Piezoelectric Corrosion Detection Circuit
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Solution Overview
Problem
Existing sensors for monitoring corrosion in metal structures embedded in concrete lack precision, durability, and are high-power consumers, making them unsuitable for large-scale industrial and field applications.
Innovation Solution
A low-cost, low-power system comprising piezoelectric transducers and an electronic circuit with a dual-phase lock-in amplifier circuit, capable of generating and analyzing sinusoidal signals within the 30-400 kHz frequency range for effective corrosion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional impedance analyzer is used for EMI measurements, then measurement precision is improved, but device cost increases, weight increases, and power consumption increases
Solution Approach 1:
The patent divides the impedance analyzer functionality into separate modular components: a microcontroller unit for signal generation and processing, and a piezoelectric transducer for measurement. This segmentation allows each component to be optimized independently, reducing overall system cost and weight while maintaining measurement precision through specialized functionality in each module.
Solution Approach 2:
The patent replaces the traditional mechanical/electronic impedance analyzer with a system based on piezoelectric transducers and electronic signal processing. The piezoelectric effect enables direct conversion between mechanical and electrical signals, eliminating the need for complex analog measurement circuits and reducing both cost and power consumption while maintaining detection accuracy.
2Measurement precision
If traditional impedance analyzer is used for EMI measurements, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic excitation signals at specific frequencies to elicit resonant responses from the piezoelectric transducer. By using periodic action rather than continuous high-power signals, the system achieves precise measurements through resonance enhancement while significantly reducing average power consumption. The microcontroller can adjust frequency and amplitude to optimize the balance between signal strength and energy usage.
3Device complexity
If piezoelectric transducers are used for EMI measurements, then device size is reduced, but signal sensitivity decreases due to high loading from concrete
Solution Approach 1:
The patent changes the operating parameters of the piezoelectric transducer by exciting it at specific resonant frequencies rather than using broad-spectrum signals. This parameter change enhances the transducer's sensitivity to mechanical stresses from corrosion, allowing it to overcome the damping effect of concrete loading. The microcontroller adjusts frequency and amplitude parameters to maximize signal-to-noise ratio while maintaining small device size.
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 system provides high sensitivity and reliability for detecting corrosion and cracks in metal structures embedded in concrete, with the ability to be easily embedded into structures for in-situ Structural Health Monitoring (SHM).
Implementation Method 1
The electromechanical interaction between the PZT patches and the host structure is the main principle to the corrosion detection in the EMI method. Exciting a sinusoidal voltage across a square bonded PZT patch, where the length is typically much larger than the thickness, deformations are produced both in the patch and in the host structure.
Implementation Method 2
an analysis circuit arranged to receive an electric return signal (IDUT) from the at least one piezoelectric transducer in response to the electric test signal (Ip), and to electrically transform said electric return signal (IDUT) from the piezoelectric transducer by means of a dual-phase lock-in amplifier circuit into a resulting electromechanical impedance or voltage representation of the metal structure
Data Source
AI summary
System and a method for detecting corrosion or cracks in a metal structure embedded in concrete. Piezoelectric transducers are arranged for contact with the metal structure embedded in the concrete: an electronic circuit generate an electric test signal for the piezoelectric transducers and receives an electric return signal from the piezoelectric transducers. The electronic circuit comprises an analysis circuit for analysing the electric return signal and for storing the result of the analysis until the results can be communicated to an external device.