Ni-Fe Alloy Strain Gage High Gauge Factor
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Solution Overview
Problem
Existing metal resistance strain gages typically have a gage factor (GF) of 4 or less, limiting their ability to measure low levels of strain with high signal-to-noise ratio, and available high-GF options are either non-metallic, brittle, or thermally sensitive.
Innovation Solution
A metal resistance strain gage with a composition of approximately 63% to 84% Ni and 16% to 37% Fe, preferably 75% Ni and 25% Fe, utilizing a Ni-Fe alloy in the L1 2 region of the NiFe phase diagram, combined with cold working and annealing, and optionally alloying components like manganese, tungsten, or chromium, to achieve a gage factor of 5 or greater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metal resistance strain gages are used, then the gage factor is limited to 4 or less, but the manufacturing process is simple and materials are readily available
Solution Approach 1:
The patent changes the chemical composition parameters of the metal alloy, specifically using a Ni-Fe alloy with 63-84% Ni and 16-37% Fe, to achieve a gage factor greater than 5. This compositional parameter change enables higher measurement precision while maintaining metal resistance strain gage characteristics
Solution Approach 2:
The patent creates a composite alloy system combining nickel and iron in specific proportions to achieve enhanced gage factor performance. The Ni-Fe composite material provides both the desired high gage factor (>5) and maintains the advantages of metal materials over non-metal alternatives
2Measurement precision
If non-metal resistance strain gages are used to achieve GF greater than 4, then the gage factor increases, but the material becomes brittle and requires careful handling
Solution Approach 1:
The patent changes the material phase parameter by selecting specific Ni-Fe alloy compositions that correspond to the L12 region in the phase diagram, which provides both high gage factor and metallic ductility, avoiding the brittleness of non-metal alternatives
Solution Approach 2:
The patent uses a metal composite alloy (Ni-Fe) instead of non-metallic composites, achieving high gage factor while maintaining the mechanical robustness, flexibility, and reliability characteristic of metallic materials
3Measurement precision
If conventional metal alloys are used, then the material is easy to manufacture, but the gage factor remains at 4 or less
Solution Approach 1:
The patent specifies precise compositional parameters (63-84% Ni, 16-37% Fe) that correspond to the L12 phase region, enabling achieving GF>5 through controlled alloy composition while maintaining manufacturability through established metalworking processes
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 solution provides strain gages with a gage factor greater than 5, enhancing signal-to-noise ratio and enabling measurement of low strain levels with improved robustness and stability, while maintaining thermal and corrosion resistance.
Implementation Method 1
combined with cold working and annealing
Implementation Method 2
combined with cold working and annealing
Implementation Method 3
The amount of strain is determined on basis of the change in the electrical resistance of an electrical circuit in the strain gage
Data Source
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AI summary
A metal resistance strain gage with a high gage factor is provided. The electrical resistance strain gage includes a strain sensitive metallic element and has a chemical composition on a weight basis of approximately 63% to 84% Ni and approximately 16% to 37% Fe and a gage factor greater than 5.