scholarly journals Experimental Assessment of the Equivalent Strain Rate for an Instrumented Charpy Test

2016 ◽  
Vol 121 ◽  
pp. 165 ◽  
Author(s):  
Enrico Lucon
Keyword(s):  
Strain Rate ◽  
Equivalent Strain ◽  
Charpy Test ◽  
Experimental Assessment ◽  
Equivalent Strain Rate

scholarly journals An An Analysis of Strain Rate Distribution Using Streamline Model and A Quick Stop Device in Metal Cutting

2019 ◽  
Vol 22 (2) ◽  
pp. 136-142
Author(s):  
Osama Ali Kadhim ◽  
Fathi A. Alshamma
Keyword(s):  
Strain Rate ◽  
Chip Formation ◽  
Metal Cutting ◽  
Equivalent Strain ◽  
Element Analysis ◽  
Rate Distribution ◽  
Equivalent Strain Rate ◽  
Cumulative Plastic Strain ◽  
Cutting Speeds ◽  
Strain Rate Distribution

In this paper, a quick stop device technique and the streamline model were employed to study the chip formation in metal cutting. The behavior of chip deformation at the primary shear zone was described by this model. Orthogonal test of turning process over a workpiece of the 6061-T6 aluminum alloy at different cutting speeds was carried out. The results of the equivalent strain rate and cumulative plastic strain were used to describe the complexity of chip formation. Finite element analysis by ABAQUS/explicit package was also employed to verify the streamline model. Some behavior of formation and strain rate distribution differs from the experimental results, but the overall trend and maximum results are approximately close. In addition, the quick stop device technique is described in detail. Which could be used in other kinds of studies, such as the metallurgical observation.

The Research and Optimization of a 6061 Aluminum Rectangular Tube Extrusion Using Porthole Dies According to the Parameter of Split Ratio

2012 ◽  
Vol 268-270 ◽  
pp. 391-395
Author(s):  
Shu Mei Lou ◽  
Guo Liang Xing ◽  
Sheng Xue Qin ◽  
Lin Jing Xiao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Strain Rate ◽  
Equivalent Strain ◽  
Tube Extrusion ◽  
Split Ratio ◽  
Die Structure ◽  
Rectangular Tube ◽  
Equivalent Strain Rate ◽  
Deform 3D

Extrusions of a 6061 aluminum rectangular tube using porthole dies with three assigned different split ratios were simulated by the software DEFORM-3D based on Finite element method. The distributions of stress, equivalent strain rate, temperature, velocity of the deformation materials and the mold stress during the three extrusion processes were obtained, respectively. By analyzing the distributions of those fields, the most reasonable split ratio is selected and then the die structure is modified.

scholarly journals In Situ Stress Effects on Smooth Blasting: Model Test and Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Renshu Yang ◽  
Shizheng Fang ◽  
Aiyun Yang ◽  
Huanzhen Xie ◽  
Liyun Yang
Keyword(s):  
Strain Rate ◽  
Confining Pressure ◽  
Equivalent Strain ◽  
In Situ Stress ◽  
Image Correlation ◽  
Propagation Mechanism ◽  
Equivalent Strain Rate ◽  
Ground Stress ◽  
Smooth Blasting

Most of the roadway excavation is completed by the drilling and blasting method. With the increase of buried depth, the existence of ground stress will generate a significant impact on the rock blasting, especially on the smooth blasting. In this study, self-made homogeneous similar materials and digital image correlation methods were used to determine influence of ground stress on the smooth blasting under uniform explosive charge parameters and various in situ stress conditions. The results show that the crack outline after blasting changes from zigzag to straight in shape, and multifractal calculation results of the rupture section between blastholes show that the fracture surface becomes flatter as ground stress increases, which is conducive to roadway formation. The strain and equivalent strain rate obviously decrease as the distance between the blasthole and measuring points increases. The same trend occurs as the confining pressure goes up. Meanwhile, a postexplosion acoustic wave test indicates that confining pressure inhibits damage of the retained rock, which is consistent with strain and equivalent strain rate results. Finally, we discussed the crack propagation mechanism of rock in smooth blasting.

Chip Prediction in Finite Element Modeling of the Chip Formation Process during Cutting Ti-6Al-4V Alloy

2011 ◽  
Vol 418-420 ◽  
pp. 1148-1153
Author(s):  
Yu Gang Ye
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Strain Rate ◽  
Equivalent Stress ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Equivalent Strain ◽  
Forming Process ◽  
Serrated Chip ◽  
Equivalent Strain Rate

Based on the theory of adiabatic shearing, the forming process of a serrated chip during cutting Ti-6Al-4V titanium alloy was analyzed by comparing the results of the finite element (FE) calculations with the cutting experiments. The results show that the equivalent stress, equivalent strain and equivalent strain rate within a ribbon chip varied a little, but they varied a lot within a serrated chip. Moreover, the effect of cutting speed on equivalent strain rate is greater than on the equivalent stress and equivalent strain within a serrated chip. It can also be found from the results that there are small gaps between the simulation results and experimental results for the chip thickness and sawtooth height, while there is a big gap for saw-tooth pitch. This means that the simulation model has its limitations for accurate simulation of micro-geometric shape of a chip during cutting the Ti-6Al-4V titanium alloy, and further research remains to be done.

Steady-State Creep Deformations and Stresses in FGM Rotating Thick Cylindrical Pressure Vessels

2014 ◽  
Vol 31 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M. Z. Nejad ◽  
Z. Hoseini ◽  
A. Niknejad ◽  
M. Ghannad
Keyword(s):  
Steady State ◽  
Strain Rate ◽  
Equivalent Strain ◽  
Pressure Vessels ◽  
Functionally Graded ◽  
Steady State Creep ◽  
Graded Materials ◽  
Equivalent Strain Rate ◽  
Closed Form Analytical Solution ◽  
Creep Deformations

AbstractIn the present study, a closed-form analytical solution for the steady-state creep stresses of rotating thick cylindrical pressure vessels made of functionally graded materials (FGMs) is carried out. Norton's law governs the creep response of the material. Exact solutions for stresses and strain rate are obtained under the plane strain condition. How different material parameters involved in Norton's law affect radial and circumferential stresses together with the equivalent strain rate in rotating thick-walled cylindrical vessels under internal pressure is investigated. The result obtained shows that the property of FGMs has a significant influence on the equivalent creep strain rate and stresses distributions along the radial direction.

AZ31 Magnesium Alloy Parameters Identification through Inverse Analysis at 713 K

2012 ◽  
Vol 504-506 ◽  
pp. 643-646 ◽  
Author(s):  
Gillo Giuliano
Keyword(s):  
Strain Rate ◽  
Power Law ◽  
Inverse Analysis ◽  
Constant Pressure ◽  
Az31 Alloy ◽  
Equivalent Strain ◽  
Strain Rate Range ◽  
Displacement Curve ◽  
Material Constants ◽  
Equivalent Strain Rate

This paper introduces a fast and accurate procedure for determining the constants of magnesium AZ31 alloy at 713 K. The material behaviour is modelled by means of the power law relationship between the equivalent flow stress, the equivalent strain and the equivalent strain-rate within a narrow equivalent strain-rate range. Bulging tests were carried out in isothermal conditions (713 K) and at constant pressure in order to determine the material constants. It is necessary to evaluate the displacement and the thickness evolutions at the dome apex of the metal sheet. The time-displacement curve was obtained by laser measurements whereas a large number of bulging tests, interrupted at preset time intervals, were carried out to evaluate the thickness. The thickness was measured directly using a two-digit micrometer. The material constants, m, n and K were obtained in the power law relationship by means of constant pressure bulging tests coupled with the use of an inverse analysis technique. The results of comparison between experimental and numerical tests are shown and they indicate that the material constants can be accurately evaluated.

Velocity Gradients and the Evolution of Material Properties in a Narrow Layer near Surfaces of High Friction in Metal Forming Processes

2012 ◽  
Vol 504-506 ◽  
pp. 549-554 ◽  
Author(s):  
Sergei Alexandrov ◽  
Yeau Ren Jeng
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Material Properties ◽  
Metal Forming ◽  
Equivalent Strain ◽  
Experimental Results ◽  
Material Layer ◽  
Narrow Layer ◽  
Velocity Gradients ◽  
Equivalent Strain Rate

Theoretical solutions for several rigid plastic models used to describe plastic flow in metal forming processes are singular in the vicinity of maximum friction surfaces. In particular, velocity gradients and the equivalent strain rate approach infinity near such surfaces. Such singular behavior can be excluded from consideration by choosing another friction law or material model. However, a different approach is proposed in the present paper. The starting point of this approach is that many experiments show that velocity gradients are very high in the vicinity of surfaces of high friction and that a narrow material layer is formed near such surfaces whose properties are very different from the properties in the bulk. Taking into account that the equivalent strain rate has a significant effect on the evolution of material properties, this experimental fact suggests that a theory based on the singular plastic solutions can be developed to describe the formation of the aforementioned material layer. In the present paper such a theory is proposed to describe the evolution of grain size. It is assumed that, in addition to the equivalent strain rate, the material spin has an effect of the evolution of grain size. It is then shown that the solutions for the material spin are singular as well. The interrelation between the present theory and strain gradient theories of plasticity is discussed. It is shown that it is necessary to account for the strain rate gradient to propose a more adequate theory to deal with the material flow near surfaces of high friction. Some experimental results on the formation of the narrow layer of ultra-fine grains in the vicinity of the fraction surface in extrusion are presented. An illustrative example to relate these experimental results and the new theory is given.

scholarly journals An Analytic Solution for an Expanding/Contracting Strain-Hardening Viscoplastic Hollow Cylinder at Large Strains and Its Application to Tube Hydroforming Design

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2161
Author(s):  
Lihui Lang ◽  
Sergei Alexandrov ◽  
Marina Rynkovskaya
Keyword(s):  
Strain Rate ◽  
Hollow Cylinder ◽  
Yield Criterion ◽  
Tube Hydroforming ◽  
Equivalent Strain ◽  
Large Strains ◽  
Flow Rule ◽  
Rigid Plastic ◽  
Equivalent Strain Rate ◽  
Pressure Independent

This paper presents a semi-analytic rigid/plastic solution for the expansion/contraction of a hollow cylinder at large strains. The constitutive equations comprise the yield criterion and its associated flow rule. The yield criterion is pressure-independent. The yield stress depends on the equivalent strain rate and the equivalent strain. No restriction is imposed on this dependence. The solution is facilitated using the equivalent strain rate as an independent variable instead of the polar radius. As a result, it reduces to ordinary integrals. In the course of deriving the solution above, the transformation between Eulerian and Lagrangian coordinates is used. A numerical example illustrates the solution for a material model available in the literature. A practical aspect of the solution is that it readily applies to the preliminary design of tube hydroforming processes.

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