Development and validation of a new joint system for sectional blades

The development and validation of a new joint system for sectional blades is presented in this paper. The system is a bolted connection located in the blade spar cap, and its geometry accommodates a higher number of bolts than any other conventional solution requiring inserts. This results in higher transmitted loads per spar cap width. The modular concept of the system is composed of cell units that can be easily integrated into the design and manufacturing of different blade architectures and used in blades of various lengths by selecting the appropriate number of cell units. The design of the system was performed using analytical and finite element analyses. The analyses were validated using risk reduction mechanical tests, which resulted in an optimized joint system. The loads to be transmitted by the joint system were calculated according to IEC61400‐1 using the GH‐Bladed Version 3.80 on a 5 MW onshore class II‐A wind turbine with a tower height of 120 m and a 61.5 m blade with double spar webs. The joint system was successfully tested in a full‐scale mechanical test for its validation under Germanischer Lloyd guidelines and supervision. Copyright © 2014 John Wiley & Sons, Ltd.