Directional Washer Orientation Indication After Fastener Installation
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Solution Overview
Problem
Directional washers, such as seal washers, require correct orientation on a fastener to ensure effective protection against hot particle ejection and electromagnetic effects during a lightning strike, but once the nut is fully installed, the orientation cannot be visually verified.
Innovation Solution
A directional washer with a washer body, a direction-dependent element, and a direction indicator. The direction indicator is formed on the washer body radially outer surface and/or on the peripheral portion of the washer body first surface, allowing for identification of the correct orientation even after installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal washer with a polymeric seal is installed on a fastener, then protection against hot particle ejection and electromagnetic effects is improved, but the ability to verify correct orientation after installation deteriorates
Solution Approach 1:
A direction indicator element is introduced as an intermediary component that visually indicates the orientation of the polymeric seal. This indicator is positioned on the washer body such that it remains visible after fastener installation, allowing verification of correct orientation without compromising the seal's protective function. The indicator acts as a mediator between the hidden seal orientation and the external observer.
Solution Approach 2:
The orientation verification problem is solved by transitioning from a three-dimensional hidden feature (seal orientation within the fastener assembly) to a two-dimensional visible indicator on the washer body surface. The direction indicator is positioned on the outer peripheral surface of the washer, converting the internal orientation state into an externally accessible visual signal that can be verified after installation.
2Reliability
If the polymeric seal is positioned to fill the void between nut and shank, then protection against hot gas generation is improved, but the visibility of the seal for orientation determination deteriorates
Solution Approach 1:
The washer assembly is segmented into functional components: the polymeric seal element that provides protection and the direction indicator element that provides information. The direction indicator is positioned on the washer body in a location that does not interfere with the seal's void-filling function, allowing both protection and orientation verification to coexist independently.
Solution Approach 2:
Instead of making the seal itself visible, a direction indicator is created as a visual copy or representation of the seal's orientation. The indicator replicates the orientation information that would otherwise be hidden, allowing verification without altering the seal's position or structure. The indicator serves as a visual surrogate for the hidden seal orientation.
Data Source
AI summary
Aa directional washer has a washer body, a direction-dependent element, and a direction indicator. The washer body has a washer body first surface, a washer body second surface, and a washer body radially outer surface. The direction-dependent element is associated with the washer body and has a geometry configured complementary to the head or nut of a fastener when the washer body first surface is in contact respectively with the head engagement surface of the head or the nut engagement surface of the nut. The direction indicator is formed on the washer body radially outer surface and/or on the peripheral portion of the washer body first surface, and is configured to identify the washer body first surface for differentiation from the washer body second surface.