Quick-Access Fastener Assembly for High-Temperature Panel Maintenance
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Solution Overview
Problem
Current fastener assemblies used to attach thermal protection panels to high-temperature structures are labor-intensive and costly to maintain, as they require the removal of thermal protection caps or layers to access fastener heads, and exposed fasteners pose a risk of short circuits and structural integrity compromise.
Innovation Solution
The use of fastener assemblies with sleeves, covers, and heat-resistant materials that secure fastener heads within sleeves, allowing quick access without removing thermal protection layers, and providing a continuous grounding path to prevent electrical hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If thermal protection sealants, caps, or plugs are used to entirely cover fasteners to maintain smooth panel surfaces, then the outer panel surface smoothness and thermal protection are improved, but maintenance becomes time- and labor-intensive as these components must be removed to access fastener heads
Solution Approach 1:
The fastener head is extracted from the recessed position and brought to the outer surface, eliminating the need for caps or sealants that would otherwise need to be removed for maintenance access
Solution Approach 2:
Instead of covering the fastener head with protective caps as in conventional designs, the fastener head itself is positioned on the outer surface and made accessible, inverting the conventional approach of hiding fasteners within recesses
2Reliability
If thermal protection sealants, caps, or plugs are used to cover fasteners, then thermal protection is improved, but in the event these components become dislodged, exposed fastener heads create electrical and thermal short circuit hazards
Solution Approach 1:
A non-conductive, heat-resistant material is introduced as an intermediary between the conductive fastener head and the thermal protection panel, preventing both thermal and electrical conduction to the panel while allowing the fastener head to remain exposed on the outer surface
Solution Approach 2:
The potentially harmful exposure of conductive fastener heads is converted into a safe configuration by using the non-conductive material to prevent harmful thermal and electrical conduction, while the exposed fastener head provides maintenance benefits
3Reliability
If fasteners are recessed and entirely sealed with thermal protection materials, then structural integrity and thermal protection are improved, but access to fastener heads for maintenance requires removal of thermal protection layers
Solution Approach 1:
The fastener head is extracted from the recessed position and positioned on the outer surface, allowing maintenance access without removing thermal protection layers while maintaining structural integrity through the non-conductive material
Solution Approach 2:
The fastener assembly is segmented into the conductive fastener head for mechanical fastening and the non-conductive material for thermal and electrical protection, allowing each component to serve its specific function independently
Data Source
AI summary
Embodiments disclosed herein include fastener assemblies. In an embodiment, a fastener assembly comprises a sleeve with a hole, an inner surface, and top and bottom ends. The top end has a planar surface, and the inner surface has a cylindrical surface. The fastener assembly includes a fastener downwardly extending through the hole, and having a drive slot, a head, a shank, and a threaded region. The head is positioned within the bottom end. The head is separated from the threaded region by the shank. The fastener assembly comprises a cover disposed on the top end and having an access hole and top and bottom surfaces. The cover is welded to the sleeve to define an inner cavity between the cover, sleeve, and fastener head. The access hole is positioned over the drive slot. The cover, sleeve, and fastener comprises materials having high temperature, strength and oxidation resistances.