Rigid-Plastic Meshfree Method for Metal Forming Simulation

Author(s):  
Young H. Park

In this paper, material processing simulation is carried out using a meshfree method. With the use of a meshfree method, the domain of the workpiece is discretized by a set of particles without using a structured mesh to avoid mesh distortion difficulties which occurred during the course of large plastic deformation. The proposed meshfree method is formulated for rigid-plastic material. This approach uses the flow formulation based on the assumption that elastic effects are insignificant in the metal forming operation. In the rigid-plastic analysis, the main variable of the problem becomes flow velocity rather than displacement. A numerical example is solved to validate the proposed method.

Author(s):  
Young H. Park

In this paper, material processing simulation is carried out using a meshfree method. The domain of the workpiece is discretized using the Lagrangian Reproducing Kernel Particle Method (RKPM) where no external meshes are used. The meshfree method is formulated for elasto-plastic material model as well as rigid-plastic model. For elasto-plastic model, a finite plasticity theory is formulated based on the multiplicative decomposition to handle large deformation problems. A rigid-plastic material model is also employed using flow formulation based on the assumption that elastic effects are insignificant in the metal forming operation. A comparative study between elasto-plastic and rigid-plastic RKPM methods was conducted to demonstrate consistency of the results from elasto-plastic and rigid-plastic simulations for a metal forming application.


Author(s):  
T X Yu ◽  
W Johnson

Based on experiments on the bending of metal strips into cylindrical dies using a semi-circular ended punch (1) a theoretical analysis of this metal forming process is presented to predict the punch load—punch travel characteristic and the clearance between the punch pole and the mid-point of the strip. Elastic/plastic and rigid/plastic material idealizations are employed, and the effect of friction between the strip and the die is also considered. The theoretical predictions show good agreement with the experimental results and are useful for designers.


2016 ◽  
Vol 713 ◽  
pp. 195-198
Author(s):  
Sergei Alexandrov

The main objective of the present paper is to demonstrate, by means of a boundary value problem permitting a closed-form solution, that no solution exists under certain conditions in the case of a rigid/plastic material model including a damage evolution equation. The source of this feature of the solution is the sticking friction condition, which is often adopted in the metal forming literature.


Author(s):  
T X Yu ◽  
W Johnson ◽  
W J Stronge

Shallow spheroidal shell segments have been press formed from rectangular plates by stamping between a die and matching punch that have two degrees of curvature. Experiments on mild steel, copper and aluminium plates that were not clamped in the die have measured the punch force, contact regions and final curvature distribution; and have observed plate buckling for a range of die curvature ratios and plate sizes. An analysis based on a rigid/plastic material idealization and decoupled in-plane forces and bending moments has been correlated with these experiments. The sequence of deformation modes has been identified; initially these are bending but in later stages, in-plane forces predominate.


1974 ◽  
Vol 10 (3) ◽  
pp. 323-326
Author(s):  
I. S. Degtyarev ◽  
V. L. Kolgomorov

1967 ◽  
Vol 34 (2) ◽  
pp. 329-336 ◽  
Author(s):  
G. B. Cline ◽  
W. E. Jahsman

Formulas are derived which describe the dynamic response of a ring of rigid-plastic material which is subjected to an arbitrarily distributed impulse load. When the impulse is distributed over half the ring in a cosine fashion, the final deformation is proportional to the square of the maximum magnitude of the applied impulse. Although the predominant deformation is in a bending or “ovaling” mode, one half of the incident energy is dissipated in the “membrane” or direct stress mode. The remainder is divided equally between bending (plastic work at the hinges) and kinetic energy.


1988 ◽  
Vol 110 (2) ◽  
pp. 124-130 ◽  
Author(s):  
F. Pourboghrat ◽  
K. A. Stelson

A simple model of pressbrake bending in the punch-sheet contact region is presented. The pressure and shear stress at the punch-sheet interface cause the stress distribution in the sheet to change as a function of angle. In Part 1 of this paper, a model to predict nonuniformities as a function of the geometry and the frictional conditions is presented. In Part 2, the model will be used to predict the formation of a gap between the sheet and the punch. Elastic and rigid-plastic material models of the sheet are considered, and are shown to produce remarkably similar results.


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