Thermoelastic solutions for orthotropic and anisotropic composite laminates

Solutions, within the framework of linear uncoupled thermoelasticity, are presented for certain problems of flexure of composite laminates. Benchmark numerical results, useful for the validation or otherwise of approximate laminate models, are tabulated. Finally, these results are used to examine the accuracy of the classical lamination theory based on Kirchhoff's hypothesis.     

Application of boundary element method to 3-D problems of coupled thermoelasticity

This paper deals with a new boundary element method for analysis of the quasistatic problems in coupled thermoelasticity. Through some mathematical manipulation of the Navier equation in elasticity, the heat conduction equation is transformed into a simpler form, similar to the uncoupled-type equation with the modified thermal conductivity which shows the coupling effects. This procedure enables us to treat the coupled thermoelastic problems as an uncoupled one, A few examples are computed by the proposed BEM, and the results obtained are compared with the analytical ones available in the literature, whereby the accuracy and versatility of the proposed method are demonstrated.     

Optical analysis of crack tip stress fields: a comparative study

Four optical techniques for evaluating stress intensity factors in opaque specimens are described in outline, and compared for both an artificial crack and a fatigue crack. The results are compared to a standard solution for the geometry considered. All the techniques gave acceptable results over a range of stress levels and crack lengths. The methods of caustics and strain gauges were less good, whilst photoelasticity gave consistent results over a wide range of stress levels. Comments on the ease of application and the resource implications are also made in order to assist practitioners.     

On dual-phase-lag thermoelasticity theory with memory-dependent derivative

A new mathematical model of generalized thermoelasticity with memory-dependent derivatives for the dual-phase-lag heat conduction law is constructed. The governing equations of the new model are applied to a half-space subjected to ramp-type heating. Laplace transforms technique is used. The solution is obtained for different types of functions representing the thermal shock and for different values of the parameter of the time fraction derivative of the model. The effects of time-delay and arbitrary kernel function on elastic material are studied and represented graphically. The predictions of the theory are discussed and compared with dynamic classical coupled theory.     

On the dynamical thermoelasticity problem for a hollow funtionally graded cylinder

A thermoelasticity problem of a pressurized infinite cylinder made of functionally graded material is solved analytically where material properties vary with radial position. Time dependent thermal and mechanical boundary conditions are assumed to act on the inner and outer surfaces of the cylinder. For thermal boundary conditions, temperature is prescribed on both surfaces, whereas for mechanical boundary conditions, tractions are prescribed on the boundaries. Obtaining distribution of temperature throughout the cylinder, the dynamical structural problem is solved and closed form relations are extracted for distributions of stress components.     

Energy-momentum-entropy consistent numerical methods for large-strain thermoelasticity relying on the GENERIC formalism

In the present paper, structure-preserving numerical methods for finite strain thermoelastodynamics are proposed. The underlying variational formulation is based on the general equation for nonequilibrium reversible-irreversible coupling (GENERIC) formalism and makes possible the free choice of the thermodynamic state variable. The notion “GENERIC consistent space discretization” is introduced, which facilitates the design of Energy-Momentum-Entropy (EME) consistent schemes. In particular, three alternative EME schemes result from the present approach. These schemes are directly linked to the respective choice of the thermodynamic variable. Numerical examples confirm the structure-preserving properties of the newly developed EME schemes, which exhibit superior numerical stability.     

Unified finite element approach for generalized coupled thermoelastic analysis of 3D beam-type structures,part 2: Numerical evaluations

This article aims to evaluate the high-fidelity one-dimensional finite elements that have been proposed in the companion article (Part 1). Simple structural configurations that are subjected to different loading and boundary conditions have been considered to demonstrate the generality of the proposed approach. Static, quasi-static, and dynamic analyses of the coupled and uncoupled thermoelasticity have been performed. The kinematics of the beam elements have been obtained using bidimensional Lagrangian expansions with different polynomial orders. In particular, bilinear, biquadratic, and bicubic expansions have been adopted to approximate both displacements and temperature change field. Convergence studies have been performed by considering finite beam elements with two, three, and four nodes. Analytical and numerical solutions have been reported to validate the current results. Besides time histories of displacements and temperature changes, the results have been presented using contour plots to highlight the three-dimensional capabilities of the refined beam elements.     

On electromagneto-thermoelastic plane waves under Green–Naghdi theory of thermoelasticity-II

The present work attempts to investigate the propagation of one-dimensional electromagneto-thermoelastic plane waves in an isotropic unbounded thermally and electrically conducting media with finite conductivity in the context of the theory of thermoelasticity of Green and Naghdi type-II. The heat conduction equation is affected with the Thomson coe?cient. Basic governing equations are modified by using Green–Naghdi theory of type-II. Our problem formulation derives two different systems. The first system is found to be coupled with the thermal field and represents the longitudinal wave. However, the second system represents transverse wave that is uncoupled with the thermal field. In both the cases, we identify waves that are affected with the magnetic field. Asymptotic expansions of dispersion relation solutions and various components of plane waves such as phase velocity, specific loss, and penetration depth are derived analytically for high- and low-frequency values in all cases. Analytical results predicting the limiting behavior of longitudinal and transverse waves are verified with the numerical results. The results of the present study are compared with the results of the thermoelastic case, and a detailed analysis of the effects of presence of the magnetic field under this theory has been presented.     

Dissipation Measurements in Steel Sheets Under Cyclic Loading by Use of Infrared Microthermography

Abstract:  Heterogeneous dissipation in steel sheets due to cyclic loading is difficult to measure, especially in the transverse direction because of the high conductivity and low thickness of the sheets. The goal of this article is thus to develop an experimental protocol allowing for the dissipation field determination from infrared thermography. The protocol is based on a specific differential measurement and an asynchronous acquisition. It reduces measurement artefacts due to coating, rigid body motion, convection, and optical deleterious effects. It is eventually applied to different specimens.     

THE CONFORMATIONAL MECHANISM OF THERMOELASTICITY OF ORIENTED POLYETHYLENE

Temperature variations of oriented polyethylene (PE) with a draw ratio of ～ 450% were measured in longitudinal adiabatic tension and compression (along the orientation axis) and transverse compression. Stress-strain curves (for tension and compression) were recorded. Linear thermal expansion coefficients in the longitudinal and transverse direction were measured. Thermoelastic characteristics and also thermal properties of oriented PE were quantitatively analyzed. It has been concluded that conformational dynamics has a dominating influence on these characteristics.