Slotted Fastener Assembly for Vibration-Resistant Clamp Load

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Solution Overview

Problem

Conventional nuts and bolts are susceptible to loosening under vibrational and other loads, and existing solutions such as multiple nuts or split washers increase cost and may not always be effective.

Innovation Solution

A vibration-resistant fastening system featuring a nut with a staged interior bore and multiple slots, combined with a collar that distributes force to the working surface, providing improved torque to clamp force correspondence and preventing loosening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional nuts and bolts are used, then the fastening system is simple and cost-effective, but the joints are susceptible to loosening under vibrational loads

Engineering Contradiction:

Improvevibrational resistanceVSAvoidfastener structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The annulus is segmented into multiple part-annular portions through the inclusion of slots, which divide the continuous structure into discrete segments. This segmentation allows the annulus to flex and deform under vibrational loads while maintaining the overall fastening function, thereby improving vibrational resistance without requiring a completely different fastener design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The annulus incorporates a tapered portion with specific geometric properties that create localized stress distribution and friction characteristics. The tapered geometry provides increased surface area and frictional engagement at specific locations along the annulus, enhancing vibrational resistance while maintaining a relatively simple overall fastener structure

Inventive Principle:

Principle #3Local quality

2Reliability

If multiple nuts or split washers are used to combat vibrational forces, then the frictional forces or spring bias are increased, but the cost and device complexity increase

Engineering Contradiction:

Improvevibrational resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The slots are integrated directly into the annulus as a single monolithic component rather than requiring separate slots or additional parts. This merging of functions into a single manufacturable component maintains ease of production while achieving the desired vibrational resistance through the slot-induced flexibility and friction characteristics

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the annulus is divided into part-annular portions through slots, then the vibrational resistance is improved, but the structural integrity may be compromised

Engineering Contradiction:

Improvevibrational resistanceVSAvoidannulus structural strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The tapered portion of the annulus incorporates specific geometric parameters including taper angles and surface area ratios that optimize both strength and vibrational resistance. The tapered geometry provides increased structural strength through distributed stress while simultaneously creating the frictional engagement needed for vibrational resistance, resolving the contradiction between strength and vibration resistance

Inventive Principle:

Principle #35Parameter changes

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 system effectively secures joints against vibrational loosening by distributing clamping force over a larger surface area, maintaining a prescribed installation torque and clamp load, while reducing the risk of joint failure.

Implementation Method 1

The tapered portion may have a surface area that is at least 1.1 times greater than a surface area of a cylindrical portion... the tapered portion extending longitudinally forward from the cylindrical portion

Methodology Applied

Scientific EffectForce distribution:

Implementation Method 2

multiple slots, extending longitudinally along the annulus, each defined through the annulus from the exterior thereof to the stage bore

Methodology Applied

Scientific EffectVibrational absorption: Damping

Data Source

PatentEP3997349B1Fastener and fastener assembly having vibrational resistance and improved torque to clamp force correspondence

Publication Date: 2026.02.18 DURAFORCE HOLDINGS LLC

Figure 1A~1B
Figure 2
Figure 3A~3C

AI summary

A vibration resistant fastening system for attaching a working surface to a threaded stud, the stud extending longitudinally through a hole defined through the working surface, includes: a nut including a forward annulus, a rearward head, and a staged interior bore extending longitudinally through the head and annulus, the head including a threaded interior for engaging the threaded stud, the threaded interior of the head defining a rearward section of the staged bore. The annulus includes: an exterior including a cylindrical portion extending longitudinally forward from the head, and a tapered portion extending longitudinally forward from the cylindrical portion; at least one smooth cylindrical interior wall defining a forward section of the staged bore forward of said rearward section defined by the threaded interior of the head; and multiple slots, extending longitudinally along the annulus, each defined through the annulus from the exterior thereof to the stage bore.