Measurement Nut Layout for Amplified Bolt Tension Detection
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Solution Overview
Problem
Conventional methods for measuring tension in mechanical systems, such as using strain gauges or measurement nuts with machined recesses, face challenges including the need for electrical coupling, high costs, instability of adhesives, and weakening of the measurement nut, which affects its mechanical properties.
Innovation Solution
A method and system that utilize a measurement nut with a contact portion attached to an object and a non-contact portion, where the dimension change caused by external loads is measured at the non-contact portion, allowing for amplification of the dimension change and improved accuracy in tension measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is fastened to the object using strain gauges with adhesive, then tension measurement is enabled, but the adhesive stability deteriorates over time requiring recalibration
Solution Approach 1:
The measurement function is extracted from the object itself and transferred to a separate measurement nut that threads onto the object. The nut contains measurement recesses with sensors that measure tension indirectly through the nut's deformation, eliminating the need for adhesive attachment to the object and avoiding the reliability issues of adhesive degradation over time.
Solution Approach 2:
The measurement nut serves as an intermediary component between the object being measured and the sensor system. Instead of attaching sensors directly to the object with adhesive, the nut threads onto the object and transmits mechanical deformation to the sensors housed within its recesses, providing a stable and reliable measurement interface.
2Measurement precision
If machined recesses are provided in the measurement nut for sensor placement, then tension sensing is enabled, but the nut's mechanical properties are weakened
Solution Approach 1:
The recesses are strategically positioned in specific locations on the measurement nut where they provide necessary sensor mounting capability while minimizing impact on overall structural strength. The local modification is concentrated only where measurement functionality is required, preserving the bulk of the nut's mechanical properties.
Solution Approach 2:
The sensors are nested within recesses that are integrated into the nut's structure. The recesses are designed to house the sensors securely while maintaining the nut's overall integrity. The measurement functionality is nested within the structural component rather than being separate, optimizing both function and strength.
3Productivity
If measurement is performed directly at the contact portion of the measurement nut, then direct tension measurement is achieved, but measurement accuracy is reduced due to lack of amplification
Solution Approach 1:
The measurement system utilizes the axial dimension of the measurement nut by placing recesses at different axial positions (first recess closer to the object, second recess farther away). This dimensional arrangement creates a lever effect that amplifies the dimensional changes detected by the sensors, improving measurement precision without sacrificing the directness of the measurement approach.
4Measurement precision
If strain gauges are used for tension measurement, then electrical coupling is established for data transmission, but system complexity and cost increase
Solution Approach 1:
The measurement nut itself serves as the sensor body, with recesses machined directly into the nut structure to house the strain gauges. This self-contained design integrates the measurement functionality into the nut, eliminating the need for separate sensor mounting mechanisms and reducing overall system complexity while maintaining measurement precision.
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 method achieves higher accuracy in measuring tension by amplifying the dimension change of the measurement nut, potentially up to 10-25 times, while maintaining the load-bearing capacity and life properties of the measurement nut, and allowing for quick and easy measurements in situ.
Implementation Method 1
exposing the object to an external load, thereby causing a dimension change of the contact portion of the measurement nut
Implementation Method 2
the non-contact portion being used to amplify the dimension change of the contact portion
Data Source
Figure 1a~1c
Figure 1d~2
Figure 3~4b
AI summary
The present invention relates to a method of determining a dimension change of a measurement nut (100), wherein the measurement nut comprises a contact portion (102), adapted for attachment to an object, such as a bolt or a threaded rod, and a non-contact portion (104), the contact portion and the non-contact portion being located coaxially, but axially offset, in relation to each other. The method comprises attaching at least part of the contact portion to the object, the non-contact portion being without direct contact to the object, exposing the object to an external load, thereby causing a dimension change of the contact portion of the measurement nut, and determining the dimension change of the measurement nut by measurement at the non-contact portion. The present invention further relates to a measurement nut (100) and a measurement system (200) comprising the measurement nut.