Insulating Fastener Lightning Strike Ignition Prevention
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Solution Overview
Problem
Existing fastener systems in aircraft and other structures storing ignitable substances are prone to electric arcs and thermal sparking due to lightning strikes, leading to ignition risks and increased manufacturing and maintenance costs due to complex designs.
Innovation Solution
A fastener system made of electrically insulating materials, such as glass, ceramics, or composite polymers, which prevents the fastener from being part of the electrical current path during a lightning strike, using a fastener body and head with a sealing material to ensure tight sealing and protection without increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal fastening elements are used to fasten surface elements to structural elements, then the fastening provides strong mechanical connection, but the metal fastener becomes part of the lightning current path causing electric arcs and ignition risks
Solution Approach 1:
The patent changes the electrical conductivity parameter of the fastening element by using electrically insulating materials (glass, ceramics, or composite polymers) instead of conductive metals. This parameter change breaks the electrical continuity for lightning current while maintaining the mechanical fastening function, thereby preventing electric arcs and ignition risks.
Solution Approach 2:
The patent employs composite material structures, particularly fiber-reinforced plastics with embedded glass fiber mats or continuous glass fibers, to create fastening elements that provide both mechanical strength and electrical insulation. These composite materials replace traditional metal fasteners, achieving both structural integrity and lightning protection.
2Reliability
If additional safety measures like electrically conductive fastening elements with isolation areas or low conductive paths are implemented, then ignition prevention is improved, but the design complexity and manufacturing costs increase
Solution Approach 1:
The patent extracts the electrical conductivity function from the fastening element, removing it entirely from the design. Instead of adding complex isolation areas or low-conductive paths to metal fasteners, the solution uses inherently insulating materials, simplifying the design to a single integrated fastening component without additional safety features.
Solution Approach 2:
Rather than using conductive materials with added insulation features (the conventional approach), the patent inverts the approach by using inherently insulating materials for the fastening element itself. This reversal eliminates the need for complex designs while achieving the same ignition prevention goal.
3Reliability
If complex lightning protection fastener designs with additional safety measures are used, then ignition prevention is improved, but the weight of the fixing structure increases
Solution Approach 1:
The patent changes the material composition parameter of the fastening element to electrically insulating materials with appropriate mechanical properties. This parameter change allows the fastener to provide both mechanical fastening and lightning protection in a single component, reducing weight compared to complex metal-based solutions with additional safety features.
Solution Approach 2:
The patent uses composite materials (glass fiber-reinforced plastics, ceramic-matrix composites) that provide high strength-to-weight ratios while maintaining electrical insulation. These composite fastening elements are lighter than equivalent metal fasteners with additional protection features, achieving weight reduction while maintaining reliability.
4Ease of manufacture
If metal fastening elements are used, then manufacturing and assembly are simple, but the fastener conducts lightning current causing thermal sparking and damage to inboard electronics
Solution Approach 1:
The patent changes the electrical conductivity parameter of the fastening element from conductive (metal) to insulating (glass, ceramics, composite polymers). This parameter change prevents thermal sparking and protection of inboard electronics while maintaining ease of manufacture through standardized fastening procedures and materials.
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 prevents electric arcing and thermal sparking, ensuring long-term insulation against lightning currents while maintaining a simple design and reducing weight and manufacturing costs, thus providing reliable protection against lightning strikes.
Implementation Method 1
the fastener comprises of an electrically insulating material... Since the fastener comprises of an electrically insulating material, the fastener is not part of the electrical current path in case a lightning strike hits the first part
Implementation Method 2
with a sealing material to ensure tight sealing and protection
Data Source
AI summary
A fastener system for ignition prevention triggered by a lightning strike. The fastener has a fastener body and a fastener head, and a fastening member configured to be mounted on a portion of the fastener body, wherein the fastener and the fastening member are configured to fasten at least a first part and a second part between the fastener head and the fastening member, and the fastener comprises an electrically insulating material. A structure comprises the fastener system, the first part that faces an outside from where the lightning strike may hit the first part and the second part.