Singular Plastic Fields in Steady Penetration of a Rigid Cone

1992 ◽  
Vol 59 (4) ◽  
pp. 706-710 ◽  
Author(s):  
David Durban ◽  
Norman A. Fleck
Keyword(s):  
Plastic Zone ◽  
Ad Hoc ◽  
Logarithmic Singularity ◽  
Cone Angle ◽  
Wall Friction ◽  
Rigid Plastic ◽  
Rigid Zone ◽  
Perfectly Plastic ◽  
Strain Jump ◽  
Friction Factors

The essential features of the active plastic zone at the tip of a penetrating rigid cone are investigated for a rigid/perfectly plastic solid. An exact solution is suggested for the plastic zone. A rigid zone exists ahead of the cone and is separated from the plastic zone by a conical surface of discontinuity. It is assumed that the material yields instantaneously by going through a “shear shock” across the rigid/plastic interface. The orientation of the interface is determined by an ad hoc requirement for minimum shear strain jump at the shear shock. Results are presented for different cone angles and friction factors. The stresses within the plastic zone admit a logarithmic singularity whose level increases with cone angle and wall friction.

Plastic Forming Processes Through Rotating Conical Dies1

2001 ◽  
Vol 68 (6) ◽  
pp. 894-902 ◽  
Author(s):  
D. Durban ◽  
G. Davidi ◽  
D. Lior
Keyword(s):  
Single Phase ◽  
Large Strain ◽  
Single Layer ◽  
Wall Friction ◽  
Nonlinear Ordinary Differential Equations ◽  
Tube Forming ◽  
Perfectly Plastic ◽  
Governing System ◽  
Plastic Forming ◽  
Exact Relations

Drawing and extrusion of single-phase and multilayered tubes through rotating conical dies is investigated within the framework of continuum plasticity. Large strain perfectly plastic J2 flow theory models constitutive behavior along with a radial-helical flow pattern. The governing system for a single-layer process is reduced to three coupled nonlinear ordinary differential equations. An approximate solution is developed for long and tapered working zones with low wall friction. That solution is used to simulate the field within each layer in composite tube forming. Exact relations are derived for the n-layered tube and it is shown that wall rotation can considerably reduce the required working loads. Dedicated to Professor Dietmar Gross on the occasion of his 60th birthday

The Estimation of Large Deflections of a Portal Frame Under Asymmetric Pulse Loading

1984 ◽  
Vol 51 (3) ◽  
pp. 494-500 ◽  
Author(s):  
J. L. Raphanel ◽  
P. S. Symonds
Keyword(s):  
Local Deformation ◽  
Elastic Response ◽  
Sensitive Material ◽  
Rigid Plastic ◽  
Finite Element Program ◽  
Perfectly Plastic ◽  
Portal Frame ◽  
Element Program ◽  
Loaded Column ◽  
Asymmetric Pulse

Modifications of a simple elastic-plastic technique [1-4] are shown which allow estimation of local deformation in the loaded column of a portal frame as well as the side-sway deflections of the frame. A wholly elastic response stage provides input to a simplified rigid-plastic solution, in which velocity patterns first of local and then of modal (side-sway) type occur, and which furnishes estimates of final plastic deflections. Maximum (elastic plus plastic) deflections are estimated by adding displacements corresponding to the elastic strain field defined by the stresses of the closing rigid-plastic mode. The method is described for perfectly plastic and for strain-rate sensitive material, and comparisons are shown here with values computed3 for both types of material by a finite element program. Emphasis in this paper is put on the inclusion of elastic and vicoplastic effects.

Buckle Propagation Analysis of Deep-Water Petroleum Transmission Pipelines with Axial Tension

2014 ◽  
Vol 1008-1009 ◽  
pp. 1134-1143 ◽  
Author(s):  
Sun Ting Yan ◽  
Yin Fa Zhu ◽  
Zhi Jiang Jin ◽  
Hao Ye
Keyword(s):  
Plastic Hinge ◽  
External Pressure ◽  
Isotropic Hardening ◽  
Rigid Plastic ◽  
Perfectly Plastic ◽  
Fitting Procedure ◽  
Plastic Materials ◽  
Buckle Propagation ◽  
Elastic Perfectly Plastic ◽  
Hinge Model

Quasi-static finite element simulation is carried out on buckle propagation phenomenon of offshore pipelines under external pressure. Arc-length method and volume-controlled static analysis by employing hydrostatic fluid element F3D4 are employed to calculate the steady buckle propagation pressure. After verifying the validity of numerical model, emphasis is on the influence of tension on propagation pressure considering isotropic hardening elastoplastic and elastic-perfectly plastic materials. Parametric study is conducted to include the effect of diameter-thickness ratio, after which two empirical equations are derived by curve fitting procedure. Finally, some comments on the results obtained through rigid-plastic hinge model are presented and a modified plastic hinge model including effect of material anisotropy is derived. The results can serve as a reference for more reasonable design of buckle arrestors.

Dynamic Response of Blast-Loaded Stiffened Plates by Rigid-Plastic Analysis

2010 ◽  
Author(s):  
Ping Yang ◽  
Ying Peng
Keyword(s):  
Dynamic Response ◽  
Yield Curve ◽  
Bending Moment ◽  
Stiffened Plates ◽  
Flow Rule ◽  
Beam Model ◽  
Rigid Plastic ◽  
Perfectly Plastic ◽  
Load Intensity ◽  
Plastic Flow Rule

The dynamic response of one-way stiffened plates with clamped edges subjected to uniformly distributed blast-induced shock loading is theoretically investigated using a singly symmetric beam model. The beam model is based on the rigid-perfectly plastic assumption. The bending moment-axial force capacity interaction relation or yield curve for singly symmetric cross-section is derived and explicitly presented. The deflection condition that a plastic string response must satisfy is determined by the linearized interaction curve and associated plastic flow rule. Moreover, the possible motion mechanisms of the beam are discussed under different load intensity. Finally the dynamic response of a one-way stiffened plate is calculated theoretically and numerically. Good agreements are obtained between the presented theoretical results and those from numerical calculations of the FEM software ANSYS and ABAQUS/Explicit. It is concluded that the basic assumptions and approximations for simplifying calculations are reasonable and the beam model in theoretical analysis is adoptable. The example also shows that an arbitrary blast load can be replaced equivalently by a rectangular type pulse.

Rigid-Plastic Finite Element Simulation of Deformation Mechanisms during Rolling of Complex Sheets Containing an Inclusion

2006 ◽  
Vol 306-308 ◽  
pp. 483-488 ◽  
Author(s):  
Dyi Cheng Chen
Keyword(s):  
Finite Element ◽  
Rolling Process ◽  
Deformation Mechanisms ◽  
Damage Factor ◽  
Rigid Plastic ◽  
Sheet Rolling ◽  
Friction Factors ◽  
Element Simulation ◽  
Simulation Results ◽  
Roll Gap

Using rigid-plastic finite element DEFORMTM 2D software, this study simulates the plastic deformation of complex sheets at the roll gap during the sheet rolling process. Specifically, the study addresses the deformation of complex sheets containing inclusion defects. Under various rolling conditions, the present numerical analysis investigates the damage factor distributions, the void length at the front and rear of the inclusion, the deformation mechanisms, and the stress-strain distributions around the inclusion. The relative influences of the thickness reduction, the roll radii, and the friction factors on the void length at the front and rear of the inclusion, respectively, are systematically examined. Additionally, the correlation between the front and rear void lengths and a series of damage factors is explored. The simulation results appear to verify the suitability of the DEFORMTM 2D software for modeling the rolling of complex sheets containing inclusions.

The Influence of Large Deflections on the Behavior of Rigid-Plastic Cylindrical Shells Loaded Impulsively

1970 ◽  
Vol 37 (2) ◽  
pp. 416-425 ◽  
Author(s):  
Norman Jones
Keyword(s):  
Cylindrical Shells ◽  
Dynamic Loads ◽  
Large Deflections ◽  
Finite Deflections ◽  
Shell Material ◽  
Governing Equations ◽  
Rigid Plastic ◽  
Perfectly Plastic ◽  
Dynamic Analyses ◽  
Circular Cylindrical Shells

A theoretical investigation is herein undertaken in order to examine the response of circular cylindrical shells subjected to dynamic loads of an intensity sufficient to cause large permanent deformations. The shell material is assumed to be rigid, perfectly plastic and the influence of finite deflections is retained in the governing equations. It emerges clearly from the study that geometry changes influence markedly the shell behavior even for quite small deflections and, therefore, they should be retained in any dynamic analyses of cylindrical shells with axial restraints.

Shakedown Loads for Pressure Vessels of Strain Hardening Materials

1969 ◽  
Vol 11 (3) ◽  
pp. 340-342 ◽  
Author(s):  
T. E. Taylor
Keyword(s):  
Strain Hardening ◽  
Power Law ◽  
Pressure Vessels ◽  
Strain Hardening Exponent ◽  
Rigid Plastic ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Creep Analysis ◽  
Family Of Curves ◽  
The Relationship

A power law, well known in creep analysis, embodies a family of curves which express the stress-strain relations for a family of materials ranging from linear elastic to rigid perfectly plastic. A linearization of the relationship between stress concentration factor and the reciprocal of strain hardening exponent for geometrically similar pressure vessels made of materials within the family has enabled a view of shakedown in vessels of strain hardening materials to be formulated. The absence of discontinuities in the power law, except at the rigid plastic end point, results in shakedown loads dependent on strain hardening exponent and previous loading history.

Finite Deformations of a Rigid Perfectly Plastic Arch

1962 ◽  
Vol 29 (3) ◽  
pp. 549-553 ◽  
Author(s):  
E. T. Onat ◽  
L. S. Shu
Keyword(s):  
Closed Form ◽  
Yield Point ◽  
Finite Deformation ◽  
Closed Form Solution ◽  
Form Solution ◽  
Finite Deformations ◽  
Deformation History ◽  
Rigid Plastic ◽  
Perfectly Plastic ◽  
History Of

The quasi-static postyield deformation of a rigid-plastic arch in the presence of geometry changes is considered. The problem is formulated in terms of a series of boundary-value problems concerned with rates of stress and velocities. In the present simple case, the consideration of the rate problem associated with the yield-point state of the structure enables one to construct a closed-form solution which describes the entire deformation history of the arch. However, the principal aim of the present study is to stress the central role played by the rate problem in the investigation of the finite deformation of structures.

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