Fiber Bragg Grating Displacement Sensor with Bidirectional Measurement and Vibration Avoidance
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Solution Overview
Problem
Existing fiber Bragg grating displacement sensors face issues with fatigue and inaccurate measurements due to long-term positive stress states and vibration-induced deformation, which limit their durability and measurement accuracy, especially in harsh environments.
Innovation Solution
A fiber Bragg grating displacement sensor design featuring a bidirectional measuring mechanism with a linear guide rail and slider, a vibration-avoiding mechanism using a cantilever beam and steel ball, and temperature compensation with a second fiber Bragg grating, allowing for positive and negative bidirectional displacement measurement while avoiding vibration deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fiber Bragg grating sensor is set to a positive displacement value (e.g., 50 mm) for reciprocating measurement, then the sensor can measure bidirectional displacement, but the cantilever beam and fiber Bragg grating are exposed to long-term positive stress state which accelerates fatigue and stress relaxation
Solution Approach 1:
The patent inverts the traditional cantilever beam configuration by positioning the fixed end at the measurement end and the free end at the base. This inversion allows the beam to experience alternating positive and negative stress states during bidirectional displacement, rather than being under constant positive stress, thereby reducing fatigue accumulation and extending sensor life while maintaining bidirectional measurement capability
Solution Approach 2:
The patent changes the stress state parameter of the cantilever beam from unidirectional positive stress to alternating bidirectional stress by inverting the beam configuration. This parameter change enables the sensor to handle reciprocating displacement without accumulating stress in one direction, improving reliability under dynamic loading conditions
2Productivity
If the existing fiber Bragg grating displacement sensor is used in vibrating environments, then the sensor can provide continuous monitoring, but vibration impact causes deformation at the free end of the cantilever beam which cross-couples with displacement measurement and reduces accuracy
Solution Approach 1:
By inverting the cantilever beam configuration, the patent changes the vibration response characteristics of the system. The inverted beam structure reduces the coupling between vibration-induced deformation and displacement measurement, allowing continuous monitoring in vibrating environments while maintaining measurement accuracy
Solution Approach 2:
The patent replaces the traditional mechanical cantilever beam system with an inverted configuration that is less sensitive to vibration. This mechanical substitution changes the system's dynamic characteristics to reduce vibration interference while maintaining the continuous monitoring function
3Ease of manufacture
If a traditional cantilever beam configuration is used with fiber Bragg grating pasted on the surface, then the structure is simple and easy to manufacture, but the measuring range is limited to positive displacement and the sensor is sensitive to vibration
Solution Approach 1:
The patent inverts the traditional cantilever beam configuration, which maintains structural simplicity while fundamentally changing the measurement capabilities. The inverted beam enables bidirectional displacement measurement and reduces vibration sensitivity, achieving enhanced adaptability without complicating the manufacturing 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
The sensor maintains measurement accuracy by keeping the cantilever beam in a zero deformation state, preventing fatigue and ensuring accurate displacement measurements even in vibrating environments, thus extending its applicability and durability.
Implementation Method 1
The fiber Bragg grating senses the strain on the surface of the cantilever beam and produces a wavelength shift
Implementation Method 2
a spring (5) which pushes the transmission rod (4) and the guider (7) to return to an initial position by applying elastic force
Implementation Method 3
a steel ball (12) which is connected to a tail end of the transmission screw (11) inside the guider (7) and limits a vibration deformation of a free end of the cantilever beam
Data Source
AI summary
The present disclosure discloses a fiber Bragg grating displacement sensor with positive and negative bidirectional measurement and free from vibration, which falls within the technical fields of fiber sensing and measurement monitoring, and aims to solve the problem that the measuring range of the existing fiber Bragg grating displacement sensor is positive, and the free end of the cantilever beam will generate vibration deformation, resulting in inaccurate displacement measurement. The sensor of the present disclosure has a positive and negative two-way displacement measurement range through the arrangement of a bidirectional measuring mechanism. In the measurement process, the cantilever beam of the vibration-avoiding mechanism is in an initial state of zero deformation, resulting in upper and lower bending deformation, so as to avoid the fatigue and failure problems caused by the cantilever beam and the fiber Bragg grating due to constant force.