Printed Coil Composite Instrumentation for Wire-Free SHM
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Solution Overview
Problem
The integration of diagnostic systems for structural health monitoring in aeronautical structures poses challenges due to the added weight and complexity of wiring, as well as difficulties in embedding piezoelectric transducers within composite materials, leading to increased maintenance time and cost.
Innovation Solution
A composite part with a rigid outer surface integrates an electronic instrumentation circuit, including piezoelectric transducers and an electronic control circuit, where coils and conductive tracks are printed on insulating layers directly on the surface, enabling electromagnetic coupling and reducing the need for physical connections, thus minimizing weight and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wiring methods are used to connect piezoelectric transducers in composite structures, then the transducers can be integrated into the structure, but the weight of the structure increases due to cables, cable ties, and connectors
Solution Approach 1:
The patent replaces mechanical wiring connections with electromagnetic induction coupling. Two coils are positioned on opposite sides of the composite structure, with one coil connected to the piezoelectric transducer and the other to the control circuit. This eliminates the need for physical cables penetrating the structure, thereby reducing weight while maintaining monitoring functionality through wireless electromagnetic energy transfer.
Solution Approach 2:
The patent introduces electromagnetic fields as an intermediary between the control circuit and the piezoelectric transducer. The coils generate electromagnetic fields that couple through the composite structure, serving as a mediator to transfer energy and signals without direct physical connection, thus avoiding the weight penalty of traditional wiring.
2Ease of manufacture
If electrical cables are passed through carbon plies to integrate transducers, then the transducers can be connected to the control circuit, but sources of failure are created in the composite structure
Solution Approach 1:
The patent replaces mechanical cable penetration through the composite plies with non-contact electromagnetic coupling. The coils are positioned on the outer surfaces of the composite structure, eliminating the need to drill holes or pass cables through the carbon plies, thus preserving the structural integrity and eliminating wiring-induced failure sources.
3Reliability
If cables and sheaths are used to connect transducers, then the transducers can be integrated into the composite material, but extra thickness is added to the material
Solution Approach 1:
The patent replaces thick mechanical cable assemblies with thin planar coils that can be integrated into the composite structure's surface. The coils are positioned on opposite faces of the composite material, enabling electromagnetic coupling without requiring thick cable sheaths to penetrate the material, thus minimizing additional thickness.
4Reliability
If diagnostic systems are wired into composite structures, then structural health monitoring is enabled, but maintenance time and cost increase due to unwiring and re-wiring requirements
Solution Approach 1:
The patent replaces wired connections with wireless electromagnetic coupling through coils positioned on the composite structure. This eliminates the need to physically disconnect and reconnect cables during maintenance operations, allowing for rapid deployment and retrieval of monitoring systems without time-consuming unwiring and re-wiring procedures.
Solution Approach 2:
The patent creates a dynamic, reconfigurable monitoring system where the coils and piezoelectric transducers can be easily added or removed from the composite structure without permanent modifications. The electromagnetic coupling allows the system to be dynamically deployed and retired, facilitating flexible maintenance operations.
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
This approach enhances compactness, miniaturization, and cost-effectiveness while reducing the disturbance to fluid flow, allowing for efficient monitoring of structural health without the need for extensive wiring, thereby optimizing maintenance processes.
Implementation Method 1
By exciting the transducer with a predefined electrical signal, the transducer transforms this electrical signal into a mechanical guided wave. This wave propagates in the structure. Upon arriving at a defect, this wave is reflected and is detected by one or more other transducers placed on or in the structure.
Implementation Method 2
Among the sensor/transducer technologies most used for detecting defects on metal structures and structures made of composite material is the use of piezoelectric transducers, for example of the PZT (Lead Titanium-Zirconate) type. By exciting the transducer with a predefined electrical signal, the transducer transforms this electrical signal into a mechanical guided wave.
Data Source
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AI summary
The invention relates to a composite (sandwich or monolithic) part (1), comprising a rigid outer surface (10), incorporating an electronic instrumentation circuit (2), the electronic instrumentation circuit (2) comprising a piezoelectric transducer (21) connected to a coil (22), an electronic control circuit (23) connected to a coil (24) located opposite the coil (22). The invention is characterised in that the coil (22) is printed on an insulating layer (25), printed directly on the rigid outer surface (10), the coil (24) is printed on an insulating layer (26) covering the coil (22) and the transducer (21), conductive tracks (27, 28) are printed on an insulating layer printed on at least one portion of the coil (24) to be connected thereto, the electronic control circuit (23) being attached to the rigid outer surface (10) and being connected to the tracks (27, 28).