Offset Spark Containment Cap for Angled Fastener Sealing
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Solution Overview
Problem
Existing spark containment caps face challenges in efficiently sealing around fasteners protruding at non-perpendicular angles from aircraft structures, leading to potential sealant leakage and misalignment issues during installation, particularly in the presence of inclined surfaces.
Innovation Solution
A spark containment cap design featuring an annular base and offset cap upper, allowing for angular adjustment and a pivotable joint, which receives an annular bead of curable sealing material to form a sealed cavity around the fastener, accommodating non-perpendicular fastener orientations and ensuring effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional spark containment cap is used with a fastener extending perpendicular to the structure surface, then the cap can be easily installed and sealed, but it cannot accommodate fasteners extending at non-perpendicular angles
Solution Approach 1:
The cap upper is made pivotable relative to the annular skirt through a ball joint mechanism, allowing the cap to dynamically adjust its orientation to accommodate fasteners at various angles while maintaining the seal between the cap body and structure surface
Solution Approach 2:
The cap is divided into two main segments: a fixed annular skirt that provides the sealing interface with the structure, and a movable cap upper that can pivot to align with the fastener axis, enabling adaptation to non-perpendicular orientations
2Adaptability or versatility
If the cap upper axis is aligned with the annular skirt axis, then the structure is simplified, but misalignment occurs when fasteners are inclined relative to the structure surface
Solution Approach 1:
The ball joint mechanism enables the cap upper to pivot dynamically, allowing the axis of the cap upper to be offset from the axis of the annular skirt, thereby accommodating inclined fastener orientations without requiring a completely complex restructured design
Solution Approach 2:
The offset between the cap upper axis and annular skirt axis is designed to accommodate specific angular deviations of fasteners from the perpendicular orientation, allowing the structure to adapt to varying inclination angles while maintaining functional integrity
3Adaptability or versatility
If the cap is designed to accommodate inclined fasteners, then adaptability to non-perpendicular orientations is improved, but sealant leakage may occur due to misalignment
Solution Approach 1:
The pivotable joint allows the cap upper to self-align with the fastener axis while the annular skirt maintains its sealing position against the structure surface, ensuring that the sealant bead remains properly positioned even when accommodating inclined fasteners
Solution Approach 2:
The ball joint acts as an intermediary mechanism that decouples the sealing function (performed by the annular skirt) from the fastener alignment function (performed by the cap upper), allowing independent optimization of both functions
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 design ensures a secure seal around fasteners with non-perpendicular orientations, minimizing sealant leakage and facilitating efficient installation by allowing for correct alignment and secure fixation of the cap to the structure, even on inclined surfaces, thereby enhancing lightning strike protection for aircraft.
Implementation Method 1
an annular bead of a curable sealing material around the opening into the cavity to provide a seal between the cap body and the structure
Data Source
AI summary
A spark containment cap forms a sealed cavity around an end of a fastener protruding from a structure. The cap has a cap body defining an air cavity enclosing the end of the fastener. The cap body includes an annular base (210) terminating at a base rim (211) surrounding an opening into the air cavity. An annular skirt of the cap provides an annular sealing volume extending around the base rim to receive an annular bead of a curable sealing material around the opening into the cavity to provide a seal between the cap body and the structure to seal a volume of gas within the cavity. The cap body includes a cap upper to receive the end of the fastener. The cap upper (220) is positionable so that an axis of the cap upper is offset from an axis of the annular skirt (230).