Frictionally Damped Fasteners Using Embedded Wire Ropes
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Solution Overview
Problem
Current mechanical fasteners exhibit low damping capacity, leading to increased joint vibration amplitude and potential failures under dynamic loading conditions, particularly in resonant situations, due to their inability to effectively dissipate vibration energy without compromising structural integrity or increasing size.
Innovation Solution
Embedding sheathed, vibration-damping metal cables or ropes made of woven wires within the fastener body during manufacturing, utilizing dry friction between the wires to enhance damping capacity without altering the fastener's dimensions or shape, achieved through processes like cold forming, hot forming, or molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional damping components (such as stacked washers) are added to improve vibration resistance, then damping capacity increases, but the overall size and complexity of the fastener system increases
Solution Approach 1:
The invention merges the damping function directly into the fastener body by embedding wire ropes within the fastener structure. This integration eliminates the need for separate damping components such as stacked washers or additional vibration-damping elements. The wire ropes are positioned inside the fastener shank or body, combining the fastening and vibration-damping functions into a single unified component, thereby reducing system complexity.
Solution Approach 2:
The fastener is designed to perform multiple functions simultaneously: it provides mechanical fastening through its threading and clamping capability, while the embedded wire ropes provide vibration damping and energy dissipation. This multi-functional design eliminates the need for separate specialized components, as the single fastener element handles both fastening and vibration protection tasks.
2Reliability
If additional damping components are added to dissipate vibration energy, then damping capacity improves, but the packaging constraints and spacing requirements for the fastener are compromised
Solution Approach 1:
The wire ropes are nested within the fastener body, specifically positioned inside the shank or hollow sections of the fastener. This nested arrangement allows the damping elements to occupy the internal volume of the fastener rather than adding external bulk. The wire ropes are contained within the existing dimensional envelope of the fastener, ensuring that no additional space is required beyond what is already allocated for the fastener itself.
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 embedded vibration-damping ropes significantly improve the integrity and durability of fastened joints by effectively dissipating dynamic loads, reducing vibration amplitude and preventing loosening or cracking, while maintaining the fastener's structural integrity and dimensions.
Implementation Method 1
utilizing dry friction between the wires to enhance damping capacity
Implementation Method 2
sheathed, vibration-damping cables or ropes comprising plural individual wires
Data Source
AI summary
A method and system for increasing damping capacity in a mechanical fastener by utilizing dry friction between individual wires of a sheathed rope is disclosed. For metal fasteners, the sheathed rope is inserted loosely into a thick-walled metal tube. The tube is then rolled to reduce the tube diameter, thereby uniformly embedding the rope into the tube material. The tube is then subjected to either cold or hot forming. After forming, the fastener blank may be threaded. For composite or plastic fasteners, the sheathed rope includes insert locators attached to the sheathing. The sheathed rope having the insert locators is placed in the mold cavity prior to the polymerizable material being injected into the mold. Regardless of the embodiment, the resulting fastener has increased damping due to the dry inter-wire friction within the embedded rope which develops between the surfaces of individual wires upon dynamic loading of a fastened joint.