Two-Layer Multi-Strand Cable for Flexibility and Bending Endurance
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Solution Overview
Problem
Existing cables used in tire apex plies lack sufficient flexibility and structural elongation, leading to high rigidity and inadequate endurance under cyclic tensile stresses, particularly in applications requiring shrink-fitting and reduced shear stress.
Innovation Solution
A multi-strand cable design with two layers of multi-strands, each strand having inner and outer layers of metal wires wound helically, optimized for low bending stress and increased metal mass relative to cable diameter, ensuring a structural elongation of at least 1.0% and an endurance criterion of Δ σ bending / (M / D) < 3000 N xm /g, where M is the linear mass and D is the cable diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a single layer of strands with high structural elongation is used, then flexibility and shaping capability are improved, but the endurance criterion is insufficient leading to reduced cable lifespan under cyclic stresses
Solution Approach 1:
The cable is divided into two distinct layers of multi-strands, with the inner layer containing X=3 or 4 multi-strands and the outer layer containing Y>1 multi-strands. Each layer can be independently optimized for different functions: the inner layer provides structural elongation (As ≥ 1.0%) for flexibility and shaping, while the outer layer enhances the endurance criterion (V1 ≤ 3000 N xm/g) to withstand cyclic tensile stresses. This segmentation allows simultaneous optimization of both contradictory requirements.
2Strength
If thicker metal wires are used to increase cable strength, then breaking strength is improved, but flexibility and structural elongation are reduced
Solution Approach 1:
Different wire diameters are used in different locations within the cable structure. The inner layer multi-strands use wires with diameter d1 that provide sufficient strength, while the outer layer multi-strands use wires with diameter d1' that are optimized for flexibility. This local differentiation of wire properties allows each layer to contribute its specific quality: the inner layer contributes to breaking strength while the outer layer enhances structural elongation and flexibility.
3Reliability
If more metal mass is added to increase endurance, then cable strength is improved, but cable diameter increases leading to reduced flexibility
Solution Approach 1:
The cable employs a nested multi-strand structure where multiple strands are wound helically around a central axis to form multi-strands, which are then nested within two layers. This nested configuration increases the effective metal mass and cross-sectional area without proportionally increasing the outer cable diameter, thereby maintaining flexibility while improving the endurance criterion. The nested arrangement optimizes the M/D ratio (metal mass to diameter) to enhance durability without sacrificing ease 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
The cable design enhances flexibility and structural elongation, reducing rigidity and improving endurance, thereby extending the lifespan of tires by alleviating tensile and bending stresses.
Implementation Method 1
the structural elongation As being equal to the elongation, in %, corresponding to the intersection between the tangent to the elastic part of the force-elongation curve
Implementation Method 2
Δ σ bending / (M / D) - in MPa.mm is the maximum bending stress per unit curvature seen by the inner and outer wires
Implementation Method 3
the cable has an endurance criterion V1 = Δ; σ bending / (M / D) and the cable has a structural elongation As such that As ≥ 1.0%
Data Source
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AI summary
The invention relates to a multi-strand cable (50) with two multi-strand layers, the cable (50) comprising: - an inner layer (CI) of the cable, made up of X = 3 or 4 multi-strands (M1) comprising K = 2, 3 or 4 strands (T1) helically wound around an axis (B), each strand (T1) being a strand with at least two layers (C1, C3); and - an outer layer (CE) of the cable made up of Y > 1 multi-strands (M2) wound around the inner Layer (CI) of the cable, each multi-strand (M2) comprising L = 2, 3 or 4 strands (T2) helically wound around an axis (A'), each strand (T2) being a strand with at least two layers (C1'; C3'), with the multi-strands of the inner layer (M1) and of the outer layer (M2) being helically wound around a main axis (A). The cable (50) has an endurance criterion V1 = Δσ bending (M/D) < 3000 N x m/g. The cable (50) has a structural elongation As such that As ≥ 1.0%.