Acoustic Emission Sensor for Composite Delamination Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for evaluating the soundness of fiber-reinforced composite materials using the Kaiser effect are inefficient, as they require constant load increase and cannot detect delamination immediately preceding breakage, especially when load retention or unloading patterns are applied, leading to potential damage and prolonged testing times.
Innovation Solution
A device and method that utilize an AE sensor, load test device, and frequency center of gravity calculation to detect delamination by applying a loading pattern with load raising, retention, and unloading, determining delamination based on a frequency center of gravity less than a predetermined frequency, allowing for early detection and reduced testing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the maximum value of the initial load applied to the test body is set too high, then the Kaiser effect cannot be observed due to material failure, but if set too low, then the tensile strength cannot be accurately evaluated
Solution Approach 1:
The patent applies preliminary loading cycles with progressively increasing maximum loads before the final evaluation cycle. This preliminary action allows the material to be pre-conditioned and the Kaiser effect to be established at each stage, ensuring that when the final evaluation is performed, the Kaiser effect is detectable and accurate tensile strength can be determined without premature material failure
Solution Approach 2:
The patent dynamically adjusts the maximum load value across multiple loading cycles, starting with lower loads and progressively increasing to higher loads. This dynamic approach allows the system to adapt to the material's response at each stress level, maintaining optimal conditions for Kaiser effect detection while progressively approaching the true tensile strength
2Productivity
If the tensile load is constantly increased over time to evaluate strength, then the inspection time is reduced, but the method cannot be applied to pre-established loading patterns that include load retention or unloading
Solution Approach 1:
The patent creates a universal evaluation method that works with multiple loading patterns including constant load increase, load retention, and load unloading cycles. By analyzing the Kaiser effect and frequency center of gravity across different loading patterns, the method achieves multi-functionality that adapts to various testing requirements while maintaining efficient inspection speed
Solution Approach 2:
The patent changes the loading pattern parameters (load magnitude, retention time, unloading rate) to optimize both inspection speed and pattern compatibility. By adjusting these parameters based on the material response and Kaiser effect characteristics, the method achieves versatility across different loading scenarios while maintaining productivity
3Reliability
If the loading pattern includes load retention or unloading, then the Kaiser effect analysis becomes complex and delamination detection is delayed, but continuous load increase may cause actual breakage before delamination is detected
Solution Approach 1:
The patent implements continuous feedback monitoring of AE wave frequency center of gravity during loading cycles. When the frequency center of gravity indicates delamination (specific frequency range detection), the system provides immediate feedback to stop or adjust loading, enabling timely delamination detection without proceeding to actual breakage, thus reducing evaluation time while maintaining detection accuracy
Solution Approach 2:
The patent performs preliminary loading cycles to establish baseline Kaiser effect characteristics and frequency ranges for different damage states. This preliminary action enables the system to recognize delamination frequency patterns in advance, allowing for faster and more accurate delamination detection during subsequent evaluation cycles without causing breakage
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 reliable and efficient detection of delamination before material breakage, reducing evaluation time and preventing damage, even with incorrect initial load settings, by calculating the frequency center of gravity of AE waves generated during varying loading patterns.
Implementation Method 1
The 'Kaiser effect' refers to an irreversible phenomenon in which, once an external stress is applied to a solid material to generate acoustic emission (AE waves), the AE waves will not be generated, even if reloaded, until the previous stress value is exceeded.
Implementation Method 2
the magnitude of the AE waves generated in the test body is measured at each time point in the test period. On the basis of the magnitude of the AE waves measured at each time point, a plurality of frequency components of the AE waves in each of a plurality of load application sections included in the test period are obtained, and the frequency center of gravity of the AE waves is obtained for each load application section
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention is equipped with an AE sensor 12, a load test device 14, a storage device 22, a frequency center of gravity calculation unit 24 and a determination device 26. A loading pattern including, raising, retaining and unloading is repeatedly applied to a test subject 1 by the load test device 14, the maximum load is sequentially increased, and the AE waves 2 detected by the AE sensor 12 are stored with the load by the storage device 22. Next, the frequency center of gravity of the AE waves is obtained from the relationship between the frequency of the AE waves 2 and the intensity thereof by the frequency center of gravity calculation unit 24, and delamination preceding breakage is determined by the determination device 26 when the frequency center of gravity 5 is less than a prescribed first frequency.