Universal Fastener Cap with Axial Locking for Washer Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for installing spark and plasma out-gassing suppression caps on fastener heads with and without washers are impractical, as they require different types and sizes of caps, complicating the assembly process and potentially compromising lightning strike performance.
Innovation Solution
A joint design featuring a cap with locking features that can be interlocked with a fastener head, allowing the cap to be securely attached regardless of the presence of washers, with the cap's position adjustable to accommodate washer thickness, ensuring a robust and reliable seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different types and sizes of caps are used for fastener heads with and without washers, then the cap can be properly fitted to each case, but the assembly process becomes complicated and multiple cap types must be managed
Solution Approach 1:
The cap is designed with a universal locking mechanism featuring multiple axially spaced locking features that can interlock with washers of different thicknesses. The pitch between locking features is selected to accommodate various washer thicknesses, allowing a single cap design to serve multiple fastener configurations (with or without washers, different washer thicknesses) without requiring different cap types.
2Ease of manufacture
If a single cap type is used for both fastener configurations, then manufacturing is simplified, but the cap may not properly accommodate washers of different thicknesses
Solution Approach 1:
The cap incorporates a dynamic adjustment mechanism where the axial position of the cap relative to the fastener head can be altered by interlocking with different locking features. This allows the cap to adapt its position based on washer thickness while maintaining a secure locked connection, enabling a single cap design to accommodate variable washer configurations.
3Reliability
If the cap is securely locked to the fastener head, then spark and plasma suppression is effective, but the locking mechanism must work regardless of washer presence
Solution Approach 1:
The locking mechanism is segmented into multiple axially spaced locking features on the cap and corresponding locking features on the fastener head or washer. This segmentation allows selective engagement of different locking feature pairs depending on whether a washer is present and its thickness, ensuring reliable locking and spark suppression in all configurations.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention proposes a joint (100) comprising a structure (110), a fastener passing through the structure (110) with an end (120) of the fastener protruding from the structure (110), and a cap (140) installed on the end (120) of the fastener. The end (120) of the fastener comprises an axially extending shaft (121), a fastener head (122) carried by the shaft (121), and one or more washers (130) located between the fastener head (122) and the structure (110), the one or more washers (130) spacing the fastener head (122) and the structure (110) apart by a distance (D). The cap (140) has a cap body with a cavity which encloses the end (120) of the fastener, and the joint (100) further comprises a cured sealing material (150) which seals the cavity. One of the fastener head (122) and the cap body is formed with two or more first locking features (143) which are axially spaced apart by a pitch (P), and the other of the cap body and the fastener head (122) is formed with one or more second locking features (123) which are each capable of interlocking with one of the first locking features (143). To secure the cap (140) to the fastener head (122) at least one of the second locking features (123) is interlocked with a respective one of the first locking features (143). In order that the joint (100) can be modified to accommodate the fastener end (120) without the one or more washer (130), the distance (D) between the fastener head (122) and the structure (110) is an integer multiple of the pitch (P) between the first locking features (143).