Dual-Layer Cable Sheath for Repeated Bending Resistance
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Solution Overview
Problem
Cables mounted on automobiles are prone to breakage when repeatedly bent at fixed points, due to concentrated force leading to wire fracture.
Innovation Solution
A cable design featuring a sheath with a two-layer structure, where the outer first sheath has a higher elastic modulus and the inner second sheath has a lower elastic modulus, allowing the second sheath to deform and absorb force during bending, thereby reducing stress on the coated electric wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cable uses a single-layer sheath with high elastic modulus to provide mechanical strength, then the cable has good abrasion resistance and scratch resistance, but the cable is prone to wire breakage when repeatedly bent
Solution Approach 1:
The sheath is divided into two distinct layers: an outer first sheath with high elastic modulus for mechanical strength, and an inner second sheath with low elastic modulus for flexibility. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between strength and bend resistance.
Solution Approach 2:
Different regions of the sheath are assigned different elastic moduli to match local functional requirements. The outer layer has high elastic modulus for abrasion and scratch resistance, while the inner layer has low elastic modulus for bending flexibility and stress absorption, creating a spatially differentiated structure that satisfies both requirements simultaneously.
2Object-affected harmful factors
If the cable uses a single-layer sheath with high elastic modulus for durability, then the cable has good abrasion and scratch resistance, but force is concentrated at fixed points during bending causing wire breakage
Solution Approach 1:
The sheath is segmented into two layers with different mechanical properties. The outer first sheath provides abrasion and scratch resistance, while the inner second sheath provides bending resistance by absorbing stress, thus resolving the contradiction between durability and bending resistance.
Solution Approach 2:
The sheath structure implements local quality by providing different mechanical properties at different locations: the outer layer resists surface damage from abrasion and scratches, while the inner layer resists internal stress concentration during bending, thereby addressing both harmful factors locally.
3Ease of manufacture
If the sheath is made with uniform elastic modulus throughout, then the manufacturing process is simple, but the cable cannot effectively distribute force during repeated bending
Solution Approach 1:
The sheath is manufactured as two separate layers with different elastic moduli. While this increases structural complexity, each layer can be manufactured using standard processes, and the overall manufacturing remains feasible through sequential extrusion or coating, balancing simplicity with performance.
Solution Approach 2:
The sheath uses a composite structure combining materials with different elastic moduli. This allows the outer layer to provide mechanical strength while the inner layer provides flexibility and force distribution, achieving effective force distribution during bending while maintaining reasonable manufacturing complexity through established composite material techniques.
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 effectively suppresses wire breakage even when repeatedly bent, by distributing the force and enhancing the mechanical strength of the sheath, thus meeting the requirements of abrasion resistance, scratch resistance, and bending resistance.
Implementation Method 1
the second sheath has a smaller elastic modulus than the first sheath... the second sheath can deform and absorb the force even when the cable is subjected to force and repeatedly flexed
Data Source
AI summary
A cable includes a plurality of coated electric wires and a sheath covering the plurality of coated electric wires, wherein the sheath includes a first sheath and a second sheath in order from an outer surface side, and wherein the second sheath has a smaller elastic modulus than the first sheath.