Nonisothermal Axisymmetric Forging

1986 ◽  
Vol 108 (4) ◽  
pp. 288-294 ◽  
Author(s):  
P. Dadras ◽  
P. R. Burte
Keyword(s):  
Thermal Analysis ◽  
Upper Bound ◽  
Total Power ◽  
Homogeneous State ◽  
Field Equations ◽  
Strain And Strain Rate ◽  
Upset Forging ◽  
Theoretical Predictions ◽  
Temperature Strain ◽  
Recorded Temperature

An approximate solution for nonisothermal upset forging is presented. A finite difference thermal analysis and an upper-bound deformation solution are used for this purpose. The thermal analysis is for a homogeneous state of strain, it ignores deformation heating, but accounts for all modes of heat flow during the transfer of the billet to the tooling and throughout the deformation. The upper-bound solution is based on admissible velocity field equations, the recorded temperature data from the thermal analysis, and constitutive equations for temperature, strain, and strain rate-dependence of flow stress. The size of the chilled zone is determined by minimization of total power for the deformation process. Theoretical predictions for load-displacement behavior and the size of the chilled zone are compared with the experimental results for 304 stainless and AISI 1042 steels.

An Analysis of Three-Dimensional Upset Forging of Regular Polygonal Blocks by Using the Upper-Bound Method

1987 ◽  
Vol 109 (2) ◽  
pp. 155-160 ◽  
Author(s):  
D. Y. Yang ◽  
J. H. Kim
Keyword(s):  
Velocity Field ◽  
Upper Bound ◽  
Pure Copper ◽  
Three Dimensional ◽  
Total Power ◽  
Total Power Consumption ◽  
Upset Forging ◽  
Theoretical Predictions ◽  
Forging Load ◽  
Good Agreement

A simple kinematically admissible velocity field for three-dimensional deformation in upset forging of regular polygonal blocks is proposed which takes into account the sidewise spread as well as the bulging along thickness. From the proposed velocity field the upper-bound load and the deformed configuration are determined by minimizing the total power consumption with respect to three chosen parameters. Experiments are carried out with annealed commercially pure copper at room temperature for different thicknesses, billet shapes and lubrication conditions. The theoretical predictions both in the forging load and the deformed configuration are in good agreement with the experimental results. It is thus shown that the velocity field proposed in this work can be conveniently used for the prediction of the forging load and deformation in the upset forging of regular polygonal blocks.

Analysis of Combined Backward-Forward Extrusion

1976 ◽  
Vol 98 (2) ◽  
pp. 438-445 ◽  
Author(s):  
B. Avitzur ◽  
W. C. Hahn ◽  
M. Mori
Keyword(s):  
Upper Bound ◽  
Process Parameter ◽  
Total Power ◽  
Deformation Region ◽  
Forward Flow ◽  
Forward Extrusion ◽  
Combined Flow ◽  
Dependent Parameter ◽  
Independent Process

The upper bound approach is used to analyze combined backward-forward extrusion. The deformation region is divided into five zones separated by planer and cylindrical surfaces of velocity discontinuities. The internal power of deformation and shear and friction losses are computed individually and summed. The pseudo-independent process parameter is the backward rate of flow with respect to which the total power of deformation is optimized. The optimal backward rate of flow is assumed to be the actual one. Thus, the backward rate of flow becomes a dependent parameter to be studied through this analysis. Conditions covering backward rates of flow from zero to maximum are demonstrated graphically. Examples are given for which combined flow results and for which either only forward flow or only backward flow occur.

scholarly journals Temperature, Strain and Strain Rate Dependence of Serrated Flow in Bulk Metallic Glasses

2007 ◽  
Vol 48 (7) ◽  
pp. 1774-1780 ◽  
Author(s):  
Florian H. Dalla Torre ◽  
Alban Dubach ◽  
Adrienne Nelson ◽  
Jörg F. Löffler
Keyword(s):  
Strain Rate ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Serrated Flow ◽  
Strain And Strain Rate ◽  
Temperature Strain

Analysis of Strip Rolling by the Upper Bound Approach

1987 ◽  
Vol 109 (4) ◽  
pp. 338-346 ◽  
Author(s):  
B. Avitzur ◽  
W. Gordon ◽  
S. Talbert
Keyword(s):  
Velocity Field ◽  
Rigid Body ◽  
Upper Bound ◽  
Velocity Fields ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Total Power ◽  
Strip Rolling ◽  
Upper Bound Technique ◽  
Independent Process

The process of strip rolling is analyzed using the upper bound technique. Two triangular velocity fields, one with triangles in linear rigid body motion and the other with triangles in rotational rigid body motion, are developed. The total power is determined as a function of the four independent process parameters (relative thickness, reduction, friction and net front-back tension). The results of these two velocity fields are compared with the established solution from Avitzur’s velocity field of continuous deformation. Upon establishing the validity of the triangular velocity field as an approach to the strip rolling problem, recommendations are suggested on how this approach can be used to study the split end or alligatoring defect.

Temperature Simulation in High-Speed Grinding by Using Deform-3D

2011 ◽  
Vol 189-193 ◽  
pp. 1849-1853 ◽  
Author(s):  
Jing Zhu Pang ◽  
Bei Zhi Li ◽  
Jian Guo Yang ◽  
Zhen Xin Zhou
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Element Analysis ◽  
Strain And Strain Rate ◽  
High Speed Grinding ◽  
Grinding Mechanism ◽  
Temperature Strain ◽  
Grinding Simulation ◽  
Deform 3D

Grinding is one of the most important operations in material processing. The study on grinding mechanism is difficult to carry out because of the difficulty in measuring the actual grinding temperature, stress and strain by experiments. Finite element analysis software Deform-3D is employed to create the Johnson-Cook material constitutive model for high-speed grinding simulation. Grinding model was constructed to reflect the temperature, strain and strain rate in the process of grinding 40Cr steel. The temperature of grinding area in simulation is analyzed to verify whether the finite element model is reasonable.

Experimental tests of a new theory of gravitation

1981 ◽  
Vol 59 (2) ◽  
pp. 283-288 ◽  
Author(s):  
J. W. Moffat
Keyword(s):  
Upper Bound ◽  
Symmetric Solution ◽  
Satellite Orbit ◽  
Experimental Tests ◽  
Spherically Symmetric ◽  
The Sun ◽  
Field Equations ◽  
Spherically Symmetric Solution ◽  
Perihelion Shift ◽  
Theory Of Gravitation

The predictions for the perihelion shift, the deflection of light, and the delay time of a light ray are calculated in the nonsymmetric theory of gravitation. An upper bound for the parameter l (that occurs as a constant of integration in the static, spherically symmetric solution of the field equations) is obtained for the sun for the experimental value of the perihelion shift of Mercury, yielding [Formula: see text]. The upper bound on [Formula: see text] obtained from the Viking spacecraft time-delay experiment is [Formula: see text]. For [Formula: see text], we find that the theory is consistent with the standard relativistic experiments for the solar system. The theory predicts that the perihelion of a satellite could reverse its direction of precession if it orbits close enough to the sun. The results for a highly eccentric satellite orbit are calculated in terms of the value [Formula: see text].

scholarly journals Effective Perihelion Advance and Potentials in a Conformastatic Background with Magnetic Field

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Abraão J. S. Capistrano ◽  
Antonio C. Gutiérrez-Piñeres
Keyword(s):  
Magnetic Field ◽  
Equations Of Motion ◽  
The Moon ◽  
Field Equations ◽  
Effective Potentials ◽  
Test Particles ◽  
Perihelion Advance ◽  
Theoretical Predictions ◽  
Analytic Expression ◽  
The Magnetic Field

Exact solutions of the Einstein-Maxwell field equations for a conformastatic metric with magnetized sources are investigated. In this context, effective potentials are studied in order to understand the dynamics of the magnetic field in galaxies. We derive the equations of motion for neutral and charged particles in a spacetime background characterized by this class of solutions. In this particular case, we investigate the main physical properties of the equatorial circular orbits and related effective potentials. In addition, we obtain an effective analytic expression for the perihelion advance of test particles. Our theoretical predictions are compared with the observational data calibrated with the ephemerides of the planets of the solar system and the Moon (EPM2011). In general, we show that the magnetic punctual mass predicts values that are in better agreement with observations than the values predicted in Einstein’s gravity alone.

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