Strain-gage measurements in regions of high stress gradient

1961 ◽  
Vol 1 (6) ◽  
pp. 199-200 ◽  
Author(s):  
C. S. Ades ◽  
L. H. N. Lee
Keyword(s):  
Strain Gage ◽  
Stress Gradient ◽  
High Stress ◽  
High Stress Gradient

Nonrectilinear Light Propagation in Integrated Photoelasticity of Axisymmetric Bodies

1984 ◽  
Vol 8 (4) ◽  
pp. 195-200 ◽  
Author(s):  
Hillar K. Aben ◽  
Bogdan R. Krasnowski ◽  
Jerzy T. Pindera
Keyword(s):  
Light Propagation ◽  
Stress Gradient ◽  
High Stress ◽  
Experimental Studies ◽  
General Character ◽  
Deflection Of Light ◽  
Order Of Magnitude ◽  
Fringe Patterns ◽  
Axisymmetric Bodies ◽  
High Stress Gradient

The general character as well as the order of magnitude of deflection of light in axisymmetric photoelastic specimens has been investigated. Experimental studies of deflection of light in case of a particular axisymmetric state of stress with high stress gradient has been carried out. It has been shown that the integral fringe patterns depend strongly on the parameters of the recording system. Fringes of a different origin have been observed together with the integral fringe pattern.

Accounting for High Stress Gradient by a Modified Weibull Failure Theory

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
S. Ekwaro-Osire ◽  
M. P. H. Khandaker ◽  
K. Gautam
Keyword(s):  
Equivalent Stress ◽  
Stress Gradient ◽  
High Stress ◽  
External Loading ◽  
Intensity Factors ◽  
Stress Gradients ◽  
Failure Theory ◽  
Modified Weibull ◽  
Material Mismatch ◽  
High Stress Gradient

A high stress gradient occurs in a component when the stress, due to external loading, rises asymptotically. The Weibull failure theory overestimates the probability of failure for components with high stress gradients generated due to the geometric irregularities, material mismatch, thermal mismatch, and contact loading. A modified Weibull failure theory is proposed in this paper. The method is based on the weight function method. The modified Weibull failure theory was applied to two specimens, and the results showed the ability of the proposed theory to handle high stress gradients. The theory considers variable equivalent stress intensity factors along the faces of cracks; hence, it considers the strength of a specimen to be dependent on the stress field.

Fatigue Life Prediction of AA1350-H19 Wire under High Stress Gradient

2019 ◽  
Author(s):  
Ian Matos ◽  
Pedro Henrique Correa Rocha ◽  
JOSE ALEXANDER ARAUJO ◽  
Fábio Castro
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Stress Gradient ◽  
High Stress ◽  
Fatigue Life Prediction ◽  
High Stress Gradient

Fatigue Crack Growth on Heterogeneous Stress Fields: Best Analytical Approach

2014 ◽  
Vol 1650 ◽  
Author(s):  
Antonio Martin-Meizoso ◽  
Jose M. Martinez-Esnaola ◽  
Asier Bergara ◽  
Shaun Falconer
Keyword(s):  
Fatigue Life ◽  
Stress Gradient ◽  
High Stress ◽  
Life Assessment ◽  
Stress Fields ◽  
Stress Concentrations ◽  
Fatigue Life Assessment ◽  
Surface Residual Stresses ◽  
High Stress Gradient ◽  
Improve Fatigue

ABSTRACTA way of estimating Stress Intensity Factors is proposed by extending available solutions (solid and crack configurations) to stress fields not considered in available formulations. The accuracy of the proposed estimation is considered with respect to fatigue life assessment and crack shape tracing. It is aimed as very fast initial estimation, in comparison with the use of Finite Elements, in those cases were a high stress gradient is observed: stress concentrations (holes, notches, grooves) or due to surface residual stresses produced by machining techniques or induced –on purpose- to improve fatigue life (for example, by shot-peening), where no SIF solutions are available.

Fatigue Life Prediction of Vortex Reducer Based on Stress Gradient

2018 ◽  
Author(s):  
Yanbin Luo ◽  
Yanrong Wang ◽  
Bo Zhong ◽  
Jiazhe Zhao ◽  
Xiaojie Zhang
Keyword(s):  
Fatigue Life ◽  
Size Effect ◽  
Stress Gradient ◽  
Fatigue Crack Initiation ◽  
High Stress ◽  
Stress Effect ◽  
Mean Stress ◽  
Notched Specimens ◽  
Life Model ◽  
The Mean

The effects of stress gradient and size effect on fatigue life are investigated based on the distributions of stress at notch root of the notched specimens of GH4169 alloy. The relationship between the life of the notched specimens and the smooth specimens is correlated by introducing the stress gradient effect factor, and a new life model of predicting the notched specimens based on the Walker modification for the mean stress effect is established. In order to improve the prediction precision of life model with the equation parameters having a definite physical significance, the relationships among fatigue parameters, monotonic ultimate tensile strength and reduction of area are established. Three-dimensional elastic finite element (FE) analysis of a vortex reducer is carried out to obtain the data of stress and strain for predicting its life. The results show that there is a high-stress gradient at the edge of the air holes of the vortex reducer, and it is thus a dangerous point for fatigue crack initiation. The prediction result of the vortex reducer is more reasonable if the mean stress, stress gradient and size effect are considered comprehensively. The developed life model can reflect the effects of many factors well, especially the stress concentration. The life of the notched specimens predicted by this model give a high estimation precision, and the prediction life data mainly fall into the scatter band of factor 2.

scholarly journals Ability of multiaxial fatigue criteria accounting for stress gradient effect for surface defective material

2018 ◽  
Vol 165 ◽  
pp. 22032
Author(s):  
Wichian Niamchaona ◽  
Fabienne Pennec ◽  
Kévin Tihay ◽  
Michel Duchet ◽  
Bastien Weber ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Surface Defects ◽  
Stress Gradient ◽  
High Stress ◽  
High Strength Steels ◽  
Fatigue Behaviour ◽  
Multiaxial Fatigue ◽  
Integral Approach ◽  
Manufacturing Defects ◽  
Material Fatigue

New high strength steels are widely used nowadays in many industrial areas as in automotive industry. These steels are more resistant and provide higher fatigue limits than latter ones but they are also more sensible to small defects. Natural defects that outcome from metallurgy (as shrinkage, inclusion, void) are not considered in this study. We focus on small manufacturing defects such as cutting edge defects generated by punching or other surface defects due to stamping. These defects are harmful on the material fatigue behaviour due to high stress concentration at defects root. They also generate stress gradient that is beneficial from the fatigue strength point of view. This study focusses on the stress gradient (it does not account for the size effect) from cylindrical defect on specimen edge. Practically a normal stress gradient is added in multiaxial fatigue criteria formulation. Both critical plane approach and integral approach are involved in the present study. This gradient is calculated from stress states at defects root by using FEM. Criteria fatigue function at N cycles is used to assess the material fatigue strength. Obviously multiaxial fatigue criteria accounting for stress gradient give more precise fatigue functions than criteria that do not consider the gradient influence.

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