Influence of Phase Shift and Amplitude Ratio on the Principal Stresses and Directions in Multiaxial Fatigue Testing

2015 ◽  
Vol 1111 ◽  
pp. 103-109 ◽  
Author(s):  
Lorand Kun ◽  
Ion Dumitru ◽  
Daniel Achiriloaiei ◽  
Karla Noemy Kun
Keyword(s):  
Shear Stress ◽  
Phase Shift ◽  
Fatigue Testing ◽  
Amplitude Ratio ◽  
Maximum Shear Stress ◽  
Multiaxial Fatigue ◽  
Experimental Program ◽  
Shear Stresses ◽  
Principal Stresses ◽  
Normal And Shear Stresses

The maximum values of normal and shear stresses are the basic parameters which influence directly the initiation and propagation of multiaxial fatigue cracks.Based on the above, the first part of the paper presents an analysis of principal stresses (normal and shear) in case of symmetrical tension-compression loadings with superimposed phase-shifted symmetrical torsion cycles. The influence of stress amplitude ratio and phase shift on the maximum (normal and shear) stresses and on the directions of the planes along which these act is analyzed and graphically represented using stress hodographs.The second part of the paper highlights the possibility of using the maximum value of the normal or shear stress as base parameter for durability studies under multiaxial fatigue, based on existing experimental data. The mentioned data is correlated with the results of an original experimental program carried out by the authors on 41Cr4 steel and conclusions are formulated with regard to the role of maximum shear stress in life-time calculation.

scholarly journals Interaction Between Normal and Shear Stresses and Its Effect on Multiaxial Fatigue Behavior

2019 ◽  
Vol 300 ◽  
pp. 16007 ◽  
Author(s):  
Shahriar Sharifimehr ◽  
Ali Fatemi
Keyword(s):  
Normal Stress ◽  
Fatigue Damage ◽  
Shear Failure ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Multiaxial Fatigue ◽  
Experimental Program ◽  
Shear Stresses ◽  
Critical Plane ◽  
Normal And Shear Stresses

Interaction between normal and shear stresses plays an important role in multiaxial fatigue damage. The aim of this study was to investigate this interaction effect on fatigue behavior of shear failure mode materials under multiaxial loading conditions. In order to model the influence of normal stress on fatigue damage, the present study introduces a method based on the idea that the normal stress acting on the critical plane orientation causes two types of influence, first by affecting roughness induced closure, and second, by a fluctuating normal stress affecting the growth of small cracks in mode II. The summation of these terms could then be used in shear-based critical plane damage models, for example FS damage model, which use normal stress as a secondary input. In order to investigate the effect of the method, constant amplitude load paths with different levels of interaction between the normal and shear stresses were designed for an experimental program. The proposed method was observed to result in improved fatigue life estimations where significant interactions between normal and shear stresses exist.

A critical look at the Wallace-Bott hypothesis in fault-slip analysis

2013 ◽  
Vol 184 (4-5) ◽  
pp. 299-306 ◽  
Author(s):  
Richard J. Lisle
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Fault Slip ◽  
Shear Stresses ◽  
Homogeneous State ◽  
Slip Direction ◽  
Fault Surface ◽  
State Of Stress ◽  
Simultaneous Movement

AbstractThe assumption is widely made that slip on faults occurs in the direction of maximum resolved shear stress, an assumption known as the Wallace-Bott hypothesis. This assumption is used to theoretically predict slip directions from known in situ stresses, and also as the basis of palaeostress inversion from fault-slip data. This paper examines different situations in relation to the appropriateness of this assumption. Firstly, it is shown that the magnitude of the shear stress resolved within a plane is a function with a poorly defined maximum direction, so that shear stress values greater than 90% of the maximum occur within a wide angular range (± 26°) degrees. The situation of simultaneous movement on pairs of faults requires slip on each fault to be parallel to their mutual line of intersection. However, the resolved shear stresses arising from a homogeneous state of stress do not accord with such a slip arrangement except in the case of pairs of perpendicular faults. Where fault surfaces are non-planar, the directions of resolved shear stress in general give, according to the Wallace-Bott hypothesis, a set of slip directions of rigid fault blocks, which is generally kinematically incompatible. Finally, a simple model of a corrugated fault suggests that any anisotropy of the shear strength of the fault such as that arising from fault surface topography, can lead to a significant angular difference between the directions of maximum shear stress and the slip direction.These findings have relevance to the design of procedures used to estimate palaeostresses and the amount of data required for this type of analysis.

scholarly journals Shear Stress Distribution in the Opening Chords of Hybrid R/C T-Beams with Opening

2018 ◽  
Vol 147 ◽  
pp. 01005
Author(s):  
Jonie Tanijaya
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Shear Force ◽  
Maximum Shear Stress ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Web Openings ◽  
The Right ◽  
Lower Corner ◽  
T Beam

This study is carried out to evaluate the potential of three hybrid T-beams with web openings theoretical shear stresses distribution. The shear stresses at the opening edges were plotted at the working stage, yielding stage and collapse stage for these three tested beams. The available experimental results from the previous research was compared to the finite element results as well as the developed analytical. The shear stress distribution at the middle of the top and bottom chords of the opening in pure bending region are zero. At the upper and lower corners of the opening occurs the maximum shear stresses. The maximum shear stress occurs at the right lower corner chord at the high moment edge and at the left upper corner chord at the low moment edge in beams with openings at high shear and high flexural – shear region. Furthermore, an extensive parametric study is performed on these beams to find the distributing ratio of the shear force between the opening chords. The shear force at an opening in hybrid R/C T-beam is carried by the top and bottom chords of the opening according to the area – moment of inertia root ratio with the correction factor 0.70.

Off-Axis Torsion Tests on Tubular Specimens of Steel

2001 ◽  
Vol 123 (3) ◽  
pp. 268-273 ◽  
Author(s):  
Takenobu Takeda ◽  
Zhongchun Chen
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Maximum Shear Stress ◽  
Torsion Test ◽  
Combined Loading ◽  
Anisotropic Hardening ◽  
Principal Stresses ◽  
Maximum Value ◽  
The Difference ◽  
Tubular Specimens

In order to analyze the anisotropic hardening behavior of metals, an off-axis torsion test by combined loading is developed. In this test, the maximum shear stress direction φ can be changed from 0 deg to 90 deg while the ratio of maximum and minimum principal stresses is kept at −1. With increasing angle φ, the yield stress of the torsional-prestrained steel decreases; the difference between the directions of the maximum shear stress and principal shear strain increment rises to a maximum value and then decreases. It is experimentally verified that anisotropy is more severe when a smaller offset strain is used in defining the yield stress.

Internal Stresses in Elastohydrodynamic Lubrication of Rolling/Sliding Contacts

1989 ◽  
Vol 111 (1) ◽  
pp. 180-187 ◽  
Author(s):  
Farshid Sadeghi ◽  
Ping C. Sui
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Internal Stress ◽  
Maximum Shear Stress ◽  
Elastohydrodynamic Lubrication ◽  
Normal Pressure ◽  
Internal Stresses ◽  
Stress Distributions ◽  
Principal Stresses ◽  
Dimensionless Velocity

The internal stress distribution in elastohydrodynamic lubrication of rolling/sliding line contact was obtained. The technique involves the full EHD solution and the use of Lagrangian quadrature to obtain the internal stress distributions in the x, y, z-directions and the shear stress distribution as a function of the normal pressure and the friction force. The principal stresses and the maximum shear stress were calculated for dimensionless loads ranging from (2.0452 × 10−5) to (1.3 × 10−4) and dimensionless velocity of 10−10 to 10−11 for slip ratios ranging from 0 to pure sliding condition.

Mechanics of Cell Mechanosensing on Patterned Substrate

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Chenglin Liu ◽  
Shijie He ◽  
Xiaojun Li ◽  
Bo Huo ◽  
Baohua Ji
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Maximum Shear Stress ◽  
Cell Monolayer ◽  
Maximum Principal Stress ◽  
Mechanical Force ◽  
Shear Stresses ◽  
Plane Shear ◽  
Cell Behaviors ◽  
Mechanical Signals

It has been recognized that cells are able to actively sense and respond to the mechanical signals through an orchestration of many subcellular processes, such as cytoskeleton remodeling, nucleus reorientation, and polarization. However, the underlying mechanisms that regulate these behaviors are largely elusive; in particular, the quantitative understanding of these mechanical responses is lacking. In this study, combining experimental measurement and theoretical modeling, we studied the effects of rigidity and pattern geometry of substrate on collective cell behaviors. We showed that the mechanical force took pivotal roles in regulating the alignment and polarization of cells and subcellular structures. The cell, cytoskeleton, and nucleus preferred to align and polarize along the direction of maximum principal stress in cell monolayer, and the driving force is the in-plane maximum shear stress. The higher the maximum shear stress, the more the cells and their subcellular structures preferred to align and polarize along the direction of maximum principal stress. In addition, we proved that in response to the change of in-plane shear stresses, the actin cytoskeleton is more sensitive than the nucleus. This work provides important insights into the mechanisms of cellular and subcellular responses to mechanical signals. And it also suggests that the mechanical force does matter in cell behaviors, and quantitative studies through mechanical modeling are indispensable in biomedical and tissue engineering applications.

Poisson Ratio Effects on the Von Mises and Maximum Shear Stresses in Cylindrical Contacts

2005 ◽  
Author(s):  
Itzhak Green
Keyword(s):  
Shear Stress ◽  
Poisson Ratio ◽  
Unit Length ◽  
Maximum Shear Stress ◽  
Critical Force ◽  
Von Mises Stress ◽  
Maximum Pressure ◽  
Shear Stresses ◽  
Wide Range ◽  
Von Mises

This work determines the location of the greatest elastic distress in cylindrical contacts based upon the distortion energy and the maximum shear stress theories. The ratios between the maximum pressure, the von Mises stress, and the maximum shear stress are determined and fitted by empirical formulations for a wide range of Poisson ratios, which represent material compressibility. Some similarities exist between cylindrical and spherical contacts, where for many metallic materials the maximum von Mises or shear stresses emerge beneath the surface. However, if any of the bodies in contact is excessively compressible the maximum von Mises stress appears at the surface. That transitional Poisson ratio is found. The critical force per unit length that causes yielding onset, along with its corresponding interference and half-width contact are derived.

Plaque Growth Functions Combining Wall Stress, Flow Shear Stress and Morphology May Provide Better Prediction for Atherosclerosis Progression: 3D FSI Studies Based on In Vivo Serial MRI

2011 ◽  
Author(s):  
Chun Yang ◽  
Gador Canton ◽  
Chun Yuan ◽  
Tom Hatsukami ◽  
Dalin Tang
Keyword(s):  
Shear Stress ◽  
Atherosclerotic Plaque ◽  
Maximum Shear Stress ◽  
Patient Specific ◽  
Plaque Morphology ◽  
Shear Stresses ◽  
Plaque Progression ◽  
Growth Functions ◽  
Plaque Growth

Atherosclerotic plaque progression involves biological, structural and mechanical factors. Previous work has shown that initiation and early progression of atherosclerotic plaque correlate negatively with flow wall shear stresses [1–2]. However, plaque growth functions based on patient-specific data to predict future plaque growth are lacking in the current literature. Six plaque growth functions based on fluid-structure-interaction (FSI) models and in vivo serial magnetic resonance image (MRI) data were proposed for progression prediction. This is to test the hypothesis that combining plaque morphology, plaque wall maximum principal stress (WS), strain (WSN) and flow maximum shear stress (FSS) could better predict plaque progression.

Shear Stresses in Bulk Carriers Due to Shear Loading

1975 ◽  
Vol 19 (03) ◽  
pp. 155-163
Author(s):  
M. A. Shama
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Structural Model ◽  
Maximum Shear Stress ◽  
Shear Loading ◽  
Shear Stress Distribution ◽  
Shear Stresses ◽  
Shearing Force ◽  
Dynamic Component ◽  
Geometrical Properties

A brief note is given on various components of the longitudinal vertical shearing force. The stillwater component is examined with particular emphasis on the effect of local cargo loading and the mechanism of shear load transmission. The main factors affecting the wave-induced and dynamic components are indicated and an approximate method is given for estimating the impulsive dynamic component. A method is then given for calculating the shear stress distribution over a typical section of a bulk carrier. The ship section is idealized by a simplified structural model comprising closed and open cells. The structural model retains all the geometrical properties of the original section. Two numerical examples are considered to examine the effect of ship section parameters on shear stress distribution. It is shown that:(i) High shear stresses may be developed in the side shell plating.(ii) The variation of ship section parameters has a negligible effect on the maximum shear stress and may have a significant local effect.(iii) The shear carrying capacity of a given ship section could be easily estimated. Alternatively, for a given shearing force, a "shear coefficient," representing shear capability, could be estimated.

MODELING OF SCHEMES OF CRACK DEVELOPMENT IN SHAPE SHELLS BASED ON TRAJECTORIES OF THE LARGEST TENSION STRESS

2021 ◽  
pp. 15-25
Author(s):  
А. Н. Аверин ◽  
Т. А. Аверина
Keyword(s):  
Lower Surface ◽  
Biaxial Stress ◽  
Shear Stresses ◽  
Tension Stress ◽  
Double Trigonometric Series ◽  
Principal Stresses ◽  
Tensile Stresses ◽  
Biaxial Stress State ◽  
Stress Functions ◽  
Normal And Shear Stresses

В статье для пологой оболочки, загруженной равномерно распределенной нагрузкой, со схемой опирания на шарнирные опоры получено аналитическое решение. Нагрузка и неизвестные функции прогиба и напряжений представлены с помощью двойных тригонометрических рядов. Выполнены расчеты напряженно-деформированного состояния, определены усилия и перемещения. Дана оценка точности суммирования рядов по перемещениям и усилиям. В окрестности точек нижней, срединной и верхней поверхностей оболочки вычислены нормальные и касательные напряжения, а также главные напряжения и главные площадки. Показана картина двухосного напряженного состояния и на ее основе построены графики траекторий наибольших растягивающих напряжений. Графики траекторий на нижней поверхности оболочки сопоставлены с экспериментальными схемами развития трещин. По траекториям наибольших растягивающих напряжений, построенных в точках нижней поверхности, делается прогноз о месте, направлении и последовательности появления трещин в оболочке. An analytical solution is obtained in the article for a shallow shell loaded with a uniformly distributed load, with a scheme of bearing on hinged supports. Load and unknown deflection and stress functions are represented using double trigonometric series. Calculations of the stress-strain state were performed, forces and displacements were determined. An assessment of the accuracy of summation of the series of displacements and efforts is given. In the vicinity of the points of the lower, middle and upper surfaces of the shell, normal and shear stresses, as well as principal stresses and principal areas, are calculated. The picture of the biaxial stress state is shown and on its basis, the graphs of the trajectories of the highest tensile stresses are constructed. The trajectory plots on the lower surface of the shell are compared with the experimental crack propagation schemes. The trajectories of the highest tensile stresses plotted at the points of the lower surface are used to predict the location, direction, and sequence of cracks in the shell.

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