Effect of Pressure-Dependency of the Yield Criterion on the Development of Plastic Zones and the Distribution of Residual Stresses in Thin Annular Disks

2011 ◽  
Vol 78 (3) ◽  
Author(s):  
Sergei Alexandrov ◽  
Yeau-Ren Jeng ◽  
Evgenii Lomakin
Keyword(s):  
Stress Distribution ◽  
Residual Stresses ◽  
Yield Criterion ◽  
Circumferential Stress ◽  
The Other ◽  
Plastic Yielding ◽  
Annular Disk ◽  
Effect Of Pressure ◽  
Other Hand ◽  
Pressure Dependency

The main objective of the present paper is to show an effect of pressure-dependency of the yield criterion on the development of the plastic zone and the distribution of residual stresses in a thin annular disk subject to a pressure over its inner edge during the loading stage. The Drucker–Prager yield criterion is adopted to account for the effect of the hydrostatic pressure on plastic yielding. The state of stress is supposed to be plane and the material model is perfectly plastic. A semi-analytical stress solution to the problem formulated is given and its qualitative features are emphasized. It is shown that the pressure at which plastic yielding starts and the pressure at which the entire disk becomes plastic are weakly affected by the pressure-dependency of the yield criterion. On the other hand, this dependency has a significant effect on the maximum possible pressure that can be supported by the disk. The minimum pressure at which reverse yielding occurs is also affected by the pressure-dependency of the yield criterion. In general, the residual radial stress distribution is more influenced by the pressure-dependency of the yield criterion than the residual circumferential stress distribution, although the magnitude of circumferential stresses is larger than the magnitude of radial stresses. On the other hand, the effect of pressure-dependency of the yield criterion on the residual circumferential stress distribution is pronounced in the vicinity of the inner edge of the disk, where this stress is important for improving fatigue performance of structures.

scholarly journals The Effect of IP Constituent Position and Foot Complexity on Timing in Polish Learner's English Pronunciation

2010 ◽  
Vol 8 ◽  
pp. 149-162
Author(s):  
Andrzej Porzuczek
Keyword(s):  
Stress Distribution ◽  
The Other ◽  
Speech Timing ◽  
Other Hand ◽  
British School ◽  
English Pronunciation ◽  
Native Speech ◽  
As Stress

This paper focuses on the effect of prominence level and stress distribution on timing in read English speech of Polish learners. We have measured and analysed the length of IP units distinguished by the traditional British School prosodic description, i.e. preheads, heads and nuclei, as well as stress feet, further divided into stressed and unstressed syllables. A comparison of native and Polish learners' performance shows similar durations of stressed and pitch accented syllables. The unstressed syllables and syllable clusters, on the other hand, are significantly longer in non-native speech, and the discrepancies increase at lower phrasal prominence levels, especially in the preheads. Similar results for both groups have been obtained with respect to the number of consecutive unstressed syllables (foot complexity). The same test repeated after seven months of pronunciation training reveals a considerable tendency towards native speech timing, although the differences concerning low prominence levels remain significant.

Plastic Collapse of a Thin Annular Disk Subject to Thermomechanical Loading

2013 ◽  
Vol 80 (5) ◽  
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeau-Ren Jeng
Keyword(s):  
Analytic Solution ◽  
Hydrostatic Stress ◽  
Yield Criterion ◽  
The Other ◽  
Collapse Mechanism ◽  
Plastic Collapse ◽  
Thermomechanical Loading ◽  
Annular Disk ◽  
Collapse Mechanisms ◽  
Inner Radius

A semi-analytic solution for plastic collapse of a thin annular disk subject to thermomechanical loading is presented. It is assumed that the yield criterion depends on the hydrostatic stress. A distinguished feature of the boundary value problem considered is that there are two loading parameters. One of these parameters is temperature and the other is pressure over the inner radius of the disk. The general qualitative structure of the solution at plastic collapse is discussed in detail. It is shown that two different plastic collapse mechanisms are possible. One of these mechanisms is characterized by strain localization at the inner radius of the disk. The entire disk becomes plastic according to the other plastic collapse mechanism. In addition, two special regimes of plastic collapse are identified. According to one of these regimes, plastic collapse occurs when the entire disk is elastic, except its inner radius. According to the other regime, the entire disk becomes plastic at the same values of the loading parameters at which plastic yielding starts to develop.

Elastic-Plastic Stress Distribution in a Plastically Anisotropic Rotating Disk

2004 ◽  
Vol 71 (3) ◽  
pp. 427-429 ◽  
Author(s):  
N. Alexandrova ◽  
S. Alexandrov
Keyword(s):  
Stress Distribution ◽  
Yield Criterion ◽  
Plastic Anisotropy ◽  
Rotating Disk ◽  
Flow Rule ◽  
Plane State ◽  
Annular Disk ◽  
Elastic Plastic ◽  
State Of Stress ◽  
Associated Flow Rule

The plane state of stress in an elastic-plastic rotating anisotropic annular disk is studied. To incorporate the effect of anisotropy on the plastic flow, Hill’s quadratic orthotropic yield criterion and its associated flow rule are adopted. A semi-analytical solution is obtained. The solution is illustrated by numerical calculations showing various aspects of the influence of plastic anisotropy on the stress distribution in the rotating disk.

Diamond Coatings for Machining: Coating Thickness Effects

2009 ◽  
Author(s):  
Feng Qin ◽  
Y. Kevin Chou ◽  
Dustin Nolen ◽  
Raymond G. Thompson
Keyword(s):  
Residual Stresses ◽  
Coating Thickness ◽  
Cutting Forces ◽  
Failure Modes ◽  
Cutting Tools ◽  
Cutting Edge ◽  
The Other ◽  
Diamond Coatings ◽  
Coated Tools ◽  
Other Hand

Chemical vapor deposition (CVD)-grown diamond films have found applications as a hard coating for cutting tools. Even though the use of conventional diamond coatings seems to be accepted in the cutting tool industry, selections of proper coating thickness for different machining operations have not been often studied. Coating thickness affects the characteristics of diamond coated cutting tools in different perspectives that may mutually impact the tool performance in machining in a complex way. In this study, coating thickness effects on the deposition residual stresses, particularly around a cutting edge, and on coating failure modes were numerically investigated. On the other hand, coating thickness effects on tool surface smoothness and cutting edge radii were experimentally investigated. In addition, machining Al matrix composites using diamond coated tools with varied coating thicknesses was conducted to evaluate the effects on cutting forces, part surface finish and tool wear. The results are summarized as follows. (1) Increasing coating thickness will increase the residual stresses at the coating-substrate interface. (2) On the other hand, increasing coating thickness will generally increase the resistance of coating cracking and delamination. (3) Thicker coatings will result in larger edge radii; however, the extent of the effect on cutting forces also depends upon the machining condition. (4) For the thickness range tested, the life of diamond coated tools increases with the coating thickness because of delay of delaminations.

The Simulation Analysis of MOSFET Channel Stress for Different Oxide/Nitride/Oxide (ONO) Spacer Thicknesses

2013 ◽  
Vol 699 ◽  
pp. 436-439
Author(s):  
J.Y. Chen ◽  
Z.H. Chen ◽  
K.C. Lin ◽  
M.J. Twu ◽  
Y.H. Hung ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Simulation Analysis ◽  
The Other ◽  
Strained Si ◽  
Other Hand ◽  
Simulation Results ◽  
Spacer Thickness ◽  
Nitride Oxide ◽  
The Impact

It is demonstrated that the strained-Si can enhance the channel stress with the contact etching stop layer (CESL) stressor. In addition to CESL, this article also includes ONO spacer and investigates the impact of ONO spacer thickness on the channel stress. It is found that the channel stress increases when the nitride thickness of the ONO spacer increases. On the other hand, the stress distribution is simulated and analyzed for the devices with or without CESL stressor. Generally speaking, based on the simulation results, the channel stress of MOSFET devices increases when the nitride stressor of ONO spacer and/or CESL increases.

scholarly journals II. On the stratification of vesicular ice by pressure

1859 ◽  
Vol 9 ◽  
pp. 209-213
Keyword(s):  
Melting Temperature ◽  
Large Scale ◽  
Freezing Point ◽  
The Other ◽  
Bounding Surface ◽  
Effect Of Pressure ◽  
Other Hand ◽  
Continuous Mass ◽  
Two Sides

In my last letter to you I pointed out that my brother’s theory of the effect of pressure in lowering the freezing-point of water, affords a perfect explanation of various remarkable phenomena involving the internal melting of ice, described by Professor Tyndall in the Number of the ‘Proceedings’ which has just been published. I wish now to show that the stratification of vesicular ice by pressure observed on a large scale in glaciers, and the lamination of clear ice described by Dr. Tyndall as produced in hand specimens by a Brahmah’s press, are also demonstrable as conclusions from the same theory. Conceive a continuous mass of ice, with vesicles containing either air or water distributed through it ; and let this mass be pressed together by opposing forces on two opposite sides of it. The vesi­cles will gradually become arranged in strata perpendicular to the lines of pressure, because of the melting of ice in the localities of greatest pressure and the regelation of the water in the localities of least pressure, in the neighbourhood of groups of these cavities . For, any two vesicles nearly in the direction of the condensation will afford to the ice between them a relief from pressure, and will occa­sion an aggravated pressure in the ice round each of them in the places farthest out from the line joining their centres; while the pressure in the ice on the far sides of the two vesicles will be some­ what diminished from what it would be were their cavities filled up with the' solid, although not nearly as much diminished as it is in the ice between the two. Hence, as demonstrated by my brother’s theory and my own experiment, the melting temperature of the ice round each vesicle will be highest on its side nearest to the other vesicle, and lowest in the localities on the whole farthest from the line joining the centres. Therefore, ice will melt from these last-mentioned localities, and, if each vesicle have water in it, the partition between the two will thicken by freezing on each side of it. Any two vesicles, on the other hand, which are nearly in a line per­pendicular to the direction of pressure will agree in leaving an aggra­vated pressure to be borne by the solid between them, and will each direct away some of the pressure from the portions of the solid next itself on the two sides farthest from the plane through the centres, perpendicular to the line of pressure. This will give rise to an in­ crease of pressure on the whole in the solid all round the two cavi­ties, and nearly in the plane perpendicular to the pressure, although nowhere else so much as in the part between them. Hence these two vesicles will gradually extend towards one another by the melting of the intervening ice, and each will become flattened in towards the plane through the centres perpendicular to the direction of press­ure, by the freezing of water on the parts of the bounding surface farthest from this plane. It may be similarly shown that two vesi­cles in a line oblique to that of condensation will give rise to such variations of pressure in the solid in their neighbourhood, as to make them, by melting and freezing, to extend, each obliquely towards the other and from the parts of its boundary most remote from a plane midway between them, perpendicular to the direction of pressure.

Stress Distribution Around Two Dental Implant Materials with New Designs: Comparative Finite Element Analysis Study

2021 ◽  
Vol 4 (1) ◽  
pp. 19
Author(s):  
Faaiz Alhamdani ◽  
Khawla H. Rasheed ◽  
Amjed Mahdi
Keyword(s):  
Stress Distribution ◽  
Dental Implant ◽  
Cancellous Bone ◽  
Stress Level ◽  
The Other ◽  
Von Mises Stress ◽  
Uniform Stress ◽  
Element Analysis ◽  
Other Hand ◽  
Von Mises

Background: The introduction of modified thread designs is one of the research areas of interest in the dental implantology field. Two suggested Buttress and Reverse Buttress thread designs in TiG5 and TiG4 models are tested against a standard TiG5 Fin Thread design (IBS®). Purpose: The study aims to compare stress distribution around the suggested designs and Fin Thread design. Methods: Three dental implant models: Fin Thread design, and newly suggested Buttress and Reverse Buttress designs of both TiG5 and TiG4 models were tested using FEA for stress distribution using static (70N, 0°) and (400N, 30°) occlusal loads. Results: The main difference between the suggested Buttress design and Fin Thread design lies in the overload (400N, 30°) condition. Maximum Von Mises stress is less in Buttress design than Fin Thread design. On the other hand the level of Von Mises stress over the buccolingual slop of the cancellous bone in Fin Thread design liess within the lowest stress level. The suggested Reverse Buttress design, on the other hand showed almost uniform stress distribution in both TiG4 and TiG4 models with maximum Von Mises stress higher than the elastic modulus of cancellous bone in overload (400N, 30°) condition. Conclusion: The suggested TiG4 Buttress design might have a minor advantage of stress level in cases of stress overload. In contrast, Fin Thread design shows minimal stress over the buccolingual slop of the cancellous bone. The suggested Reverse Buttress design might be more suitable for the D1 bone quality region with the advantage of almost uniform stress distribution

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>

Non-Euclidean Stress-Free Configuration of Arteries Accounting for Curl of Axial Strips Sectioned From Vessels

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Keiichi Takamizawa ◽  
Yasuhide Nakayama
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Riemannian Geometry ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Arterial Walls ◽  
Physiological Loading ◽  
Residual Strains

It is well known that arteries are subject to residual stress. In earlier studies, the residual stress in the arterial ring relieved by a radial cut was considered in stress analysis. However, it has been found that axial strips sectioned from arteries also curled into arcs, showing that the axial residual stresses were relieved from the arterial walls. The combined relief of circumferential and axial residual stresses must be considered to accurately analyze stress and strain distributions under physiological loading conditions. In the present study, a mathematical model of a stress-free configuration of artery was proposed using Riemannian geometry. Stress analysis for arterial walls under unloaded and physiologically loaded conditions was performed using exponential strain energy functions for porcine and human common carotid arteries. In the porcine artery, the circumferential stress distribution under physiological loading became uniform compared with that without axial residual strain, whereas a gradient of axial stress distribution increased through the wall thickness. This behavior showed almost the same pattern that was observed in a recent study in which approximate analysis accounting for circumferential and axial residual strains was performed, whereas the circumferential and axial stresses increased from the inner surface to the outer surface under a physiological condition in the human common carotid artery of a two-layer model based on data of other recent studies. In both analyses, Riemannian geometry was appropriate to define the stress-free configurations of the arterial walls with both circumferential and axial residual strains.

Sources and Consequences of Residual Stresses due to Welding

2014 ◽  
Vol 783-786 ◽  
pp. 2777-2785 ◽  
Author(s):  
Thomas Nitschke-Pagel ◽  
Klaus Dilger
Keyword(s):  
Residual Stresses ◽  
The Other ◽  
Production Factor ◽  
Other Hand ◽  
Welding Processes

A detrimental parameter which is always connected with welding processes is the distortion which may occur in welded components. The reduction of distortion is a very costly production factor and in complex constructions the disposal of the distortion might be very complicate or even impossible. On the other hand we know that every step which is done to increase the stiffness of a welded component in order to avoid distortion is connected with the possibility of the generation of higher tensile residual stresses.

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