) plate and apply the extended finite element method with enrichment functions to simulate the mechanical behavior of those discontinuous interfaces. The inclusions also have FGM properties. Numerical examples are considered and their obtained results are compared with the COMSOL, the finite element method software.
Natural energy such as wind, wave and other natural vibrations is one of the high potential renewable energy sources. The Wells turbine is based on the use of bidirectional turbines, which act as axial-flow self-rectifying turbines that employs a symmetrical blade profile and rotating unidirectionally in reciprocating airflows generated by the air chamber to extract energy from vibrations. These topics have been extensively studied both numerically and experimentally such as research on the parameters of the effects of structure, angle of attack, blade shape, etc. In this paper, numerical simulation is carried out using commercially available tool Fluent for fluid dynamics analysis and focus on oscillating predictions, with particular attention to the behavior of the flow. Based on the Numerical Wave Tank (NWT) model is simulated in a two dimensional used in this model, which is constructed mainly based on the spatially averaged Navier Stokes equation with the k-ε model for simulating the turbulence and modeled with Volume of Fluid (VOF). Axial-flow turbines system and future development as well as the proposed limitations will be discussed in detail.
Predicting crack trajectory when crack propagation occurs plays an important role in fracture mechanics problems because this will evaluate whether important areas of structure are heavily influenced by crack propagation. This article will introduce three theories to predict crack path, including maximum tangential stress theory, maximum energy release rate theory and minimum strain energy density theory. Besides, the FRANC2D program is used to simulate the crack propagation based on three above theories.
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