An Upper Bound Solution Analysis of Equal Channel Angular Pressing

2005 ◽  
Vol 23 ◽  
pp. 109-112
Author(s):  
Wei Wei ◽  
Guang Chen
Keyword(s):  
Equal Channel Angular Pressing ◽  
Upper Bound ◽  
Maximum Load ◽  
Equivalent Strain ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Angular Pressing ◽  
Good Agreement

The purpose of this study is to obtain an upper bound solution of ECAP at 0 = ψ and φ=90 deg, which aims at analysis of the relations between ECAP upper bound pressure and the die angles of φ and ψ. The results show that the value of pressing load and the equivalent strain, e ε , decreases as the angle ψ increases at φ=90 deg, but the equivalent strain, e ε , decreases rapidly and no less than 0.90. The measured maximum load required for ECAP is in good agreement with the values obtained from the upper bound solution.

A Control Strategy and Upper Bound Solution for Non-Flat Tool Open Die Forging Automation

1999 ◽  
Author(s):  
T. J. Nye
Keyword(s):  
Control Strategy ◽  
Upper Bound ◽  
Sequence Generation ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Die Forging ◽  
Strategy Model ◽  
Model Predictions ◽  
Open Die Forging ◽  
Good Agreement

Abstract The open die forging process can provide a number of benefits if its costs can be made competitive through automation. This paper describes a control strategy for automated open die forging forming sequence generation. An upper bound solution for forging with radiused tools is developed, along with a method for using this solution to estimate forming results, a necessary component of the control strategy. Model predictions are compared to physical experimental data using plasticine, and show good agreement.

An Upper Bound Solution for Upsetting of Two-Layer Cylinder

2006 ◽  
Vol 505-507 ◽  
pp. 1303-1308 ◽  
Author(s):  
Gow Yi Tzou ◽  
Sergei Alexandrov
Keyword(s):  
Velocity Field ◽  
Upper Bound ◽  
Limit Load ◽  
Equivalent Strain ◽  
Industrial Applications ◽  
Upper Bound Theorem ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Perfectly Plastic ◽  
Plastic Materials

An upper bound solution for axisymmetric upsetting of two-layer cylinder made of rigid perfectly plastic materials is provided. An important feature of the solution is that the kinematically admissible velocity field, in addition to the necessary requirements of the upper bound theorem, satisfies the frictional boundary condition in stresses, the maximum friction law. The latter is archived by introducing a singular velocity field such that the equivalent strain rate approaches infinity at the friction surface. The dependence of the upper bound limit load on geometric parameters and the ratio of the yield stresses of the two materials is analyzed. The solution can be used in industrial applications for evaluating the load required to deform two-layer cylinders.

The Upper-Bound Solution as Applied to Three-Dimensional Extrusion and Piercing Problems

1962 ◽  
Vol 84 (4) ◽  
pp. 397-404 ◽  
Author(s):  
C. T. Yang
Keyword(s):  
Experimental Data ◽  
Upper Bound ◽  
Close Agreement ◽  
Three Dimensional ◽  
Slight Modification ◽  
Graphical Solution ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Region Approach ◽  
Good Agreement

The upper-bound solution for plane-strain problems is modified and applied to three-dimensional extrusion and piercing. Johnson’s graphical solution is used to solve axisymmetric, eccentric, and two-bar extrusion problems of a lead billet. Kudo’s unit-deforming region approach is employed to solve cylindrical piercing problems of six nonferrous metals. The analytical extrusion pressure is compared with Frisch and Thomsen’s experimental data. A reasonably close agreement is obtained in the first two cases. The calculated piercing pressure is compared with the experimental results of Fukui, et al. A remarkably good agreement is observed for all six cases. Therefore the upper-bound solution after slight modification can be extended to three-dimensional problems in extrusion and piercing. A general conclusion for extending the upper-bound approach to all forming operations cannot be drawn until further study is done along this line.

Thermo-Mechanical Modeling and Analysis of Equal Channel Angular Pressing

2005 ◽  
Vol 23 ◽  
pp. 263-266 ◽  
Author(s):  
Qing Xiang Pei ◽  
B.H. Hu ◽  
C. Lu
Keyword(s):  
Equal Channel Angular Pressing ◽  
Temperature Rise ◽  
Flow Behavior ◽  
Material Model ◽  
Workpiece Material ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Die Geometry ◽  
Angular Pressing ◽  
Good Agreement

Thermo-mechanical finite element analysis was carried out to study the deformation behavior and temperature distribution during equal channel angular pressing (ECAP). The material model used is the Johnson-Cook constitution model that can consider the multiplication effect of strain, strain rate, and temperature on the flow stress. The effects of pressing speed, pressing temperature, workpiece material and die geometry on the temperature rise and flow behavior during ECAP process were investigated. The simulated temperature rise due to deformation heating was compared with published experimental results and a good agreement was obtained. Among the various die geometries studied, the two-turn die with 0° round corner generates the highest and most uniform plastic strain in the workpiece.

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