1126 Fracture Mechanics Parameter Evaluation Based on Thermoelastic Stress Distribution Measurement

Most of fracture analyses often require an accurate knowledge of the stress/displacement field over the investigated body. However, this can be sometimes problematic when only one (singular) term of the Williams expansion is considered. Therefore, also other terms should be taken into account. Such an approach, referred to as multi-parameter fracture mechanics is used and investigated in this paper. Its importance for short/long cracks and the influence of different boundary conditions are studied. It has been found out that higher-order terms of the Williams expansion can contribute to more precise description of the stress distribution near the crack tip especially for long cracks. Unfortunately, the dependences obtained from the analyses presented are not unambiguous and it cannot be strictly derived how many of the higher-order terms are sufficient.

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Three-dimensional flow velocity and wall shear stress distribution measurement on a micropillar-arrayed surface using astigmatism PTV to understand the influence of microstructures on the flow field

Microfluidics and Nanofluidics ◽

10.1007/s10404-018-2095-8 ◽

2018 ◽

Vol 22 (7) ◽

Cited By ~ 7

Author(s):

Yoshiyasu Ichikawa ◽

Ken Yamamoto ◽

Masahiro Motosuke

Keyword(s):

Shear Stress ◽

Stress Distribution ◽

Wall Shear Stress ◽

Flow Field ◽

Flow Velocity ◽

Three Dimensional ◽

Three Dimensional Flow ◽

Distribution Measurement ◽

Wall Shear Stress Distribution ◽

Dimensional Flow

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A Probabilistic Evaluation Model for Welding Residual Stress Distribution at Piping Joint in Probabilistic Fracture Mechanics Analysis

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2008-61421 ◽

2008 ◽

Cited By ~ 3

Author(s):

Hiroto Itoh ◽

Jinya Katsuyama ◽

Kunio Onizawa

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Fracture Mechanics ◽

Failure Probability ◽

Evaluation Model ◽

Residual Stress Distribution ◽

Welding Residual Stress ◽

Probabilistic Fracture Mechanics ◽

Probabilistic Evaluation ◽

Aging Knowledge

Stress corrosion cracking (SCC) has been observed at some piping joints made by Austenitic stainless steel in BWR plants. In JAEA, we have been developing probabilistic fracture mechanics (PFM) analysis methods for aged piping based on latest aging knowledge and an analytical code, PASCAL-SP. PASCAL-SP evaluates the failure probability of piping at aged welded joints under SCC by a Monte Carlo method. We proposes a simplified probabilistic model which can be applied to the failure probability analysis based on PFM for welded joint of piping considering the uncertainty of welding residual stress. And the probabilistic evaluation model is introduced to PASCAL-SP. A parametric PFM analysis concerning uncertainties of residual stress distribution using PASCAL-SP was performed. The PFM analysis showed that the uncertainties of residual stress distribution largely influenced break probability. The break probability increased with increasing the uncertainties of residual stress.

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Microscopic Residual Stress Distribution Measurement on the Surface of Shot Peening

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.63.655 ◽

2014 ◽

Vol 63 (9) ◽

pp. 655-661 ◽

Cited By ~ 6

Author(s):

Shoichi YASUKAWA ◽

Shinichi OHYA ◽

Koichi TANGO ◽

Kazuya TAKEDA ◽

Akira TANGE

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Shot Peening ◽

Residual Stress Distribution ◽

Distribution Measurement

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Accounting for Constraint in Probabilistic Fracture Mechanics Analysis of Welds in Floating Production, Storage and Off-Loading (FPSO) Vessels

Volume 3: Materials Technology; Ocean Engineering; Polar and Arctic Sciences and Technology; Workshops ◽

10.1115/omae2003-37440 ◽

2003 ◽

Author(s):

Jens P. Tronskar

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Fracture Mechanics ◽

Crack Growth ◽

North Sea ◽

Failure Probability ◽

Crack Tip ◽

Probabilistic Fracture Mechanics ◽

Crack Tip Constraint

Revision 4 of the British Energy R6 document: “Assessment of the integrity of structures containing defects” provides methods to allow for loss of crack tip constraint for shallow weld flaws. The document also provides methods to estimate upper-bound values of the through thickness residual stress distribution for a range of common weld joint configurations. The present paper presents results of analyses where approaches to modify the R6 Option 1 or 2 failure assessment diagrams (FADs) for loss of crack tip constraint pertaining to primary and non-uniform residual stress have been applied. The modified FAD were formulated for probabilistic fracture mechanics analyses of semi-elliptical surface cracks located at transverse deck welds of Floating Production, Storage and Off-loading (FPSO) vessels designed to operate in the North Sea. The objective was to study the influence on the failure probability of modifying the FAD for constraint and allowing for non-uniform residual stress. Another objective was to study the influence of constraint correction on the combined fatigue and fracture failure probability for the vessels subjected to wave loading. Material and weld tensile properties and fracture toughness distributions for input to the probabilistic fracture mechanics analyses were obtained from testing of welded panels prepared using welding procedures for actual FPSO fabrication. The loading conditions were derived based on North Sea wave data pertaining to the offshore field where the FPSO is operating. The stresses were obtained from global FE analysis and fitted Weibull long-term and extreme value distributions. The results of the analyses demonstrate clearly the importance of correcting for crack tip constraint pertaining to both primary and secondary stress and to allow for non-uniform residual stress for shallow surface flaws of known crack heights. However, in combination with fatigue crack growth the effects become less prominent as the failure probability is governed by the uncertainty in the parameters of the crack growth relationship and the long-term stress distribution.

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