EE5940: Wind Essen.als. Materials and Structural Reliability Sue Mantell Mechanical Engineering

Transcription

1 EE5940: Wind Essen.als Materials and Structural Reliability Sue Mantell Mechanical Engineering

2 Focus on Rotor Blades Overview the most complex structural component of a wind turbine Quick overview of Loads Typical characteris.cs of rotor blades Material Selec.on Manufacturing Reliability

3 What are the loads on a rotor blade? gravity lift Variable wind speed along the.p of the blade Loads are both sta.c and dynamic (varied wind speed, and rota.on) Flapwise bending Can.lever bending

4 What is the Blade Size?

5 Desirable Rotor Blade Features Aerodynamic shape Taper Lightweight Size Size/twist

6 Desirable Material Proper.es Rotor Qualities Size Lightweight Stiff Strong Complex Shape Long Fatigue Life Material Properties Modulus Density Fracture toughness Specific Strength (Y/ρ) Specific Stiffness (E/ρ)

7 Modulus, Strength, Toughness Modulus: slope Strength: maximum stress Toughness: area beneath curve

8 Materials Selec.on Merit index for a beam Considerations of beam weight (f (ρ,t)) and stiffness (f(e,t 2 )) GFRP: Glass fiber reinforced plastic CFRP: Carbon fiber reinforced plastic

9 Other Considera.ons: Strength vs. Toughness

10 Composite Materials Layers with Directional properties Heat, pressure Laminate Add core material for stiffness in bending Fibers with a polymer matrix Samples of material, laminates, core materials

11 Composite Materials Fibers Resins Specific strength: Y/ρ Specific stiffness: E/ρ Thermosets (epoxy, heat cured) Thermoplastics (can be reheated and reformed)

12 Anatomy of a Rotor Blade How should fibers be oriented?

13 Blade Manufacture: VARIM Vacuum Assisted Resin Infusion Molding

14 Forming the shell Laying up woven fiber sheets Resin infusion

15 Finishing steps Interior webs provide shear stiffness Completed blade halves are bonded together, surface checked for smoothness

16 Improvements in Manufacturing Lead to Reduced Weight

17 Health Monitoring Cost effective Wind Energy: Critical to achieving the 2020/30 DOE goal Reliability leads to reduced costs: Health monitoring and early fault detection can reduce maintenance costs and system downtime Condition Based Maintenance (CBM): System-wide sensors, mathematical models, and fault detection algorithms are key to improved cost effectiveness

18 Approach to Health Monitoring Blade: Fiber optic strain sensors Gearbox: Accelerometers, tachometer Gearbox Generator: current, voltage Generator Performance Assessment (sensors) Blade control: Hydraulic pressure, temperature, and flow sensors Additional Environmental Sensors In Nacelle All turbine sensor data Controller/ Data Collection Model based Observer Data Acquisition Estimate/Predict Performance (algorithms, system models) In Nacelle or Ground Remote PC-GBS Internet 2.3 mw Siemens Turbine Main Rotor Bearing Gearbox Generator High Speed Shaft Brake Yaw Drive Blade Pitch/brake hydraulics Compare sensor data with expected performance Detect Incipient Failures

19 Real.me Evalua.on of Blade Health Sensor Location lift gravity lift Where do you expect failure? Various types of sensors Strain Gages Acoustic Emission Accelerometers Smart Materials (PZT)

20 Sensor Loca.ons (1) Strain gages

21 Sensor Loca.ons (2) Smart materials

22 Sensor Loca.ons (3) Acoustic Emissions Sensors

23 Turbine Health Monitoring: Jobs Wind Farm Opera<ons & Maintenance 40% of long term direct employment 80,000 jobs predicted by 2030 Assumes 20- year turbine life Wind farm developers offering abermarket services Economic Benefits of CBM/Health Maintenance Early fault detec.on CBM (Condi.on Based Monitoring) Avoid costly repairs & lead.me Common repair, maintenance & overhaul profile Skilled U.S.- based workforce vs. overseas abermarket shops Job Impact for Sensor, Data acquisi<on & Analysis Engineers: sensing & control subsystems Knowledge workers: on- site / remote monitoring 3rd party providers: asset management and CBM

24 Clicker Quiz Which of the following properties is NOT important when selecting a material for wind turbine rotor blades? a. Toughness b. Density c. Specific heat d. Modulus