Interlocking Grommet-Stud Fastener Assembly for Stable Positioning
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Solution Overview
Problem
Existing fastener and grommet assemblies for aircraft insulation experience issues with load concentration, grommet migration, and relative movement between components, leading to unreliable positioning and assembly stability.
Innovation Solution
The design incorporates a grommet with internal interengaging elements, such as compressible or elastically deformable features, and a stud with complementary interengagement elements, allowing for precise axial and angular positioning and accommodating different grommet lengths, thereby enhancing assembly stability and load resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If material is cut or gapped at the wings to separate them from retaining surfaces, then the structure can be assembled, but load concentration increases at the cuts or gaps
Solution Approach 1:
The grommet is divided into multiple functional segments: wings for positioning, a body for structural support, and an interengaging element for mechanical coupling. This segmentation allows each part to perform its specific function optimally while distributing loads across different regions, preventing concentration at any single point.
Solution Approach 2:
The interengaging element acts as an intermediary between the grommet and stud, providing a dedicated load transfer path. This intermediary component absorbs and distributes mechanical loads, preventing direct stress concentration at the wing-retaining surface interfaces.
2Manufacturing precision
If external rings are added to the grommet to engage the structure opening, then positioning in the opening is improved, but the grommet may migrate within the opening
Solution Approach 1:
The positioning and migration resistance functions are merged into a unified system. The wings provide precise positioning within the structure opening, while the interengaging element simultaneously prevents migration by mechanically coupling the grommet to the stud. This combination eliminates the need for separate external rings while achieving both positioning accuracy and migration resistance.
Solution Approach 2:
The solution transitions from two-dimensional external ring engagement to three-dimensional internal interengagement. The interengaging element extends into the stud, creating a depth-based mechanical lock that prevents migration in multiple directions, while the wings maintain planar positioning accuracy.
3Ease of manufacture
If the grommet and stud are designed with simple structures, then manufacturing is easier, but they cannot reliably withstand expected loading
Solution Approach 1:
The grommet features local quality variations: the wings have a geometry optimized for positioning, the body provides structural support, and the interengaging element has a specific shape for mechanical coupling with the stud. This localized optimization of geometry at different regions allows the overall structure to remain simple while achieving high load resistance through strategically placed functional features.
4Stability of the object's composition
If fixed grommet-stud positioning is used, then assembly stability is achieved, but the assembly cannot accommodate different grommet lengths
Solution Approach 1:
The interengaging element is designed with universal engagement capability that works with multiple grommet lengths. The element's geometry allows it to engage studs of varying lengths while maintaining stable positioning, enabling a single stud design to accommodate a family of grommets with different axial lengths. This universal design achieves both stability and adaptability.
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
This configuration ensures reliable positioning and stability of the grommet and stud assembly, reduces load concentration, and allows for the use of various grommet sizes with identical studs, improving assembly efficiency and structural integrity.
Implementation Method 1
The interengaging element or any of them is compressible and/or elastically deformable
Implementation Method 2
The interengaging element or any of them is compressible and/or elastically deformable
Data Source
AI summary
A grommet (200, 300, 400), a stud (102), an assembly of a grommet and a stud forming a fastener (100), and a method of assembling a grommet and a stud to form a fastener has the grommet with an interengaging element (250) in a channel wall of the grommet for engaging a cooperating, compatible or complementary interengaging element in a wall of the stud. The grommet and the stud can be assembled by moving the grommet and the stud relative to each other until the interengaging element in the grommet engages the complementary interengaging element in the stud. A family of grommets is described.