Structural health monitoring of wind turbine blades

As electric utility wind turbines increase in size, and correspondingly, increase in initial capital investment cost, there is an increasing need to monitor the health of the structure. Acquiring an early indication of structural or mechanical problems allows operators to better plan for maintenance, possibly operate the machine in a de-rated condition rather than taking the unit off-line, or in the case of an emergency, shut the machine down to avoid further damage. This paper describes several promising structural health monitoring (SHM) techniques that were recently exercised during a fatigue test of a 9 meter glass-epoxy and carbon-epoxy wind turbine blade. The SHM systems were implemented by teams from NASA Kennedy Space Center, Purdue University and Virginia Tech. A commercial off-the-shelf acoustic emission (AE) NDT system gathered blade AE data throughout the test. At a fatigue load cycle rate around 1.2 Hertz, and after more than 4,000,000 fatigue cycles, the blade was diagnostically and visibly failing at the out-board blade spar-cap termination point at 4.5 meters. For safety reasons, the test was stopped just before the blade completely failed. This paper provides an overview of the SHM and NDT system setups and some current test results.

[1]  Dale E. Berg,et al.  Accurate Time-Linked Data Acqusition System Field Deploymemt and Operational Experience , 2000 .

[2]  G. H. James.  Development of structural health monitoring techniques using dynamics testing , 1996 .

[3]  Sandia Report,et al.  Innovative Design Approaches for Large Wind Turbine Blades Final Report , 2003 .

[4]  H. J. Sutherland,et al.  The application of non-destructive techniques to the testing of a wind turbine blade , 1994 .

[5]  Herbert J. Sutherland,et al.  On the Fatigue Analysis of Wind Turbines , 1999 .

[6]  Anindya Ghoshal,et al.  Structural Health Monitoring Static Test of a Wind Turbine Blade , 2002 .

[7]  Charles R. Farrar,et al.  Nonlinear System Identification for Damage Detection , 2007 .

[8]  Sandia Report,et al.  Design of 9-Meter Carbon-Fiberglass Prototype Blades: CX-100 and TX-100 , 2007 .

[9]  Cheng-Huat Ong,et al.  The use of carbon fibers in wind turbine blade design: A SERI-8 blade example , 2000 .

[10]  Jonathan White,et al.  Impact Loading and Damage Detection in a Carbon Composite TX-100 Wind Turbine Rotor Blade , 2008 .

[11]  Herbert J. Sutherland,et al.  LIST/BMI Turbines Instrumentation and Infrastructure , 2001 .

[12]  Don W. Lobitz,et al.  Load mitigation with twist-coupled HAWT blades , 1999 .

[13]  Paul S. Veers,et al.  Performance of twist-coupled blades on variable speed rotors , 2000 .

[14]  Jeroen van Dam,et al.  Structural Testing of 9m Carbon Fiber Wind Turbine Research Blades , 2007 .

[15]  Joshua A. Paquette,et al.  Evaluation of NASA PZT Sensor/Actuator for Structural Health Monitoring of a Wind Turbine Blade , 2007 .

[16]  Jay Johnson,et al.  Fatigue Testing of 9 m Carbon Fiber Wind Turbine Research Blades , 2008 .

[17]  Dayton A. Griffin.  Evaluation of Design Concepts for Adaptive Wind Turbine Blades , 2002 .

[18]  Daniel J. Inman,et al.  Impedance-based structural health monitoring of wind turbine blades , 2007, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[19]  Paul S. Veers,et al.  Aeroelastic tailoring in wind-turbine blade applications , 1998 .

[20]  Paul S. Veers,et al.  AEROELASTIC BEHAVIOR OF TWIST-COUPLED HAWT BLADES , 1998 .

[21]  Gunjit Bir,et al.  The Use of Twist-Coupled Blades to Enhance the Performance of Horizontal Axis Wind Turbines , 2001 .

[22]  Thomas G. Carne,et al.  Development of Validated Blade Structural Models , 2008 .

[23]  Mark A. Rumsey,et al.  Hardware and software developments for the Accurate Time-Linked Data Acquisition System , 1999 .

[24]  Jose R. Zayas,et al.  Accurate GPS Time-Linked data Acquisition System (ATLAS II) user's manual. , 2004 .

[25]  Thomas D. Ashwill,et al.  Concepts to Facilitate Very Large Blades. , 2007 .