Effect of the Yield to Tensile Ratio, Y/T, on Structural Reliability of Linepipes Subject to Bend Loading

2004 ◽  
Author(s):  
Hugo A. Ernst ◽  
Richard E. Bravo ◽  
Jose´ A. Villasante ◽  
Alfonso Izquierdo
Keyword(s):  
Structural Reliability ◽  
Defect Tolerance ◽  
Deformation Control ◽  
Critical Defect ◽  
Control Situations ◽  
Critical Defect Size ◽  
Circumferential Defects ◽  
T Values ◽  
Lower Limits ◽  
Leak Before Break

A model based on elastic-plastic fracture mechanics (EPFM) and plasticity theory, was developed to study the effect of the Yield (Y) to Tensile (T) ratio, Y/T, on the structural reliability of linepipes with part through the thickness (PTT) circumferential defects subject to bend loading. The analysis allows for load or deformation control situations. The results are shown in terms of curves of critical defect size vs. the controlling variable, i.e. load or deformation. For each one of the materials studied, different cases with different Y/T values were considered. Even for the lower limits of experimental data, i.e. larger Y/T, the materials have adequate defect tolerance. A Leak Before Break Analysis was also conducted.

Effect of the Yield to Tensile Ratio, Y/T, on Structural Reliability of Linepipes

2003 ◽  
Author(s):  
Hugo A. Ernst ◽  
Jose´ A. Villasante ◽  
Alfonso Izquierdo
Keyword(s):  
Structural Reliability ◽  
Plasticity Theory ◽  
Defect Size ◽  
Defect Tolerance ◽  
Deformation Control ◽  
Critical Defect ◽  
Control Situations ◽  
Critical Defect Size ◽  
T Values ◽  
Lower Limits

The effect of the Yield (Y) to Tensile (T) ratio, Y/T, on the structural reliability of linepipes with longitudinal defects was studied in this work. A model based on elastic-plastic fracture mechanics (EPFM) and plasticity theory, was developed for that purpose. The analysis allows for load or deformation control situations. The results are shown in terms of curves of critical defect size vs. the controlling variable, i.e. load or deformation. For each one of the several materials studied, different cases with different Y/T values were considered. Even for the lower limits of experimental data, i.e. larger Y/T, the materials have adequate defect tolerance.

Effect of the Yield to Tensile Ratio on Structural Integrity of Line Pipes Subjected to Bending Loads

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Hugo A. Ernst ◽  
Richard E. Bravo
Keyword(s):  
Structural Integrity ◽  
Defect Tolerance ◽  
Deformation Control ◽  
Critical Defect ◽  
Bending Loads ◽  
Critical Defect Size ◽  
Circumferential Defects ◽  
T Values ◽  
Lower Limits ◽  
Leak Before Break

This work studies the effect of the yield (Y) to tensile (T) ratio, Y∕T, on the structural integrity of line pipes with part through the thickness (PTT) circumferential defects subject to bend loading. A model based on elastic-plastic fracture mechanics and plasticity theory was developed for that purpose. The analysis handles situation with load or deformation control conditions. The results are shown in terms of curves of critical defect size versus the controlling variable, i.e., load or deformation. For each one of the different materials studied, cases with different Y∕T values were considered. Even for the lower limits of experimental data, i.e., larger Y∕T, the materials have adequate defect tolerance. A leak before break analysis of a PTT circumferential defect growing into a through the thickness defect growing circumferentially was performed.

Effect of the Yield to Tensile Ratio on Structural Integrity of Linepipes Subjected to Internal Pressure

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Hugo A. Ernst ◽  
Richard E. Bravo ◽  
José A. Villasante ◽  
Alfonso Izquierdo
Keyword(s):  
Internal Pressure ◽  
Structural Integrity ◽  
Defect Size ◽  
Defect Tolerance ◽  
Deformation Control ◽  
Critical Defect ◽  
Control Situations ◽  
Critical Defect Size ◽  
T Values ◽  
Lower Limits

The effect of the yield (Y) to tensile (T) ratio Y∕T on the structural integrity of linepipes with part through the thickness longitudinal defects subject to internal pressure was studied in this work. A model based on elastic-plastic fracture mechanics and plasticity theory was developed for that purpose. The analysis allows for load or deformation control situations. The results are shown in terms of curves of critical defect size versus the controlling variable, i.e., load or deformation. For each one of the several materials studied, different cases with different Y∕T values were considered. Even for the lower limits of experimental data, i.e., larger Y∕T, the materials have adequate defect tolerance.

Leak-before-break analysis of a pipe containing circumferential defects

2015 ◽  
Vol 58 ◽  
pp. 369-379 ◽  
Author(s):  
X.B. Ren ◽  
B. Nyhus ◽  
H.L. Lange ◽  
M. Hauge
Keyword(s):  
Circumferential Defects ◽  
Leak Before Break

Investigation of the Improvements on Mechanical Properties and Thermal Performance of MgO-MgAl2O4 Composite Refractories by Additions of ZnO-Al2O3 to MgO

2012 ◽  
Vol 445 ◽  
pp. 530-535 ◽  
Author(s):  
Cemail Aksel
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Thermal Performance ◽  
Industrial Applications ◽  
Sem Analysis ◽  
Defect Size ◽  
Structural Variations ◽  
Factors Affecting ◽  
Critical Defect ◽  
Critical Defect Size

The variations and developments with the reasons on the mechanical properties of MgO-MgAl2O4 and MgO-ZnO-Al2O3 composite refractories were examined and thermal parameters affecting the durability of composites at high temperatures were investigated. The density, porosity, strength, modulus of elasticity, fracture toughness, fracture surface energy, critical defect size and mean MgO grain size values of composites were measured/calculated and evaluated. In addition, microstructural changes using XRD measurements and SEM analysis were examined. Thermal stress/shock parameters R and Rst that are used for determining high temperature performance of composites were calculated. The relationships between mechanical properties and structural variations for different compositions and the factors affecting this connection were investigated. With the additions of various amounts of ZnO-Al2O3 to MgO, significant improvements were achieved on both mechanical properties and R-Rst parameters of in-situ formed M-S-ZnAl2O4 composite refractories, compared to MgO-MgAl2O4 materials containing preformed spinel, by factors of up to 3.6 and 2.0, respectively. The important parameters increasing mechanical properties and thermal performance of M-S-ZnAl2O4 composites were determined as follows: i) formation of ZnAl2O4 phase leading to a high resistance to crack initiation and propagation, ii) propagation of microcracks formed in the structure for a short distance by interlinking to each other, iii) arresting or deviation of microcracks when reaching pores or ZnAl2O4 particles, and additionally iv) co-presence of both intergranular and transgranular types of cracks on fracture surfaces, and with the incorporations of ZnO-Al2O3, v) increase in density, vi) rise in critical defect size, and vii) a significant reduction in MgO grain size. The optimisation of M-S-ZnAl2O4 composite refractories that could be used for obtaining longer service life in industrial applications was performed.

Evaluation of the static cracking resistance of the metal calculating the critical defect size in bands of large compound support rolls

1990 ◽  
Vol 26 (2) ◽  
pp. 176-182
Author(s):  
O. N. Romaniv ◽  
Yu. A. Grushko ◽  
N. A. Adamova ◽  
A. N. Takach ◽  
T. Ra. Yus'kiv ◽  
...  
Keyword(s):  
Defect Size ◽  
Cracking Resistance ◽  
Critical Defect ◽  
Critical Defect Size ◽  
Large Compound

scholarly journals The effect of microstructural heterogeneities on the High Cycle Fatigue scatter of cast aluminium alloys: from an elementary volume to the structure

2018 ◽  
Vol 165 ◽  
pp. 14006 ◽  
Author(s):  
Driss El Khoukhi ◽  
Franck Morel ◽  
Nicolas Saintier ◽  
Daniel Bellett ◽  
Pierre Osmond
Keyword(s):  
Size Effect ◽  
Aluminium Alloys ◽  
Fatigue Testing ◽  
Numerical Approach ◽  
Stressed Volume ◽  
Cast Aluminium ◽  
Critical Defect ◽  
Loaded Material ◽  
Critical Defect Size ◽  
Lost Foam

Cast Al-Si alloys have been widely used in automobile applications thanks to their low density and excellent thermal conductivity. A lot of components made of these alloys are subjected to cyclic loads which can lead to fatigue failure. Furthermore, the well know size effect in fatigue, whereby the fatigue strength is reduced in proportion to an increase in size, can be important. This is caused by a higher probability of initiating a crack in larger specimens (i.e. statistical size effect). This paper analyses the role of casting defects on the statistical size effect. For that, a uniaxial fatigue testing campaign (R=0.1) has been conducted using two cast aluminium alloys, fabricated by different casting processes (gravity die casting and lost foam casting), associated with the T7 heat treatment, and with different degrees of porosity. Different specimens (smooth and notched) with different stressed volumes have been investigated. The first part of this article is dedicated to the experimental characterization of the statistical size effect in both alloys via the concept of the Highly Stressed Volume. The second part investigates the effect of the Highly Stressed Volume on the critical defect size via diagram of Kitagawa-Takahashi. The results show that the presence of statistical size effect is strongly linked to the characteristics of the pore population present in the alloy. A numerical approach, linking the observed pore distribution to the volume of loaded material, is proposed and discussed.

A New Retention Method for Sub-10 nm Liquid Filtration Using Fluorescent CdSe QDs

2012 ◽  
Vol 195 ◽  
pp. 217-220
Author(s):  
Su Wen Liu ◽  
Hai Zheng Zhang
Keyword(s):  
Pore Size ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Universal Method ◽  
Cdse Qds ◽  
Lithographic Patterning ◽  
Membrane Performance ◽  
Chemical Structures ◽  
Critical Defect ◽  
Critical Defect Size

As advances are made in the lithographic patterning process and critical defect size continues to shrink, new filters are required to remove particles in the sub-10 nm size range. Membrane filtration separates unwanted particles from a fluid by retaining particles on the membrane surface and pores, in much the same manner as a sieve. One key parameter of membrane performance is pore size, usually expressed as pore diameter. However, for nanofiltration, especially for the membranes whose pore size measures under 30 nm, manufacturers may use different methods to rate the membranes pore. Considering the different chemical structures of membranes, the vast combination of materials, and the methods of manufacturing, it is highly unlikely that a universal method can be used for all combinations.

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