Internal Strain Sensor Structure for Concentrated Strain Detection
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Solution Overview
Problem
Existing strain sensors fail to measure strain with high accuracy in subjects such as machine tool structures.
Innovation Solution
A strain sensor is installed inside a subject with a flexure plate, strain gauge, and protruding portions, housed in a tubular cover that expands to increase its outer diameter, allowing for high-accuracy strain measurement by concentrating strain at a specific region and using a Wheatstone bridge circuit with multiple strain sensitive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a strain sensor is installed inside a subject to measure strain, then the measurement position is flexible, but the outer diameter of the tubular cover must be reduced to fit inside the subject, which limits the sensor's ability to amplify strain
Solution Approach 1:
The tubular cover is designed with a variable outer diameter that can expand radially outward when the protruding portions push against it during strain measurement. This dynamic expansion allows the cover to fit inside the subject with a smaller initial diameter while still achieving the necessary strain amplification capability when deployed
Solution Approach 2:
The sensor is divided into separate functional components: the flexure plate with protruding portions for strain sensing, and the tubular cover for housing and strain amplification. This segmentation allows each component to be optimized independently - the flexure plate can be made compact for installation while the cover can expand to provide sufficient strain amplification
2Measurement precision
If the outer diameter of the tubular cover is increased to amplify strain effectively, then strain measurement accuracy improves, but the sensor cannot be installed inside subjects with limited space
Solution Approach 1:
The tubular cover transitions from a compact state for installation to an expanded state for measurement. The cover's outer diameter increases radially when strain is applied, allowing the sensor to fit within space constraints during installation while achieving the necessary size for effective strain amplification during operation
Solution Approach 2:
The flexure plate with protruding portions is nested within the tubular cover. This nesting arrangement allows the compact sensor core to be housed within the cover, which then expands outward to provide the necessary strain amplification capability without increasing the initial installation size
3Stability of the object's composition
If the tubular cover is made rigid to maintain structural stability, then the sensor composition is stable, but the protruding portions cannot push the cover to increase its outer diameter for strain amplification
Solution Approach 1:
The tubular cover exhibits different mechanical properties in different locations and directions: it has high radial flexibility to allow expansion when pushed by the protruding portions, while maintaining axial and circumferential rigidity to preserve structural stability and proper sensor composition during operation
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 accurately measures strain with enhanced sensitivity by amplifying strain at a concentrated region, improving detection accuracy and measurement precision.
Implementation Method 1
a strain gauge attached to a region sandwiched between the pair of protruding portions, the region being in the flexure plate
Data Source
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AI summary
According to the present invention, a strain sensor (100) installed inside a device under test comprises a flat plate-form distortion-inducing plate (F), a strain gauge (112) affixed to the distortion-inducing plate, and a pair of protruding parts (PI, P2) that protrude from the distortion-inducing plate toward both sides along an in-plane direction of the distortion-inducing plate. The strain gauge is affixed to a region (SC) of the distortion-inducing plate that is sandwiched between the pair of protruding parts.