Initial Thermal Stresses Research Articles

Elimination of the initial thermal stresses in wound articles made from composites by varying the winding angle over the thickness

Elimination of the initial thermal stresses in wound articles made from composites by varying the winding angle over the thickness

Allowance for initial thermal stresses in investigating the energy storage capacity of wound composite flywheels

Allowance for initial thermal stresses in investigating the energy storage capacity of wound composite flywheels

Time-scales for redistribution of stress in creep of structures

On the basis of some reasonable assumptions about the behaviour of structures in creep, a simple formula is derived for the time taken for the redistribution of stress in a structure, subject to step loading, from an initial state to a final steady state to be practically complete. The time taken is expressed in terms of the time taken for creep strain to become equal to a certain multiple of the elastic strain in a constant-stress creep test; this test is performed at a stress level which depends on the steady-state distribution of stress in the structure. The formula agrees remarkably well with numerical results in the literature, both for structures which are initially stress free and for structures with initial thermal stress. The formula seems to be well suited for practical use in engineering design.

Vibrations of thin cylindrical shells under axisymmetric thermal stresses.

Approximate analytical solutions of temperature distributions and thermal stresses, as well as the natural frequencies associated with radial vibrations, in the presence of initial thermal stress, are discussed in this study for thin, circular, cylindrical shells. The problem of temperature distribution is solved approximately by employing the heat conduction equation for a thin rod; the thermal stresses are determined on the basis of a linear stress-temperature relation, and the vibrational frequencies are obtained from Donnell-type equations of motion with the aid of Galerkin's method. Experimental determination of frequencies of a cylinder subjected to axisymmetric line heating at the midsection is reported. Numerical results indicate that the change in frequency induced by thermal hoop stress in a simply supported cylinder is very small except when the cylinder is extremely short and thin. Large changes, however, can be expected for clamped cylinders, and the changes are primarily a result of the presence of a constant axial stress brought about by the temperature increase.