Grounding Sleeve for Aircraft Composite Lightning Protection
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Solution Overview
Problem
Existing methods for grounding composite components in aircraft gas turbine engines to protect against lightning strikes are either hardware-intensive or compromise the durability and corrosion resistance of the components, as they require additional hardware or stripping of insulating coatings.
Innovation Solution
A grounding sleeve is inserted along with a bolt into a hole through the composite and metal components, with an elongated element deflecting to contact the carbon fibers and maintaining contact with the bolt, providing a grounding path without modifying the components' integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal rivet is attached to the composite component with a wire to provide grounding, then electrical grounding is achieved, but additional hardware and drilling of additional holes are required
Solution Approach 1:
The grounding function is merged with the existing fastener system. The fastener serves dual purposes: mechanically fastening the composite component to the metal component and providing electrical grounding through its conductive structure that contacts both the composite component and the metal component.
Solution Approach 2:
The fastener is designed to perform multiple functions simultaneously: structural fastening and electrical grounding. This eliminates the need for separate grounding hardware, as the same fastener that secures the components together also provides the electrical path to ground.
2Reliability
If the outer layer of the composite component is stripped to expose carbon fibers for grounding, then electrical contact is achieved, but the durability of the composite component is affected
Solution Approach 1:
The fastener acts as an intermediary element that provides electrical contact without requiring direct exposure of the carbon fibers. Instead of stripping the composite, the fastener makes contact with the composite component through its structure, serving as a mediator that achieves grounding while preserving the composite's protective outer layer.
3Reliability
If additional holes are drilled in the composite component to house rivets, then grounding is achieved, but the structural integrity of the composite component is compromised
Solution Approach 1:
The existing fastener holes serve dual purposes: mechanical fastening and electrical grounding. By designing the fastener to provide both functions, no additional holes need to be drilled, thereby preserving the structural integrity of the composite component while achieving reliable grounding.
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 effectively grounds composite components to metal components without additional hardware or compromising durability, ensuring electrical safety during lightning strikes while maintaining the structural integrity of both composite and metal components.
Implementation Method 1
the elongated element bows away from the bolt and into contact with the composite component inside the hole when the bolt is tightened
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A grounding sleeve for grounding an electrically insulated element disposed between two metal components includes an annular body extending between a first end and a second end. At least one window is formed in the annular body between the first end and the second end.