Papers by Keyword: Orthotropy

Paper TitlePage

Authors: Wei Zhou Zhong, Xi Cheng Huang, Zhi Ming Hao, Ruo Ze Xie, Gang Chen
Abstract: The curves of stress versus strain along spruce wood axial, radial and tangential directions are gained by static compression experiments. Moisture content and density of the spruce wood are 12.72% and 413 kg/m3 respectively. The results indicate that spruce compression process includes elastic, yield and compaction phases. Failure modes of spruce subjected to axial compression are fiber buckling and wrinkle. And failure modes under radial or tangential compression are wood fiber slippage and delamination. Axial compression yield strength is about nine times as that of radial and tangential compression. Radial and tangential compression yield strengths are almost equal. Energy absorption efficiency and ideality energy absorption efficiency of spruce along different loading directions are analyzed. And theory analytic solution to single wood cell buckling under axial compression is done. The obtained expression shows that the mean limit loading is relative to yield stress, cell structure dimension and wrinkle length for complete wrinkle cases.
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Authors: Il Sup Chung, Young Suck Chai
Abstract: In the analysis of materials containing regularly placed in-homogeneities, the evaluation of homogenized properties is an important issue. Common procedure for the homogenization is to define a unit cell, load it somehow, and investigate its structural response. A periodic variation of strain appears when the periodically heterogeneous material is under uniform macro-stress, and therefore, the implementation of this characteristic behavior would be essential to the material characterization based on a unit cell analysis. With the method proposed here, conventional finite element analysis tools can be used with no modification, and it is applicable to the skew-arrayed in-homogeneity problems. The orthotropic elastic and creep properties of materials with voids are examined, and the accuracy and effectiveness are demonstrated.
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Authors: Wei Zhou Zhong, Xi Cheng Huang, Zhi Ming Hao, Ruo Ze Xie, Gang Chen
Abstract: Compression experiments of spruce along axial, radial and tangential loading directions are implemented by INSTRON equipment. Mechanical properties of spruce along three directions are gained. Spruce microscopic cell failure modes under axial, radial and tangential compression condition are observed by scan electron microscope. Results show that failure modes of spruce are fiber buckling and wrinkle when loading direction is along the grain. When loading direction is along radial or tangential across to the grain, failure modes are wood fiber slippage and delamination. Theory analytic solution to single wood cell failure under different direction compression is done. The obtained expression shows that mean limit loading is relative to yield stress, cell structure dimension and wrinkle length for complete wrinkle cases.
556
Authors: Milagros Sánchez, Nando Troyani
Abstract: Results for stress concentration in short members for isotropic plates with centered circular holes have been reported in the literature. More recently the influence of length for orthotropic holed plates has been examined and published as well. However, important aspects of stress considerations were missing such as the influence of load direction vs. material orientation which happens to have a strong influence on stress concentrations. Additionally, implied important misleading inaccuracies were reported. This analysis is meant to provide essential corrections to the published material.
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Authors: Wei Zhou Zhong, Shun Cheng Song, Ruo Ze Xie, Xi Cheng Huang, Gang Chen
Abstract: Numerical simulation on container cushion behavior in three impact loading directions is implemented in the present work. The results show that the energy absorption abilities are different in axial, radial and tangential loading directions. For certain deformation condition, energy absorption in axial loading is the most. And energy absorption abilities along radial and tangential loading are nearly equal. For certain energy absorption quantity, the deformation in axial loading is the least and the deformations in radial and tangential loading are larger. It can be concluded that wood grain should be perpendicular to protected object for low velocity, small energy absorption case. And wood radial or tangential direction should be perpendicular to protected object for high velocity, large energy absorption case.
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Authors: Tomáš Profant, Jan Klusák, Oldřich Ševeček, Michal Kotoul
Abstract: The assessment of conditions of crack initiation in a tip of a bi-material notch composed of two orthotropic materials is dealt. The assessment of the bi-material orthotropic notch stability criteria based on standard linear elastic fracture mechanics can lead to incorrect results due to a change of fracture mechanics properties. The change of the fracture mechanics properties are taken into account in the discussed stability criterion. It is shown that the criterion of this kind can qualitatively and quantitatively influence the results, and it contributes to more reliable assessment of components with geometrical and/or material discontinuity.
545
Authors: H.P. Truong Qui, Horst Lippmann
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Authors: Jing Zhang, Chang Yu Zhou, Xiao Hua He
Abstract: The structure of cylindrical shell with nozzle has been widely used in pressure equipment. The analysis and design for the structure of cylindrical shell with nozzle are generally based on the isotropy of metal at present, which may cause certain error and risk. Because of the approaches of rolling, heat treatment, and so on, the materials’ properties are different along each direction in practical engineering. In this paper, based on anisotropic thin shell theory, the analysis for orthotropic pressurized structure of thin-walled cylindrical shell with nozzle was conducted by using finite element software Ansys. The influences of thickness ratio and elastic modulus ratio were comprehensively considered, and also compared with the stress results under isotropic structure. The analysis results show that the values of stress and stress concentration factor for the structure of cylindrical shell with nozzle decrease with elastic modulus ratio, but increase with thickness ratio. Compared with the influence of thickness ratio, the elastic modulus ratio has significant effect on stress level. The rational use of the material anisotropic property can optimize the structure of thin-walled cylindrical shell with nozzle. The results in present paper provided a reference for the design of orthotropic pressurized structure of cylindrical shell with nozzle.
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Authors: Zhi Lan Zhan, Yi Ren Chen, Jing Song Wang
Abstract: The trapezoidal tearing method was utilized for the polyurethane coated fabrics with five different Silicone contents. The correlation of elastic modulus, shear modulus and tearing strength were studied and the results showed that the tearing strength increased following the decrease of elastic modulus. Finite element results were analyzed for the coated fabrics by using orthotropic model. The calculation results showed good agreement with the experimental results.
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