Stepped Blocking Element for Aeronautical Glazing Fail-Safe
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Solution Overview
Problem
Current pinched glazings in pressurized aircraft fail to meet the 'full fail safe' pressure resistance requirement, as the breakage of structural elements leads to loss of rigidity and deflection of the glazing, causing potential removal.
Innovation Solution
A laminated glazing design with a stepped element that creates a two-way connection between the mounting structure and the glazing, independent of structural plies, using a nonstructural glass sheet with a network of conductive wires and a structural glass sheet, where the stepped element provides sealing, mechanical strength, and electrical continuity, eliminating the need for an injected seal and enhancing positioning precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seal alone is used to hold the glazing in the mounting structure, then the glazing can be assembled with simple structure, but the glazing cannot maintain position and pressure resistance when structural elements break
Solution Approach 1:
The holding function is segmented between the seal (for pressure sealing) and the stepped element with blocking protrusion (for positional holding and mechanical strength). This segmentation allows each component to specialize in its function, with the stepped element providing fail-safe holding independent of the seal's structural integrity.
Solution Approach 2:
The blocking function is extracted from the seal and transferred to the stepped element. The blocking protrusion on the stepped element engages with the mounting structure to provide positional holding, while the seal focuses solely on pressure sealing, eliminating the need for the seal to bear mechanical holding loads.
2Manufacturing precision
If the seal provides both sealing and structural holding functions, then the overall structure can be simplified, but the positioning precision and sealing reliability deteriorate when glass plies break
Solution Approach 1:
The functions are segmented: the stepped element with blocking protrusion handles positioning and mechanical support, while the seal handles pressure sealing. This allows the blocking protrusion to provide precise positioning independent of sealing requirements, improving manufacturing precision without compromising sealing reliability.
Solution Approach 2:
The stepped element acts as an intermediary between the glazing assembly and the mounting structure. It provides a stable mechanical interface with blocking protrusions that engage with corresponding features in the mounting structure, ensuring precise positioning and reliable mechanical support independent of the seal's structural integrity.
3Reliability
If multiple seals are used to ensure fail-safe pressure resistance, then the pressure resistance improves, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The holding and sealing functions are segmented into separate components (stepped element with blocking protrusion and seal), allowing a single seal to be used without requiring multiple seals for fail-safe operation. The blocking protrusion provides mechanical retention that maintains positioning even if structural elements fail, simplifying assembly while ensuring reliability.
Solution Approach 2:
The blocking protrusion on the stepped element provides beforehand mechanical retention that cushions against the effects of structural element failure. This pre-established mechanical connection ensures the glazing remains positioned and supported even before any seal failure occurs, simplifying the overall assembly while maintaining fail-safe reliability.
Data Source
AI summary
A laminated glazing includes a first exterior glass sheet and a second sheet, an adhesive layer, the edge of the sheet being set back with respect to that of the sheet, a portion of the free surface and the edge face of the sheet, 0 to 100% of the edge face of the layer and a portion of the surface of the sheet or of the layer, projecting beyond the sheet, describing a contour covered by an element, the glazing being attached to the structure by a window retainer, the element extending between the window retainer and the structure so as to constitute blocking of the element and of the glazing in the plane thereof; and the application of this glazing to an aeronautical clamped glazing.