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In this paper, the eXtended Finite Element Method is implemented to model the effect of the mechanical and thermal shocks on a cracked 2D orthotropic media. The uncoupled thermoelasticity equations are considered. Isoparametric four-node and eight-node rectangular elements are used to discrete governing equations. The dynamical stress intensity factors are computed by the interaction integral method. The Newmark and the Crank–Nicolson time integration schemes are used to numerical solve the spatial-discretized elastodynamic and thermal equations, respectively. A MATLAB code is developed to carry out all stages of the calculations from mesh generation to post-processing. Several elastic and thermoelastic numerical examples are implemented, to check the accuracy of the results and to investigate the effect of the orthotropic direction on the stress intensity factors.

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Fracture phenomenon in orthotropic materials, generally associates with fracture process zone (damaged zone) in crack tip vicinity. Determination of Mechanical properties in this region can help to predict the value or even the direction of crack growth in orthotropic materials. This area contains a multitude of micro cracks which cause difficulties in analytical process of the region Also cause energy waste in damaged zone that can affect the material fracture properties. So far, several models have been proposed to determine the mechanical properties of this region, but due to the immense complexity of this region, the results have not been expressed the behavior of this region properly. Moreover, the existence methods have not been verified with new experimental and numerical data, yet. In present research, a new approach based on experimental and numerical results proposed to investigate the orthotropic damaged zone properties. This model, unlike previous models by offering a range for effective elasticity modulus, can determine the mechanical properties of this region for the presence or absence of micro-cracks interaction among them. The proposed model also, validated and compared with experimental and numerical results.

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In this paper, shape and size of the Crack Tip Plastic Zone (CTPZ) are investigated for orthotropic materials based on Tsai-Hill and Hoffman yield criteria under various loading conditions and plane stress state for an infinite and central-cracked plate. It is assumed that the size of CTPZ is negligible verses the crack length for all loading conditions. For instance, the CTPZ is determined for orthotropic Boron-Epoxy and isotropic steel and effect of the crack’s axis angle on the CTPZ is analyzed for different loading conditions. The loading conditions were selected to obtain the CTPZ for mode I, mode II and combination of mode I and II. Dimensionless area of the CTPZ concept is used to compare the results obtained from Tsai-Hill and Hoffman yield criteria. The results show that in the same loading conditions, the size of CTPZ of Boron-Epoxy on Tsai-Hill yield criterion was smaller than on Hoffman yield criterion and this disagreement is less than the 10% and 13% based on the dimensionless area and radius of the CTPZ respectively. In a specific loading condition, the dimensionless radius of the CTPZ of isotropic materials is unique; however, it depends on the mechanical characteristics in orthotropic materials.