Method for monitoring deformation of a rotating element via a monitoring device employing optical fibre, and wind turbine equipped with such a device

A method for predicting mechanical failure of a part capable of undergoing a rotary movement, the method comprising:

• emitting a light signal at a first end of an optical fiber, at least one section of the optical fiber being stretched in a pre-stressed condition along at least part of a periphery of a rotation bearing of the part;
• extracting a received light signal made of the emitted signal having reached a second end of the optical fiber, the second end being opposed to the first end with respect to a developed length of the fiber;
• measuring a characteristic of the received light signal, said characteristic varying as a function of the developed length of the optical fiber between the first end and the second end of the optical fiber;
• plotting the measured characteristic of the received signal as a function of time;
• and
• comparing the plotted characteristic of the received light signal with a reference.