Thomas P. Kieffer
Research Subjects
Thomas P. Kieffer has a total of 1 co-authors. Here are the top co-authors by number of shared publications:
- Kara Peters
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA
1 shared publication
Latest Publications
- 1 January 2026
- Published by Rzeszow University of Technology in Advances in Mechanical and Materials Engineering
- Vol. 43, 239-251
Analysis of Transverse Sensitivity of Foil Strain Gage
This paper provides an analysis of the transverse sensitivity of a strain gage made with cold rolled, Cu-Ni foil (constantan) by examining the individual contributions of the grid lines and end loops of the strain gage. The analysis utilizes two types of finite element models. Two dimensional models of the electrical current flow through the grid lines and end loops are used to determine the electrical resistance of each component. Three dimensional models of the strain gage attached to a rigid substrate subjected to transverse loading are used to determine the surface strain in each component. Results of both models are combined to determine strain gage transverse sensitivity - replicating standards for physical measurement of transverse sensitivity. Several end loop configurations are considered including geometry (rectangular, curved, and H-shape); size (length and width), and foil material property (modulus of elasticity and electrical resistivity). The factors contributing most to transverse sensitivity of the strain gage are the electrical resistance and surface strain in the transverse direction of the end loops. Good correlation is found between analytical model results and physical test results.
- 1 January 2026
- Published by Rzeszow University of Technology in Advances in Mechanical and Materials Engineering
- Vol. 43, 239-251
Analysis of Transverse Sensitivity of Foil Strain Gage
This paper provides an analysis of the transverse sensitivity of a strain gage made with cold rolled, Cu-Ni foil (constantan) by examining the individual contributions of the grid lines and end loops of the strain gage. The analysis utilizes two types of finite element models. Two dimensional models of the electrical current flow through the grid lines and end loops are used to determine the electrical resistance of each component. Three dimensional models of the strain gage attached to a rigid substrate subjected to transverse loading are used to determine the surface strain in each component. Results of both models are combined to determine strain gage transverse sensitivity - replicating standards for physical measurement of transverse sensitivity. Several end loop configurations are considered including geometry (rectangular, curved, and H-shape); size (length and width), and foil material property (modulus of elasticity and electrical resistivity). The factors contributing most to transverse sensitivity of the strain gage are the electrical resistance and surface strain in the transverse direction of the end loops. Good correlation is found between analytical model results and physical test results.
The effect of short range order on the thermal output and gage factor of Ni3FeCr strain gages
The ability of alloy 70Ni‐27.5Fe‐2.5Cr to form an ordered crystalline structure upon application of elevated temperature and the resulting effects on a variety of physical properties such as magnetism, strength, electrical resistance, and specific heat are well known. This paper demonstrates that strain gages made with 70Ni‐27.5Fe‐2.5Cr foil with an ordered crystalline structure have both high gage factors and high thermal outputs. The thermal output for strain gages made of 70Ni‐27.5Fe‐2.5Cr foil is demonstrated to be about 1,374 μΩ/Ω/K. The gage factor is nonlinear ranging in magnitude from about 5.0 to 3.6 for applied strains of 300 and 1,300 μE, respectively. The magnitude of gage factor and thermal output correspond with transformation of the crystalline structure from a state of disorder to a state of order. Comparisons to strain gages made with 36Ni‐57Fe‐7Cr foil are provided because of its use in the manufacturing of metal foil strain gages and their demonstrated high gage factors and high thermal outputs. Practical application for 70Ni‐27.5Fe‐2.5Cr strain gages is demonstrated by dead‐weight loading of shear‐beam load cells at low applied strain levels to minimise the effect of nonlinear gage factor; and Wheatstone bridge cancellation of high thermal output.
The effect of short range order on the thermal output and gage factor of Ni3FeCr strain gages
The ability of alloy 70Ni‐27.5Fe‐2.5Cr to form an ordered crystalline structure upon application of elevated temperature and the resulting effects on a variety of physical properties such as magnetism, strength, electrical resistance, and specific heat are well known. This paper demonstrates that strain gages made with 70Ni‐27.5Fe‐2.5Cr foil with an ordered crystalline structure have both high gage factors and high thermal outputs. The thermal output for strain gages made of 70Ni‐27.5Fe‐2.5Cr foil is demonstrated to be about 1,374 μΩ/Ω/K. The gage factor is nonlinear ranging in magnitude from about 5.0 to 3.6 for applied strains of 300 and 1,300 μE, respectively. The magnitude of gage factor and thermal output correspond with transformation of the crystalline structure from a state of disorder to a state of order. Comparisons to strain gages made with 36Ni‐57Fe‐7Cr foil are provided because of its use in the manufacturing of metal foil strain gages and their demonstrated high gage factors and high thermal outputs. Practical application for 70Ni‐27.5Fe‐2.5Cr strain gages is demonstrated by dead‐weight loading of shear‐beam load cells at low applied strain levels to minimise the effect of nonlinear gage factor; and Wheatstone bridge cancellation of high thermal output.