Wireless Bolt Tension Monitoring With Embedded Strain Sensors

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Solution Overview

Problem

Existing techniques for monitoring the tension in threaded fixings, such as bolts and studs, are complex and require time-consuming calibration, making them inefficient for securing structurally critical components.

Innovation Solution

A tension monitoring apparatus with a strain sensor embedded in the shank of the fixing, a data processing module, and a wireless transmitter, allowing for remote monitoring of tension through a wireless communication system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ultrasonic transducer or mechanical load monitoring arrangement is used to monitor bolt tension, then tension monitoring capability is achieved, but device complexity and calibration difficulty increase

Engineering Contradiction:
Improvetension monitoring capabilityVSAvoidmonitoring arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical monitoring systems (ultrasonic transducers, mechanical load cells) with a simplified strain sensor system. The strain sensor directly measures tension in the bolt shank and transmits data wirelessly, eliminating the need for complex calibration procedures and reducing overall system complexity while maintaining measurement accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the essential measurement function from complex monitoring systems. By using a simple strain sensor embedded in the bolt shank rather than external ultrasonic transducers or mechanical load cells, the system achieves tension monitoring with minimal complexity and no calibration required.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If traditional monitoring arrangements are implemented, then tension data can be obtained, but time-consuming calibration is required

Engineering Contradiction:
Improvetension measurement accuracyVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The strain sensor system is self-calibrating through its direct integration with the bolt shank. The sensor naturally measures the relationship between bolt elongation and tension without requiring external calibration procedures. The system automatically provides accurate tension measurements from installation, eliminating time-consuming calibration steps.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The strain sensor is pre-installed and integrated into the bolt shank during manufacturing, positioning it to directly measure tension forces. This preliminary integration ensures the sensor is ready for immediate use without requiring field calibration, as the measurement relationship is established during bolt fabrication.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If strain sensor with embedded installation is used, then calibration process is simplified, but sensor integration complexity increases

Engineering Contradiction:
Improvecalibration process simplicityVSAvoidsensor integration complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the strain sensor with the bolt shank structure itself, creating an integrated tension monitoring bolt. The sensor is embedded within the shank material, combining the structural function of the bolt with the measurement function of the sensor. This integration simplifies the overall system while the modular design keeps the integration process manageable.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The strain sensor serves multiple functions: it measures tension forces, transmits data wirelessly, and integrates structurally with the bolt shank. This multi-functionality reduces the need for separate calibration systems and external monitoring components, simplifying both manufacturing and deployment while maintaining measurement capabilities.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables efficient and accurate remote monitoring of securing force, reducing the risk of loose connections in critical components by providing real-time data transmission and simplifying the calibration process.

Implementation Method 1

a strain sensor embedded in the shank of the fixing and configured to generate a strain sensor signal corresponding to tension in the shank

Methodology Applied
Scientific EffectStrain: Deformation

Data Source

PatentEP4298416B1Tension monitoring apparatus
Publication Date: 2025.11.05 COPPER STATE BOLT & NUT CO INC
  • EP4298416B1 patent drawingFigure 1~2
  • EP4298416B1 patent drawingFigure 3
  • EP4298416B1 patent drawingFigure 4

AI summary

Disclosed herein is a tension monitoring apparatus. The apparatus comprises a fixing with a shank which in use is under tension, a strain sensor embedded in the shank of the fixing and configured to generate a strain sensor signal corresponding to tension in the shank. The apparatus further comprises a data processing means configured to receive the strain sensor signal, process the strain sensor signal in accordance with one or more characterising parameters associated with the strain sensor and thereby generate corresponding strain sensor data indicative of a strain to which the shank is subject. Additionally, the apparatus comprises a wireless transmitter for communicating the strain sensor data to a remote receiver, wherein the data processing means and the wireless transmitter are mounted in a module fixed to an end of the fixing.