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Zhengong Zhou - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Stress intensity factors of two 3d rectangular permeable cracks in a transversely isotropic piezoelectric material under a time harmonic elastic p wave
International Journal for Numerical Methods in Engineering, 2016Co-Authors: Haitao Liu, Zhengong ZhouAbstract:Summary The Dynamic behavior of two 3D rectangular permeable cracks in a transversely isotropic piezoelectric material is investigated under an incident harmonic Stress wave by using the generalized Almansi's theorem and the Schmidt method. The problem is formulated through double Fourier transform into three pairs of dual integral equations with the displacement jumps across the crack surfaces as the unknown variables. To solve the dual integral equations, the displacement jumps across the crack surfaces are directly expanded as a series of Jacobi polynomials. Finally, the relations among the Dynamic Stress field and the Dynamic electric displacement filed near the crack edges are obtained, and the effects of the shape of the rectangular crack, the characteristics of the harmonic wave, and the distance between two rectangular cracks on the Stress and the electric intensity factors in a piezoelectric composite material are analyzed. Copyright © 2015 John Wiley & Sons, Ltd.
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Dynamic Stress intensity factors of two 3d rectangular cracks in a transversely isotropic elastic material under a time harmonic elastic p wave
Wave Motion, 2014Co-Authors: Haitao Liu, Zhengong ZhouAbstract:Abstract The Dynamic Stress intensity factors (DSIFs) of two 3D rectangular cracks in a transversely isotropic elastic material under an incident harmonic Stress wave are investigated by generalized Almansi’s theorem and the Schmidt method in the present paper. Using 2D Fourier transform and defining the jumps of displacement components across the crack surface as the unknown functions, three pairs of dual integral equations are derived. To solve the dual integral equations, the jumps of the displacement components across the crack surfaces are expanded in a series of Jacobi polynomials. Numerical examples are provided to show the effects of the geometric shape of the rectangular crack, the characteristics of the harmonic wave and the distance between two rectangular cracks on the DSIFs of the transversely isotropic elastic material.
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Dynamic Stress intensity factors around two parallel cracks in a functionally graded layer bonded to dissimilar half planes subjected to anti plane incident harmonic Stress waves
International Journal of Engineering Science, 2004Co-Authors: Zhengong ZhouAbstract:The time-harmonic problem of determining the Stress field around two parallel cracks in functionally graded materials (FGMs) is studied. The Fourier transform technique is used to reduce the boundary conditions to four simultaneous integral equations which are then solved by expanding the differences of crack surface displacements in a series. The unknown coefficients in the series are obtained by the Schmidt method. Numerical calculations are carried out for Dynamic Stress intensity factors (DSIF) in FGMs.
Shunhua Zhou - One of the best experts on this subject based on the ideXlab platform.
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differential settlement and soil Dynamic Stress of a culvert embankment transition zone due to an adjacent shield tunnel construction
Ksce Journal of Civil Engineering, 2018Co-Authors: Yao Shan, Shunhua ZhouAbstract:The effects of shield tunnel construction on the differential settlement and the distribution of soil Dynamic Stress of an adjacent culvert-embankment transition zone are investigated. A construction project of shield tunnels in Hangzhou (China) beneath an existing railroad culvert-embankment transition zone is employed as a case study. Firstly, the shield tunneling activities in the vicinity of a culvert-embankment transition zone are simulated by a three-dimensional (3D) Finite Element Analysis (FEA) method. The differential settlement of the transition zone is calculated to evaluate the influence of the shield tunneling on the safety of the passing train. Secondly, a plane strain model is employed to investigate the discipline of the soil Dynamic Stress in transition zones, which is induced by the passing train and the shield tunnel beneath the railroad. Results indicate that the reinforcement treatment of the foundation is required since the embankment differential settlement is significantly affected by the shield tunneling. Finally, a recommended treatment is introduced according to the property of the surrounding soil. Numerical simulation reveals that this treatment is appropriate for reducing the differential settlement and soil Dynamic Stress of the transition zone.
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differential settlement and soil Dynamic Stress of a culvert embankment transition zone due to an adjacent shield tunnel construction
Ksce Journal of Civil Engineering, 2018Co-Authors: Yao Shan, Shunhua ZhouAbstract:The effects of shield tunnel construction on the differential settlement and the distribution of soil Dynamic Stress of an adjacent culvert-embankment transition zone are investigated. A construction project of shield tunnels in Hangzhou (China) beneath an existing railroad culvert-embankment transition zone is employed as a case study. Firstly, the shield tunneling activities in the vicinity of a culvert-embankment transition zone are simulated by a three-dimensional (3D) Finite Element Analysis (FEA) method. The differential settlement of the transition zone is calculated to evaluate the influence of the shield tunneling on the safety of the passing train. Secondly, a plane strain model is employed to investigate the discipline of the soil Dynamic Stress in transition zones, which is induced by the passing train and the shield tunnel beneath the railroad. Results indicate that the reinforcement treatment of the foundation is required since the embankment differential settlement is significantly affected by the shield tunneling. Finally, a recommended treatment is introduced according to the property of the surrounding soil. Numerical simulation reveals that this treatment is appropriate for reducing the differential settlement and soil Dynamic Stress of the transition zone.
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three dimensional multilayer cylindrical tunnel model for calculating train induced Dynamic Stress in saturated soils
Computers and Geotechnics, 2016Co-Authors: Shunhua Zhou, Xiaohui Zhang, Zhe LuoAbstract:Abstract This study proposes an improved tunnel model for evaluating train-induced Dynamic Stress in saturated soils, which can consider multiple moving loads, grouting layer and pore-water pressure. Using Shanghai Metro’s actual parameters for train speed, tunnel, grouting layer and soils, the analysis of the spatial distribution of Dynamic Stress for soils and Stress state of various locations under moving train loads shows that neglecting effects such as pore-water pressure can lead to underestimating Dynamic normal Stress and overestimating Dynamic shear Stress in the soils below tunnel. This model can be further extended to investigate principal Stress axes rotations and tunnel settlement.
Zhijun Zheng - One of the best experts on this subject based on the ideXlab platform.
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Dynamic crushing of cellular materials a unique Dynamic Stress strain state curve
Mechanics of Materials, 2016Co-Authors: Yuanyuan Ding, Zhijun Zheng, Shilong Wang, Liming YangAbstract:Abstract Cellular materials under high loading rates have typical features of deformation localization and Stress enhancement, which have been well characterized by one-dimensional shock wave models. However, under moderate loading rates, the local Stress–strain curves and Dynamic response of cellular materials are still unclear. In this paper, the Dynamic Stress–strain response of cellular materials is investigated by using the wave propagation technique, of which the main advantage is that no pre-assumed constitutive relationship is required. Based on virtual Taylor tests, a series of local Dynamic Stress–strain history curves under different loading rates are obtained by Lagrangian analysis method. The plastic stage of local Stress-strain history curve under a moderate loading rate presents a crooked evolution process, which demonstrates the Dynamic behavior of cellular materials under moderate loading rates cannot be characterized by a shock model. A unique Dynamic Stress–strain state curve of the cellular material is summarized by extracting the critical Stress–strain points just before the unloading stage on the local Dynamic Stress–strain history curves. The result shows that the Dynamic Stress–strain states of cellular materials are independent of the initial loading velocity but deformation-mode dependent. The Dynamic Stress–strain states present an obvious nonlinear plastic hardening effect and they are quite different from those under quasi-static compression. Finally, the loading-rate and strain-rate effects of cellular materials are investigated. It is concluded that the initial crushing Stress is mainly controlled by the strain-rate effect, but the Dynamic densification behavior is velocity-dependent.
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Dynamic Stress strain states for metal foams using a 3d cellular model
Journal of The Mechanics and Physics of Solids, 2014Co-Authors: Zhijun Zheng, S R Reid, Changfeng Wang, John J HarriganAbstract:Abstract Dynamic uniaxial impact behaviour of metal foams using a 3D cell-based finite element model is examined. At sufficiently high loading rates, these materials respond by forming ‘shock or consolidation waves’ ( Tan et al., 2005a , Tan et al., 2005b ). However, the existing Dynamic experimental methods have limitations in fully informing this behaviour, particularly for solving boundary/initial value problems. Recently, the problem of the shock-like response of an open-cell foam has been examined by Barnes et al. (2014) using the Hugoniot-curve representations. The present study is somewhat complementary to that approach and additionally aims to provide insight into the ‘rate sensitivity’ mechanism applicable to cellular materials. To assist our understanding of the ‘loading rate sensitivity’ behaviour of cellular materials, a virtual ‘test’ method based on the direct impact technique is explored. Following a continuum representation of the response, the strain field calculation method is employed to determine the local strains ahead of and behind the resulting ‘shock front’. The Dynamic Stress–strain states in the densification stage are found to be different from the quasi-static ones. It is evident that the constitutive behaviour of the cellular material is deformation-mode dependent. The nature of the ‘rate sensitivity’ revealed for cellular materials in this paper is different from the strain-rate sensitivity of dense metals. It is shown that the Dynamic Stress–strain states behind a shock front of the cellular material lie on a unique curve and each point on the curve corresponds to a particular ‘impact velocity’, referred as the velocity upstream of the shock in this study. The Dynamic Stress–strain curve is related to a layer-wise collapse mode, whilst the equivalent quasi-static curve is related to a random shear band collapse mode. The findings herein are aimed at improving the experimental test techniques used to characterise the rate-sensitivity behaviour of real cellular materials and providing data appropriate to solving Dynamic loading problems in which cellular metals are utilised.
Haitao Liu - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Stress intensity factors of two 3d rectangular permeable cracks in a transversely isotropic piezoelectric material under a time harmonic elastic p wave
International Journal for Numerical Methods in Engineering, 2016Co-Authors: Haitao Liu, Zhengong ZhouAbstract:Summary The Dynamic behavior of two 3D rectangular permeable cracks in a transversely isotropic piezoelectric material is investigated under an incident harmonic Stress wave by using the generalized Almansi's theorem and the Schmidt method. The problem is formulated through double Fourier transform into three pairs of dual integral equations with the displacement jumps across the crack surfaces as the unknown variables. To solve the dual integral equations, the displacement jumps across the crack surfaces are directly expanded as a series of Jacobi polynomials. Finally, the relations among the Dynamic Stress field and the Dynamic electric displacement filed near the crack edges are obtained, and the effects of the shape of the rectangular crack, the characteristics of the harmonic wave, and the distance between two rectangular cracks on the Stress and the electric intensity factors in a piezoelectric composite material are analyzed. Copyright © 2015 John Wiley & Sons, Ltd.
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Dynamic Stress intensity factors of two 3d rectangular cracks in a transversely isotropic elastic material under a time harmonic elastic p wave
Wave Motion, 2014Co-Authors: Haitao Liu, Zhengong ZhouAbstract:Abstract The Dynamic Stress intensity factors (DSIFs) of two 3D rectangular cracks in a transversely isotropic elastic material under an incident harmonic Stress wave are investigated by generalized Almansi’s theorem and the Schmidt method in the present paper. Using 2D Fourier transform and defining the jumps of displacement components across the crack surface as the unknown functions, three pairs of dual integral equations are derived. To solve the dual integral equations, the jumps of the displacement components across the crack surfaces are expanded in a series of Jacobi polynomials. Numerical examples are provided to show the effects of the geometric shape of the rectangular crack, the characteristics of the harmonic wave and the distance between two rectangular cracks on the DSIFs of the transversely isotropic elastic material.
Yang Yeh Hisen - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Stress intensity factors of a semi infinite crack in an orthotropic functionally graded material
Mechanics of Materials, 2008Co-Authors: Xuefeng Yao, Xiqiao Feng, Yang Yeh HisenAbstract:Abstract The plane strain problems of semi-infinite cracks in an infinite functionally graded orthotropic material are studied. Two uniform impact loading modes are considered, i.e. opening and in-plane shear. Laplace and Fourier transforms along with the Winner–Hopf technique are employed to solve the displacement formulation of the equations of motion. Closed-form solutions of the Dynamic Stress intensity factors are obtained. It is observed that the Stress intensity factors are not all proportional to the square root of time as expected. The results can be reduced to the known solutions derived independently for orthotropic or isotropic materials.
