Entropy-Based Impact Identification for Composite Structures
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Solution Overview
Problem
Current methods for detecting damage in composite aircraft structures, such as laminated composite materials, are labor-intensive, costly, and unable to identify subsurface damages like ply delamination or core crushing in real-time, especially in heterogeneous structures like helicopters, due to their complex materials and varying stiffness.
Innovation Solution
A method using sparse sensor arrays and entropy-based impact identification techniques to estimate load magnitudes and locations, allowing for focused inspections and reducing costs by simulating field environments to compensate for error sources, with a high accuracy of locating impacts to within a few grid points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current inspection methods (x-ray, coin tap tests) are used to detect damage in composite structures, then damage detection capability is provided, but the inspection process becomes labor-intensive and time-consuming
Solution Approach 1:
The patent replaces mechanical inspection methods (x-ray, coin tap tests) with an acoustic-based system that uses microphones to capture impact sounds and entropy analysis to automatically identify damage locations and severity, eliminating the need for manual inspection processes
Solution Approach 2:
The patent creates a digital model of the structure's acoustic response characteristics and uses this model to interpret actual impact sounds, enabling automated damage identification without physical inspection of each potential damage location
2Reliability
If current inspection methods are used to detect subsurface damages, then damage identification is possible, but the cost becomes prohibitively high
Solution Approach 1:
The patent uses inexpensive microphones and standard computing resources to perform damage detection, replacing expensive specialized inspection equipment like x-ray machines with readily available, low-cost components
Solution Approach 2:
The patent substitutes expensive mechanical inspection equipment with an acoustic-based system using microphones and entropy analysis, achieving subsurface damage detection through sound wave analysis rather than costly imaging or physical testing
3Measurement precision
If frequency domain location identification methods are applied to heterogeneous structures like helicopters, then impact location can be identified, but the method becomes difficult to apply due to varying stiffness and frequency bandwidths
Solution Approach 1:
The patent transforms the problem from frequency domain to time domain analysis, using entropy calculation on temporal signal characteristics rather than frequency spectrum analysis, which makes the method insensitive to variations in structural stiffness and frequency bandwidth
Solution Approach 2:
The patent creates a unified entropy-based analysis framework that treats all impact locations uniformly, eliminating the need for location-specific frequency range selections and making the method consistently applicable across heterogeneous structures with varying material properties
Data Source
AI summary
Methods and apparatus for identifying the location of the load on a structure. Various embodiments include calculating a plurality of potential loading sites, assessing the statistical order of each of those predictions, and selecting regions of the structure where the load most likely occurred based on the orderliness (or randomness) of the assessments.