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Graphite is applied to structural material of the high temperature reactor and nozzle of high energy rocket engine. The excessive vibration and stress field can be occurred for this material due to the severe thermal condition. In this study, the thermal stress and vibration characteristics of ATJ graphite under high temperature condition are investigated by finite element analysis (FEA). The specimen is designed as a disk shape in order to simulate the rocket nozzle combustion condition. The experiment of thermal heat is also conducted using by CO₂ laser.

This paper dealt with the thermal shock damages of MoSi₂ intermetallics by a nondestructive technique. The flexural strength of MoSi₂ intermetallics depending on the thermal shock cycles has been also investigated. The thermal shock test was repeatedly performed up to 80 cycles at the temperature difference of 423 K. The flexural strength of MoSi₂ intermetallics decreased with the increase of thermal shock cycle, due to the creation of crack and its propagation. MoSi₂ intermetallics represented the drastic reduction of ultrasonic wave velocity at the thermal shock of 40 cycles. The attenuation coefficient of MoSi₂ intermetallics increased with increasing the thermal shock cycle due to the activation of damage degree

In this paper, the response of a bounded one-dimensional medium (strip) subjected to a thermal shock is investigated. The strip is made of a linear visco-elastic material, of which the time-dependency of the elastic modulus is described by the simple Kelvin–Voigt model. To obtain the displacement, stress and temperature within the strip, the Lord and Shulman theory of generalized thermo-elasticity containing a single relaxation time is used. Three coupled equations, namely, the equation of motion, the modified Fourier law and the second law of thermodynamics, are established in terms of the displacement, temperature and heat flux. It is worth noting that the second law of thermodynamics is not linearized and is kept in the nonlinear form. The equations derived are first represented in a dimensionless presentation. Then, they are discretized using the well-known generalized differential quadrature. To obtain the response of the strip in time, the Newmark time marching scheme is implemented. It should be mentioned that due to the nonlinear nature of the governing equations, the successive Picard algorithm is used. The results of the present study are compared with those available in the literature for an elastic strip. Besides, numerical results are given for a strip made of Kelvin–Voigt visco-elastic material. The effects of visco-elastic parameter, coupling parameter, thermal relaxation time and nonlinearity are discussed in numerical examples.

In this research, a thick hollow cylindrical shell made of bidirectional functionally graded open cell porous materials under internal thermal shock according to the classical theory of linear thermo-elasticity is examined for the first time. The cylinder is made of a porous cellular material and its porosity varies along both radial and axial directions continuously. The governing motion equations are obtained by using 2D-axisymmetric theory of linear thermo-elasticity rather than shell theories. This theory represents thickness stretching and gives more precise results. Graded finite element method is employed to model the problem. Applying this method rather than conventional FEM leads to more accurate results, especially for dynamic analyses. The cubic higher order element is used for dividing the solution domain. To obtain transient temperatures, Crank–Nicolson algorithm is used and then the Newmark procedure is used to derive time responses of displacement and stress components. The time history of displacements and stress components for different radial and axial power law exponents, porosity coefficient, boundary conditions, length-to-thickness ratio and two different porosity patterns are investigated in detail. The obtained results show that thermal-induced vibration is generally caused by hoop stress, and frequency and amplitude of vibrations and velocity of stress waves are considerably influenced by the porosity distribution, porosity coefficient and power law exponents in both directions.

The generalized dynamic theory of thermoelasticity is used to investigate the propagation of plane harmonic waves in anisotropic layered media using the Spectral Finite Element Method (SFEM). Two different theories, due to Lord and Shulman (LS model) and Green and Lindsay (GL model), are considered for spectral layer element (SLE) formulation. The element is formulated in the frequency domain and the exact solution of the transformed equation is used as the interpolating polynomial of the unknown variables, which are the mechanical displacements and the thermal field. Consequently, single element captures the essential wave response of a layer of arbitrary thickness, when subjected to high frequency impact loading. This element is used to study the characteristic of the thermal wave, also known as the second sound, using nominal computational resource. The study is directed towards finding the justification of using the non-classical model of thermoelasticity and the effect of different parameters on the overall thermal and mechanical field. Stress state within a layered media with general ply-stacking is studied and the limitation of the classical theory in stress prediction is shown. Thermal wave propagation due to temperature burst and heat flux is captured and their properties are discussed.

Ceramic foams made by replica techniques containing sharp-edged cavities, which are potential crack initiators and therefore have to be analyzed using fracture mechanical methods. The ceramic foams made of novel carbon bonded alumina are used as filters in metal melt filtration applications, where the filters are exposed to a thermal shock. During the casting process the filters experience a complex thermo-mechanical loading, which is difficult to measure. Modern numerical methods allow the simulation of such complex processes.

As a simplified foam structure an open Kelvin cell is used as a representative volume element. A three-dimensional finite element model containing realistic sharp-edged cavities and three-dimensional sub-models along these sharp edges are used to compute the transient temperature, stress and strain fields at the Kelvin foam. The sharp edges are evaluated using fracture mechanical methods like the $J$-integral technique.

The results of this study describe the influence of the pore size, relative density of the ceramic foam, the heat transfer and selected material parameters on the fracture mechanical behaviour.

In this work the magneto-thermoelastic problem of a semi-infinite body with voids and temperature-dependent material properties placed in a transverse magnetic field is investigated in the context of different theories of generalized thermoelasticity. The upper surface of the body is subjected to a zonal time-dependent heat shock. The solution is obtained by solving finite element governing equations of the problem. The results, including temperature, stresses, displacements, the change in volume fraction field, induced magnetic field and induced electric field are presented graphically. Comparisons are made in the results obtained under different theories of generalized thermoelasticity and three forms of temperature-dependent material properties (absolute temperature-dependent, reference temperature-dependent, and temperature-independent). Finally the voids effects in the theory of thermoelasticity are presented graphically.

Knowledge of size effect of thermal shock properties of ceramics is a prerequisite in engineering applications. In the present study, the size effect of the cracking in the ceramic materials subjected to water quenching has been experimentally conducted. Based on the Rizk model, the equivalent specimen width of the elastic strip with cracks is introduced and modified to describe the effect of cracks on the deformation of the elastic strip underwater quenching. It is found that the simulation obtained from the proposed modified model is in good agreement with the experimental results. And the reasons for the size effect of crack depth and crack growth into the compressive region are well analyzed by theoretical results. The proposed model is expected to provide a powerful tool to characterize and predict the size effect on thermal shock crack of ceramic materials.

The paper is devoted to simulating the impact of a thermal shock on a thin homogeneous plate in the ANSYS package. The assessment of the stress–strain state is carried out and the dynamics of changes in the temperature field of the plate is determined. The obtained results were compared with the data of other authors and can be used when taking into account the thermal shock of large elastic elements of spacecraft.

Ceramic has a great broad application in high-temperature environment due to its favorable mechanical, antioxidant and corrosion resistance properties. However, it tends to exhibit severe crack or fail under thermal shock resulting from its inherent brittleness. Microstructure property is a vital factor and plays a critical role in influencing thermal shock property of ceramic. The present study experimentally tested and characterized thermal-shock crack and residual strength of ceramic under different quench temperature, while two kinds of alumina ceramics with different grain size are employed. A two-dimensional (2D) numerical model based on statistical mesoscopic damage mechanics is introduced to depict the micro-crack propagation of ceramic sheet under water quenching. The effects of grain size on critical thermal shock temperature, crack characteristics and residual strength are studied. And the microscopic mechanism of the influence of grain size on thermal shock resistance of ceramic is discussed based on the crack propagation path obtained from experimental and simulation results. The qualitative effect and evolution change of grain size on thermal shock property of alumina ceramic will be summarized.

SiC/Zr-Si-C coatings were fabricated on the surface of C/SiC composites by molten salt method and CVD method, and then mechanical and structural evolution of SiC/Zr-Si-C coated C/SiC Composites under thermal shock tests were studied. The results showed the degradation of the flexural strength properties and no mass variation. The composition of SiC/Zr-Si-C coatings was characterized by SEM and XPS. The results showed that the main constitute of the coatings was not changed after thermal shock tests. The structural of coating was changed owe to the tensile stress. Due to the debonding of the coating-matrix interfaces, the flexural strength decreased after thermal shock tests.

The paper is devoted to simulating the impact of a thermal shock on a thin homogeneous plate in the ANSYS package. The assessment of the stress–strain state is carried out and the dynamics of changes in the temperature field of the plate is determined. The obtained results were compared with the data of other authors and can be used when taking into account the thermal shock of large elastic elements of spacecraft.