Phased Array Ultrasonic Method for Robotic Preload Measurement in Offshore Wind Turbine Bolted Connections.

Area of Science:

• Mechanical Engineering
• Materials Science
• Robotics

Background:

• Bolted connections are critical in offshore wind structures.
• Accurate preload measurement is essential for structural integrity.
• Existing methods face challenges with accuracy and defect detection.

Purpose of the Study:

• To present a novel robotic Phased Array Ultrasonic Testing (PAUT) approach for preload measurement in offshore wind applications.
• To address the impact of minor defects on preload measurements.
• To enable simultaneous defect detection and preload measurement.

Main Methods:

• Combination of robotics, PAUT, nonlinear acoustoelasticity, and Finite Element Analysis (FEA).
• Implementation of a robotic system to overcome errors from manual transducer orientation.
• Utilisation of FEA for average preload calculations.

Main Results:

• The robotic PAUT method significantly improves measurement accuracy compared to single-element approaches.
• Errors up to 140 MPa in bolt stress measurement were observed with non-automated methods.
• Simultaneous defect detection and preload measurement were successfully demonstrated.

Conclusions:

• The robotic PAUT approach offers substantial improvements in accuracy and simultaneous measurement capabilities.
• This method is highly recommended for offshore wind preload measurement.
• Investment in hardware, software, and skilled personnel is necessary for adoption.