An Experimental Investigation Into the Plastic Flow and Strain Hardening of Mild Steel Under Proportional and Abruptly Changing Deformation Paths at a Controlled Rate

1983 ◽  
Vol 105 (3) ◽  
pp. 147-154 ◽  
Author(s):  
S. A. Meguid ◽  
L. E. Malvern
Keyword(s):  
Plastic Strain ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Plastic Strain Rate ◽  
Isotropic Hardening ◽  
Rate Vector ◽  
Vector Direction ◽  
Von Mises Equivalent Stress ◽  
Strain Rate Vector ◽  
Von Mises

Tension-torsion tests are reported on thin-walled tubes up to strains of the order of five percent. Attention was given to the question of whether, as has been suggested, in the continued loading after a sudden direction change in the deformation path, the behavior of the material quickly approaches that predicted by a von Mises plastic potential and isotropic hardening. The results show a slower approach of the deviatoric stress vector direction to the plastic strain-rate vector direction than had been expected, as well as considerable variations in the von Mises equivalent stress versus equivalent plastic strain curves.

Finite element analysis of the wheel–rail impact behavior induced by a wheel flat for high-speed trains: The influence of strain rate

2017 ◽  
Vol 232 (4) ◽  
pp. 990-1004 ◽  
Author(s):  
Liangliang Han ◽  
Lin Jing ◽  
Longmao Zhao
Keyword(s):  
Shear Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
High Speed ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Impact Behavior ◽  
Wheel Flat ◽  
Von Mises Equivalent Stress ◽  
Von Mises

The wheel–rail impact response induced by a wheel flat for high-speed trains is simulated numerically, based on the strain rate-dependent constitutive parameters of wheel–rail materials, using the finite element software LS-DYNA explicit algorithm. Influences of the speed of the train, the length of the wheel flat, and axle load on the wheel–rail impact behavior are discussed over a wide range, in terms of the vertical impact force, von Mises equivalent stress, shear stress, and equivalent plastic strain. The maximum wheel–rail impact forces are 2.6–4.4 times greater than the corresponding static axle loads due to the presence of a wheel flat. The maximum von Mises equivalent stress and equivalent plastic strain have occurred on the wheel–rail contact surface, while the maximum xy shear stress has often occurred on the subsurface of 4–6 mm below the contact surface. The wheel–rail impact responses induced by a wheel flat are sensitive to the speed of trains, flat length, and axle load. Besides, the strain rate effect of wheel–rail materials has a significant influence on the maximum von Mises equivalent stress, shear stress, and equivalent plastic strain, while it has no influence on the maximum vertical impact force. These findings are very helpful to guide the maintenance and repair of wheel–rail components in rail transport.

An Experimental Study of the Structure of Constitutive Equations for Nonproportional Cyclic Plasticity

1985 ◽  
Vol 107 (4) ◽  
pp. 307-315 ◽  
Author(s):  
D. L. McDowell
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Yield Surface ◽  
Hysteresis Loops ◽  
Cyclic Plasticity ◽  
304 Stainless Steel ◽  
Plastic Strain Rate ◽  
Hardening Modulus ◽  
Rate Vector ◽  
Strain Rate Vector

Three type 304 stainless steel specimens of the same geometry were subjected to complex, cyclic axial-torsional histories characterized by varying degrees of non-proportionality of straining. All tests were at room-temperature. The data from cyclically stable hysteresis loops were reduced and the direction of the plastic strain rate vector, variation of plastic hardening modulus, and direction of translation of a rate and time-independent yield surface were studied. It is shown that the independent variables in a Mroz-type formulation map the experimental results with a higher degree of uniqueness than other popular formulations studied for both the hardening modulus and direction of yield surface translation. Also, the plastic strain rate is not, in general, in the direction of the deviatoric stress or stress rate.

Computational Study of the Effect of Cutting Speeds on Tool Wear during Machining of AISI 316L Steel

2012 ◽  
Vol 622-623 ◽  
pp. 409-413
Author(s):  
Wisansart Satana ◽  
Karuna Tuchinda ◽  
Anantawit Tuchindac ◽  
Surachate Chutima
Keyword(s):  
Tool Wear ◽  
Wear Behavior ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Cutting Speed ◽  
Aisi 316L ◽  
316L Steel ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Cutting Speeds

This research aims to study the effect of cutting speeds on wear behaviors of TiAlN coated insert during the machining process of AISI 316L steel. Experimental investigation and finite element method were employed. The two-dimensional (2D) plane strain orthogonal cutting model was focused at the initial continuous chip formation. The effect of cutting speeds, i.e. 50, 75,120 and 150 m/min, was studied. The tool wear behavior was then further investigated based on computational results which are temperature, von-mises equivalent stress, equivalent plastic strain and contact pressure. High temperature developed at rake face during high cutting speed, i.e. the cutting speed above 120 m/min, suggesting crater wear or diffusion wear. High equivalent plastic strain, i.e. greater than the fracture strain at failure of AISI 316L steel, were observed all along the tool edge around the contact area suggesting the built up edge (BUE) wear at all cutting speed investigated. The adhesive wear was expected on the edge radius at low cutting speed (50 to 75 m/min) based on the von-mises equivalent stress distributions. The overall severity of sliding wear was found to be around the tool nose due to high contact pressure in all cases. The experiments were also conducted with the tail stock constrained in all experiments to reduce the effect of vibration. The insert tool wear was examined by Scanning Electron Microscope. Wear was observed on flank face and rake face of the insert tools with different wear behavior at different cutting speed which agreed well with computational predictions.

Nonlinear Analysis of Piercing Rolling Process by Element-Free Galerkin Method

2010 ◽  
Vol 26-28 ◽  
pp. 285-288
Author(s):  
Jian Hua Hu ◽  
Yuan Hua Shuang
Keyword(s):  
Plastic Strain ◽  
Galerkin Method ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Rolling Process ◽  
Plastic Strain Rate ◽  
Element Free Galerkin Method ◽  
Rigid Plastic ◽  
Element Free Galerkin ◽  
Element Free

During piercing rolling simulation, extreme mesh deformation cannot be solved by the finite element method (FEM). Re-meshing is necessary to prevent the effect of severe mesh distortion. However, the element-free method can solve this problem because the continuous body is discretized with a set of nodes, not meshes. In this paper, three-dimension rigid-plastic element-free Galerkin Method (EFG) is introduced to analyze the piercing rolling process. The approximation functions are calculated considering a moving least squares (MLS) approach. The Newton-Raphson method is used for the solution of the nonlinear system of equations. The equivalent stress, the equivalent plastic strain and the equivalent plastic strain rate obtained by EFG and rigid-plastic FEM are analyzed and compared. The simulation results of the EFG method are in agreement with those obtained by using the rigid-plastic FEM and the effectiveness of the model is verified.

A Criterion for Low-Cycle Fatigue Failure Under Biaxial States of Stress

1981 ◽  
Vol 103 (1) ◽  
pp. 1-6 ◽  
Author(s):  
D. Lefebvre ◽  
K. W. Neale ◽  
F. Ellyin
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Yield Function ◽  
Plastic Strain Amplitude ◽  
Multiaxial Fatigue ◽  
Cycle Fatigue ◽  
Stress Ratios ◽  
Von Mises

The plastic strain energy required for failure in low-cycle biaxial fatigue is estimated using the energy in uniaxial fatigue and assumptions from the theory of plasticity. A criterion for high-strain multiaxial fatigue of the form Δε¯pΔσ¯=KNƒc is developed, where the equivalent stress amplitude Δσ and the equivalent plastic strain amplitude Δεp are based on the von Mises yield function of plasticity. The parameters K and c are assumed to depend on the mechanical properties of the material and to be functions of the stress ratio. These functions can be evaluated from uniaxial fatigue data and are compared with tests performed on thin-walled tubes of mild steel at different stress ratios. The proposed criterion seems to yield a promising approach for the low-cycle fatigue analysis of metals under biaxial states of stress.

An Analysis of Filament Overwound Toroidal Pressure Vessels and Optimum Design of Such Structures

2002 ◽  
Vol 124 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Shuguang Li ◽  
John Cook
Keyword(s):  
Optimum Design ◽  
Equivalent Stress ◽  
Mechanical Damage ◽  
Stress Rupture ◽  
Optimization Procedure ◽  
Pressure Vessels ◽  
Thickness Variation ◽  
Von Mises Equivalent Stress ◽  
Metal Liner ◽  
Von Mises

This paper is concerned with the membrane shell analysis of filament overwound toroidal pressure vessels and optimum design of such pressure vessels using the results of the analysis by means of mathematical nonlinear programming. The nature of the coupling between overwind and linear has been considered based on two extreme idealizations. In the first, the overwind is rigidly coupled with the liner, so that the two deform together in the meridional direction as the vessel dilates. In the second, the overwind is free to slide relative to the linear, but the overall elongations of the two around a meridian are identical. Optimized designs with the two idealizations show only minor differences, and it is concluded that either approximation is satisfactory for the purposes of vessel design. Aspects taken into account are the intrinsic overwind thickness variation arising from the winding process and the effects of fiber pre-tension. Pre-tension can be used not only to defer the onset of yielding, but also to achieve a favorable in-plane stress ratio which minimizes the von Mises equivalent stress in the metal liner. Aramid fibers are the most appropriate fibers to be used for the overwind in this type of application. The quantity of fiber required is determined by both its short-term strength and its long-term stress rupture characteristics. An optimization procedure for the design of such vessels, taking all these factors into account, has been established. The stress distributions in the vessels designed in this way have been examined and discussed through the examples. A design which gives due consideration of possible mechanical damage to the surface of the overwind has also been addressed.

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