Theory of compression of a compressible rigid-plastic material

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

Stamping Rectangular Plates into Doubly-Curved Dies

1984 ◽  
Vol 198 (2) ◽  
pp. 109-125 ◽  
Author(s):  
T X Yu ◽  
W Johnson ◽  
W J Stronge
Keyword(s):  
Plastic Material ◽  
Rectangular Plates ◽  
Rigid Plastic ◽  
Punch Force ◽  
Plate Buckling ◽  
Rigid Plastic Material ◽  
Force Contact ◽  
Curvature Distribution ◽  
Doubly Curved ◽  
Deformation Modes

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.

Response of a Rigid-Plastic Ring to Impulse Loading

1967 ◽  
Vol 34 (2) ◽  
pp. 329-336 ◽  
Author(s):  
G. B. Cline ◽  
W. E. Jahsman
Keyword(s):  
Incident Energy ◽  
Plastic Material ◽  
Maximum Magnitude ◽  
Impulse Loading ◽  
Rigid Plastic ◽  
Plastic Ring ◽  
Stress Mode ◽  
Rigid Plastic Material ◽  
Impulse Load ◽  
Final Deformation

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.

Rigid-Plastic Meshfree Method for Metal Forming Simulation

2003 ◽  
Author(s):  
Young H. Park
Keyword(s):  
Metal Forming ◽  
Plastic Material ◽  
Meshfree Method ◽  
Large Plastic Deformation ◽  
Rigid Plastic ◽  
Mesh Distortion ◽  
Forming Simulation ◽  
Rigid Plastic Material ◽  
Plastic Analysis ◽  
Main Variable

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.

Pressbrake Bending in the Punch-Sheet Contact Region—Part 1: Modeling Nonuniformities

1988 ◽  
Vol 110 (2) ◽  
pp. 124-130 ◽  
Author(s):  
F. Pourboghrat ◽  
K. A. Stelson
Keyword(s):  
Shear Stress ◽  
Simple Model ◽  
Stress Distribution ◽  
Plastic Material ◽  
Contact Region ◽  
Rigid Plastic ◽  
Material Models ◽  
Rigid Plastic Material

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.

A Theoretical Analysis of the Bending into Cylindrical Dies of Metal Strips

1984 ◽  
Vol 198 (2) ◽  
pp. 99-108 ◽  
Author(s):  
T X Yu ◽  
W Johnson
Keyword(s):  
Theoretical Analysis ◽  
Metal Forming ◽  
Plastic Material ◽  
Forming Process ◽  
Rigid Plastic ◽  
Rigid Plastic Material ◽  
Punch Load ◽  
Theoretical Predictions ◽  
Metal Forming Process ◽  
Good Agreement

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.

Corotational Rates for Kinematic Hardening at Large Plastic Deformations

1983 ◽  
Vol 50 (3) ◽  
pp. 561-565 ◽  
Author(s):  
Y. F. Dafalias
Keyword(s):  
Simple Shear ◽  
Plastic Material ◽  
Kinematic Hardening ◽  
Back Stress ◽  
Analytical Form ◽  
Rigid Plastic ◽  
Plastic Deformations ◽  
Novel Approach ◽  
Rigid Plastic Material ◽  
Large Plastic Deformations

To illustate the effect of the choice of corotational rates at large plastic deformations, expressions for the stresses developing in large simple shear are obtained in closed analytical form under the assumptions of a rigid-plastic material response and a Mises type isotropically and kinematically hardening constitutive model for two different corotational rates applied to the stress and the back-stress tensors. The observed difference in the simple shear response and the relative merits of the foregoing and other corotational rates are discussed, and a novel approach is proposed based on Mandel’ work and the representation theorem for isotropic second-order antisymmetric tensor valued functions.

The permanent deformation of a cantilever struck transversely at its tip

1955 ◽  
Vol 228 (1175) ◽  
pp. 462-476 ◽  
Keyword(s):  
Plastic Material ◽  
Permanent Deformation ◽  
Rigid Plastic ◽  
Accurate Definition ◽  
Special Cases ◽  
Rigid Plastic Material ◽  
The One ◽  
Definition Of ◽  
Falling Weight ◽  
The Impact

An analysis is given for the deformation of a cantilever made from a rigid-plastic material struck transversely at its tip by a moving mass. Two special cases are found to be of interest: mass of striker large, and mass of striker small. Experiments were carried out on model mildsteel cantilevers under these two extreme conditions: in the one case the striker was a falling weight, in the other a rifle bullet. The theoretical and experimental results are compared, and it is shown that there is good agreement at points remote from the impact, but that prediction of local damage depends on accurate definition of the conditions of striking.

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