A note on the yielding of an accelerating, non-homogeneous disc of varying thickness and density with radial loading

1978 ◽  
Vol 13 (1) ◽  
pp. 59-63
Author(s):  
G V Gurushankar
Keyword(s):  
Uniform Density ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Uniform Thickness ◽  
Varying Thickness ◽  
Von Mises Criterion ◽  
Yield Loci ◽  
Von Mises ◽  
Radial Loading ◽  
Special Case

The influences of non-homogeneity and density on the normal stresses and shear stresses developed due to the acceleration of a disc, of varying thickness, at any particular instant, are analysed. Yield loci, on the basis of von Mises' criterion, are found for discs of varying thickness and uniform thickness with a bore ratio ( a/ b) of 0.25 and also for linearly varying ( p = 1.0, q = 1.0) and nonlinearly varying ( p = 0.5, q = 0.5) density and homogeneity. A homogeneous, uniform density and uniform thickness disc forms a special case of the analysis.

An Experimental Investigation of the Yield Loci of 1100-0 Aluminum, 70:30 Brass, and an Overaged 2024 Aluminum Alloy After Various Prestrains

1986 ◽  
Vol 108 (4) ◽  
pp. 313-320 ◽  
Author(s):  
D. E. Helling ◽  
A. K. Miller ◽  
M. G. Stout
Keyword(s):  
Aluminum Alloy ◽  
Small Strain ◽  
Yield Locus ◽  
Material Behavior ◽  
Shear Stresses ◽  
2024 Aluminum Alloy ◽  
Yield Loci ◽  
Aluminum Alloy 2024 ◽  
Von Mises ◽  
Normal And Shear Stresses

The multiaxial yield behaviors of 1100-0 aluminum, 70:30 brass, and an overaged 2024 aluminum alloy (2024-T7) have been investigated for a variety of prestress histories involving combinations of normal and shear stresses. Von Mises effective prestrains were in the range of 1.2–32%. Prestress paths were chosen in order to investigate the roles of prestress and prestrain direction on the nature of small-strain offset (ε = 5 × 10−6) yield loci. Particular attention was paid to the directionality, i.e., translation and distortion, of the yield locus. A key result, which was observed in all three materials, was that the final direction of the prestrain path strongly influences the distortions of the yield loci. Differences in the yield locus behavior of the three materials were also observed: brass and the 2024-T7 alloy showed more severe distortions of the yield locus and a longer memory of their entire prestrain history than the 1100-0 aluminum. In addition, more “kinematic” translation of the subsequent yield loci was observed in brass and 2024-T7 than in 1100-0 aluminum. The 2024-T7 differed from the other materials, showing a yield locus which decreased in size subsequent to plastic straining. Finally, the implications of these observations for the constitutive modeling of multiaxial material behavior are discussed.

Stress

2020 ◽  
pp. 9-28
Author(s):  
Adrian P. Sutton
Keyword(s):  
Shear Stress ◽  
Stress Tensor ◽  
Elastic Energy ◽  
Functional Derivative ◽  
Shear Stresses ◽  
Mechanical Equilibrium ◽  
Normal Stresses ◽  
Atomic Interactions ◽  
Insightful Analysis ◽  
Von Mises

The concept of stress is introduced in terms of interatomic forces acting through a plane, and in the Cauchy sense of a force per unit area on a plane in a continuum. Normal stresses and shear stresses are defined. Invariants of the stress tensor are derived and the von Mises shear stress is expressed in terms of them. The conditions for mechanical equilibrium in a continuum are derived, one of which leads to the stress tensor being symmetric. Stress is also shown to be the functional derivative of the elastic energy with respect to strain,which enables the stress tensor to be derived in models of interatomic forces. Adiabatic and isothermal stresses are distinguished thermodynamically and anharmonicity of atomic interactions is identified as the reason for their differences. Problems set 2 containsfour problems, one of which is based on Noll’s insightful analysis of stress and mechanical equilibrium.

A Generalized von Mises Criterion for Yield and Fracture

1980 ◽  
Vol 47 (2) ◽  
pp. 297-300 ◽  
Author(s):  
W. H. Yang
Keyword(s):  
Bauschinger Effect ◽  
Hydrostatic Stress ◽  
Fracture Criteria ◽  
Deformation History ◽  
Von Mises Criterion ◽  
Effect On Yield ◽  
Von Mises ◽  
New Criterion ◽  
Physical Phenomena ◽  
Special Case

Yield and fracture criteria for real materials are to a varying degree affected by a state of hydrostatic stress. Some materials, after certain deformation history, exhibit different yield point when the direction of the stress is reversed, a behavior known as the Bauschinger effect. These physical phenomena are not represented by the von Mises criterion. Based on a convexity theorem of matrices, a generalization of the von Mises criterion is presented. The new criterion satisfies the convexity requirement of plasticity theory and, with two scalar functions of deformation history α and β, produces a class of hardening behavior. The current values of α and β account for the effect of hydrostatic stress and an aspect of the Bauschinger effect on yield and fracture. The generalized criterion reduces to the form of the von Mises criterion as a special case.

Effect of Yield Criterion on Stress Distribution and Maximum Safe Pressure for an Autofrettaged Gun Barrel

2017 ◽  
Vol 67 (5) ◽  
pp. 504
Author(s):  
Amit Bhetiwal ◽  
Sunil Kashikar ◽  
Haribhau Markale ◽  
Shailendra Gade
Keyword(s):  
Stress Distribution ◽  
Yield Criterion ◽  
The Other ◽  
Uniform Thickness ◽  
Theoretical Weight ◽  
Gun Barrel ◽  
Von Mises Criterion ◽  
Tresca Criterion ◽  
Von Mises

<p>World artillery in the present scenario is changing its role from defensive to aggressive nature and is attempting to achieve higher penetration into enemy targets. Even for an autofrettaged gun barrel, higher ranges requirement leads to higher barrel weight and its associated demerits. The design of gun barrel is based on the choice of yield criteria. Tresca yield criterion provides conservative design for a ductile barrel material. On the other hand, more accurate von Mises criterion presents complexity. The two criteria to evaluate various parameters required for design of an autofrettaged gun barrel are compared. The methodology for evaluation of maximum safe pressure, based on von Mises criterion, for an autofrettaged gun barrel is also included in the paper. Based on case study included in the article, for an autofrettaged gun barrel or pressure vessel with uniform thickness, a theoretical weight reduction of approximately 16 per cent is feasible with von Mises criterion as compared to Tresca criterion.</p>

scholarly journals Comprehensive finite-element study of processes for the production of titanium strips by asymmetric cold rolling of a powder followed by sintering

2019 ◽  
pp. 173-192
Author(s):  
I.Yu Prykhodko ◽  
M.O. Dedik ◽  
Stefan Brandt ◽  
K.O. Gogaev ◽  
A.I Itsenko ◽  
...  
Keyword(s):  
Finite Element ◽  
Sintered Material ◽  
Compression Modulus ◽  
Hydrostatic Compression ◽  
Thin Plates ◽  
Uniform Density ◽  
Shear Stresses ◽  
Production Processes ◽  
Von Mises ◽  
Sintering Processes

Finite-element numerical modeling was implemented and a study of the production processes of thin titanium strips was carried out on the basis of two key sequential processes: asymmetric powder rolling and sintering of the rolled product using the Brand-Nielson model. The results of studying the processes of compaction and sintering of titanium powder using a single mathematical model proposed by Jan Brandt are presented. For the calculations we used experimentally determined shear stresses and volumetric compression modulus under hydrostatic compression and uniaxial compression. The friction conditions between the surfaces of the rolls and the powder were determined as a function of the change in the Coulomb coefficient of friction on the relative sliding speed of the surfaces of the roll and the workpiece. An analysis of the results allows a quantitative assessment of the influence of the technology parameters of the compaction and sintering processes on the change in the stress state and relative density in the volume of products at the stages of production processes. It is shown that the application of the von Mises density and stress diagrams for the correction of the sintering regime allows avoiding the appearance of defects (insufficiently uniform density of the sintered material and the presence of microcracks) during intense heating of the metal in the furnace. The development of sintering modes based on the Brand-Nielson model simplifies the improvement of technology in the sintering of bulk bodies, which is a more time-consuming process than sintering of thin plates. This model can be used in the development of sintering regimes for various materials since it takes into account the influence of basic phenomena in this process. By varying the technology parameters it is possible to achieve targeted effects on product quality indicators and prevent the formation of microcracks in them.

Reduction of Free-Edge Stress Concentration

1985 ◽  
Vol 52 (4) ◽  
pp. 801-805 ◽  
Author(s):  
P. R. Heyliger ◽  
J. N. Reddy
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Three Dimensional ◽  
Element Model ◽  
Free Edge ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Interlaminar Shear ◽  
Three Dimensional Elasticity

A quasi-three dimensional elasticity formulation and associated finite element model for the stress analysis of symmetric laminates with free-edge cap reinforcement are described. Numerical results are presented to show the effect of the reinforcement on the reduction of free-edge stresses. It is observed that the interlaminar normal stresses are reduced considerably more than the interlaminar shear stresses due to the free-edge reinforcement.

Mechanics of Composite Layered Rough Medium in Contact

2013 ◽  
Vol 703 ◽  
pp. 200-203
Author(s):  
Shao Biao Cai ◽  
Yong Li Zhao
Keyword(s):  
Material Properties ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Normal Loading ◽  
Layered Coatings ◽  
Pressure Profiles ◽  
Tangential Traction ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Tangential Friction

This study presents a first attempt to develop a numerical three-dimensional multilayered (more than 2 composite layered coatings) elasticperfectly plastic rough solids model to investigate the contact behavior under combined normal loading and tangential traction. Contact analyses are performed to study the effects composite thin film layers. Local contact pressure profiles, von Mises stresses, and shear stresses as a function of material properties and applied normal and tangential friction loads are calculated.

scholarly journals A Computational Model to Assess Poststenting Wall Stresses Dependence on Plaque Structure and Stenosis Severity in Coronary Artery

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Zuned Hajiali ◽  
Mahsa Dabagh ◽  
Payman Jalali
Keyword(s):  
Coronary Arteries ◽  
Computational Models ◽  
Strong Dependence ◽  
Internal Stresses ◽  
Shear Stresses ◽  
Stress Concentrations ◽  
Opening Pressure ◽  
Fibrous Cap ◽  
Stent Restenosis ◽  
Von Mises

The current study presents computational models to investigate the poststenting hemodynamic stresses and internal stresses over/within the diseased walls of coronary arteries which are in different states of atherosclerotic plaque. The finite element method is applied to build the axisymmetric models which include the plaque, arterial wall, and stent struts. The study takes into account the mechanical effects of the opening pressure and its association with the plaque severity and the morphology. The wall shear stresses and the von Mises stresses within the stented coronary arteries show their strong dependence on the plaque structure, particularly the fibrous cap thickness. Higher stresses occur in severely stenosed coronaries with a thinner fibrous cap. Large stress concentrations around the stent struts cause injury or damage to the vessel wall which is linked to the mechanism of restenosis. The in-stent restenosis rate is also highly dependent on the opening pressure, to the extent that stenosed artery is expanded, and geometry of the stent struts. The present study demonstrates, for the first time, that the restenosis is to be viewed as a consequence of biomechanical design of a stent repeating unit, the opening pressure, and the severity and morphology of the plaque.

Nonlinear Theory for Composite Laminated Shells With Interfacial Damage

1998 ◽  
Vol 65 (3) ◽  
pp. 711-718 ◽  
Author(s):  
Zhen-qiang Cheng ◽  
S. Kitipornchai
Keyword(s):  
Nonlinear Theory ◽  
Virtual Work ◽  
Shear Stresses ◽  
Interfacial Damage ◽  
Laminated Shells ◽  
Lines Of Curvature ◽  
Perfect Bonding ◽  
Transverse Shear Stresses ◽  
Bounding Surfaces ◽  
Special Case

Interfacial damage is incorporated in the proposed nonlinear theory. for composite laminated shells. A spring-layer model is employed to characterize damaged interfaces spanning from perfect bonding to different degrees of imperfect bonding in shear. By enforcing compatibility conditions for transverse shear stresses both at interfaces and on two bounding surfaces of a laminated shell, only five unknowns are needed for modeling its behavior. The principle of virtual work is used to derive the governing equations, which are of 14th order in lines of curvature coordinates, variationally self-consistent with seven prescribed boundary conditions. This theory includes the conventional higher-order zigzag model for a perfectly bonded shell as a special case. Numerical results provide a physical understanding of the effect of interracial damage on bending and buckling responses of composite laminated shells.

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