scholarly journals Validation of notch stress estimation schemes for different constraints, strain gradients and loading conditions on low C-Mn steel

2021 ◽  
Author(s):  
Shreebanta Kumar Jena ◽  
Punit Arora ◽  
Suneel Gupta ◽  
J. Chattopadhyay
Keyword(s):  
Maximum Principal Stress ◽  
Loading Conditions ◽  
Strain Gradients ◽  
Strain Estimation ◽  
Notch Stress ◽  
Energy Equivalence ◽  
Stress Components ◽  
Stress Estimation ◽  
Low Constraint ◽  
Mn Steel

The present study is aimed at validation of notch stress/ strain estimation schemes such as classical Neuber, Hoffmann-Seeger and recently developed Ince-Glinka method for Nuclear piping material (low C-Mn steel). The study has considered different constraints, loading conditions, various hole sizes to accommodate strain gradient variations and equivalent peak strains. The notch stress field evaluated using these schemes is compared with corresponding stress using elastic-plastic Finite Element (FE) analyses. The comparisons have brought out that the Hoffmann-Seeger scheme results in reasonably accurate assessment of stress localization nearly for all constraint geometries, loadings and strain gradients. However, the classical Neuber scheme is more suitable for low constraint geometries and intermediate constraint geometries whereas it results in under-estimation of maximum principal stress for high constraint geometries, thereby leading to over-prediction of fatigue life. Further, the suitability of energy equivalence equations of Ince-Glinka model for individual stress components, has been reviewed.

scholarly journals Numerical Estimation of Notch Stress Intensity Factors of Sharp V-Notches

2018 ◽  
Vol 172 ◽  
pp. 03001
Author(s):  
Mirzaul Karim Hussain ◽  
K.S.R.K. Murthy
Keyword(s):  
Finite Element ◽  
Present Method ◽  
Mixed Mode ◽  
Least Squares Method ◽  
Mode I ◽  
Intensity Factors ◽  
Notch Stress ◽  
Stress Components ◽  
Mode Stress ◽  
Notch Stress Intensity Factors

In the present work a simple and efficient least squares method is implemented for accurate estimation of notch stress intensity factors (NSIFs) of sharp V-notches. Finite element (FE) stress components near a notch tip is used in the present method for determining the NSIFs. Pure mode I and mixed mode (I/II) examples are considered for numerical investigations. The mixed mode stress components are disintegrated into opening mode and shear mode stress components to separate out the mode I and mode II singularities. Thereafter, least squares method is implemented to calculate mixed mode NSIFs. The present method is easy to incorporate in existing standard finite element codes. The results obtained by the present method are found to be in good agreement with the published data.

Notch Stress and Strain Estimation Considering Multiaxial Constraint

1993 ◽  
Author(s):  
Daniel A. Klann ◽  
Steven M. Tipton ◽  
Thomas S. Cordes
Keyword(s):  
Stress And Strain ◽  
Strain Estimation ◽  
Notch Stress

Crack Initiation Predictions of the AFM-Specimen under Bend and Torsion Loading

2011 ◽  
Vol 488-489 ◽  
pp. 266-269
Author(s):  
Shi Fan Zhu ◽  
Li Zhu ◽  
Qing Fen Li
Keyword(s):  
Crack Initiation ◽  
Principal Stress ◽  
Crack Front ◽  
Complex Loading ◽  
Strain Energy Release ◽  
Maximum Principal Stress ◽  
Loading Conditions ◽  
Energy Release Rates ◽  
Strain Energy Release Rates ◽  
Computational Predictions

In this paper, the computational predictions of crack initial breakpoint and deflection angles under bend and torsion loading conditions are investigated in conjunction with the modified virtual crack closure integral (MVCCI)-method by using the all fracture modes (AFM) specimen and commercial software ANSYS. The separated strain energy release rates (SERRs) along the crack front are calculated and subsequently converted to the stress intensity factors (SIFs) by using Irwin´s equations. Based on the SIFs results, the crack initiation predictions are presented by the maximum principal stress σ1'-criterion. Results show that when the AFM-model under a series of combined proportional bend and torsion loading conditions, asymmetrical stress fields are produced along the crack front. The presented investigation also shows that the maximum principal stress σ1'-criterion in conjunction with the MVCCI-method provides a powerful numerical tool for general computational approach to the fracture analysis of complex loading conditions.

Constraint Parameter for a Longitudinal Surface Notch in a Pipe Submitted to Internal Pressure

2008 ◽  
Vol 399 ◽  
pp. 3-11 ◽  
Author(s):  
Mohammed Hadj Meliani ◽  
M. Benarous ◽  
Z. Azari ◽  
G. Pluvinage
Keyword(s):  
Stress Distribution ◽  
Fracture Mechanics ◽  
Internal Pressure ◽  
Loading Conditions ◽  
Notch Stress ◽  
T Stress ◽  
Surface Notch ◽  
Pipe Geometry ◽  
Two Parameters ◽  
Method Approach

The use of two parameters fracture mechanics criterion as a tool for structural design and analysis has increased significantly in recent years. First, we discuse the elastic solution for the stress distribution at crack tip for two dimensional geometries and particularly constraint as T-stress under various loading conditions. Secondly, using notch fracture mechanics and particularly the Volumetric Method approach, we study the stress distribution at the tip of a notch in pipes submitted to internal pressure. The Notch Stress Intensity Factor Kρ and the effective T-stress are combined into a two-parameter fracture criterion (KIρ-Tef). This approach is then used to quantify the constraint of notch-tip fields for various pipe geometry and loading conditions.

The Influence of Notches on Mechanical Behavior at Elevated Temperatures: Some Metallographic Observations

1968 ◽  
Vol 90 (1) ◽  
pp. 37-44 ◽  
Author(s):  
R. M. Goldhoff ◽  
A. J. Brothers
Keyword(s):  
Crack Initiation ◽  
Principal Stress ◽  
Elevated Temperatures ◽  
Maximum Principal Stress ◽  
Crack Initiation And Propagation ◽  
Metallographic Study ◽  
Initiation And Propagation ◽  
Section Size ◽  
Notch Geometry ◽  
Stress Components

A metallographic study of ruptured and unruptured notch bars is reported in this paper. The alloys are Cr-Mo-V steels tested in the range 1000–1050 deg F. Crack initiation and propagation in these alloys are studied as a function of the steel’s ductility with test bar section size and notch geometry as variables. It is shown that these factors interact in a complex way to control crack initiation and propagation. The mode and rate of crack initiation and propagation in ductile alloys depend mainly on shear processes although principal stress components are important under certain conditions. Alternatively, the maximum principal stress dominates the behavior in low ductility steels. In the former case, notched bar life is limited by crack propagation while in the latter case it is controlled by crack initiation. The influence of geometrical variables and metallurgical factors are discussed.

scholarly journals Generalized continuum overall modelling of periodic composite structures

2011 ◽  
Vol 33 (4) ◽  
pp. 245-258
Author(s):  
Duy Khanh Trinh ◽  
Samuel Forest
Keyword(s):  
Composite Structures ◽  
Continuum Models ◽  
Loading Conditions ◽  
Macroscopic Strain ◽  
Generalized Continua ◽  
Scale Separation ◽  
Strain Gradients ◽  
Generalized Continuum ◽  
Periodic Composite ◽  
Homogenization Methods

Classical homogenization methods fail to reproduce the overall response of composite structures when macroscopic strain gradients become significant. Generalized continuum models like Cosserat, strain gradient and micromorphic media, can be used to enhance the overall description of heterogeneous materials when the hypothesis of scale separation is not fulfilled. We show in the present work how the higher order elasticity moduli can be identified from suitable loading conditions applied to the unit cell of a periodic composite. The obtained homogeneous substitution generalized continuum is used then to predict the response of a composite structure subjected to various loading conditions. Reference finite element computations are performed on the structure taking all the heterogeneities into account. The overall substitution medium is shown to provide improved predictions compared to standard homogenization. In particular the additional boundary conditions required by generalized continua makes it possible to better represent the clamping conditions on the real structure.

Notch stress-strain estimation method based on pseudo stress correction under multiaxial thermo-mechanical cyclic loading

2020 ◽  
Vol 199 ◽  
pp. 144-157 ◽  
Author(s):  
Dao-Hang Li ◽  
De-Guang Shang ◽  
Long Xue ◽  
Luo-Jin Li ◽  
Ling-Wan Wang ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Estimation Method ◽  
Stress Strain ◽  
Strain Estimation ◽  
Notch Stress

scholarly journals Direct Estimation of the Reynolds Stress Vertical Structure in the Nearshore

2007 ◽  
Vol 24 (1) ◽  
pp. 102-116 ◽  
Author(s):  
Falk Feddersen ◽  
A. J. Williams
Keyword(s):  
Reynolds Stress ◽  
Vertical Structure ◽  
Estimation Methods ◽  
Bottom Stress ◽  
Stress Components ◽  
Waves And Currents ◽  
Stress Estimation ◽  
Alongshore Current ◽  
Stress Layer ◽  
First Time

Abstract Measurements of the vertical Reynolds stress components in the wave-dominated nearshore are required to diagnose momentum and turbulence dynamics. Removing wave bias from Reynolds stress estimates is critical to a successful diagnosis. Here two existing Reynolds stress estimation methods (those of Trowbridge, and Shaw and Trowbridge) for wave-dominated environments and an extended method (FW) that is a combination of the two are tested with a vertical array of three current meters deployed in 3.2-m water depth off an ocean beach. During the 175-h-long experiment the instruments were seaward of the surfzone and the alongshore current was wind driven. Intercomparison of Reynolds stress methods reveals that the Trowbridge method is wave bias dominated. Tests of the integrated cospectra are used to reject bad Reynolds stress estimates, and the Shaw and Trowbridge estimates are rejected more often than FW estimates. With the FW method, wave bias remains apparent in the cross-shore component of the Reynolds stress. However, the alongshore component of Reynolds stress measured at the three current meters are related to each other with a vertically uniform first EOF containing 73% of the variance, indicating the presence of a constant stress layer. This is the first time the vertical structure of Reynolds stress has been measured in a wave-dominated environment. The Reynolds stress is, albeit weakly, related to the wind stress and a parameterized bottom stress. Using derived wave bias and bottom stress parameterizations, the effect of wave bias on Reynolds stress estimates is shown to be weaker for more typical surfzone conditions (with both stronger waves and currents than those observed here).

Probabilistic modelling of the size effect on ductility of a C-Mn steel

1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-63-Pr8-70
Author(s):  
S. Carassou ◽  
M. Soilleux ◽  
B. Marini
Keyword(s):  
Size Effect ◽  
Probabilistic Modelling ◽  
Mn Steel
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