Bolt Shear Force Sensor Deformable Ring Design
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Solution Overview
Problem
Current technologies inadequately measure fastener shear forces, which are crucial for assessing structural integrity in mechanically fastened joints, especially under dynamic loading conditions, and do not allow for continuous, real-time monitoring in service applications.
Innovation Solution
A bolt shear force sensor featuring a deformable ring with strain sensing elements and a signal conditioner to capture hoop strain and convert it into shear force measurements, enabling continuous and real-time monitoring of shear forces in both static and dynamic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional strain gage methods are used to measure fastener forces, then axial forces can be measured, but shear forces cannot be adequately measured
Solution Approach 1:
The sensor ring is segmented into multiple discrete strain gage locations around the circumference, with each segment oriented to detect shear force components in different directions. This segmentation allows the system to measure multi-directional shear forces by combining signals from individual gage segments.
Solution Approach 2:
The invention transitions from one-dimensional axial force measurement to two-dimensional shear force measurement by arranging strain gages in a circumferential pattern around the fastener. The ring geometry enables detection of forces in multiple directions simultaneously through spatial distribution of sensing elements.
2Measurement precision
If pressure sensitive films are mounted between fasteners to measure shear forces, then shear force patterns can be obtained, but continuous real-time monitoring is not possible
Solution Approach 1:
The sensor ring provides continuous monitoring capability through its closed-loop geometry that remains in place during joint operation. The strain gages continuously detect deformation as the fastener experiences shear forces, enabling real-time monitoring without requiring disassembly or reconfiguration of the measurement system.
Solution Approach 2:
The sensor ring is designed to be installed on the fastener and remain in place throughout the service life of the joint. The system self-monitors without requiring external intervention, maintaining measurement capability continuously as the joint undergoes loading and unloading cycles.
3Reliability
If existing monitoring devices are used, then axial forces can be monitored, but shear forces and cumulative stress effects cannot be tracked
Solution Approach 1:
The sensor ring serves multiple functions simultaneously: it measures shear forces in multiple directions, monitors axial forces, and detects cumulative stress effects. The unified ring geometry with strategically placed strain gages provides comprehensive force measurement capability that supports thorough structural integrity assessment.
Solution Approach 2:
The sensor ring provides continuous feedback on fastener loading conditions through real-time strain measurements. This feedback enables monitoring of shear force magnitude and direction, allowing assessment of cumulative stress effects that contribute to joint degradation over time.
4Ease of manufacture
If deformation theory is used to analyze joint behavior, then theoretical predictions can be made, but actual fastener behavior from structural tests is not available
Solution Approach 1:
The sensor ring creates a physical copy of the fastener's mechanical behavior by directly measuring deformation and force transmission. This experimental data collection approach complements theoretical deformation theory by providing actual measured values that validate or refine analytical models.
Solution Approach 2:
The invention replaces purely theoretical mechanical analysis with direct experimental measurement using strain gages. The sensor ring substitutes for complex theoretical calculations by providing straightforward, direct measurements of force and deformation that can be used to validate design methods.
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
The sensor provides accurate and continuous monitoring of shear forces in fasteners, improving the assessment of structural integrity and design validation in joints with multiple fasteners, and can be used without degrading the fastener's strength or stiffness.
Implementation Method 1
a deformable ring with channel-like cross-sections as a circumference and a wire egress extending thru one of the flanges (arms) of the channel. Strain sensing elements are mounted to an outer face of the circumference in a central area (mid-section) of the channel region. The deformable ring surrounds a bolt or mechanical fastener positioned or attached in an operating system.
Data Source
AI summary
A bolt shear force sensor for in-service monitoring is provided in which the sensor includes a deformable ring with channel-like cross-sections and a wire egress hole. The ring surrounds a bolt or fastener to be tested. The channel-like cross sections face exterior to a center of the ring. Strain sensing elements are mounted within the channel cross-sections as an outer circumference of the ring. The sensing elements capture hoop strain from surrounding plates of the operating system which holds the fastener. A signal conditioner operationally connected via wire conductors is used to convert strain sensing signals from the sensing elements to strain output. The strain outputs are then used in conjunction with a calibration curve of shear force versus strain to determine the magnitudes and directions of the resultant shear forces.