Technical Damage in Wind Rotor Blade under Static Load at Environment Conditions

Abstract

Accidents with a wind rotor blade are frequently observed in the wind farms and the simulation study of its undesired damage and its full degradation has to be done. As usual the full degradation of the wind rotor blade happens in a sequence of appearing first transitive (I mode crack) and then interface delamination (II mode crack) between the involved layers of a rotor blade laminate. The question of the risk value of the interface delamination is important for further reliability of wind blade to work safety. In the present approach the unacceptable interface delamination in a pre-cracked (1st mode) bi-material structureas a part of the straight line of wind rotor blade under static mechanical, temperature, and electric loading and moisture will be considered. With this first step, the influence of environment conditions such as moisture and temperature as well as the properties of the bi-material plate will be assumed to be linear. The investigation will be performed by using a simple 1D shear lag model of the unit cell of wind rotor blade. The electric voltage acting on the first piezoelectric plate of bi-material structure will be used as a sensor identifying the possible delamination between the layers. The material and physical properties of the structure are taken from literature. The obtained results are illustrated by figures and discussed. Some recommendations for safety work of the wind rotor blade as well as a criterion for identifying the interface delamination through the electric gradient will be proposed.