Interlayer Thermal Resistance Research Articles

High-temperature property of carbon/carbon composite joints bonded with ternary Ti–Si–C compound

Carbon/carbon composites were joined using Ti–Si–C compound as interlayer and high-temperature shear strength and thermal shock resistance of these joints were investigated in this paper. In order to improve thermal shock resistance of the joints, a SiC transition layer was introduced between carbon/carbon substrates and interlayer. Microstructures and phase composition of the as-received joints were characterized by electron backscattered diffraction and X-ray diffraction. Mechanical strength and thermal shock resistance of the joints were measured by high-temperature shear test and thermal cycle test, respectively. The shear test results show that, with test temperature increasing from 273 K to 1673 K, shear strength of joints gradually increases to a maximum value of 46 MPa at 1473 K, then drops suddenly at higher temperature. Joints with SiC transition layer exhibit better thermal shock resistance than the ones without SiC transition layer and strength retention can be kept up to 85%, even after 30 thermal cycles from 1673 K to room temperature.

Estimation of heat flux and thermal stresses in multilayer gun barrel with thermal contact resistance

In this study, a conjugate gradient method based on an inverse algorithm is applied to estimate the unknown time-dependent heat flux at the inner surface of gun barrel, in which the interlayer thermal contact resistance between the steel cylinder and the chrome coating is taken into account in the boundary conditions. While knowing the temperature history at the measuring position, no prior information is needed on the functional form of the unknown heat flux. The temperature data calculated from the direct problem are used to simulate the temperature measurement. The influence of measurement errors and initial guess values upon the precision of the estimated results is also investigated. Results show that an excellent estimation on the time-dependent heat flux, temperature distributions, and thermal stresses can be obtained for the case considered in this study.

Thermal Stresses in Multilayer Gun Barrel with Interlayer Thermal Contact Resistance

A hybrid numerical method of the Laplace transformation and the finite difference is applied to solve the transient heat transfer problem of a gun barrel, in which the interlayer thermal contact resistance between the steel cylinder and the chrome coating is taken into account in the boundary conditions. The general solutions of the governing equations are first solved in the transform domain. Then the inversion to the real domain is completed by the method of Fourier series technique. The transient distributions of temperature and thermal stresses for the gun barrel in the real domain are calculated numerically.

Transient thermal loading induced optical effects in single-coated optical fibers with interlayer thermal resistance

The transient microbending loss and refractive index changes in a single-coated optical fiber subjected to thermal loading with stress-dependent interlayer thermal resistance are investigated. The effects of interlayer thermal resistance on the transient microbending loss and refractive index changes of the optical fiber are analyzed and discussed. Results show that the interlayer thermal resistance will increase the transient thermal loading induced lateral pressure in the single-coated optical fiber and, thus, the microbending loss. To the contrary, the interlayer thermal resistance will decrease the transient thermal loading induced refractive index changes.

Multi-layer transient heat conduction using transition time scales

The solution of multi-layer transient heat conduction problems may be simplified by analyzing the different transition times of the various layers of a composite slab. These transition times, in fact, allow the ‘disturbance’ effect of each layer on the eigenvalues of the composite slab to be analyzed and estimated. It was found that the eigenvalues may be obtained in the first approximation by merging in increasing order the suitable corrected eigenvalues of each layer for which explicit equations are available. The errors in the resulting dimensionless temperatures are of one order of magnitude larger than the deviations between the exact and approximate eigenvalues. In particular, when one of the two outer boundaries is kept at constant temperature and the transition times of the layers are quite different, the eigenvalues may be written down very simply as the eigenvalues of the layer whose exposed surface is not at prescribed temperature. In this paper the temperature solution for the case of a two-layer slab with interlayer thermal contact resistance is presented.

INVERSE PROBLEMS IN AN AXISYMMETRIC MULTILAYER ANNULAR CLINDER WITH AN INTERLAYER THERMAL RESISTANCE

A numerical approach to estimate an unknown heat flux for axisymmetric multilayer annular cylinder with an interlayer thermal resistance is presented. The effects of interlayer thermal resistance upon temperature response to predict the subjected heat flux are investigated and discussed. The conjugate gradient method of minimization with an adjoint equation is successfully used to solve the inverse problem in estimating the unknown inner heat flux of multi-layer annular cylinder with an interlayer thermal resistance. While knowing the temperature history at any point of the annular cylinder, the inner boundary time-varying heat flux can be computed. In the analysis, the thermal resistance effect between interlayer is taken into account in the governing equation of heat conduction and the convection heat transfer. No prior information is available on the functional form of the unknown heat flux in the present study: thus, it is classified as the function estimation in inverse calculation. The accuracy of the inverse analysis is examined by using simulated and inexact measurements obtained within the medium

Thermal Stresses in a Multilayered Anisotropic Medium With Interface Thermal Resistance

This note is concerned with thermoelastic analysis of a multilayered anisotropic medium under the state of generalized plane deformation with interlayer thermal contact resistance. The powerful flexibility/stiffness matrix method is adopted here to obtain the complete solution of the entire layered medium by introducing the thermal and mechanical boundary and layer interface conditions including interlayer imperfect thermal contact conditions. As a numerical illustration, the effects of interlayer thermal resistance on the distributions of temperatures and thermal stresses in a laminated anisotropic slab subjected to a uniform surface temperature rise are presented.

THERMAL STRESSES IN AN AXISYMMETRIC DOUBLE-LAYER ANNULAR CIRCULAR CYLINDER WITH INTERLAYER THERMAL RESISTANCE

An analytical approach for axisymmetric double-layer annular circular cylinder subjected to thermal loadings with stress-dependent interlayer thermal resistance is presented. The effects of interlayer thermal resistance upon temperature and thermal stress distributions are investigated and discussed. The solution and results given here may serve a useful purpose in providing a check upon other solution procedures.