Effect of Specimen Size on J-Integral and Stress-Intensity Factor at the Onset of Crack Extension

2009 ◽  
pp. 217-217-15 ◽  
Author(s):  
HP Keller ◽  
D Munz
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Extension ◽  
Specimen Size ◽  
J Integral

Stress Intensity Factor for Cracks at the Toe of Welded Joints

2007 ◽  
Vol 348-349 ◽  
pp. 257-260
Author(s):  
Paolo Livieri ◽  
Roberto Tovo
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Welded Joints ◽  
Crack Extension ◽  
J Integral ◽  
Intensity Factors ◽  
Toe Angle ◽  
The Stability

This paper proposes a method for evaluation of the Stress Intensity Factors (SIFs) of embedded cracks lying along the bisector of the welded toe angle. The SIFs are calculated on the basis of the JV parameter (extension of the J-integral to a sharp V-notch) for a path radius equal to the crack extension without modelling the crack. The numerical calculations in the paper show the stability of the proposed method also with course meshes.

Propose of Simplified Stress Intensity Factor Equation for SCC Extension of the Pipe Welds

2008 ◽  
Author(s):  
Mayumi Ochi ◽  
Kiminobu Hojo ◽  
Itaru Muroya ◽  
Kazuo Ogawa
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Crack Extension ◽  
Crack Depth ◽  
Alloy 600 ◽  
Intensity Factors ◽  
Axial Crack ◽  
Extension Analysis

Alloy 600 weld joints have potential for primary water stress corrosion cracks (PWSCC). At the present time it has been understood that PWSCC generates and propagates in the Alloy 600 base metal and the Alloy 600 weld metal and there has been no observation of cracking the stainless and the low alloy steel. For the life time evaluation of the pipes or components the crack extension analysis is required. To perform the axial crack extension analysis the stress intensity database or estimation equation corresponding to the extension crack shape is needed. From the PWSCC extension nature mentioned above, stress intensity factors of the conventional handbooks are not suitable because most of them assume a semi-elliptical crack and the maximum aspect ratio crack depth/crack half length is one (The evaluation in this paper had been performed before API 579-1/ASME FFS was published). Normally, with the advance of crack extension in the thickness direction at the weld joint, the crack aspect ratio exceeds one and the K-value of the conventional handbook can not be applied. Even if those equations are applied, the result would be overestimated. In this paper, considering characteristics of PWSCC’s extension behavior in the welding material, the axial crack was modeled in the FE model as a rectangular shape and the stress intensity factors at the deepest point were calculated with change of crack depth. From the database of the stress intensity factors, the simplified equation of stress intensity factor with parameter of radius/thickness and thickness/weld width was proposed.

Finite Element Fracture Mechanics Study of Pre-Northridge Connections

2006 ◽  
Vol 324-325 ◽  
pp. 1007-1010 ◽  
Author(s):  
Hong Bo Liu ◽  
Chang Hai Zhai ◽  
Yong Song Shao ◽  
Li Li Xie
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Behavior ◽  
Integral Approach ◽  
J Integral ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Weld Root

The objective was to quantify the variation of stress intensity factor to weld root flaw sizes in steel frame connections. Finite-element analyses were used to study fracture toughness in welded beam-column connections. Investigations of fracture behavior mainly focused on the standard pre-Northridge connection geometry. Finite element analysis was performed using the ANSYS computer program. Stress intensity factor was calculated through a J-integral approach. Results show that stress intensity factor is not uniform and is largest in the middle of beam flange. Stress intensity factor increases nearly linear with the increase of flaw size. Backing bars have little effect on weld fractures.

Formulation for Stress Intensity Factors and J-Integral Calculation by Eddy Current Testing

2015 ◽  
Vol 660 ◽  
pp. 225-230 ◽  
Author(s):  
Salaheddine Harzallah ◽  
Mohamed Chabaat ◽  
Sekoura Benissad
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Eddy Current ◽  
Eddy Currents ◽  
J Integral ◽  
Intensity Factors ◽  
Magnetic Vector ◽  
Current Testing ◽  
Set Up

In this paper, we present a method for computing the Stress Intensity Factor (SIF) and J-Integral, by measuring and testing related Eddy currents. In the process, we provide a magnetic vector based formulations for the theoretical set up. Furthermore, we provide relevant applications having theory consistent results.

An Atomistic Computer Simulation of Crack Extension in Cubic Silicon Carbide

1992 ◽  
Vol 278 ◽  
Author(s):  
Akitaka Sawamura ◽  
Yoichi Watanabe ◽  
Ryoichi Yamamoto
Keyword(s):  
Stress Intensity Factor ◽  
Computer Simulation ◽  
Silicon Carbide ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Main Crack ◽  
Crack Extension ◽  
Crack Tip ◽  
Cubic Silicon Carbide ◽  
Atomistic Computer Simulation

AbstructAn atomistic computer simulation of mode I crack extension in cubic silicon carbide has been performed using a realistic many–body interatomic potential computed by Tersoff. The crack front is parallel to the [110] direction and the crack plane lies in the (111) plane. The stable crack tip configurations were calculated and the effective stress intensity factor and the effective crack tip position were evaluated in the relaxed atomic configuration by the least-square method. The crack was stable over a wide range of the stress intensity factors from 0. 6KG to 3. 4KG, where KG is the Griffith critical stress intensity factor. At 3.5KG an interatomic bond near the tip across the (001) plane ruptured and the crack advanced. When the crack is stable, the effective K is larger than the given K by nearly 0. 2KG to 0.4KG. Crack tip process was also simulated over a range of temperatures. At 1000K. secondary cracks were nucleated and grew like voids around the main crack, and thus the main crack was blunted.

scholarly journals Influence of Pressure and Thermal Parameters on Stresses Analysis of Pressurized and Cracked Pipes

2019 ◽  
Vol 35 (6) ◽  
pp. 1640-1646
Author(s):  
Abdullah K. Okab ◽  
Khalid A. Mohammed ◽  
Abdurahman A. Gatta
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
J Integral ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Modeling Process ◽  
Oil Gas ◽  
Pressurized Cylinder

Due to the dangerous alarm for many engineering applications such as energy generating systems and pipelines transporting oil, gas and its derivatives under high-pressure, a study of the effect of thermal and mechanical loading on the cracked materials and pipes at high-temperature environments is required. In this work, the influence of the thermal loadings on stresses analysis of pressurized and cracked pressurized pipes has been solved numerically where the mode I crack's type has been considered. The modeling process mainly aims to find the stress intensity factor, J-integral calculations and the stress distributions. The accuracy of the results has been compared with analytical solutions of a pressurized cylinder. The mesh around the crack have been modeled in a careful way to obtain accurate stress distributions. It was found that the surface’s temperature has a significant effect on stress distributions, for example, the stresses increased by 50% with increasing the temperature differences between the inner and outer pipe’s diameter. Additionally, the stress intensity factor and the J-integrals values were calculated for different crack length ratios and temperature differences. It is found at the crack length ratio of 0.6 the stress intensity factors increased up to 50% from 45 to 76 and J-integral increased by 77% from 250 kN/m to 430 kN/m. Also, the influence of fluid’s temperature investigated, and the result showed that by increasing the fluid’s temperature without cracks, the stresses decreased by 33%. Also, it was found that for different crack length ratios the J-integral and stress intensity reduces when the fluid’s temperature increases.

scholarly journals Determination of fracture toughness for steel 22k from the results of tests of different types specimens

2021 ◽  
pp. 20-25
Author(s):  
Andriy Kravchuk ◽  
Ievgen Kondriakov
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Energy ◽  
Critical Stress ◽  
Critical Stress Intensity Factor ◽  
J Integral ◽  
Heat Resistant Steel ◽  
Impact Tests

Nowadays, in various industries, in particular in nuclear energy, to determine the fracture toughness, along with standard tests of compact specimens, which are quite expensive and complex, methods are developed to determine these characteristics by impact tests of Charpy specimens using different correlations between Charpy impact fracture energy (CVN) and critical stress intensity factor (J-integral). The paper analyzes correlation and analytical methods, the authors of which consider them universal for a certain class of steels. Correlation methods are divided into one-stage and two-stage. One-stage methods allow to obtain the value of the critical stress intensity factor by the known fracture energy. Two-stage methods in the first stage offer the calculation of the dynamic critical stress intensity factor, in the second the temperature shift and obtaining a static critical stress intensity factor. Analytical methods according to the іmpact fracture diagram of the specimen allow to construct a J-R curve and calculate the value of the J-integral. A series of fracture tests of CT specimens made of heat-resistant steel 22K was carried out, the reference temperature T0 was determined according to the single-temperature method of the ASTM-1921 standard and the Master curve was constructed. A series of standard Charpy specimens impact tests in the temperature range -50…+100°С was performed using an instrumented drop-weight impact testing machine equipped with a high-speed registration system. According to the results of Charpy specimens impact tests, the fracture toughness were determined using different methods. It is established that both analytical and correlation methods cannot be universal and can be used to determine the fracture toughness of 22K steel. Therefore, a new exponential correlation was proposed between the fracture energy of the Charpy specimens and the critical stress intensity factor for heat-resistant steel 22K.

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