Flat Conductor Wire Rounded Corners Prevent Cracking
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Solution Overview
Problem
Related art flat conductor wires made of aluminum tend to crack when bent due to locally applied stress at the corner portions, especially when routed in vehicles where space-saving designs lead to flat or rectangular cross-sections.
Innovation Solution
A flat conductor wire with a cross-section having rounded corner portions, where the radius of curvature is equal to or greater than one fourth of the thickness, and a width that satisfies specific elongation conditions to prevent cracking during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the flat conductor has sharp corner portions to maintain a rectangular cross-section for space-saving routing, then the area utilization is improved, but stress concentration occurs at the corners during bending, leading to cracks
Solution Approach 1:
The corner portions of the flat conductor cross-section are rounded with a radius of curvature R satisfying 0.05t ≤ R < t/4, where t is the thickness. This curvature eliminates sharp corners that concentrate stress during bending, preventing crack initiation while maintaining space-efficient routing capabilities
2Productivity
If the flat conductor width is increased to reduce the number of wires, then the routing efficiency is improved, but the stress during bending increases, making cracks more likely
Solution Approach 1:
The width-to-thickness ratio W/t is controlled to satisfy 0.1 < W/t ≤ 60ε/(1-ε), where ε is uniform elongation. This parameter optimization allows wider conductors for better routing efficiency while maintaining stress levels below crack initiation thresholds through appropriate dimensional ratios
3Reliability
If the radius of curvature at corner portions is increased to reduce stress concentration, then crack resistance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The radius of curvature R is set to satisfy 0.05t ≤ R < t/4, providing sufficient corner rounding to eliminate stress concentration without requiring excessive manufacturing precision. This partial rounding approach achieves crack prevention while remaining feasible with standard manufacturing tolerances
Data Source
AI summary
A flat conductor wire includes a flat conductor made of aluminum containing inevitable impurities. A cross section of the flat conductor orthogonal to a longitudinal direction of the flat conductor has a rounded corner portion, a radius of curvature of the corner portion being equal to or greater than one fourth of a thickness of the cross section of the flat conductor. A width of the cross section of the flat conductor is equal to or smaller than 60ε/(1−ε), ε being a uniform elongation of the flat conductor.