Lamb Wave Anomaly Characterization in Composite Laminate Structures
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Solution Overview
Problem
Existing non-destructive inspection methods face challenges in accurately detecting and measuring the size of wrinkles in laminate composite structures, particularly in curved areas, as they can cause structural degradation and require precise quality assurance in aerospace and other industries.
Innovation Solution
The method involves propagating ultrasonic lamb waves through a laminate structure using piezoelectric transducers to measure wave group velocity, which is directly proportional to the laminate's bulk modulus and density, allowing for the detection and characterization of wrinkles by correlating changes in wave velocity with wrinkle size and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through-thickness bulk waves or B-scan waves are used for inspection, then the presence of anomalies can be detected, but accurate measurement of wrinkle sizes with large heights is difficult
Solution Approach 1:
The patent changes the inspection parameter from through-thickness bulk waves to guided Lamb waves that propagate along the plane of the laminate. This parameter change enables both reliable anomaly detection and accurate wrinkle height measurement by utilizing wave propagation characteristics that are sensitive to both presence and dimensional characteristics of defects
Solution Approach 2:
The patent replaces the traditional B-scan imaging approach with a wave propagation-based measurement system that uses piezoelectric transducers to generate and detect Lamb waves. This substitution enables more precise measurement of wrinkle dimensions by measuring wave velocity changes rather than relying on image interpretation
2Ease of manufacture
If traditional NDI methods are used, then inspection can be performed, but correlating wrinkle sizes with high degree of accuracy is difficult
Solution Approach 1:
The patent utilizes the relationship between Lamb wave group velocity and laminate modulus, changing the measurement parameter from direct imaging to velocity-based characterization. This enables accurate correlation of wrinkle sizes with material property degradation while maintaining a relatively simple inspection process using standard piezoelectric transducers
Solution Approach 2:
The patent implements a feedback mechanism where the measured group velocity of Lamb waves is correlated back to wrinkle dimensions and material properties. By measuring the wave velocity and comparing it to reference values or theoretical models, the system provides accurate wrinkle size correlation with a degree of accuracy that traditional methods cannot achieve
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 enables accurate detection and characterization of wrinkles, correlating wave group velocity changes with structural stiffness and strength reduction, facilitating precise quality assurance and certification by distinguishing healthy regions from those with anomalies.
Implementation Method 1
propagating ultrasonic lamb waves or stress waves through a composite structure from one piezoelectric transducer to another piezoelectric transducer
Implementation Method 2
The wave group velocity is directly proportional to the square root of the bulk laminate modulus divided by the density. Therefore, if a lamb wave is propagated through the wrinkled zone of the structure, the group velocity will be lower as compared to a healthy region.
Implementation Method 3
receiving the transmitted lamb wave at a sensor at another predetermined location on the surface of the laminate structure
Data Source
AI summary
A method for inspecting a laminate structure may include transmitting a lamb wave through a selected portion of the laminate structure from an actuator at a predetermined location on a surface of the laminate structure. The method may also include receiving the transmitted lamb wave at a sensor at another predetermined location on the surface of the laminate structure. The method may additionally include detecting and characterizing an anomaly in the laminate structure based on the received lamb wave.