Fatigue Strength Of Shafts Research Articles

Method to estimate the fatigue-strength scatter of shafts in the high-cycle and very-high-cycle fatigue regimes

The fatigue strength of shafts is subject to scatter. Knowledge of this scatter is essential for producing safe shaft designs. Therefore, this paper investigates the possibility of quantifying the fatigue-strength scatter in the high-cycle and very-high-cycle fatigue regimes. For this purpose, experimental tests were carried out on exemplary shafts to determine the fatigue-strength scatter. A probabilistic model was developed that considers the failure mechanisms of quenched and tempered steels from the surface and the interior. Therefore, the scatter-influencing parameters were statistically modelled. The parameters act as input in local-strength approaches for the failure mechanisms. Using Monte Carlo simulations, shafts can be randomly generated. The shafts so generated are submitted to the approaches for the failure mechanisms by means of finite-element analyses. By statistical evaluation of fictitious nominal stress levels with respect to calculated failures and runouts of the shafts, the probability distribution of the fatigue strength can be determined.

Simple tensile test for determination of fatigue strength of shafts surfaced by different welding techniques

Simple tensile test for determination of fatigue strength of shafts surfaced by different welding techniques

Effects of arc surfacing on the fatigue strength of shafts

Effects of arc surfacing on the fatigue strength of shafts

Evaluation of the fatigue strength of shafts with different stress raisers

Evaluation of the fatigue strength of shafts with different stress raisers

Examination of fatigue resistance in turbine rotors on large models

1. The fatigue failures in the rotors of turbine generators can be classified from the dynamics of the fatigue process into slow ones characteristic of nominal working conditions and sudden ones occurring during normal or emergency overload when there are cracks of critical length. 2. The most hazardous points for fatigue failure in the sections of shafts containing segment grooves are the points of emergence of the grooves on the cylindrical surface. 3. It has been shown that SPD methods give good strengthening of rotor steel. which is due to the high residual compressive stresses in the surface layer. 4. Surface plastic deformation methods give high performance in increasing the fatigue strength of shafts with segment grooves.

Fatigue strength of shafts

Fatigue strength of shafts

Effect of the nature of contacting metals on the fatigue strength of shafts

Effect of the nature of contacting metals on the fatigue strength of shafts

Fatigue strength of shafts cooled abruptly from below the critical temperature

1. Abrupt cooling from below the critical temperature ensures that the fatigue resistance of shafts with with a press fitting and manufactured from steel 45 or 40 Kh is not lower than that produced by thermal improvement. The effect of the former thermal treatment is related to the generation of a favorable residual stress field which is the main factor determining the fatigue strength of shafts with stress concentrators. 2. Abrupt cooling of thin and very thick shafts (diameters up to 160 mm) with a press fitting from 650\dgC (in water or in oil) may be recommended, instead of thermal improvement. This cooling is less laborious, reduces warping, oxidation and removal of carbon. 3. Strengthening by cold plastic deformation of the surface and the recommended thermal treatment are effective means for improving the fatigue strength of shafts with a press fitting. These recommended procedures have been introduced into the Starokramatorsk machine works.