Coaxial Measurement Nut for Amplified Tension Sensing
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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 tension is measured at the non-contact portion, allowing for amplification of the dimension change and improved accuracy.
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 contact portion and transferred to the non-contact portion of the measurement nut. The non-contact portion measures dimension changes indirectly through the nut body, eliminating the need for direct sensor attachment to the object with unstable adhesive.
Solution Approach 2:
The measurement nut itself acts as an intermediary between the object and the measurement system. The non-contact portion of the nut serves as a mediator that translates object dimension changes into measurable signals without requiring direct contact sensors on the object.
2Measurement precision
If a machined recess is provided in the measurement nut for sensor placement, then tension sensing is enabled, but the nut's mechanical strength deteriorates
Solution Approach 1:
The sensor placement function is extracted from the nut body by using the non-contact portion that extends beyond the object surface. This eliminates the need for weakening recesses in the nut, as measurements are taken from the intact outer surface of the non-contact portion.
Solution Approach 2:
The measurement location is shifted from the internal structure (requiring recesses) to the external surface of the non-contact portion. This dimensional shift allows measurement without compromising the nut's structural integrity.
3Productivity
If measurement is performed at the contact portion of the measurement nut, then direct tension measurement is achieved, but measurement accuracy is limited due to small dimension changes
Solution Approach 1:
The non-contact portion acts as a lever arm that counterbalances the small dimension changes at the contact portion. By measuring at the extended non-contact portion, small contact portion deformations are amplified into larger, more accurately measurable dimension changes.
Solution Approach 2:
The measurement is transferred from the contact portion (small dimension changes) to the non-contact portion (amplified dimension changes). This spatial dimensionality change enables higher measurement precision while maintaining measurement efficiency.
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 up to 10-25 times, while maintaining the load-bearing capacity and life properties of the measurement nut, and allowing for measurements in situ without the need for electrical coupling.
Implementation Method 1
By measuring at the non-contact portion of the measurement nut, instead of at the contact portion of the measurement nut, the non-contact portion may be 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 (500), wherein the measurement nut comprises a contact portion (502), adapted for attachment to an object, such as a bolt or a threaded rod, and a non-contact portion (504), 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 (500) and a measurement system (200) comprising the measurement nut.