摘要:

A computational model for quenching simulations of thin plates has been developed. The model is examined by comparisons with experiments With one-sided -water spray cooling. With this experiment, the thermomechanical behavior of the material can be monitored throughout the time history of the test. Experiments have been performed with a material that undergoes only martensitic transformation during quenching. For the conditions examined, the plate exhibits permanent deformation after quenching. In the stress calculation, transformation plasticity is included in the effective-stress-function (ESF) algorithm as an additional strain component related to the stress and to the progress of transformation. Analyses of the present experiments show that the permanent deformation of the plate is exclusively due to transformation plasticity.

ISSN:0149-5739    

DOI:10.1080/01495739708956124

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A steady heat conduction problem within an anisotropic domain is formulated. Considering an arbitrary behavioral functional, its first and second sensitivities with respect to variation of domain shape are derived using the material derivative concept and direct as well as adjoint approaches. Then the shape optimal design problem is formulated and the optimization algorithms of the first and second order are discussed.

ISSN:0149-5739    

DOI:10.1080/01495739708956125

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Concerning the extraction of geothermal energy from a deep thermal reservoir by the downhole coaxial heat exchanger with a thermally insulated inner pipe proposed by Morita et al, we obtained rough estimates of a size of the fractured zone induced by thermal stresses due to injecting cold water into the hot rock mass through the pipe. We assumed complete spherical symmetry of the temperature and stress fields. At the rough estimation, we considered three typical or extreme cases. (1) The fracturing affects neither the loading capacity of a fractured rock mass nor the temperature distribution within the formation. (2) The fractured zone completely loses its loading capacity and is fully invaded by the borehole water. No disturbance of the fracturing makes any difference in the temperature. (3) The rock formation is assumed to have an appropriately increased fictitious conduction substituted for the heat transfer enhanced by the expected convection within the fractured zone in order to discuss the effects of an occurrence of heat convection within the fractured zone on the temperature and stress distributions and the fractured zone size. As a result, the size of the zone has been estimated to be about ten or more times the borehole radius.

ISSN:0149-5739    

DOI:10.1080/01495739708956126

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A refined averaged theory of a rigid heat conductor with a microperiodic structure is used to solve a one-dimensional initial boundary value problem of heat conduction in a periodically layered plate with a large number of homogeneous isotropic layers. In such a theory, the temperature θ = θ(x,t) (0 ≤ x ≤ L, t ≥ 0)is approximated by θ(x,t) = θ0(x,t) + η(x)θ1(x,t) where θ0(x,t) is a temperature-corrector and η = η(x) is a prescribed microshape function; and the functions θ0= θ0(x,t) and θ1= theta;1(x,t) are to be found by solving an initial-boundary value problem described by a system of linear partial differential equations with averaged coefficients subject to suitable initial and boundary conditions. A uniqueness theorem for the averaged problem is proved and two closed-form solutions for a periodically layered semispace are obtained. One of the two solutions represents the temperature field in the layered semispace due to a sudden heating of the boundary plane, while the other stands for the temperature field in the layered semispace produced by laser surface heating. Numerical examples are included.

ISSN:0149-5739    

DOI:10.1080/01495739708956127

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A procedure is developed for obtaining fundamental thermoelastic two-dimensional solutions for thermal and/or mechanical loadings moving unsteadily over the surface of a half-space. These solutions are within the bounds of the transient coupled thermoelastodynamic theory of M. A. Biot. The concentrated line loadings (sources) are suddenly applied on the surface of the half-space and then move in a fixed direction with nonuniform speed. The problem is of basic interest in contact mechanics and tribology, and it is especially related to the well-known heat checking problem (thermo-mechanical cracking in an unflawed half-space material from high-speed asperity excitations). Here, an exact and general formulation is considered and explicit results are given for some special cases. These results are obtained by generating asymptotic expressions from one- and two-sided Laplace transforms and then performing the inversions in an exact manner.

ISSN:0149-5739    

DOI:10.1080/01495739708956128

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor