Pre-stretched Plastic Fiber Core Cable with Steel Strands
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Solution Overview
Problem
High-strength plastic fibers in ropes are not effectively utilized due to their delayed load absorption and mismatched elongation behavior with steel wires, limiting their load-bearing capacity in combined rope constructions.
Innovation Solution
The monofilament bundles are pre-stretched to achieve a stable cross-section, which is then fixed by a braiding or wrapping sheathing, and an elastic intermediate layer is introduced to approximate the elongation behavior of steel wires, allowing for efficient load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If high-strength plastic fibers are used in combined ropes, then weight and volume are reduced, but load-bearing capacity is not effectively utilized due to delayed load absorption
Solution Approach 1:
The plastic fiber core is pre-stretched during manufacturing to reduce its diameter and set its cross-section before use. This preliminary action eliminates the initial relaxation phase that would otherwise delay load absorption, allowing the fibers to immediately bear load according to Hooke's law when the rope is put into service.
Solution Approach 2:
The plastic fibers undergo a permanent dimensional change through pre-stretching, reducing their diameter and altering their mechanical state. This parameter change ensures that when the rope is loaded, the fibers start from a stabilized state rather than a relaxed state, improving their immediate load-bearing contribution.
2Strength
If plastic fibers are stretched to reduce diameter, then load-bearing capacity increases, but the elongation behavior mismatches with steel wires
Solution Approach 1:
An intermediate layer is introduced between the pre-stretched plastic fiber core and the steel wire strands. This intermediate layer acts as a mediator that accommodates the elongation difference between the plastic fibers and steel wires, allowing both materials to function at their optimal stress levels without mismatch.
Solution Approach 2:
The rope employs a composite structure with three distinct layers: pre-stretched plastic fiber core, intermediate material layer, and steel wire strands. This composite design allows each layer to contribute its specific properties - the plastic provides high strength-to-weight ratio, the intermediate layer manages elongation compatibility, and the steel provides durability and visible wear indicators.
3Productivity
If a sheathing is applied to fix the cross-section, then immediate elastic stretching is enabled, but the structure becomes more complex
Solution Approach 1:
The sheathing is applied during manufacturing to pre-fix the cross-section of the plastic fiber core before the rope is put into service. This preliminary action eliminates the need for the core to undergo cross-section changes during use, enabling immediate elastic stretching and load absorption from the start of operation.
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 approach enhances the load-bearing capacity of the rope by enabling immediate elastic stretching according to Hooke's law and reduces the rope's diameter while maintaining load-bearing capacity, and allows for reversible expansion under load, optimizing the rope's performance in applications like hoisting and deep-sea use.
Implementation Method 1
The normal load absorption under elastic stretching of the plastic fibers according to Hooke's law can start immediately
Implementation Method 2
The elastic resilience of the intermediate layer and the spacing of the wire strands from one another allow the helices described by the strands to be lengthened
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a combined cable having a core cable made of high-strength plastic fibers present as a twisted monofilament bundle (1) or a plurality of twisted monofilament bundles (6), and having an external layer (2, 7) of steel wire strands (4, 5), characterized in that the monofilament bundle or bundles (1, 6) is or are stretched to reduce the diameter and held in a cladding (2, 7), particularly braided cladding, in this state. The strain of the core cable under load is thus reduced, so that the load distribution between the steel cross-section and the plastic cross-section of the cable is improved. In the same sense, in reverse, in order to have the strain behavior of the strand layer approach that of the core cable, the cable has an intermediate layer (3) made of an elastic plastic, in which the steel wire strands are pressed at a distance from each other, such that the external layer stretches under load and contracts radially.