Acoustic Camera for Composite Vacuum Bag Leak Detection
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Solution Overview
Problem
During the fabrication of composite parts using vacuum-assisted resin infusion or prepreg technology, identifying and locating air leaks between the vacuum bag and the mould is challenging, leading to incomplete resin infusion and reduced strength of the composite part, potentially resulting in the entire part being scrapped.
Innovation Solution
The use of an acoustic camera unit to detect air leaks by acquiring optical images and generating acoustic maps based on sound waves emitted during and after evacuating the mould cavity, specifically focusing on the ultrasonic frequency range to quickly identify and locate any leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional leak detection methods are used during vacuum bag sealing, then the fabrication process can proceed, but air leaks may remain undetected leading to incomplete resin infusion and reduced composite part strength
Solution Approach 1:
The patent replaces traditional mechanical leak detection methods (such as visual inspection or manual testing) with acoustic emission detection technology. The system uses acoustic sensors to detect the characteristic sounds generated by air leaks at the vacuum bag-mould interface, enabling non-contact, automated detection that significantly improves reliability while reducing detection difficulty.
Solution Approach 2:
The patent introduces acoustic waves as an intermediary medium to detect air leaks. Instead of directly observing or mechanically testing for leaks, the system uses acoustic emissions generated by the leaking air itself as a mediator to indicate the presence and location of leaks, transforming an invisible problem into a detectable signal.
2Productivity
If manual inspection methods are used to detect air leaks, then equipment complexity remains low, but fabrication cycle time increases and productivity decreases
Solution Approach 1:
The patent enables the detection system to automatically identify and locate air leaks without requiring manual intervention. The acoustic emission system continuously monitors the vacuum bag-mould interface, automatically detects leaks when they occur, and provides real-time alerts, allowing the fabrication process to proceed without stopping for manual inspection thereby improving productivity.
Solution Approach 2:
The patent transforms the detection approach by monitoring acoustic parameters (sound frequency, intensity, and pattern) rather than using complex mechanical or visual inspection systems. By focusing on specific acoustic emission characteristics of air leaks, the system achieves rapid detection with relatively simple equipment, reducing both detection time and system complexity.
3Reliability
If leak detection is performed continuously throughout the fabrication process, then air leaks are quickly identified improving reliability, but energy consumption and process complexity increase
Solution Approach 1:
The patent performs acoustic emission monitoring specifically during the critical vacuum bag sealing phase when air leaks are most likely to occur and have the greatest impact on product quality. By focusing detection efforts on this preliminary critical period rather than continuously throughout the entire fabrication process, the system maintains high reliability for detecting leaks when they matter most while minimizing energy consumption during non-critical phases.
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 method significantly reduces fabrication cycle time by allowing operators to quickly identify and address air leaks, ensuring a sealed cavity and complete resin infusion, thereby preventing dry spots and enhancing the strength of composite parts.
Implementation Method 1
detecting sound waves emitted from the mould during and/or after the step of evacuating air from the mould cavity
Implementation Method 2
evacuating air from the mould cavity
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method of fabricating a composite part comprising fibre reinforced material in a mould (10a, 10b, 10c), the method comprising the steps of: depositing fibre material on a mould surface; covering the fibre material with a vacuum film to create a mould cavity that contains the fibre material and is substantially sealed; evacuating air from the mould cavity; detecting if there is an air leak into the mould cavity with an acoustic camera unit (31) during and/or after the step of evacuating air from the mould cavity.