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Structural Test Laboratory

NREL engineers design and configure structural test laboratory plans and apply representative forces, moments, and torques needed to properly simulate in-water loading.

Photo of a small marine and hydrokinetic device blade in a large yellow testing device.

Component and full-scale structural testing of marine and hydrokinetic blades and other structural components can validate models, demonstrate system reliability, inform design margins, and assess structure "readiness" for deployment.

Capabilities

NREL is developing test methods and protocols for marine and hydrokinetic devices by applying its expertise in innovative testing for wind technologies. Below are some of the inventive ways in which NREL engineers can utilize the structural test laboratory for marine and hydrokinetic devices.

Property Testing

  • Evaluate inherent structural properties, including mass and center of gravity, to ensure compliance with design goals

Dynamic Characterization

  • Use modal testing to provide designers with the natural frequencies, damping values, and mode shapes of components or systems
  • Apply data from modal testing to validate distributed system parameters, such as mass and stiffness, which are critical inputs to dynamic models

Static Strength Testing

  • Validate design parameters and demonstrate the ability of a component or system to handle extreme design load cases
  • Use load cases to simulate the response of the structure to extreme conditions, such as inflow direction changes, extreme flow conditions, and loss of grid connection
  • Simulate extreme condition events by establishing representative boundary conditions, then applying loads that simulate the flow or forcing function through hydraulic actuators, cranes, or winches 
  • Apply loads while measuring specific data, including strain and displacement

Fatigue Testing

  • Demonstrate the durability of a component or system by loading a component with millions of load cycles applied during the course of several weeks or months and measuring displacement and strain
  • Reveal design and manufacturing problems at an early stage of development
  • Apply nondestructive evaluation techniques including acoustic emission and thermography

Laboratory Equipment

  • 70-meter (m) test preparation facility for instrumentation and testing of the test blades
  • 1,800 m2 of laboratory space for instrumentation and testing
  • Five test stands with overturning moment capacities from 100 kilonewton-meters (kN-m) to 16.7 millinewton-meters
  • 100-kN and 500-kN load frames
  • Hydraulic actuators with stroke distances to 1.5 m and force capacities from 5 kN-m to 500 kN-m
  • Servo-electric multipart winches for quasi-static load application.

Read NREL's fact sheet on structural testing at the NWTC.