Electrical Contact Spring Material Tuning for Stress Relaxation Resistance
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Solution Overview
Problem
Existing electrical contact springs used in high-temperature environments face challenges in maintaining spring reaction force due to stress relaxation phenomena, necessitating a simple method to achieve both improved spring reaction force and stress relaxation resistance.
Innovation Solution
An electrical contact spring with a metallic material where the S/Y ratio, derived from the Voce equation, is controlled between 1.2 and 2.5, optimizing the balance between elastic and plastic regions to enhance spring load and stress relaxation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional copper alloy materials are used in high-temperature environments, then the spring structure can maintain contact by reaction force, but the reaction force decreases due to stress relaxation phenomenon
Solution Approach 1:
The patent applies parameter changes by controlling the S/Y ratio (maximum true stress to elastic limit stress ratio) within a specific range of 1.05 to 1.30. This parameter optimization allows the spring to maintain both high reaction force and stress relaxation resistance in high-temperature environments, resolving the contradiction between strength and reliability.
Solution Approach 2:
The patent employs composite materials by using a copper-based alloy with specific compositional ranges: Cr (0.10-0.50%), Ti (0.005-0.50%), and Si (0.005-0.20%). This multi-element composition creates a material that simultaneously achieves high strength, good conductivity, and excellent stress relaxation resistance, addressing both the spring reaction force and reliability requirements.
2Strength
If alloy components and internal structure are adjusted to improve spring reaction force and stress relaxation resistance, then performance is enhanced, but many experiments are required and the process becomes complex
Solution Approach 1:
The patent simplifies the optimization process by identifying a critical parameter - the S/Y ratio - and specifying its optimal range (1.05-1.30). By focusing on this single parameter along with defined compositional ranges, the patent reduces the complexity of material optimization while still achieving both high spring reaction force and stress relaxation resistance.
Solution Approach 2:
The patent replaces extensive experimental trial-and-error with a theoretical framework based on the Voce equation and S/Y ratio analysis. This substitution of mechanical experimentation with mathematical modeling and parameter optimization significantly reduces the number of experiments required while maintaining optimization effectiveness.
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 electrical contact spring achieves both excellent spring load and stress relaxation resistance by controlling the S/Y ratio, ensuring effective performance in high-temperature environments.
Implementation Method 1
high voltage terminals having a spring structure and keeping contact by reaction force of the spring
Implementation Method 2
when such high voltage terminals are used in a high-temperature environment, the reaction force of the spring may decrease due to a stress relaxation phenomenon
Data Source
AI summary
An electrical contact spring includes a metallic material, wherein S/Y is 1.2 or more and 2.5 or less when a vicinity of a boundary between an elastic region and a plastic region in a true stress−true strain curve of the metallic material is approximated using the Voce equation expressed in equation σ=S−(S−Y)exp−cε, where S is a maximum value of true stress σ of the metallic material, Y is elastic limit stress of the metallic material, and c is a constant related to logarithmic plastic strain ε of the metallic material.