Failures in Trailing Edge Bondlines of Wind Turbine Blades

Bonded joints in composite structures are often en object for concern. This is also true for wind turbine blades, where damage occurs in the trailing edge due to fatigue loads. Reliability of wind turbines becomes increasingly important when used offshore, where operation and maintenance costs constitute a significant part of the cost per kWh produced. However, the wind turbine industy is reluctant to share statistical values for damages, and this makes it more difficult to assess the reliability. Instead of analyzing the joint and reinforce the connection, research at Risø DTU has shown, that it possible to reduce the deformation of the trailing edge panels and thereby reduce the peeling stresses in the trailing edge joint. A basic solution patented by Risø DTU is presented. The research is based on a combination of numerical analysis and full-scale testing. The research has shown the need for improved full scale testing.