Stepped Metal Element Electrostatic Discharge Suppression
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Solution Overview
Problem
Aircraft cockpit glazings experience issues with moisture penetration through interlayer adhesive layers, leading to delamination and electrical system damage, and electrostatic charging of metal elements like the 'zed' can cause disruptive discharges, startling pilots and interfering with aircraft equipment.
Innovation Solution
A laminated glazing design featuring a stepped metal element covered by an air- and watertight seal, with an electrical conductor connected to the metal element and positioned to initiate a controlled, low-energy electrostatic discharge, ensuring the conductor is securely oriented and electrically linked to the mounting structure to manage potential differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stepped metal element is applied peripherally to prevent moisture penetration, then the durability and moisture resistance of the laminated glazing is improved, but the metal element becomes electrically isolated and accumulates electrostatic charge, leading to high discharge potentials that can startle pilots and interfere with aircraft equipment
Solution Approach 1:
An electrical conductor is introduced as an intermediary element between the stepped metal element and the aircraft structure. This conductor provides a controlled discharge path that prevents dangerous electrostatic accumulation while maintaining the moisture barrier function of the metal element. The conductor acts as a mediator that safely transfers electrostatic charge from the isolated metal element to the aircraft structure.
Solution Approach 2:
The electrical discharge function is extracted from the stepped metal element itself and transferred to a separate dedicated electrical conductor. This allows the metal element to focus solely on its moisture barrier function while the separate conductor handles the electrostatic discharge, preventing interference with the metal element's primary sealing function.
2Reliability
If the stepped metal element is electrically isolated to maintain its moisture barrier function, then the sealing effectiveness is improved, but the metal element cannot dissipate electrostatic charge, resulting in potential differences that cause disruptive discharges
Solution Approach 1:
The electrical conductor serves as an intermediary that bridges the electrical isolation created by the sealing requirement. It allows the metal element to remain electrically isolated for sealing purposes while providing a separate pathway for charge dissipation, thus resolving the contradiction between electrical isolation and charge management.
Solution Approach 2:
The system is segmented into distinct functional components: the stepped metal element handles moisture barrier functions, the electrical conductor handles charge dissipation, and the sealant maintains electrical isolation. This segmentation allows each component to optimize its specific function without compromising the others.
3Reliability
If a conformal metal element is applied to prevent water penetration, then the protection against delamination and moisture damage is improved, but the metal element becomes part of the sealed structure, creating electrostatic potential differences with the aircraft structure
Solution Approach 1:
The electrical conductor acts as a mediator that decouples the electrical relationship between the metal element and aircraft structure. It allows the metal element to remain integrated with the sealed structure for moisture protection while providing a separate electrical pathway to prevent dangerous potential differences.
Solution Approach 2:
The electrical charge management function is extracted from the sealed metal element structure and assigned to a separate electrical conductor system. This separation allows the sealed structure to maintain its protective function while the extracted conductor system handles electrostatic potential management.
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
This design effectively prevents high discharge potentials by promoting localized, inaudible electrostatic discharges, maintaining the structural integrity and reducing electromagnetic interference while ensuring the glazing's durability and aerodynamic properties.
Implementation Method 1
an electrical conductor has a first end that is electrically linked to the stepped metal element and a second tapered end at a non-zero distance at most equal to 1 mm from the window press
Implementation Method 2
A common counter to the penetration of moisture into the lamination interlayer adhesive layers consists in peripherally applying a conformal metal element to a peripheral zone of the laminated glazing
Implementation Method 3
a window press that is rigidly connected to the structure for mounting the laminated glazing and the shape of which is substantially complementary to that of the continuous stepped contour making contact with the laminated glazing in the volume described by the continuous stepped contour
Data Source
AI summary
A laminated glazing includes a first and a second glass sheet that are bonded by a first interlayer adhesive layer, a peripheral zone of the laminated glazing being covered by a stepped metal element, a window press that is rigidly connected to the structure for mounting the laminated glazing making contact with the laminated glazing, so as to hold the laminated glazing secure to its mounting structure, an electrical conductor having a first end that is electrically linked to the stepped metal element and a second tapered end at a non-zero distance at most equal to 1 mm from the window press.