Flexible Conductive Material for High-Cycle Fatigue Resistance
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Solution Overview
Problem
Conductive materials used in robots and automobiles are not sufficiently resistant to cyclic bending, with existing technologies only lasting for 50,000 cycles, whereas actual usage exceeds this limit, necessitating a material that can withstand one million cycles of dynamic driving.
Innovation Solution
A flexible conductive material with an average crystal grain size of 2 µm or less, combined with nanoparticles, is developed using methods like supercool rolling, differential speed rolling, and rapid sintering, to enhance crack diversion and prevent crack growth, thereby increasing flexibility and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive wire is made with normal crystal grain size, then the manufacturing process is simple, but the fatigue life is insufficient (only 50,000 cycles)
Solution Approach 1:
The patent applies parameter changes by reducing the average crystal grain size to 2 μm or less, which fundamentally changes the material's fatigue resistance properties. This parameter modification enables the conductive material to withstand one million cycles of dynamic driving, resolving the contradiction between simple manufacturing and high reliability.
Solution Approach 2:
The patent employs composite materials by incorporating nanoparticles (0.1-20 mass%) into the metal matrix. This composite structure creates multiple interfaces that deflect and arrest crack propagation, significantly enhancing fatigue life while maintaining manufacturing feasibility through established metallurgical processes.
2Reliability
If the crystal grain size is reduced to increase fatigue resistance, then the material becomes more resistant to cyclic bending, but the manufacturing difficulty increases
Solution Approach 1:
The patent implements parameter changes by controlling the average crystal grain size to 2 μm or less through specific processing techniques. This parameter control achieves superior resistance to cyclic bending while managing manufacturing complexity through documented methods such as supercool rolling and differential speed rolling.
Solution Approach 2:
The patent replaces conventional mechanical processing with advanced techniques like supercool rolling and differential speed rolling. These methods enable precise crystal grain size control at 2 μm or less, achieving high fatigue resistance while maintaining ease of manufacture through optimized processing systems.
3Duration of action of stationary object
If advanced processing methods like supercool rolling are used to reduce crystal grain size, then the fatigue life increases to one million cycles, but the processing complexity increases
Solution Approach 1:
The patent applies parameter changes by implementing supercool rolling and differential speed rolling processes that achieve average crystal grain sizes of 2 μm or less. These parameter-modified processing methods extend the fatigue life to one million cycles while managing processing complexity through systematic process design.
Solution Approach 2:
The patent applies preliminary action by performing crystal grain refinement through supercool rolling before final wire drawing and forming operations. This preliminary structural preparation ensures the material possesses the required fatigue resistance from the outset, simplifying subsequent processing steps.
4Reliability
If the conductive material is designed for high fatigue resistance, then it can withstand one million cycles, but the flexibility may be compromised
Solution Approach 1:
The patent employs composite materials by dispersing nanoparticles (0.1-20 mass%) within the metal matrix. This composite structure provides crack deflection and arrest mechanisms that enhance fatigue resistance to one million cycles while maintaining material flexibility through the ductile metal matrix.
Solution Approach 2:
The patent applies local quality by creating heterogeneous microstructures with regions of refined crystal grains (2 μm or less) and nanoparticle distributions. This local structural variation provides crack resistance in critical areas while maintaining overall material flexibility and ductility.
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 material is resistant to one million cycles of dynamic driving, preventing wire or cable breakage and improving reliability and maintenance efficiency in robotic and automotive applications.
Implementation Method 1
when the generated cracks grow, the cracks can frequently come into collision with the crystal grains. By this, each growth direction of the cracks is changed. At the same time, divarications of the cracks are promoted, thereby reducing a growth rate of the cracks
Implementation Method 2
a method of rapid rate sintering (e.g., plasma discharge sintering, etc.) metal powders crushed to be 2 μm or less in average
Implementation Method 3
a processing method such as a supercool rolling (including drawing) and a differential speed rolling
Implementation Method 4
a miniaturizing method, in which an alternating current and a direct current magnetic field are applied to a solidifying metal (a metal under being solidified) and thereby electromagnetic oscillations are given to the solidifying metal
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(C)
AI summary
A flexible conductive material and a cable using the same, being resistant to one million times or more of dynamic driving and particularly suitable for wiring robots or automobiles. An average crystal grain size of crystal grains 20 forming a metal texture of a base material is 2 µm or less, in which the crystal grains 20 being 1 µm or less are included at least 20% or more in a cross sectional ratio. Also, it is preferable to include 0.1 mass% to 20 mass% of nanoparticles 22.