J. R. Thomas

THERMAL STRESSES IN A LONG CIRCULAR CYLINDER SUBJECTED TO SUDDEN COOLING DURING TRANSIENT CONVECTION HEATING

An analysis is presented of the thermal stresses encountered during cooling of a solid circular cylinder initially heated from uniform temperature by Newtonian convection, followed by sudden cooling prior to reaching thermal equilibrium during the heating phase of the cycle. The numerical results indicate that the magnitude of the stresses attained during the cooling phase increases with increasing duration of heating, but are less than the corresponding values encountered for convective cooling from a condition of initial uniform temperature. The relevance of these results to the prediction or interpretation of thermal fatigue behavior is noted.

ANALYSIS OF THERMAL STRESSES IN A SOLID CIRCULAR CYLINDER SUBJECTED TO CONDUCTIVE HEAT TRANSFER WITH THERMAL BOUNDARY CONDUCTANCE

An analysis is presented of the effect of a finite boundary conductance on the magnitude of the thermal stresses in a solid circular cylinder, subjected to conductive heat transfer from an infinite mechanically noninteracting surrounding medium.

ANALYSIS OF THERMAL STRESSES IN A FLAT PLATE SUBJECTED TO CONDUCTIVE HEAT TRANSFER WITH THERMAL BOUNDARY CONDUCTANCE

An analysis is presented of the effect of a finite boundary conductance on the magnitude of the thermal stresses in a flat plate subjected to symmetric and asymmetric conductive heat transfer from an infinite, mechanically noninteracting medium.

FREQUENCY DEPENDENCE OF THE MAGNITUDE OF THERMAL STRESSES IN A FLAT PLATE SUBJECTED TO RAPID THERMAL CYCLING BY CONVECTIVE HEATING AND COOLING

Abstract A study was conducted of the effect of the thermal stresses in a plate subjected to thermal cycling by changes in ambient temperature involving convective heat transfer, at frequencies sufficiently high that thermal equilibrium (;i.e., temperature uniformity) is not achieved within each cycle. The results obtained indicate that at any specific value of the Biot number the magnitude of maximum thermal stress within any cycle decreases with increasing frequency. Furthermore, at any given frequency the magnitude of the peak stress exhibits its maximum value during the first cycle and decreases to a constant value from cycle to cycle with increasing number of cycles

EFFECT OF INTERFACE REFLECTIONS AND ANGLE OF INCIDENCE OF RADIATION ON THERMAL STRESSES IN SEMI-TRANSPARENT MATERIALS

Abstract The objectives are to determine the effects of internal reflections on the thermal stresses generated by radiation absorption in a semi-transparent flat plate, and to study the effect of varying the angle of incidence. Both suddenly applied and suddenly removed radiation from an established steady-state condition are considered.

Stresses Due to Thermal Trapping in Semi-Absorbing Materials Subjected to Intense Radiation

Analytical results are presented for the thermal stresses resulting from “thermal trapping” in semi-absorbing materials subjected to symmetric and assymmetric radiation heating and convective cooling with finite heat transfer coefficient, h. The transient stresses during heat-up in both cases were found to be an inverse function of the heat transfer coefficient, h, and increase monotonically with the optical thickness, μa. In contrast, the steady state stresses were independent of h and exhibited a maximum at μa ≃ 1.3 for symmetric heating and at μa = 2 for assymmetric heating with zero stresses at μa = 0 and ∞. For the symmetrically heated plate, the transition from the transient to the steady-state condition involved a reversal in the sign of thermal stress at any position. For the assymmetrically heated plate the steady state maximum tensile thermal stresses occur at the position of the highest temperature, ie. the front surface.

ROLE OF ABSORPTION COEFFICIENT IN THE FREQUENCY DEPENDENCE OF THE THERMAL STRESSES IN A PARTIALLY ABSORBING PLATE SUBJECTED TO CYCLIC THERMAL RADIATION: A BRIEF NOTE

Abstract The frequency dependence of the thermal stresses in a partially absorbing plate subjected to cyclic thermal radiation is shown to be a function of optical thick ness.

Role of Thermal Expansion in Thermal Stress Resistance of Semi-Absorbing Brittle Materials Subjected to Severe Thermal Radiation

An analysis is presented of the thermal stresses resulting from “thermal trapping” in semi-absorbing brittle ceramic materials in the form of a thin flat plate subjected to intense thermal radiation. Solutions for the thermal stresses are presented for symmetric and asymmetric radiation heating and convective cooling with limiting values of the heat transfer coefficient, h = 0 and ∞. For h = ∞, the stresses are identically equal to zero for values of the optical thickness pa of 0 and ∞, and reach their maximum value at μa ≃ 1.3 and 2.0 for symmetric and asymmetric heating respectively. For h = 0, the magnitude of thermal stress increases with increasing optical thickness.

Thermal stress in materials heated internally by radiation absorption

Abstract Analysis and results are reported for thermal stress in materials heated internally by radiation absorption. Two modes of heating are considered: radiation suddenly applied from one side and held constant thereafter, and radiation incident from one side but having a periodic variation in time. In both cases it is found that the radiation absorption coefficient plays a large role in determining the thermal stress, and conclusions are drawn concerning desirable optical thicknesses. With periodic heating, the stress can cycle between tensile and compressive values. This phenomenon could be especially significant for materials prone to cyclic fatigue failure.