Infrared Camera Detects Missing Tows in Composite Layup
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Solution Overview
Problem
Conventional methods for detecting missing tows in composite layups are inaccurate and labor-intensive, often requiring extensive material removal during rework due to the difficulty in visually or tactically identifying depressions in the layup surface, especially when the composite layup has overlapping plies with minimal contrast.
Innovation Solution
A system and method utilizing an infrared camera mounted on a fiber placement head to generate real-time thermal images of the composite layup during tow application, allowing for precise detection of missing tows by identifying localized differences in heat signatures, and a preheating mechanism to enhance tack between the tow and substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection is used to detect missing tows, then no additional equipment is needed, but detection accuracy is poor due to small tow dimensions and minimal contrast
Solution Approach 1:
The patent replaces visual inspection (mechanical/optical system) with thermal imaging technology. The infrared camera detects temperature differences caused by missing tows, converting a visual detection problem into a thermal field detection problem, thereby achieving high-precision detection without requiring complex optical equipment for magnification.
Solution Approach 2:
The patent changes the detection parameter from visual appearance (color, shape) to thermal characteristics (temperature distribution). By preheating the substrate and detecting temperature differences through thermal imaging, the system can identify missing tows based on thermal field changes rather than visual contrast, solving the detection accuracy problem.
2Productivity
If tactile inspection is used to detect missing tows, then no equipment is needed, but the process is impractical for large surface areas and yields poor results
Solution Approach 1:
The patent replaces manual tactile inspection with automated thermal imaging technology. The infrared camera mounted on the fiber placement head automatically scans and captures thermal images of the entire layup surface, eliminating the need for manual touch inspection and dramatically improving both productivity and detection accuracy.
Solution Approach 2:
The patent creates a thermal field copy (thermal image) of the physical layup surface. This thermal image serves as a virtual representation that can be analyzed without physically touching the workpiece, enabling fast, non-contact inspection of large surface areas while maintaining high detection accuracy.
3Productivity
If conventional inspection methods are used, then the fiber placement machine can continue operating, but extensive material removal is required during rework
Solution Approach 1:
The patent implements real-time feedback by mounting the infrared camera on the fiber placement head to continuously monitor the layup process. When a missing tow is detected, the system immediately alerts the operator, allowing for immediate correction before subsequent plies are applied, thereby minimizing material waste while maintaining continuous production flow.
Solution Approach 2:
The patent performs preliminary detection during the layup process itself rather than after completion. By detecting missing tows in real-time and alerting operators immediately, the system enables correction before extensive material is applied over the defect, significantly reducing the amount of material that would need to be removed during rework.
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 immediate and accurate detection of missing tows, minimizing material removal and rework by providing a real-time visual indication of tow placement errors, thus reducing the time and cost associated with correcting these errors.
Implementation Method 1
an infrared camera mounted on a fiber placement head and configured to generate a real-time thermal image of the composite layup
Implementation Method 2
a heating device for preheating the substrate prior to application of the tow band
Implementation Method 3
a heating device for preheating the substrate prior to application of the tow band
Data Source
AI summary
A system for detecting a missing tow in a tow band may include a fiber placement head for applying a tow band to a substrate forming a composite layup. The system may further include a heating device for preheating the substrate prior to application of the tow band. The system may additionally include an infrared camera mounted to the fiber placement head and configured to generate a real-time thermal image of the composite layup during the application of the tow band to the substrate.