DBPapers
DOI: 10.5593/sgem2017/42/S17.036

FINITE ELEMENT METHODS TO EVALUATE FATIGUE LIFE FOR HYDROPOWER PLANT MAINTENANCE

C. DRAGOI, V. F. PIRAIANU, P. C. IRIMIA, C. Husar, M. GROVU
Tuesday 12 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-07-2 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 42, 285-292 pp, DOI: 10.5593/sgem2017/42/S17.036

ABSTRACT

Fatigue damage is determined from time signals of loading, usually in the form of stress or strain. However, there are many design scenarios when the loading, or fatigue damage process, cannot easily be defined using time signals. In these cases the design/operation engineer usually has to use a test based approach to evaluate the fatigue life of the structure or the component.

Alternatively, a frequency based fatigue calculation can be used where the loading and response are represented using Power Spectral Density (PSD) functions. There are also many situations where structures from the hydropower plants equipment are subjected to a random form of loading coming from the hydraulic shocks (during sudden closing of the intake valves or fast opening to take the unit to the requested power when the grid is requesting in order to keep the safety in operation and supply), electrical power fluctuation with a strong and fast variation of frequency to the grid and therefore a powerful response from the speed governor (for grid safety purposes), etc.

All of these situations can be analyzed using new and modern techniques of fatigue life estimation that can now be incorporated into the Finite Elements Analysis (FEA) environment, enabling fatigue life calculations to be done at a computer model level.

The aim of proposed paper is to develop a reliable and accurate methodology to evaluate the fatigue life of the turbine shaft based on operational data.

Keywords: failure analysis, shaft, finite element method, maintenance, hydropower