Variable-Porosity Metallic Patches for Anisotropic Composite Repair
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Solution Overview
Problem
The difficulty in performing repairs to composite structures in commercial airframes due to anisotropy of material properties and the challenge of deploying complex equipment at remote locations, which are common in composite structures, is addressed by the patch for defect repair.
Innovation Solution
A patch with a metallic body having variable porosity and specific material properties, including zones with different porosities and material properties to match the anisotropic properties of the composite structure, is applied using additive layer manufacturing to ensure compatibility and effective load transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a patch with uniform material properties is used, then the manufacturing process is simple, but the patch cannot accommodate the anisotropic properties of composite structures
Solution Approach 1:
The patent applies local quality by creating zones within the patch body that have different material properties (density, elastic modulus, strength) tailored to match the specific anisotropic characteristics of different regions of the composite structure. This allows the patch to adapt to the varying properties of the host structure without requiring a completely complex design throughout.
Solution Approach 2:
The patent utilizes composite materials by combining multiple materials with different properties within the patch body. This enables the patch to simultaneously provide structural support while accommodating the anisotropic properties of the composite airframe, resolving the contradiction between simplicity and adaptability.
2Reliability
If complex equipment such as autoclave processing is used, then repair quality is improved, but the equipment cannot be deployed at remote locations
Solution Approach 1:
The patent employs a disposable patch system that can be applied without requiring expensive, complex equipment like autoclaves. The patch is designed to be self-contained and installable at remote locations, sacrificing the reusability of expensive equipment for the benefit of deployability while maintaining adequate repair quality.
Solution Approach 2:
The patent changes the parameters of the repair process by using materials and methods that do not require extreme processing conditions (such as autoclave temperatures and pressures). This allows the repair to be performed with simpler equipment at remote locations while still achieving reliable results.
3Measurement precision
If material removal is performed to improve defect knowledge, then measurement precision is improved, but the repair process becomes more complex
Solution Approach 1:
The patent applies preliminary action by incorporating compliance features and variable density zones into the patch design before application. This pre-planned complexity in the patch structure eliminates the need for complex material removal and inspection processes, as the patch is designed to adapt to the defect without requiring extensive preparation.
Data Source
AI summary
A patch (100) for repair of a structure (180) with a defect (182) having a topography, the patch (100) including:a patch body (102) that is at least partially metallic;a bonding surface (104) that is compatible with the topography of the defect (182); anda patch surface (106) opposite the bonding surface (104),wherein the patch (100) has a variable porosity and a set of material properties; andwherein at least one material property of the set of material properties varies as a result of the variable porosity.