Conductive Device for Composite Structures
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Solution Overview
Problem
The integration of conductive elements into composite material structures for electrical connections poses challenges due to low conductivity, mechanical stress from thermal variations, and the difficulty in visually detecting impact damage, leading to increased mass, size, and production time, particularly in aircraft structures.
Innovation Solution
A conductive device with a metal braid or foil conductive element, an insulating interface layer, and a protective composite layer that can deform visibly upon impact, allowing for flexible mounting and reduced mechanical stress, enabling efficient electrical connection and impact detection without additional fastening elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard conductive elements (monolithic conductors, cables) are attached to composite material structures, then electrical connections can be established, but mechanical stresses occur due to differential thermal expansion and contraction
Solution Approach 1:
The patent employs a flexible conductive element consisting of a metallic braid or foil rather than rigid monolithic conductors. This flexible structure can accommodate differential thermal expansion and contraction between the composite material and the conductive element, preventing mechanical stress and potential detachment while maintaining reliable electrical connections throughout temperature variations.
Solution Approach 2:
The patent changes the physical parameters of the conductive element by using a metallic braid or foil with specific geometric characteristics (mesh size, flexibility) rather than solid conductors. This parameter change enables the conductive element to deform elastically with thermal cycles, resolving the contradiction between maintaining electrical connectivity and avoiding mechanical stress.
2Strength
If composite material structures are designed with increased size to improve impact resistance, then structural integrity is enhanced, but visual detection of low-energy impact damage becomes impossible
Solution Approach 1:
The patent incorporates a visual indicator system that changes color or appearance when the composite structure undergoes low-energy impact damage. This indicator layer or integrated sensor provides immediate visual feedback about structural integrity, allowing operators to detect damage without needing to visually inspect the entire oversized structure, thus resolving the detection difficulty despite increased structural dimensions for impact resistance.
3Weight of moving object
If non-metallic composite materials are used to reduce mass and manufacturing cost, then weight and cost decrease, but electrical conductivity becomes insufficient for current return functions
Solution Approach 1:
The patent merges the electrical conduction function with the composite material structure by integrating flexible metallic braided conductive elements within or on the composite structure. This combination maintains the lightweight advantage of composite materials while providing the necessary electrical conductivity for current return functions, eliminating the need for heavy metal structural components.
Solution Approach 2:
The patent creates a hybrid composite system combining non-conductive composite materials with conductive metallic braid or foil elements. This composite approach allows the structure to benefit from the low density and cost advantages of composite materials while incorporating sufficient electrical conductivity through the integrated metallic conductive elements, resolving the contradiction between weight reduction and electrical functionality.
4Reliability
If conductive elements are securely mounted on composite structures, then electrical connections are maintained, but the mounting process increases equipment mass, size, and manufacturing time
Solution Approach 1:
The patent applies adhesive or bonding agents in advance to the conductive element or substrate surface before assembly. This preliminary action ensures that when the conductive element is mounted on the composite structure, it adheres immediately and securely without requiring complex fastening procedures or additional processing steps, thereby maintaining connection reliability while reducing manufacturing time and complexity.
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 solution allows for efficient electrical conductivity, reduced mechanical stress, and visible impact detection, optimizing mass savings and integration ease while maintaining structural integrity and impact resistance.
Implementation Method 1
These stresses are primarily due to differential expansions that occur in the materials constituting the various assembled elements when the structure is subjected to significant temperature variations
Implementation Method 2
the protective layer is made of composite material so as to present, in the event of a low energy impact, a deformation visible to an observer in the area of the impact
Data Source
Figure 1~2
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Figure 5~6
AI summary
The subject of the invention is a conductive device (11) for forming electrical connections on the surface of a structure (15) made of composite material. The device includes a thin interface layer (13) having a face via which the device is fixed to the surface of the structure (15) made of composite material; a conductive metal element (12) placed on the face of the interface layer (13) opposite the face making contact with the surface of the structure (15), said element being configured so as to be able to undergo without damage tensile and compressive stresses; and a protective layer configured to protect the conductive element (12) from attack from the environment surrounding the structure (15). These various elements are arranged relative to one another in such a way that the length of the conductive element (12) is able to vary as a function of temperature variations independently of the amplitude of the variations undergone by the structure on which the device is mounted.