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.

A Weibull Failure Theory for Contact Loading in Gears With Asymmetric Teeth

2008 ◽  
Author(s):  
M. Dhorje ◽  
S. Ekwaro-Osire ◽  
M. P. H. Khandaker ◽  
F. Karpat
Keyword(s):  
Stress Gradient ◽  
High Stress ◽  
Probability Of Failure ◽  
Contact Loading ◽  
Gear Teeth ◽  
Stress Gradients ◽  
Failure Theory ◽  
The Face ◽  
Modified Weibull ◽  
Material Mismatch

Meshing gear pairs have regions of high stress gradients due to contact loading. In other applications, high stress gradients can also be generated due to geometric irregularities, material mismatch, or thermal mismatch. In meshing gear pairs, the extent of the region with a high stress gradient depends on the material and the geometric properties. It is common that failure, through crack initiation, will occur in the region of high stress and strain gradients. The conventional Weibull failure theory fails to accurately predict the probability of failure of components with high stress gradients. In this research, the contact loading in a gear pair, with asymmetric teeth, is analyzed. Thus, the objective of this work is to develop a Weibull failure theory to handle the high stress gradients due to contact loading in gear pairs with asymmetric teeth. The modified Weibull failure theory developed uses the weight function approach to account for the variation of the critical stress along the face of natural flaws. For contacting gear teeth, it is demonstrated that the modified Weibull failure theory generates monotonous trends for the probability of failure with respect to increasing Weibull modulus.

Modified Weibull Failure Theory for Size Effect Prediction of Brittle Thin Film

2006 ◽  
Author(s):  
M. Khandaker ◽  
M. Dhorje ◽  
S. Ekwaro-Osire
Keyword(s):  
Thin Film ◽  
Size Effect ◽  
Statistical Approach ◽  
High Stress ◽  
Geometrical Constraint ◽  
Stress Gradients ◽  
Failure Theory ◽  
Modified Weibull

A brittle thin film bonded to a substrate is common in MEMS components. At the edge of the interface, high stress gradients exist. It has been observed that mechanical strengthening of the thin film with decreasing film size occurs due to two constraints, namely, the microstructural constraint and the geometrical constraint. Consideration of both these constraints is required to properly predict the size effect impact on the strength of a brittle thin film. In this paper, a statistical approach is developed to predict the size effect of a brittle thin film on a substrate.

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.

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

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.

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