Hybrid Frangible Resilient Sensor for Structural Health Monitoring
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Solution Overview
Problem
Conventional methods for monitoring structural integrity, such as visual inspection, X-ray testing, dye penetrant testing, and eddy current testing, are time-consuming, costly, and require disassembly, making them inefficient for detecting fractures and corrosion in structural elements, especially in aircraft and other structures.
Innovation Solution
A hybrid sensor device with a frangible material layer and a resilient material layer, including a breakable conductor sense loop and a conductive corrosion sense loop, bonded to the structural element, which detects disruptions and changes in electrical properties to indicate fractures and corrosion without the need for disassembly, using a shared wireless communications tag or electrical connector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inspection methods (visual inspection, X-ray, dye penetrant, eddy current) are used to detect structural fractures and corrosion, then detection capability is provided, but the inspection process becomes time-consuming and requires extensive disassembly
Solution Approach 1:
The sensor is divided into two distinct functional layers: a frangible layer with a breakable conductor sense loop for fracture detection, and a resilient layer with a conductive corrosion sense loop for corrosion detection. This segmentation allows each layer to specialize in detecting specific damage types independently, enabling simultaneous multi-mode detection without requiring multiple separate inspection processes.
Solution Approach 2:
The sensor device is pre-installed and bonded to the structural element during manufacturing or initial setup. The frangible layer is pre-positioned to fracture when the underlying structure fractures, and the corrosion sense loop is pre-exposed through weep holes to monitor for corrosion. This preliminary action eliminates the need for time-consuming disassembly and inspection procedures later, as the sensor continuously monitors structural health in-situ.
2Reliability
If conventional inspection methods are used, then structural integrity can be assessed, but disassembly and removal of equipment are required to access areas of interest
Solution Approach 1:
The frangible layer and resilient layer are combined into a single integrated sensor device that is bonded directly to the structural element. This merging allows both fracture detection (through the frangible layer) and corrosion detection (through the resilient layer with exposed sense loop) to occur simultaneously at the same location, eliminating the need for separate inspection procedures and providing comprehensive structural health monitoring in one accessible package.
Solution Approach 2:
The resilient non-conductive material layer acts as an intermediary that protects the corrosion sense loop while allowing selective exposure through weep holes. This intermediary layer enables the corrosion sense loop to monitor structural health without requiring full disassembly, as it can access corrosion indicators through the controlled openings while remaining protected otherwise.
3Measurement precision
If specialized inspection techniques (X-ray, dye penetrant, eddy current) are employed, then detection precision is improved, but the complexity of facilities and procedures increases
Solution Approach 1:
The patent replaces complex mechanical and chemical inspection systems (X-ray machines, dye penetrant application equipment, eddy current coils) with a simple electrical sensing system. The breakable conductor sense loop provides binary fracture detection through continuity monitoring, and the conductive corrosion sense loop provides corrosion detection through electrical property changes. This substitution dramatically simplifies the inspection system while maintaining detection precision for the specific damage modes targeted.
Solution Approach 2:
The frangible layer with its breakable conductor sense loop is designed as a disposable element that fractures when the underlying structure fractures. Once the frangible layer breaks, it serves its purpose and can be replaced. This approach eliminates the need for expensive, complex, and reusable inspection equipment, using instead a simple, inexpensive sensor that provides definitive fracture detection through its own structural failure.
4Reliability
If multiple separate sensors are used to detect fractures and corrosion, then comprehensive monitoring is achieved, but device complexity and cost increase
Solution Approach 1:
The frangible layer and resilient layer are merged into a single bonded sensor device where both layers work simultaneously to detect different damage modes. The frangible layer's breakable conductor sense loop detects fractures, while the resilient layer's conductive corrosion sense loop detects corrosion. This merging achieves comprehensive monitoring of both fracture and corrosion without requiring multiple separate sensor systems, reducing overall complexity and integration effort.
Solution Approach 2:
The integrated sensor device performs multiple functions: fracture detection through the frangible layer, corrosion detection through the resilient layer, and both layers can be monitored through a shared wireless communications tag or electrical connector. This multi-functionality allows a single device to replace what would otherwise require multiple separate sensors and monitoring systems, simplifying the overall sensor system while maintaining comprehensive structural health monitoring capabilities.
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 quick and reliable monitoring of structural integrity for both fractures and corrosion without the need for special facilities, training, or extensive disassembly, reducing maintenance costs and downtime, and providing early detection of potential issues.
Implementation Method 1
A fracture in the bonded structural element induces a disruption in both the frangible membrane and the thin breakable conductor sense loop
Implementation Method 2
corrosion of the conductive corrosion sense loop changes its electrical properties
Implementation Method 3
A fracture in the bonded structural element induces a disruption in both the frangible membrane and the thin breakable conductor sense loop
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~2C
AI summary
A sensor for monitoring and testing for both possible fractures and corrosion in structural elements is disclosed. A frangible material layer including a thin breakable conductor sense loop and a resilient material layer including a conductive corrosion sense loop bonded on top of the frangible layer form an assembly which is bonded to a structural element to be tested. Portions of the conductive corrosion sense loop are exposed through weep holes in the resilient material layer. A fracture in the bonded structural element induces a disruption in both the frangible membrane and the thin breakable conductor sense loop and corrosion of the conductive corrosion sense loop changes its electrical properties. Measured electrical property changes of the disrupted conductor sense loop and/or the conductive corrosion sense loop reveal possible damage. Both sensor layers may utilize a single shared wireless communications tag to couple to an electrical measuring device.