Conductive Coated Fastener for CFRP Electrical Grounding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft constructed with carbon fiber reinforced plastic (CFRP) structural elements face poor electrical conductivity between metallic fasteners and CFRP, leading to electrostatic charge buildup, corrosion, and increased manufacturing costs due to the use of sleeved fasteners which are expensive and time-consuming to install.
Innovation Solution
A fastener with an electrically conductive coating of varying thickness is used, heated to a softened state for insertion, which acts as a lubricant and fills gaps between the fastener and CFRP, establishing a continuous electrical connection and reducing installation forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sleeved fasteners are used to achieve electrical conductivity and closer proximity, then electrical connectivity is improved, but manufacturing cost and installation time increase significantly
Solution Approach 1:
The patent extracts the electrical conductivity function from a separate sleeve component and integrates it directly into the fastener body through a conductive coating applied to the shank. This eliminates the need for a separate sleeve while maintaining the electrical connectivity function, thereby reducing assembly complexity and installation time.
Solution Approach 2:
The patent merges the structural fastening function and the electrical conductivity function into a single integrated fastener component. The conductive coating on the fastener shank combines both mechanical fastening and electrical grounding capabilities, eliminating the need for separate sleeved fasteners and reducing manufacturing costs.
2Reliability
If sleeved fasteners are used to achieve closer proximity of carbon fiber to fastener, then electrical conductivity is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the separate sleeve component from the fastener assembly and instead applies a conductive coating directly to the fastener shank. This extraction of the conductivity function from a separate component simplifies the overall device structure while maintaining electrical connectivity.
Solution Approach 2:
The patent uses a composite structure where a conductive material coating is applied to the fastener shank. This composite approach combines the mechanical properties of the fastener material with the electrical conductivity of the coating material, achieving both structural integrity and electrical connectivity in a single component.
3Ease of manufacture
If rough surfaces of bolt and CFRP are used, then manufacturing is simpler, but gaps are created leading to poor electrical connectivity and electrostatic charge buildup
Solution Approach 1:
The conductive coating on the fastener shank acts as an intermediary substance that bridges the gap between the rough fastener surface and the rough CFRP surface. This intermediary layer ensures continuous electrical contact by conforming to the surface irregularities, eliminating the need for precise surface finishing while maintaining electrical connectivity.
Solution Approach 2:
The patent changes the physical state of the coating material during installation by heating it to a softened state, allowing it to flow and conform to the rough surfaces of both the fastener and CFRP. This parameter change enables the coating to adapt to surface irregularities, ensuring good electrical contact without requiring precise surface preparation.
4Force
If heating and softening of coating is used during insertion, then installation forces are reduced and coating fills gaps, but additional process steps are required
Solution Approach 1:
The patent utilizes the phase transition of the coating material from solid to softened state through heating during installation. This phase transition allows the coating to become more pliable and flow into gaps between the fastener and CFRP, reducing installation forces and ensuring good electrical contact. The coating then solidifies after installation to provide structural support and maintain electrical connectivity.
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 provides a cost-effective and efficient method to ensure electrical conductivity between fasteners and CFRP structural elements, reducing damage and manufacturing time while maintaining structural integrity and preventing electrostatic charge buildup.
Implementation Method 1
heating the fastener and the coating to a melting temperature of the coating to place the coating into a softened state
Implementation Method 2
heating the fastener and the coating to a melting temperature of the coating
Implementation Method 3
inserting the fastener into an opening formed in the assembly such that a sidewall of the opening causes the coating to deform during insertion
Implementation Method 4
the coating is electrically conductive and comprises a varying thickness along the shank... establishes a continuous electrical connection
Data Source
AI summary
A fastening device for coupling an assembly includes a fastener comprising a head, a threaded portion, and a shank extending between the head and the threaded portion. The fastening device also includes a coating formed around the fastener, wherein the coating is electrically conductive and comprises a varying thickness along the shank.