Non-Contact Coda Acoustic Inspection for 3D Defect Localization
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Solution Overview
Problem
Existing non-destructive testing methods for structures, such as ultrasonic C-Scan, require wetting or immersing the structure, leading to high costs and equipment scalability issues, especially for large structures, and are time-consuming due to point-by-point acoustic acquisition.
Innovation Solution
A non-contact, non-destructive testing system using CODA acoustic waves and laser interferometry for defect detection and characterization, allowing measurement without surface preparation and reducing equipment costs and preparation operations, with a system comprising a compressed air jet generator and laser interferometry for precise defect localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic C-Scan imaging process is used to inspect structure volume, then three-dimensional defect detection capability is improved, but equipment cost and complexity increase due to transducer scaling for large structures
Solution Approach 1:
The patent replaces mechanical transducers with optical measurement means (laser interferometry) to detect acoustic waves. The excitation means generate acoustic waves without mechanical contact, and the optical system measures surface vibrations caused by these waves, eliminating the need for scaled transducer equipment while maintaining three-dimensional defect detection capability
Solution Approach 2:
The patent introduces an intermediary optical measurement system that detects surface vibrations caused by acoustic waves propagating through the structure. This intermediary approach allows indirect measurement of internal defects without direct mechanical contact, reducing equipment complexity while preserving detection precision
2Productivity
If transducers are used to implement C-Scan process, then acoustic acquisition can be performed, but surface preparation and waterproofing operations are required which increase cost and time
Solution Approach 1:
The patent replaces mechanical transducers requiring surface contact with optical measurement means that detect acoustic waves through non-contact laser interferometry. This substitution eliminates the need for surface preparation, waterproofing, and drying operations, directly improving productivity while reducing manufacturing complexity
Solution Approach 2:
The optical measurement system measures surface vibrations caused by acoustic waves without requiring any preparation of the structure surface. The system is self-sufficient and does not depend on surface conditions, eliminating auxiliary preparation operations
3Ease of operation
If point-by-point acoustic acquisition is performed with laser interferometry, then non-contact measurement is achieved, but inspection time increases for large structures
Solution Approach 1:
The patent combines multiple measurement points into a simultaneous measurement process. The optical system is arranged to direct laser beams toward multiple measurement points at once, and the excitation means generate acoustic waves that propagate through the entire structure volume, allowing parallel acquisition of data from multiple locations and reducing total inspection time
Solution Approach 2:
The patent transitions from sequential point-by-point measurement to a three-dimensional volume inspection approach. By generating acoustic waves that propagate through the structure volume and measuring vibrations at multiple points simultaneously, the system inspects the entire volume in one operation rather than scanning point by point
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 cost-effective, efficient, and rapid non-destructive testing of structures by eliminating contact requirements and reducing the need for extensive surface preparation, providing detailed volume information on defects with improved precision.
Implementation Method 1
a) carrying out an acoustic excitation of the structure by means of excitation means arranged to generate an acoustic wave in the structure without contact
Implementation Method 2
b) carrying out measurements with measurement means of the laser interferometry type arranged to measure vibrations of the structure at N measurement points
Data Source
Figure 1~2
Figure 3
Figure 4.a~4.c
AI summary
The invention relates to a system intended to inspect a structure (1) with coda acoustic waves, via a given surface (S) that is accessible from the exterior of the structure, said system including: means (4) that are arranged to acoustically excite said structure (1) at at least one set excitation point (Pe1) of the given surface (S) with an ultrasonic pulse of set form; means (6, 7, 8) that are arranged to measure vibrations at at least three set measurement points (Pmi) on the given surface (S), during a time window set with respect to the ultrasonic pulse; electronic means (9) that are arranged to exploit the vibration measurements delivered by said measuring means (6, 7, 8) in order to define an indication (Pd) in said structure of at least one possible defect (2) using a coda acoustic-wave signal at each of said measurement points (Pmi), said system being characterised in that the measuring means (6, 7, 8) are arranged to perform the measurements in air and without contact with the structure (1). The invention also relates to a method corresponding to the implementation of said system.