Investigation of Stress‐Strain Relations of Metal Wires by Electrical Resistance Changes

1952 ◽  
Vol 23 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Irwin Vigness
Keyword(s):  
Electrical Resistance ◽  
Stress Strain ◽  
Metal Wires

scholarly journals Theoretical and Numerical Study on Electrical Resistivity Measurement of Cylindrical Rock Core Samples Using Perimeter Electrodes

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4382
Author(s):  
Ji-Won Kim ◽  
Chang-Ho Hong ◽  
Jin-Seop Kim ◽  
Song-Hun Chong
Keyword(s):  
Numerical Simulation ◽  
Electrical Resistivity ◽  
Hydraulic Conductivity ◽  
Lower Bound ◽  
Electrical Resistance ◽  
Equipotential Surface ◽  
Theoretical Equation ◽  
Simulation Tool ◽  
Stress Strain ◽  
Core Samples

The estimation of hydraulic and mechanical properties of bedrock is important for the evaluation of energy-related structures, including high-level nuclear waste repositories, hydraulic fracturing wells, and gas-hydrate production wells. The hydraulic conductivity and stress–strain curves of rocks are conventionally measured through laboratory tests on cylindrical samples. Both ASTM standards for hydraulic conductivity and compressive strength involve the use of the planar bases of a cylindrical sample. Hence, an alternative test method is required for the simultaneous measurement of hydraulic conductivity and stress–strain curves. This study proposes a novel electrical resistivity estimation method using two perimeter electrodes for the estimation of hydraulic properties. The theoretical background for the perimeter electrode setup is derived and the COMSOL MultiPhysics® finite element numerical simulation tool is employed to verify the derived theoretical equation. The accuracy of the numerical simulation tool is first validated by simulating the ASTM standard testing method for electrical resistivity. The electrical resistance values derived from the theoretical equation and numerical simulation are compared for different electrical resistivity and electrode radius. The assumed equidistant, circular equipotential surface results in a theoretical lower bound for the measured electrical resistance in the cylindrical specimen. The introduction of a phenomenological distortion factor to correct for the theoretical equipotential surface results in a good fit with the numerical simulation results. The effects of electrode length and equivalent strap electrodes were investigated to assess the applicability of the suggested method for laboratory testing. Consequently, this study presents an effective alternative theoretical assessment method for the lower bound electrical resistivity of cylindrical rock core samples under confining conditions when the installation of base electrodes is infeasible.

Cure Monitoring and Stress-Strain Sensing of Single-Carbon Fiber Composites by the Measurement of Electrical Resistance

2005 ◽  
Vol 297-300 ◽  
pp. 676-684 ◽  
Author(s):  
Sang Il Lee ◽  
Dong Jin Yoon ◽  
Seung Seok Lee ◽  
Joung Man Park
Keyword(s):  
Residual Stress ◽  
Carbon Fiber ◽  
Electrical Resistance ◽  
Fiber Composites ◽  
Curing Temperature ◽  
Fiber Axis ◽  
Carbon Fiber Composites ◽  
Strain Sensing ◽  
Stress Strain ◽  
Cure Monitoring

Cure monitoring and stress-strain sensing of single-carbon fiber composites were nondestructively evaluated by the measurement of electrical resistance. The difference of electrical resistance before and after curing increased highest when gauge length of the specimen was the smallest. As curing temperature increased, the electrical behavior of steel fiber was different from that of semi-conductive carbon and SiC fibers. Residual stress built in the fiber was the highest at the fiber axis direction. Whereas residual stress built in the matrix was relatively high at the fiber circumference and radius directions. Residual stress calculated from the experiment was consistent with the results from the finite element analysis (FEA). The strain at low curing temperature was larger than that of higher temperature until the load reached maximum value. The apparent modulus of the electrodeposited composites was higher than that of the untreated composites due to the improved interfacial shear strength (IFSS). The electrical resistance was responded quantitatively with stress-strain behavior during the test. Electrical resistance measurement can be feasible nondestructive techniques to evaluate cure monitoring and stress-strain sensing in the conductive fiber composites.

Advances in ultramicrotomy for physical sciences applications

1993 ◽  
Vol 51 ◽  
pp. 710-711
Author(s):  
G. McMahon ◽  
T. Malis
Keyword(s):  
Particle Surface ◽  
Zeolite Catalysts ◽  
Physical Sciences ◽  
Pull Out ◽  
Large Particles ◽  
Novel Applications ◽  
Metal Wires ◽  
Frequent Problem ◽  
Specific Orientation ◽  
Diamond Knife

As with all techniques which are relatively new and therefore underutilized, diamond knife sectioning in the physical sciences continues to see both developments of the technique and novel applications.Technique Developments Development of specific orientation/embedding procedures for small pieces of awkward shape is exemplified by the work of Bradley et al on large, rather fragile particles of nuclear waste glass. At the same time, the frequent problem of pullout with large particles can be reduced by roughening of the particle surface, and a proven methodology using a commercial coupling agent developed for glasses has been utilized with good results on large zeolite catalysts. The same principle (using acid etches) should work for ceramic fibres or metal wires which may only partially pull out but result in unacceptably thick sections. Researchers from the life sciences continue to develop aspects of embedding media which may be applicable to certain cases in the physical sciences.

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