Reliability assessment of a turbogenerator coil retaining ring based on low cycle fatigue data
Journal Title: Archive of Mechanical Engineering - Year 2014, Vol 0, Issue 1
Abstract
Turbogenerator coil retaining rings are shrunk-fitted onto the rotor over the coils, in order to restrain them against the centrifugal force. They are typically subjected to low cycle fatigue, with a cycle being completed at every machine switch-on and switch-off. The subject of this paper consists in the determination of the failure probability of a coil retaining ring. The failure mode of the ring cracking, when it swells in tension, due to the centrifugal force is here considered. The reliability assessment is preceded by the study of the input variables affecting the low-cycle fatigue load and of their stochastic distributions. This question is tackled by the experimental determination of the static, cyclic and fatigue curves of the involved material and by the application of a statistical model to compute related parameters and their standard deviations. Upon the determination of variable distributions, the probability of failure is estimated in the form of a cumulative distribution function by a computationally efficient methodology, based on the Advanced Mean Value approach. The obtained results account for the material response and the local stress-strain states at the most loaded coil retaining ring region. The determined probability at the end of the machine life, in the order of 10^(-12,) is compatible with reference values for structures under fatigue in the mechanical and aeronautical fields.
Authors and Affiliations
Giorgio Olmi, Alessandro Freddi
Keywords
Related Articles
- EP ID EP166656
- DOI 10.2478/meceng-2014-0001
- Views 46
- Downloads 0
Free vibration of piezo-nanowires using Timoshenko beam theory with consideration of surface and small scale effects
This paper investigates the influence of surface effects on free transverse vibration of piezoelectric nanowires (NWs). The dynamic model of the NW is tackled using nonlocal Timoshenko beam theory. By implementing this t...
Implementation of a geometric constraint regularization for multibody system models
Redundant constraints in MBS models severely deteriorate the computational performance and accuracy of any numerical MBS dynamics simulation method. Classically this problem has been addressed by means of numerical decom...
Effect of tool geometry and welding speed on mechanical properties and microstructure of friction stir welded joints of aluminium alloys AA6082-T6
Friction stir welding is a solid state innovative joining technique, widely being used for joining aluminium alloys in aerospace, marine automotive and many other applications of commercial importance. The welding parame...
Experimental study and response surface methodology for investigation of FSP process
The article presents the effect of rotational and travelling speed and down force on the spindle torque acting on the tool in Friction Stir Processing (FSP) process. The response surface methodology (RSM) was applied to...
Geometric interpretation of a non-linear beam finite element on the Lie group SE(3)
Recently, the authors proposed a geometrically exact beam finite element formulation on the Lie group SE(3). Some important numerical and theoretical aspects leading to a computationally efficient strategy were obtained....