Piezoelectric Actuator-Sensor Stack for In-Situ Defect Inspection
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Solution Overview
Problem
Existing inspection methods for internal defects in powerplant components are inefficient and often require destructive testing or significant downtime for aircraft.
Innovation Solution
A non-destructive inspection method using a piezoelectric actuator and sensor stack that induces vibrations in the component, measures the vibratory response, and compares it to a model signature to detect defects, allowing in-situ inspection with minimal aircraft downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional inspection methods are used for internal defects in powerplant components, then inspection accuracy may be maintained, but aircraft downtime increases and operational efficiency decreases
Solution Approach 1:
The patent applies mechanical vibration by using a piezoelectric actuator to generate vibrations at resonant frequencies of the component. The actuator is coupled to the component and excited by an actuation voltage to produce vibrations that propagate through the structure, enabling detection of internal defects through the vibratory response without requiring component removal or shutdown of the aircraft.
Solution Approach 2:
The inspection system uses periodic action by applying actuation voltage at specific frequencies to excite the component. The system sweeps through a frequency range to identify resonant frequencies, then applies periodic vibrations at these frequencies to maximize the vibratory response for defect detection, enabling rapid inspection during brief maintenance windows.
2Productivity
If piezoelectric actuator and sensor stack are used, then inspection speed improves, but electrical isolation requirements increase device complexity
Solution Approach 1:
The patent uses an electrical isolator as an intermediary component positioned between the piezoelectric actuator and the piezoelectric sensor stack. This isolator provides the necessary electrical isolation to prevent signal interference while allowing mechanical vibration transmission, thus enabling the use of piezoelectric devices without compromising the inspection signal integrity.
Solution Approach 2:
The electrical isolator serves multiple functions: it provides electrical isolation between the actuator and sensor, maintains mechanical coupling for vibration transmission, and supports the sensor stack while allowing free vibration of the component. This multi-functionality reduces overall device complexity despite the addition of the isolator.
3Measurement precision
If resonant frequency vibration is applied, then defect detection sensitivity improves, but precise frequency control requirements increase measurement complexity
Solution Approach 1:
The patent implements feedback by using the piezoelectric sensor stack to measure the vibratory response of the component and comparing it to the actuation voltage. The system identifies resonant frequencies by detecting peaks in the frequency response, then uses this feedback information to adjust and maintain vibrations at these optimal frequencies for maximum defect detection sensitivity.
Solution Approach 2:
The inspection system applies dynamics by sweeping through a range of frequencies to dynamically identify the resonant frequencies of the component. Rather than requiring precise prior knowledge of the resonant frequency, the system dynamically adapts by measuring the frequency response and adjusting the actuation frequency to match the component's natural resonances, simplifying the measurement process while maintaining high sensitivity.
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
Enables accurate detection of internal defects in powerplant components while the aircraft is operational, reducing downtime and maintenance costs.
Implementation Method 1
The piezoelectric actuator includes a piezoelectric device configured to induce vibrations in the specimen component
Implementation Method 2
The sensor includes a piezoelectric device configured to measure a vibratory response in the specimen component
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An inspection method is provided during which an inspection device is arranged with a specimen component (22). The inspection device includes a piezoelectric actuator (40), an isolator (58) and a piezoelectric sensor (42). The piezoelectric actuator (40) engages and is preloaded against a surface of the specimen component (22) sequentially through the isolator (58) and the piezoelectric sensor (42). The isolator (58) electrically isolates the piezoelectric actuator (40) from the piezoelectric sensor (42). Vibrations are induced in the specimen component (22) using the piezoelectric actuator (40). A vibratory response in the specimen component (22) excited by the vibrations is measured using the piezoelectric sensor (42). Response data indicative of the vibratory response measured is provided using the piezoelectric sensor (42).