Infrared Resin Thickness Measurement for CFRP Composites
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods, such as ultrasonic non-destructive testing, fail to accurately measure resin pockets deeper than 0.015 inches in composite structures due to poor accuracy and difficulty in detecting thick resin regions, especially in carbon fiber reinforced plastic (CFRP) composites with black carbon fibers, which can impact the quality and performance of the structure.
Innovation Solution
A system utilizing near-infrared (IR) spectroscopy with a holding fixture and IR measurement sensors that match the contour of the resin, emitting near-IR energy and correlating absorbance levels to known calibrations for precise resin thickness measurement, enabling non-destructive detection of resin pockets greater than 0.015 inches deep.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic non-destructive testing is used to measure resin thickness, then the measurement can be performed non-contact, but the accuracy deteriorates for resin pockets deeper than 0.070 to 0.080 inches
Solution Approach 1:
The patent replaces ultrasonic mechanical wave-based NDT methods with optical infrared spectroscopy. The infrared measurement sensor emits infrared energy that penetrates the resin and carbon fiber composite, and the transmitted energy is detected to calculate resin thickness. This optical substitution overcomes the limitation of ultrasonic methods which cannot reliably detect resin pockets deeper than 0.070-0.080 inches.
Solution Approach 2:
The patent changes the measurement parameter from ultrasonic wave propagation to infrared energy transmission. By using infrared energy in the 2.5-25 micrometer wavelength range, the system achieves better penetration through carbon fiber reinforced plastics and obtains more accurate measurements for resin pockets greater than 0.0150 inches deep.
2Ease of operation
If visual inspection is used to detect resin pockets in carbon fiber reinforced plastic, then the inspection can be performed directly, but the detection capability deteriorates due to poor reflectivity of black carbon fibers
Solution Approach 1:
The patent replaces visual inspection with infrared spectroscopy measurement. The infrared measurement sensor emits infrared energy that penetrates through the carbon fiber reinforcement and interacts with the resin, allowing detection of resin pockets regardless of the poor visual reflectivity of black carbon fibers.
Solution Approach 2:
The patent uses infrared energy as an intermediary to detect resin pockets. The infrared energy penetrates the carbon fiber layer and is absorbed differently by the resin, creating a detectable signal that bypasses the visual detection limitation caused by black carbon fiber reflectivity.
3Measurement precision
If close contact with the part is required for measurement, then the measurement can be performed with existing methods, but the ease of operation deteriorates and productivity decreases
Solution Approach 1:
The patent replaces contact-based ultrasonic measurement with non-contact infrared spectroscopy. The infrared measurement sensor can measure resin thickness through air gap without requiring close contact with the part surface, significantly improving ease of operation and productivity while maintaining measurement capability for resin pockets greater than 0.0150 inches deep.
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
The system provides accurate, non-contact measurements of resin thickness, enabling the identification of wrinkles and improving the quality assessment of composite structures by detecting resin pockets with higher precision than existing methods, suitable for both flat and contoured surfaces.
Implementation Method 1
Each of the plurality of infrared measurement sensors emits a beam of near-infrared energy therethrough and detects a level of absorbance of the near-infrared energy
Implementation Method 2
correlating a level of absorbance from each of the plurality of infrared measurement sensors to a known calibration for resin thickness
Data Source
AI summary
A system for surface resin thickness measurement on a fiber reinforced polmer composite includes a holding fixture configured to match a contour of a composite part in which a resin thickness is to be measured, a plurality of infrared measurement sensors in the holding fixture which can be moved along the surface to create a map of the surface to be measured, a computer-based data acquisition system interfacing with the plurality of infrared measurement sensors and calibration software supporting the data acquisition system.