Effects of Plastic Strain on Mechanical and Electrical Conductivity Response of (100) Monocrystalline Copper

2020 ◽  
Vol 12 (7) ◽  
pp. 1004-1011
Author(s):  
Lijia Li ◽  
Dan Zhao ◽  
Xingdong Sun ◽  
Shunbo Wang ◽  
Yue Guo ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Elastic Modulus ◽  
Plastic Strain ◽  
Contact Area ◽  
Recovery Rate ◽  
Plastic Region ◽  
Maximum Load ◽  
Quantitative Relation ◽  
Total Work ◽  
Strain Sensing

The physical characteristics of material would be influenced by its stress states. In this paper, nanoindentation experiments with a maximum load of 100 mN and strain-sensitive resistance tests were conducted on (100) monocrystalline copper with tension-induced plastic strain to investigate the influences of plastic strain on mechanical and electrical characteristics. By theoretical and experimental analysis, indentation depth, elastic modulus, recovery rate of total work, contact area, pile-up and apparent hardness of the deformed and virgin material were obtained and the corresponding investigation was compared and analyzed. The experimental results revealed that under the same conditions, tensile pre-deformed material would like to generate more penetration depth to achieve the same load during indentation. As the plastic strain increased in the uniform plastic region, both the total and elastic indentation work increased, while the recovery rate of total work, contact area, apparent hardness, and elastic modulus decreased. Meanwhile, the contribution of plastic strain to electrical resistivity was also investigated. The quantitative relation between electrical resistivity and plastic strains was extracted from experiments. The understanding of the role of plastic strain in mechanical and electrical properties of monocrystalline copper would be helpful to the application in damage detection systems and strain sensing sensor.

scholarly journals Description of Residual Stress and Strain Fields in FGM Hollow Disc Subject to External Pressure

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 440 ◽  
Author(s):  
Stanislav Strashnov ◽  
Sergei Alexandrov ◽  
Lihui Lang
Keyword(s):  
Elastic Modulus ◽  
Plastic Strain ◽  
Yield Stress ◽  
Plastic Region ◽  
External Pressure ◽  
Plastic Strain Rate ◽  
Constant Thickness ◽  
Stress And Strain ◽  
Strain Fields ◽  
Tensile Yield Stress

Elastic/plastic stress and strain fields are obtained in a functionally graded annular disc of constant thickness subject to external pressure, followed by unloading. The elastic modulus and tensile yield stress of the disc are assumed to vary along the radius whereas the Poisson’s ratio is kept constant. The flow theory of plasticity is employed. However, it is shown that the equations of the associated flow rule, which are originally written in terms of plastic strain rate, can be integrated with respect to the time giving the corresponding equations in terms of plastic strain. This feature of the solution significantly facilitates the solution. The general solution is given for arbitrary variations of the elastic modulus and tensile yield stress along the radial coordinate. However, it is assumed that plastic yielding is initiated at the inner radius of the disc and that no other plastic region appears in the course of deformation. The solution in the plastic region at loading reduces to two ordinary differential equations. These equations are solved one by one. Unloading is assumed to be purely elastic. This assumption should be verified a posteriori. An illustrative example demonstrates the effect of the variation of the elastic modulus and tensile yield stress along the radius on the distribution of stresses and strains at the end of loading and after unloading. In this case, it is assumed that the material properties vary according to power-law functions.

A study of indentation work in homogeneous materials

2006 ◽  
Vol 21 (6) ◽  
pp. 1363-1374 ◽  
Author(s):  
Mengxi Tan
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Elastic Energy ◽  
Size Effects ◽  
Unit Volume ◽  
Plastic Work ◽  
Total Work ◽  
Indentation Size ◽  
Scaling Relationships ◽  
Homogeneous Materials

The work of indentation is investigated experimentally in this article. A method of using the elastic energy to extract the elastic modulus is proposed and verified. Two types of hardness related to the work of indentation are defined and examined: Hwtis defined as the total work required creating a unit volume of contact deformationand Hwp is defined as the plastic work required creating a unit volume of plastic deformation; experiments show that both hardness definitions are good choices for characterizing hardness. Several features that may provide significant insights in understanding indentation measurements are studied. These features mainly concern some scaling relationships in indentation measurements and the indentation size effects.

A Finite Element Based Study on the Elastic-Plastic Transition Behavior in a Hemisphere in Contact With a Rigid Flat

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
S. Shankar ◽  
M. M. Mayuram
Keyword(s):  
Finite Element ◽  
Contact Area ◽  
Plastic Material ◽  
Plastic Region ◽  
Real Contact Area ◽  
Real Contact ◽  
Perfectly Plastic ◽  
The Difference ◽  
Elastic Perfectly Plastic ◽  
Green Model

An axisymmetrical hemispherical asperity in contact with a rigid flat is modeled for an elastic perfectly plastic material. The present analysis extends the work (sphere in contact with a flat plate) of Kogut–Etsion Model and Jackson–Green Model and addresses some aspects uncovered in the above models. This paper shows the critical values in the dimensionless interference ratios (ω∕ωc) for the evolution of the elastic core and the plastic region within the asperity for different Y∕E ratios. The present analysis also covers higher interference ratios, and the results are applied to show the difference in the calculation of real contact area for the entire surface with other existing models. The statistical model developed to calculate the real contact area and the contact load for the entire surfaces based on the finite element method (FEM) single asperity model with the elastic perfectly plastic assumption depends on the Y∕E ratio of the material.

Electric Potential Drop Method for Evaluating Crack Initiation and Crack Propagation: The Help of FE Simulation

2019 ◽  
Author(s):  
Patrick Le Delliou
Keyword(s):  
Electrical Resistivity ◽  
Plastic Strain ◽  
Electric Potential ◽  
Thermal Conduction ◽  
Voltage Drop ◽  
Potential Drop ◽  
Metallic Materials ◽  
Ductile Tearing ◽  
Practical Applications ◽  
Plastic Case

Abstract The electric potential drop (EPD) method is a laboratory technique to monitor the initiation and the propagation of a crack, mainly in the field of fatigue research. It can also be used in fracture experiments, involving plasticity and large deformations. The size of a crack in a metallic member is predicted by applying a constant d.c. (direct current) or a.c. (alternating current) to the member and by measuring an increase in electric resistance due to the crack. Practically, several pairs of probes are attached to the specimen crossing over the crack and the voltage drop is measured periodically along the test. The main difficulty is to correlate the EPD changes to the crack extension. Thanks to the analogy between the thermal conduction problem and the electrical conduction problem, a classical thermo-mechanical finite element solver can be used to predict the EPD along a crack, given the electrical resistivity of the material, the current intensity and the geometry of the structure and of the crack. This technique works well for fatigue studies, where the structure remains elastic and whose shape is unchanged. However, in fracture experiments, the change in geometry and the possible effect of the plastic strain on electrical resistivity make the problem much more complex. The paper presents the principle of the EPD method, a work on the effect of the plastic strain on the electrical resistivity, FE computations for the elastic case (for fatigue pre-cracking) and for the plastic case (for ductile tearing experiments). Several practical applications will be presented on various metallic materials.

Effect of plastic strain and ductile damage on elastic modulus of multiphase steel and its impact on springback prediction

2019 ◽  
Author(s):  
Sebastian Münstermann ◽  
Yannik Sparrer ◽  
Yuan Yao ◽  
Junhe Lian ◽  
Rickmer Meya ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Plastic Strain ◽  
Ductile Damage ◽  
Multiphase Steel ◽  
Springback Prediction

scholarly journals Developing a Multi-Element Sensor to Non-Destructively Monitor Several Fundamental Parameters Related to Concrete Durability

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5607 ◽  
Author(s):  
Ming Jin ◽  
Yuefeng Ma ◽  
Haoyu Zeng ◽  
Jiaping Liu ◽  
Linhua Jiang ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Diffusion Coefficient ◽  
Steel Corrosion ◽  
Health Condition ◽  
Quantitative Relation ◽  
Corrosion Monitoring ◽  
Concrete Durability ◽  
Fundamental Parameters ◽  
Damage Degree ◽  
Critical Content

A design scheme of multi-element sensor which included electrical resistivity probes, multiple Cl− selective electrodes, and a steel corrosion monitoring system was proposed in this work. Embedding this multi-element sensor in concrete enables the real-time and non-destructive monitoring of internal electrical resistivity, free Cl− (Clf) contents in the concrete pore solution at different depths, and steel corrosion parameters. Based on the monitoring data obtained by the multi-element sensor, the freezing-thawing (F-T) damage degree, the Clf diffusion coefficient, the quantitative relation between F-T damage degree and Clf diffusion coefficient, the initiation period of steel corrosion, and the critical content related to steel corrosion are determined. To conclude, the multi-element sensor provides key durability parameters for the establishment of the Clf diffusion model, the assessment of health condition, and the prediction of service life of concrete under the coexistence of the F-T cycle and Cl−.

Material Properties of Thick Aluminum Coating Made by Cold Gas Dynamic Spray Deposition

2007 ◽  
Vol 345-346 ◽  
pp. 1097-1100
Author(s):  
Jae Chul Lee ◽  
Doo Man Chun ◽  
Sung Hoon Ahn ◽  
Caroline S. Lee
Keyword(s):  
Electrical Resistivity ◽  
Elastic Modulus ◽  
Cold Spray ◽  
Material Properties ◽  
Gas Dynamic ◽  
Macro Scale ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Scale Deposition ◽  
Cold Gas

Cold gas dynamic spray is a relatively new coating process by which coatings can be produced without significant heating during the process. Cold gas dynamic spray is conducted by powder sprayed using supersonic gas jet, and generally called the kinetic spray or cold spray. Its low process temperature can minimize the thermal stress and also reduce the deformation of the substrate. In this study, thick or macro scale deposition was studied while most researches on cold-spray have focused on micro scale coating. Measured material properties of macro scale deposition layer showed that elastic modulus and hardness were lower and electrical resistivity was higher than those of reference substrate material. The main causes of changed material properties were investigated by FE-SEM (Field Emission Scanning Electron Microscope) and EDS (Energy Dispersive X-ray Spectrometer) data. In this result, porous micro structure generated by imperfect plastic deformation might cause decrease in elastic modulus and hardness of the deposition layer by cold spray, and oxidized Al particles increased the electrical resistivity.

scholarly journals Sliding-induced adhesion of stiff polymer microfibre arrays. I. Macroscale behaviour

2008 ◽  
Vol 5 (25) ◽  
pp. 835-844 ◽  
Author(s):  
Jongho Lee ◽  
Carmel Majidi ◽  
Bryan Schubert ◽  
Ronald S Fearing
Keyword(s):  
Elastic Modulus ◽  
Contact Area ◽  
Shear Force ◽  
Contact Region ◽  
Pure Shear ◽  
Shear Loading ◽  
High Shear ◽  
Polypropylene Fibres ◽  
True Contact Area ◽  
True Contact

Gecko-inspired microfibre arrays with 42 million polypropylene fibres cm −2 (each fibre with elastic modulus 1 GPa, length 20 μm and diameter 0.6 μm) were fabricated and tested under pure shear loading conditions, after removing a preload of less than 0.1 N cm −2 . After sliding to engage fibres, 2 cm 2 patches developed up to 4 N of shear force with an estimated contact region of 0.44 cm 2 . The control unfibrillated surface had no measurable shear force. For comparison, a natural setal patch tested under the same conditions on smooth glass showed approximately seven times greater shear per unit estimated contact region. Similar to gecko fibre arrays, the synthetic patch maintains contact and increases shear force with sliding. The high shear force observed (approx. 210 nN per fibre) suggests that fibres are in side contact, providing a larger true contact area than would be obtained by tip contact. Shear force increased over the course of repeated tests for synthetic patches, suggesting deformation of fibres into more favourable conformations.

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