Angled Fastening Collar Geometry for Lower Bearing Stress
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Solution Overview
Problem
Conventional fastening collars experience high bearing stress during installation due to limited contact surface area, leading to potential damage to coatings and increased operational stress, which affects the longevity and reliability of fastening systems.
Innovation Solution
A fastening collar design featuring an elongate portion with a first region comprising a taper or concave radius and a second region with a flange, extending at an angle offset from the perpendicular, which increases contact surface area and reduces installation force requirements, thereby minimizing bearing stress and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional fastening collars are used during installation, then the fastening process can be completed, but high bearing stress occurs due to limited contact surface area, leading to potential damage to coatings and increased operational stress
Solution Approach 1:
The second collar end extends away from the longitudinal axis at an angled offset (1-30 degrees from perpendicular), transforming the contact geometry from a single-plane interface to a multi-dimensional contact zone. This angular extension creates additional contact surface area with the bore surface, distributing bearing stress across a larger area and reducing peak stress concentrations during installation.
Solution Approach 2:
The first region of the elongate portion comprises a concave radius (at least 0.060 inches) that curves inward, creating a rounded contact surface. This curvature allows for more uniform stress distribution across the contact interface compared to flat surfaces, reducing stress concentrations and minimizing damage to coatings during the fastening process.
2Force
If conventional fastening collars with limited contact surface area are used, then installation can proceed, but excessive installation force is required which increases operational stress and reduces fastener longevity
Solution Approach 1:
The angled extension of the second collar end creates additional contact surface area that distributes installation forces across a larger area of the bore. This dimensional change reduces the peak force required during installation while simultaneously reducing operational stress, thereby extending the operational life of both the fastener and the surrounding structure.
Solution Approach 2:
The invention modifies the geometric parameters of the collar, specifically the angle of the second collar end (1-30 degrees from perpendicular) and the concave radius (at least 0.060 inches), to optimize the distribution of forces. These parameter changes enable lower installation forces while maintaining structural integrity and extending operational life.
3Ease of manufacture
If conventional fastening collars are used, then the fastening process can be completed, but coatings on the fastener or surrounding structure may be damaged due to high bearing stress
Solution Approach 1:
The concave radius in the first region creates a curved contact surface that distributes bearing stress more uniformly, preventing stress concentrations that could damage coatings. This curved geometry allows the collar to interface smoothly with the bore surface, protecting coating integrity during installation and operation.
Solution Approach 2:
The angled extension of the second collar end distributes contact forces across a larger area, reducing peak bearing stress that could otherwise damage coatings on the fastener or surrounding structure. This multi-dimensional contact geometry protects coating integrity while maintaining fastening functionality.
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 enhanced contact surface area and angled design reduce the force required for installation, minimize damage to coatings, and improve the operational life of fastening collars and tools by distributing stress more evenly, ensuring a secure and reliable fastening process.
Implementation Method 1
deforming the elongate portion onto the shank of the pin
Implementation Method 2
A force required during forcibly contacting the elongate portion to deform the elongate portion onto the shank of the pin is reduced compared to a force required to forcibly contact and deform onto the pin a comparative elongate portion that does not comprise a second collar end extending away from a longitudinal axis of the elongate portion at the first angle offset from the angle perpendicular to the longitudinal axis
Data Source
AI summary
The present disclosure relates to fastening collars, multi-piece fasteners, and methods for fastening. A fastening collar comprises a first collar end, a second collar end, and an elongate portion intermediate the first collar end and the second collar end and defining a longitudinal axis of the fastening collar. The elongate portion comprises a first region adjacent the first collar end, extending a first distance along the longitudinal axis; a second region adjacent to the second collar end, extending a second distance along the longitudinal axis, and comprising a flange; and an inner collar surface defining collar cavity extending through the elongate portion from the first collar end to the second collar end. The second collar end extends away from the longitudinal axis of the elongate portion at a first angle offset from an angle perpendicular to the longitudinal axis of the elongate portion.