Piezoelectric Patch Bolt Preload Detection via Single Echo Time-of-Flight
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Solution Overview
Problem
Existing bolt preload detection methods suffer from high measurement errors, structural damage, and high costs, particularly due to the use of ultrasonic probes with uncontrollable couplant thickness and limited repeatability.
Innovation Solution
A piezoelectric patch-based system is used to directly measure bolt preload by analyzing the change in time-of-flight of a single echo, eliminating the need for couplant and improving precision through line fitting without material property measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ultrasonic probe is used for bolt preload detection, then detection capability is provided, but measurement precision deteriorates due to uncontrollable couplant thickness and poor repeatability
Solution Approach 1:
The invention extracts and eliminates the couplant from the measurement system by directly pasting the piezoelectric patch on the bolt head. This removes the source of measurement error related to couplant thickness variation, achieving direct contact between the sensor and the measurement surface without requiring any intermediate coupling medium.
Solution Approach 2:
The invention uses a piezoelectric patch that can be directly pasted on the bolt head to replicate the functionality of an ultrasonic probe without requiring couplant. The patch serves as a simplified copy of the ultrasonic detection function, eliminating the problematic couplant interface while maintaining the core measurement capability.
2Reliability
If a piezoelectric patch is pasted on the bolt head to eliminate couplant, then repeatability improves, but measurement resolution may be insufficient without single echo analysis
Solution Approach 1:
The invention segments the ultrasonic echo signal into multiple distinct echoes (first echo, second echo, third echo). By specifically analyzing the time-of-flight difference between the first and second echoes, or alternatively using the third echo, the system achieves high-resolution measurement of preload variations. This segmentation of the signal allows for precise extraction of measurement information from specific echo components.
Solution Approach 2:
The system uses the time-of-flight difference of specific echoes as feedback to determine preload magnitude. By establishing a relationship between the echo time difference and preload force, the system provides precise feedback-based measurement that converts the temporal characteristics of the ultrasonic echo into quantitative preload information with high resolution.
3Ease of operation
If double echo time difference is used for measurement, then detection is possible, but measurement precision is limited due to low resolution
Solution Approach 1:
The invention uses a disposable piezoelectric patch that is pasted on the bolt head for measurement and then removed. This single-use approach eliminates the need for expensive, complex ultrasonic probes while achieving sufficient measurement precision. The patch serves its measurement purpose effectively and is discarded, avoiding the high costs and complexity of reusable probe systems.
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
This approach significantly reduces measurement errors to about 1% and lowers costs while maintaining structural integrity, providing a precise and cost-effective method for real-time bolt preload detection.
Implementation Method 1
a piezoelectric patch is pasted on the head of the bolt to substitute an ultrasonic probe
Implementation Method 2
the change of time-of-flight of a first echo is used to characterize the variation of preload
Implementation Method 3
the characteristic of single echo measurement is used for further improving the measurement precision
Data Source
AI summary
The present invention discloses a piezoelectric patch-based real-time and high-precision bolt preload detection method and system. A piezoelectric patch is used as an ultrasonic excitation source and pasted on the head of a bolt, and the high-precision fitting relationship between the ultrasonic change of time-of-flight and the bolt preload is established according to the law of the ultrasonic change of time-of-flight of single echo with the stress so that the real-time detection of the bolt preload is realized by using the mathematical relationship. Compared with the previous method using ultrasonic probes, the present invention eliminates the error caused by the uncertainty of couplant thickness and further improves the measurement precision by using the change of time-of-flight of single echo. Meanwhile, the low-error rate measurement of the bolt preload is realized at a low cost and without affecting the structural performance.