A novel method of strain - bending moment calibration for blade testing

P Greaves,G Ingram,C Van Beveren,R Dominy,J Gaffing,R Prieto

doi:10.1088/1742-6596/753/4/042014

Abstract

A new method of interpreting strain data in full scale static and fatigue tests has been implemented as part of the Offshore Renewable Energy Catapult's ongoing development of biaxial fatigue testing of wind turbine blades. During bi-axial fatigue tests, it is necessary to be able to distinguish strains arising from the flapwise motion of the blade from strains arising from the edgewise motion. The method exploits the beam-like structure of blades and is derived using the equations of beam theory. It offers several advantages over the current state of the art method of calibrating strain gauges.

Highlights

The rotor blades are some of the most critical components of a wind turbine
The applied bending moments were calculated from the axial distance of each section from the calibration saddle, the applied load as measured by the load cell and the load vector as measured by the FARO Focus 3D scanner
A sensitivity analysis to the strain gauge coordinates showed that the method is very insensitive to these values

Summary

Introduction

The rotor blades are some of the most critical components of a wind turbine. Structural failure of a blade can cause widespread damage to the turbine and its surroundings, so certifying bodies require full scale testing of new designs of blades to ensure that they can withstand the loads which are predicted in service.These tests are typically performed by cantilevering the blade from a static hub and applying loads to it. The rotor blades are some of the most critical components of a wind turbine. Structural failure of a blade can cause widespread damage to the turbine and its surroundings, so certifying bodies require full scale testing of new designs of blades to ensure that they can withstand the loads which are predicted in service. These tests are typically performed by cantilevering the blade from a static hub and applying loads to it. During the process of testing a full size wind turbine blade both static and fatigue tests will be performed. The loads are introduced using saddles, which closely conform to the surface profile of the blade at the location at which they are mounted

Methods

Results

Conclusion