摘要:

The effect of thermal residual stress on the two-dimensional interlaminar crack extension behavior in a cross-ply laminate subjected to transverse loading is estimated. Attention is focused on the contribution of thermal residual stress to the local energy release rate along the interlaminar crack front. Computational simulations are carried out on the basis of constant critical energy release rates in order to examine implicitly how the two-dimensional size and shape would be changed by the presence of thermal residual stress. A considerably large amount of energy is found to be supplied for the interlaminar crack extension by thermal residual stress, while little influence is perceived with respect to the apparent extension behavior including the shape of the interlaminar crack.

ISSN:0149-5739    

DOI:10.1080/01495739708956100

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We analyze the stress intensity factors for multiple-edge cracks emanating from a circular hole in an infinite plate with a moving heat source rotating around the circular hole. Numerical calculations for the stress intensity factors are carried out for the case of two radial edge cracks. The interference effects on the stress intensity factors with the included angle between two radial cracks are investigated, and the effects of the angular velocity on the results are also considered In addition, for the case of standing heat source, we attempt to measure the thermal stress intensity factors using the strain gage We compare the experimental results with the current numerical results.

ISSN:0149-5739    

DOI:10.1080/01495739708956101

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The stress-focusing effect is the phenomenon in which, due to an instantaneous concentrated heat source, stress waves propagating from the free surface of the sphere result in very high stresses at the center. Using the ray theory, the Fourier transformed solution of stress waves in the sphere is sorted out into rays according to the ray path of multiply reflected waves. In the study, in order to denote the strength of the stress focusing, we introduce the stress-focusing intensity factor, SFi, which is defined by the relation σi= SFi/r−3(i = r, θ, ϕ) at the focusing point. The numerical results reveal that stresses peak out periodically with a constant period.

ISSN:0149-5739    

DOI:10.1080/01495739708956102

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

This article is concerned with the dynamic treatment of thermally induced stress waves in an infinite elastic plate subjected to impulsive electromagnetic radiation. The plate is assumed to be a functionally graded material (FGM), meaning that the material is composed of multiconstituents in ceramics and metals, the volume fractions of which distribute continuously inside the material. The mathematical problem is one of wave propagation in a typical nonhomogeneous material The radiation absorption is assumed to occur at a constant rate for the duration of the pulse and to diminish exponentially with distance from the surface of the plate, assuming negligible heat conduction. In treating problems, the nature of the stress-wave buildup in the plate is studied for the case of a temperature-dependent solid, that is, when material properties vary with temperature. The numerical procedure employs the characteristic method based on the integration of the governing equations along the characteristics. Numerical calculations are carried out for ceramic-metal FGM plates showing the influences of the temperature-dependent material properties and the volume fractions of the phases composing the FGM on the magnitude of the dynamic thermal stresses.

ISSN:0149-5739    

DOI:10.1080/01495739708956103

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Thermal stress at an off-angled interface is considered as a model analysis for “weld line” in an injection-molded FRP. The off-angled interface is a line interface between two bonded anisotropic solids, at which the axis ofanisotropy in each solid is inclined to the interface. Applying the regular technique of integral transforms, we obtain the exact solution for temperature and stress induced by a spontaneous heat source. Especially for the temperature we get a closed-form solution in one term of the exponential function. Extensive numerical computations are carried out for a Nylon 66 compounded with 33 wt% glass fiber and show the stress field near the weld line (off-angled interface). The interfacial shear stress attains its maximum value more quickly than the normal stress. However, the highest normal stress on the interface increases with increasing off-angle, the highest shear stress has a maximum at 43-deg off-angle. The shear stress is 2.8 times greater than that in the isotropic solid and is also 1.34 times greater than that for 90-deg off-angle. This indicates that the lowest strength of the weld line would occur when the off-angle is about 43 deg for our case of Nylon 66.

ISSN:0149-5739    

DOI:10.1080/01495739708956104

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The method of an analytical development of thermoelastic problems for a medium with Kassir's nonhomogeneous material properties is developed. For isothermal problems of such a nonhomogeneous body, an analytical method of development has already been proposed by M. K. Kassir under the assumption that the shear modulus of elasticity G is changed arbitrarily with the variable z of the axial coordinate according to the relation G(z) = Gozm. However, the analytical procedure for the thermoelastic field has not been established. In this article, introducing the thermoelastic displacement potential function, the analytical method of development for the axisymmetrical thermoelastic field is established. As an illustrative example, we consider the thermoelastic problem of a slab. Assuming that the shear modulus of elasticity G, the thermal conductivity λ, and the coefficient of linear thermal expansion α vary with the variable ẑ of the dimension-less axial coordinate according to the relation G(ẑ) = Goẑm, λ(ẑ) = λ0ẑl, α(ẑ) = α0ẑn, the axisymmetric temperature solution in a steady state for the slab is obtained and the associated thermal stress components are evaluated theoretically. Numerical calculations are carried out for several cases, taking into account the variety of the nonhomogeneous material properties. Numerical results are shown graphically.

ISSN:0149-5739    

DOI:10.1080/01495739708956105

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Most analyses of thermal stresses generated in a brake drum are studies within either an elastic or a plastic region with constant yield strength. As a matter of fact, however, a severe brake application will create a thermal environment on the friction surface with an excessively high surface temperature. At a high temperature, the degradation of yield strength of a drum material may become significant and an important factor to be taken into account in the analysis. This article deals with the thermoelasto-plastic stresses and the thermal distortions produced in a brake drum during a severe braking condition, taking account of the temperature dependence of the yield strength of a drum material. It is found that high compressive thermoelastoplastic stresses are created during a brake application but eventually residual tensile stresses are developed in the vicinity of the rubbing surface in the course of cooling. These residual tensile stresses are strongly presumed to be one of the significant factors causing the heat crack in a brake drum. In addition, the thermal distortions of the drum suggest a loss of the contact area between the drum fictional surface and the brake shoe linings during braking.

ISSN:0149-5739    

DOI:10.1080/01495739708956106

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The application of the discrete linear inhomogeneous layer element, so-called LILE, is shown to estimate the elastic wave reflectance of a gradient inhomogeneous layer. The LILE stacking model is effectively used in analyzing backscatter inspection of the inhomogeneous solid The discussion focuses on the availability of the new element for computer calculation of the backscatter intensity from a thermally deteriorated layer. The numerical results show the possibilities of inhomogeneous structural inspection and developing images of the affected inhomogeneous region by suitable impedance matching with the surrounding medium.

ISSN:0149-5739    

DOI:10.1080/01495739708956107

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Thermal stress problems of a functionally gradient plate as one of the advanced high-temperature materials capable of withstanding the extreme temperature environments, with and without an edge crack, are discussed One of the most important problems of the thermal stress in the functionally gradient plate with the crack are how to decrease the thermal stress intensity factor and how to determine the optimally continuous profile of the composition of the plate. The functionally gradient plate is subjected to a cycle of heating and cooling on the ceramics surface of the plate. The material properties of the functionally gradient plate are dependent on the temperature and the position. The optimally continuous profile of the composition of the plate is discussed. The numerical results for thermal stresses and the thermal stress intensity factor are shown for many temperature conditions and for many continuous profiles of the composition of the plate.

ISSN:0149-5739    

DOI:10.1080/01495739708956108

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Using the thermoporoelastic theory previously proposed, thermal stresses are analyzed that are induced in a fluid-saturated poroelastic hollow sphere, whose inner surface is exposed to burning gas and the wall of which is cooled by the fluid injection from its outer surface. Two loading histories are considered: (i) the sphere is subjected to a sudden rise in temperature of the gas and simultaneously pressurized at its outer surface to cool the wall; and (ii) steady-state cooling is abruptly disturbed by a sudden loss of pressurization and, after a while, is recovered. The main focus is on the effect of heat advection due to active fluid injection on the reduction of temperature and thermal stresses. Since the formulated problem is axisymmetric, the displacement field is decoupled from the temperature and pore pressure fields, which are still coupled to each other. The coupled nonlinear diffusion equations are solved by the Crank-Nicolson implicit method. It has been concluded that the active fluid pressurization and injection are effective in suppressing the maximum thermal hoop stress at the outer surface without the occurrence of the excess compressional stress at the inner surface.

ISSN:0149-5739    

DOI:10.1080/01495739708956109

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor