Braided Flat Cable Fiber Gap Expansion Control
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Solution Overview
Problem
Conventional braided ultra-high molecular weight polyethylene fiber cables for surgical use tend to expand in cross section area when relaxed, leading to increased contact with living tissues and accelerated degradation, especially when applied to soft tissues.
Innovation Solution
A method of producing braided ultra-high molecular weight polyethylene fiber cables by applying a tensile stress of at least 22.7 N/mm² for a predetermined length of time, followed by drawing the cables to a draw ratio of at least 109%, resulting in reduced fiber gaps and a cross section area that remains less than 110% of the stressed state even in a relaxed state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional braided ultra-high molecular weight polyethylene fiber cables are used for surgical applications, then high strength and flexibility are achieved, but the cross section area expands when relaxed leading to increased contact with living tissues and accelerated degradation
Solution Approach 1:
The cable is pre-stretched to a draw ratio of 109% or more during manufacturing, which permanently sets the fiber configuration in a stretched state. This preliminary action ensures that when the cable is implanted and subsequently relaxed in the body, the fibers remain relatively close together with reduced gap expansion, minimizing contact with living tissues and preventing accelerated degradation while maintaining the required tensile strength
2Reliability
If the cross section area of the cable is reduced to minimize fiber gap expansion, then contact with living tissues is reduced, but the cable may not provide sufficient tensile force for secure bone fixation
Solution Approach 1:
The invention changes the physical parameter of fiber configuration through controlled drawing to a draw ratio of 109% or more. This parameter change reduces the cross section area and minimizes fiber gap expansion when relaxed, while the high strength properties of ultra-high molecular weight polyethylene fibers ensure that sufficient tensile force is maintained for secure bone fixation despite the reduced cross section area
3Shape
If the fibers are allowed to come into close contact during braiding, then the cable maintains small cross section area in relaxed state, but the manufacturing complexity increases
Solution Approach 1:
Instead of attempting to maintain small cross section area through complex braiding patterns, the invention applies a preliminary drawing action after braiding. The cable is stretched to a draw ratio of 109% or more, which permanently sets the fiber configuration. This simpler approach achieves the desired shape stability without increasing braiding process complexity
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 method significantly reduces the expansion of fiber gaps in the relaxed state, minimizing degradation and maintaining tensile strength over time, especially when applied to bones and soft tissues, thereby enhancing safety and effectiveness in surgical applications.
Implementation Method 1
it has been found that ultra-high molecular weight polyethylene fiber is a material which could degrade, thought only slowly, through oxidation
Implementation Method 2
in a relaxed state when they are released from the tensile force, their cross section expands because of expansion of the gaps between the fibers and decrease in the degree of their congestion
Data Source
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AI summary
Disclosed is a flat cable formed by braiding ultra-high molecular weight polyethylene fibers, in which degree of the fibers' close contact in a condition where no tensile force is applied is elevated compared with conventional ones. The cable is a flat cable formed by braiding ultra-high molecular weight polyethylene fibers, the area of whose cross section under a load of no tensile stress is not more than 110% of the cross section area under a load of a tensile stress of 22.7 N/mm2.