The Role of Testing and Characterization in the Methodical Development of Sensor-Integrating Bolts for Multi-Axial...

Area of Science:

• Mechanical Engineering
• Sensor Technology
• Materials Science

Background:

• Sensor-integrating bolts enable in situ data acquisition by embedding sensing into machine elements.
• Standardized interfaces and performance are crucial for widespread adoption, creating a conflict between mechanical and sensory requirements.
• Existing multi-axial force-measuring bolts do not adequately address these conflicting objectives.

Purpose of the Study:

• To develop and characterize sensor-integrating bolts that maintain mechanical performance while enabling multi-axial force measurement.
• To investigate the trade-offs between mechanical integrity and sensory performance in integrated bolts.
• To iteratively improve prototype designs based on performance characterization.

Main Methods:

• Methodical development of evolving sensor-integrating bolt prototypes.
• Integration of strain gauges and a custom electronics platform with Bluetooth Low Energy (BLE) for data acquisition.
• Testing under axial and bending loads to evaluate mechanical and sensory performance indicators.

Main Results:

• Prototypes demonstrated significant improvements in linearity errors, reducing them from 3.3% to 1% (axial) and 3.7% to 0.1% (bending).
• Sensitivities achieved were approximately 10 µV/V/kN (axial) and 1 µV/V/Nm (bending), with errors below 6%.
• Mechanical performance reduction ranged from 1.3% to 24.6% due to sensor integration, highlighting the need for compensation strategies.

Conclusions:

• The developed sensor-integrating bolts show promise for multi-axial force measurement in retrofitting applications.
• Iterative design and testing successfully reduced performance errors, though mechanical performance trade-offs require further attention.
• The presence of superimposed bending torques even in axial load cases necessitates further investigation into loadability effects.