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Shearography has proved to be a highly effective nondestructive testing (NDT) method, especially when it comes to composite and polymer materials used in automotive, aerospace engineering, nuclear and oil industries. Although its application in material testing and material research already has achieved acceptance in research, its applications need a highly considerations in limitations and its parameters. In this paper the application of digital shearography in the defect detection of polymer materials is studied. In this regard, a proper set-up of shearography is presented. A polyethylene plate with several defects in different sizes and depths have been made and tested with the presented set-up. The shearograms then have been compared to evaluate the shearographic system in defect detection. The effects of shear size and system of thermal loading have also been studied.

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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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This paper investigates static behavior of multilayered functionally grated piezoelectric plates under thermal loads. The plate with functionally graded piezoelectric material (FGPM) is assumed to be graded through the thickness by a simple power law distribution in terms of the volume fractions of the constituents. Considering the thermal coefficients of piezoelectric material in the constitutive equations (the terms that will couple temperature effects to the piezoelectric properties, named pyroelectric constants) and using the kinematic assumptions of first-order shear plate theory (FSDT), the constitutive equation of FGP plate is written. Then, by using principle of virtual work, the governing equations of a FGP plate is obtained. These equations are solved by finite element method using eight node shell element. Functionally graded piezoelectric plate under static loading, different layers and boundary conditions are considered and results in various thermal loadings have been obtained. Deflection and voltage results for different power law exponent and different boundary conditions are shown. In this paper, the influence of power law index on the static behavior of FGPM plate (including deflection and voltage) under thermal loading is investigated. These responses can be used as a criteria for design of FGP sensors and actuators in the thermal environment.

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In this paper, the extended Finite Element Method (XFEM) is implemented to compute the Stress Intensity Factors (SIFs) for rectangular media subjected to a hygrothermal loading. In governing hygrothermoelasticity equations, the cross coupled of temperature and moisture fields and temperature-dependent diffusion in some cases are considered. Furthermore, an interaction integral for hygrothermal loading is developed to compute the stress intensity factors. The non uniform mesh of isoparametric eight-nod rectangular element is used in XFEM to decrease the absolute error in SIFs computations. In order to numerical results validation, the SIF of mode I is obtained analytically. The coupled governing equations are firstly decoupled in terms of new variables and then solved by the separation of variable method. According to the results, the moisture concentration gradient has a significant effect on the SIFs so should be considered in the model. Up to reaching temperature to its steady state, the cross coupled of temperature and moisture synchronies their time variation which affects on the time variation of SIF. At early time of thermal shock, the SIF for shorter cracks is not necessarily lesser than the longer ones. Also, the mode I SIF for longer and inclined cracks is smaller. On the other hand, considering the moisture concentration as a temperature function increases the time required to reach the moisture steady state.