Bolt Axial Force Detector With Flat Strain Sensing Surface
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Solution Overview
Problem
Existing strain gauge technologies face challenges in accurately detecting slight loosening of fastening members due to difficulties in applying strain gauges on curved surfaces and horizontal placement, leading to reduced sensing precision.
Innovation Solution
A detector with a strain element having a through hole and a strain sensing sensor disposed on a planar portion or a protruding thin-plate portion, utilizing a bridge circuit to enhance strain detection precision by positioning strain detecting elements at optimal locations for strain measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a strain gauge is applied to a curved outer circumferential face of a cylindrical member, then the strain gauge can be installed on the member, but the sensing precision of strain deteriorates due to disposing defects
Solution Approach 1:
The cylindrical member is segmented by introducing axial grooves to create a planar measurement surface from the curved outer circumferential face. This segmentation allows the strain gauge to be installed on a flat surface rather than a curved one, eliminating disposing defects and improving strain sensing precision while maintaining ease of installation
Solution Approach 2:
The measurement surface is transformed from a curved two-dimensional surface to a planar surface by creating a groove along the axial direction. This dimensional change provides a flat mounting surface for the strain gauge, enabling proper adhesive bonding and eliminating the disposing defects that occur on curved surfaces
2Ease of operation
If a strain gauge is provided horizontally on the same face as a bolt head, then the installation is simple, but slight loosening of the bolt cannot be detected with high precision
Solution Approach 1:
Axial grooves are introduced in advance to create a planar portion on the outer circumferential face before strain gauge installation. This preliminary action provides an optimal measurement surface that is sensitive to axial loading changes, enabling high-precision detection of slight bolt loosening while maintaining ease of gauge installation
Solution Approach 2:
A localized planar portion is created on the curved surface through axial grooves, concentrating the measurement function in a specific region. This local quality change provides a flat surface for the strain gauge that is optimally positioned to detect axial strain, improving loosening detection precision without complicating the overall installation process
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
Improves the sensing precision of strain in fastening elements by accurately detecting strain at multiple positions, allowing for high-precision strain detection and output of precise strain data through wireless communication.
Implementation Method 1
a strain sensing sensor that senses strain of the strain element
Data Source
AI summary
A detector is a detector that detects fastening axial force applied by a fastening unit in an axial direction. The detector includes a strain element that has a through hole through which a bolt portion that the fastening unit has is inserted, and a strain sensing sensor that senses strain of the strain element. The strain element has a block-like form and has a planar portion following the axial direction on a side face thereof. The strain sensing sensor is provided on the planar portion.