Evaluation of damage mechanics of industrial wind turbine gearboxes

In recent years global wind power capacity has grown steadily at an annual rate of around 20%. This has led to wind energy becoming the most important renewable energy source on a global scale, with the total installed capacity reaching 430 GW. However, the strong growth of offshore wind power has been somewhat inhibited from a number of operational challenges that are yet to be addressed in full. The most important of these challenges appears to be the reliability of the wind turbine gearbox (WTG). WTGs are currently unable to survive their anticipated design lifetime of 20-25 years. Most of them hardly reach a useful operational lifetime of more than 7 years without serious refurbishment or replacement, whereas for offshore wind turbines failures have been reported as early as within 1 to 2 years. In this paper, the damage mechanisms influencing WTGs are evaluated by microstructural analysis of failed in-field components, finite element analysis simulations for the damage initiation and propagation (FEA), and acoustic emission condition monitoring data acquired from the field.