Rate of Strain Effect in Metal Cutting

1963 ◽  
Vol 85 (4) ◽  
pp. 335-337 ◽  
Author(s):  
P. L. B. Oxley
Keyword(s):  
Yield Stress ◽  
Metal Cutting ◽  
Strain Curve ◽  
Strain Effect ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Initial Yield Stress ◽  
Shear Yield ◽  
Experimental Cutting ◽  
Plastic Stress

An analysis of the cutting process is presented which in conjunction with experimental cutting data enables the initial shear yield stress and the mean slope of the corresponding plastic stress-strain curve to be calculated for different rates of strain. It is found that for an increase in the strain rate the initial yield stress increases and the slope of the plastic stress-strain curve decreases.

Increasing Initial Yield Stress at Small Length Scales

2003 ◽  
Vol 778 ◽  
Author(s):  
I. Spary ◽  
A.J. Bushby ◽  
N.M. Jennett ◽  
G.M. Pharr
Keyword(s):  
Yield Stress ◽  
Size Effects ◽  
Strain Curve ◽  
Compression Tests ◽  
Small Length ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Length Scales ◽  
Initial Yield Stress ◽  
Initial Yield

AbstractPlasticity size effects are well known in a wide variety of situations where either the material microstructure or a strain gradient exist at small length scales. Several theories have been developed to describe changes in the work hardening behaviour under these conditions but none that predict a change in the initial yield stress. Careful studies by Chaudhri et al and Pharr et al have unambiguously demonstrated plasticity size effects in ductile metals. In those experiments indentation stress-strain curves were generated using spherical indenters with radii ranging from a few micrometres to several hundred micrometres and these were compared to data from conventional compression tests. Large radius indenters produced a single indentation stress-strain curve independent of indenter radius with a power law hardening coefficient equivalent to that in the compression tests. However, the indentation stress-strain curves appeared at progressively higher pressures for smaller radius indenters. In this paper we model those experiments using finite element analysis methods. By inputting the uniaxial stress-strain data to the model (effectively, using von Mises criterion) the indentation stress-strain curves for the macro size indenters are reproduced. However, the model shows no length scale dependence for any size of indenter. We show that by off-setting the compression stress-strain curve by increasing the initial yield stress and inputting this data to the model, the indentation behaviour of the smaller radius indenters can be modelled. The increase in yield stress with decreasing indenter radius is demonstrated for Cu, Wand Ir and is shown to be consistent with the initiation of yielding over a finite volume.

scholarly journals The mechanism of plastic deformation of crystals. Part II.—Comparison with observations

1934 ◽  
Vol 145 (855) ◽  
pp. 388-404 ◽  
Keyword(s):  
Elastic Limit ◽  
Large Range ◽  
Strain Curve ◽  
Pure Metal ◽  
The Other ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Essential Characteristic ◽  
Small Strains ◽  
Plastic Stress

According to the theory give in Part I the strain-hardening or plastic stress strain curve for a pure metal should be parabola. In figs. 1, 2, and 3, Part I, Parabolas are drawn, the parameters being chosen so that they lie as close as possible to the points which represent actual observations. It will be seen that for aluminium and gold the agreement is good. For a single crystal of copper the agreement is not good, but, on the other hand, the plastic stress-strain curve for polycrystalline specimens of copper which is shown in fig. 1 is very nearly parabolic over a large range. The observations for iron seem to show that there is a small finite elastic limit, i. e. , S T may be finite. Parabolas corresponding with the existence of a small elastic limit and with no elastic limit have been drawn. It seems that the observed points lie rather closer to the former curve. In any case, the observed curves have the essential characteristic of the theoretical ones that they are very steep at small strains, but get less and less steep as the strain increases.

Strain-Rate Effects on Constitutive Behavior of Sn3.8-Ag0.7-Cu Lead-Free Solder

2009 ◽  
Author(s):  
Kok Ee Tan ◽  
John H. L. Pang
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Strain Curve ◽  
Tensile Tests ◽  
Lead Free ◽  
Indentation Hardness ◽  
Strain Rates ◽  
Test Results ◽  
Stress Strain Curve ◽  
Stress Strain

In this paper, the strain-rate dependent mechanical properties and stress-strain curve behavior of Sn3.8Ag0.7Cu (SAC387) solder is presented for a range of strain-rates at room temperature. The apparent elastic modulus, yield stress properties and stress-strain curve equation of the solder material is needed to facilitate finite element modeling work. Tensile tests on dog-bone shaped bulk solder specimens were conducted using a non-contact video extensometer system. Constant strain-rate uni-axial tensile tests were conducted over the strain-rates of 0.001, 0.01, 0.1 and 1 (s−1) at 25°C. The effects of strain-rate on the stress-strain behavior for lead-free Sn3.8Ag0.7Cu solder are presented. The tensile yield stress results were compared to equivalent yield stress values derived from nano-indentation hardness test results. Constitutive models based on the Ramberg-Osgood model and the Cowper-Symond model were fitted for the tensile test results to describe the elastic-plastic behavior of solder deformation behavior.

Molecular dynamics simulations of the effect of temperature and strain rate on the plastic deformation of body centred cubic iron nanowires

2021 ◽  
pp. 1-19
Author(s):  
Qian Wu ◽  
Yong Wang ◽  
Tao Han ◽  
Hongtao Wang ◽  
Laihui Han ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Strain Curve ◽  
Dislocation Slip ◽  
Stress Strain Curve ◽  
Stress Strain

Abstract The tensile tests of BCC Fe nanowires were simulated through molecular dynamics methods. The temperature and strain rate effects on the mechanical properties as well as the orientation-dependent plastic deformation mechanism were analyzed. For [001]-oriented BCC Fe nanowires, as the temperature increased, the yield stress and Young's modulus decreased. While the yield stress and Young's modulus increased as the strain rate increased. With the increase of temperature, when the temperature was less than 400 K, the twin propagation stress decreased dramatically, and then tended to reach a saturation value at higher temperatures. Under different temperatures and strain rates, the [001]-oriented Fe nanowires all deformed by twinning. The oscillation stage in the stress-strain curve corresponds to the process from the nucleation of the twin to the reorientation of the nanowire. For [110]-oriented Fe nanowires, the plastic deformation is dominated by dislocation slip. The independent events such as the nucleation, slip, and annihilation of dislocations are the causes of the unsteady fluctuations in the stress-strain curve. The Fe nanowires eventually undergo shear damage along the dominant slip surface.

Dynamic Constitutive Equations and Behaviour of Brass at High Strain Rates

1995 ◽  
Vol 209 (4) ◽  
pp. 287-293 ◽  
Author(s):  
L-Y Li ◽  
T C K Molyneaux
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Equations ◽  
High Strain ◽  
Strain Curve ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
High Strain Rates ◽  
Stress Strain

This paper presents an experimental study of the mechanical properties of brass at high strain rates. The brass tested is the copperzinc alpha-beta and beta two-phase alloy in the cold-worked state. Experiments were conducted using an extended tension split Hopkinson bar apparatus. It is found that, at lower strain rates, the stress-strain curve is smooth, exhibiting no well-defined yield stress, but at higher strain rates the stress-strain curve not only shows a well-defined yield stress but also displays a very pronounced drop in stress at yield. The flow stress is found to increase with increasing strain rate, but the increase is more significant for the yield stress than for the flow stress, showing that the yield stress is more sensitive to the strain rate than the flow stress away from the yield point. Based on the experimental results, empirical strain-rate-dependent constitutive equations are recommended. The suggested constitutive equations provide a reasonable estimate of the strain-rate-sensitive behaviour of materials.

Use of Chip Tension to Obtain a Stress-Strain Curve From Metal Cutting Tests

1963 ◽  
Vol 85 (4) ◽  
pp. 351-355 ◽  
Author(s):  
I. Finnie ◽  
J. Wolak
Keyword(s):  
Metal Cutting ◽  
Strain Curve ◽  
Commercial Purity ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Wide Range ◽  
Shear Strains ◽  
The Difference ◽  
Commercial Purity Aluminum

By pulling the chip at various angles during metal cutting, it has been possible to greatly decrease the shear strains and thus to obtain a wide range of shear strains with a single tool. Using this technique, stress-strain curves for commercial purity aluminum have been obtained at −320 deg F (78 deg K) and 68 deg F (293 deg K). These results lie above those obtained from compression tests on the same material and the difference is ascribed largely to strain rate. Limits are imposed on the chip-pulling technique by an instability which appears when the direction of pulling makes too great an angle with the tool face and by fracture.

scholarly journals Crack-Bridging Property Evaluation of Synthetic Polymerized Rubber Gel (SPRG) through Yield Stress Parameter Identification

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7599
Author(s):  
Jong-Yong Lee ◽  
Hyun-Jae Seo ◽  
Kyu-Hwan Oh ◽  
Jiang Bo ◽  
Sang-Keun Oh
Keyword(s):  
Yield Stress ◽  
Strain Curve ◽  
Strain Ratio ◽  
Curve Analysis ◽  
Cohesive Failure ◽  
Stress Strain Curve ◽  
Grout Injection ◽  
Stress Strain ◽  
Stress Point ◽  
Acrylic Epoxy

Yield stress parameter derivation was conducted by stress-strain curve analysis on four types of grout injection leakage repair materials (GILRM); acrylic, epoxy, urethane and SPRG grouts. Comparative stress-strain curve analysis results showed that while the yield stress point was clearly distinguishable, the strain ratio of SPRG reached up to 664% (13 mm) before material cohesive failure. A secondary experimental result comprised of three different common component ratios of SPRG was conducted to derive and propose an averaged yield stress curve graph, and the results of the yield stress point (180% strain ratio) were set as the basis for repeated stress-strain curve analysis of SPRGs of up to 15 mm displacement conditions. Results showed that SPRG yield stress point remained constant despite repeated cohesive failure, and the modulus of toughness was calculated to be on average 53.1, 180.7, and 271.4 N/mm2, respectively, for the SPRG types. The experimental results of this study demonstrated that it is possible to determine the property limits of conventional GILRM (acrylic, epoxy and urethane grout injection materials) based on yield stress. The study concludes with a proposal on potential application of GILRM toughness by finite element analysis method whereby strain of the material can be derived by hydrostatic pressure. Comparative analysis showed that the toughness of SPRG materials tested in this study are all able to withstand hydrostatic pressure range common to underground structures (0.2 N/mm2). It is expected that the evaluation method and model proposed in this study will be beneficial in assessing other GILRM materials based on their toughness values.

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