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1.On the simple example of a rotor with a heat channel subjected to axial tension the finite element method has been used to study the dependence of stress and strain concentration factors on the relative depth and relative radius of the channel. Accuracy of the determination has been confirmed by the good agreement of data obtained with classical solutions for this simple case provided in the work of Peterson.2.A dependence for the strain concentration factor (with material operating in the plastic region) on the radial temperature drop and gradient with a unidimensional temperature field has been obtained.3.Satisfactory agreement of results for thermal strain concentration factors calculated by the Makhutov approximate equation (with preliminary use of the Barry-Johnson equation) with more accurate calculation by the FEM has been noted.4.Calculations for an actual rotor with different starting schedules taking account of temperature changes along the radius and axis show that values of strain concentration factor are in the range 3 to 8.

Conclusions 1.The FEM has been used in two-dimensional schemes for determining the state of stress in the arch part of a coil system providing a toroidal magnetic field.2.There may be a deviation from contact between the coils when the system is subject to ponderomotive forces and a temperature distribution. The zones determined in this way from both schemes are similar.

Conclusions 1.A radial temperature gradient has no effect, and the regularity of the change of temperature along the radius has but a slight effect on the concentration factors of the nominal elastic stresses in annular heat grooves of rotors but both these factors have a considerable effect on the concentration factors of elastoplastic strains.2.Operational determination of the concentration factors of nominally elastic stresses in the zone of the groove can be carried out with the use of the approximate formulas (1)-(6) or of the curves presented in Figs. 3–5.

Conclusions 1.The apparatus described in this article makes it possible to obtain sufficiently accurate data on the strength of bimetal joints.2.Electro-slag melting of grade M1 copper on steel St. 3 under correct conditions and with the aid of a suitable flux ensures the formation of faultless joints whose strength is approximately equal to that of annealed copper.