• Composites Research
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• v.22 no.4
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• pp.20-26
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• 2009

In the current study, thermoforming and compression analysis were carried out for the woven composite egg-box panel with the non-orthogonal constitutive material model, which is proposed by Xue et al. The material model is implemented in commercial engineering software, LS-DYNA, with a user subroutine. Directional properties in non-orthogonal coordinates are determinedusing the deformation gradient tensor and the material modulus matrix in local coordinate is updated at eaeh corresponding time step. After the implemented non-orthogonal constitutive model is verified by the bias extension test, the egg-box panel simulations are performed. The egg-box panel simulations are divided into two categories: thermoforming (draping) and crushing. The finite element model for crushing analysiscan be obtained using the displacement result of thermoforming process.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.93-105
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• 2012

This paper compares the two- and three-dimensional (2D and 3D) approaches for the numerical determination of the equivalent mechanical properties of fractured rock masses. Both orthogonally-fractured model and discrete fracture networks (DFN) were used for the geometry and 2D models were cut in various directions from 3D model to compare their mechanical properties. Geological data were loosely based on the data available from Sellafield, UK. Analytical method based on compliance tensor transformation was used for investigation in orthogonally fractured rock and numerical experiments were conducted on fractured rock mass with DFN geometry. It is shown that 2D approach always overestimates the elastic modulus of fractured rock masses by a factor of up to around two because fractures are assumed to be perpendicular to the model plane in 2D problems. Poisson ratios tend to have larger values in 2D analysis while there is opposite trend in some sections. The study quantitatively demonstrates the limitation of the 2D approach that uses the simplified model from true 3D geometry.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.424-435
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• 1991

To develop the photoelastic experiment method for the orthotropic material under pure torsional moment is the main objective of this research. In the development of photoelastic experiment for orthotropic material under pure torsional moment, the important problems and their solutions are the same as following. In the model material for photoelastic experiment, it was found that C.F.E.C.(Copper Fiber Epoxy Composite) can be used as the model material of photoelastic experiment for orthotropic material. In the stress freezing cycle, it was assured that stress freezing cycle for epoxy can be used as the stress freezing cycle of the photoelastic experiment for orthotropic material. In the slicing method, it was found that the negative oblique slicing method can be effectively used as slicing method in 3-dimensional photoelastic experiment. In the measuring method of stress fringe values and physical properties in the high temperature, it was found that stress fringe values can be directly measured by experiment and physical properties can be directly or indirectly by equation between stress fringe values and physical properties developed by author. In the stress analysis method of orthotropic material under pure torsional moment by photoelastic experiment, it will be studied in the second paper.