Influence of the Notch Rounding Radius on Estimating the Elastic Notch Stress Concentration Factor in a Laser Welded Tee Joint

2012 ◽  
Vol 726 ◽  
pp. 100-105 ◽  
Author(s):  
Karol Niklas ◽  
Janusz Kozak
Keyword(s):  
Stress Concentration ◽  
Laser Welding ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Local Stress ◽  
Thin Plates ◽  
Outer Side ◽  
Notch Stress ◽  
Sandwich Type ◽  
Welding Technique

In recent years an increased interest of industry in sandwich-type metal structures can be observed. These structures consist of thin plates of 2.5 mm in thickness separated by stiffeners of different shapes and forms. Welds joining the plates and stiffeners are made on the outer side of the plates using laser welding technique. A locally focused source of heat causes the plate to melt creating a very narrow and elongated joint. As a result, sharp geometric notches are formed on the side of the root of a weld – a place which is inaccessible and cannot be checked. Geometries of individual welded joints vary, sometimes considerably, and this makes their analysis even more complicated. Additionally, the use of laser welding technique influences the formation of untypical distribution of changes in material properties in weld zones. The effect is a joint whose behaviour under load is significantly different from the behaviour of a welded tee joint made with the use of classical methods. Fatigue strength calculations for this type of joints can be conducted based on local stress values in notches, which can be determined with the use of Finite Element Method (FEM). This article analyses the influence of the notch rounding radius on the elastic notch stress concentration factor Kt The aim of the analysis is to evaluate the notch stress concentration according to local notch stress approach.

Effects of Microstructure on Cavity Nucleation in Creeping Ceramics Containing Viscous Grain Boundary Phase

2008 ◽  
Vol 368-372 ◽  
pp. 1084-1087
Author(s):  
Chao Wang ◽  
Jun Liang ◽  
Yang Liu ◽  
Jie Cai Han
Keyword(s):  
Stress Concentration ◽  
Grain Boundary ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Critical Stress ◽  
Local Stress ◽  
Viscosity Coefficient ◽  
Boundary Phase ◽  
Cavity Nucleation ◽  
Grain Sizes

A theoretical model considering the distribution of the grain sizes and grain-boundary ledges was developed for cavity nucleation in creeping ceramics containing viscous grain boundary phase. The critical stress involving the effects of various shapes of cavities and viscosity coefficient (η) for cavity nucleation was presented. Then, the local stress concentration factor concerning different distributions of grain-boundary ledges was calculated and discussed. The results showed that various shapes of cavities and η are not the main influencing factors on the critical stress. The stress concentration factor increases with the increase of grain-boundary ledge size or the density. Therefore, it would be liable to cause cavity nucleation at gain boundary when the density of grain-boundary ledges is high and the size is large.

scholarly journals Parametric Formula for Stress Concentration Factor of Fillet Weld Joints with Spline Bead Profile

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4639
Author(s):  
Yixun Wang ◽  
Yuxiao Luo ◽  
Seiichiro Tsutsumi
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Case Scenario ◽  
Worst Case ◽  
Fillet Weld ◽  
Line Model ◽  
Cruciform Joints ◽  
The Real ◽  
Notch Stress

The existing parametric formulae to calculate the notch stress concentration factor of fillet welds often result in reduced accuracy due to an oversimplification of the real weld geometry. The present work proposes a parametric formula for the evaluation of the notch SCF based on the spline weld model that offers a better approximation of the real shape of the fillet weld. The spline model was adopted in FE analyses on T-shape joints and cruciform joints models, under different loading conditions, to propose a parametric formula for the calculation of the SCF by regression analysis. In addition, the precision of parametric formulae based on the line model was examined. The magnitude of the stress concentration was also analyzed by means of its probability distribution. The results show that the line model is not accurate enough to calculate the SCF of fillet weld if the weld profile is considered. The error of the SCF by the proposed parametric formulae is proven to be smaller than 5% according to the testing data system. The stress concentration of cruciform joints under tensile stress represents the worst case scenario if assessed by the confidence interval of 95% survival probability.

scholarly journals Reduction of the Local Stress Field around Holes through Porous Shaped Structures

2018 ◽  
Vol 20 (3) ◽  
pp. 36-41
Author(s):  
Stefano Monti
Keyword(s):  
Mechanical Properties ◽  
Stress Concentration ◽  
Stress Field ◽  
Present Article ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Laser Cutting ◽  
Local Stress ◽  
Hole Boundary ◽  
Local Stress Field

Geometrical discontinuities in mechanical components are detrimental for the mechanical properties of the product itself. Actually, in proximity of such features, the stress increases due to the stress concentration factor, that in the case of a circular hole is equal to 3. Several solutions have been proposed to reduce the stress concentration value. In the present article, the application of a particular porous pattern that can be obtained by laser cutting with the appropriate finishing requirements is introduced in order to modify the local stress field and reduce the stress concentration value near the hole boundary.

scholarly journals Determination of a U-Notch Stress Concentration Factor Using Thermoelasticity

2016 ◽  
Vol 6 (2) ◽  
Author(s):  
R. B. Vieira ◽  
S. Kurunthottikkal Philip ◽  
G. L. G. Gonzáles ◽  
B. Yang ◽  
R. E. Rowlands
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Notch Stress

The Stress and Strain Concentrations Associated with Two Interacting Holes in a Finite Thickness Elastic Plate Subjected to Tensile Stress

2011 ◽  
Vol 462-463 ◽  
pp. 48-53 ◽  
Author(s):  
Zheng Yang ◽  
Jian Hou ◽  
Guo Yin Wang ◽  
Zhi Hua Xiong
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Maximum Stress ◽  
Finite Thickness ◽  
Plate Thickness ◽  
Thin Plates ◽  
Stress And Strain ◽  
Stress Concentrations ◽  
Strain Concentration

The elastic stress and strain fields of a finite-thickness plate containing two interacting holes are systematically investigated using the finite element method. The maximum stress and strain concentrations occur on the mid plane only in the thin plates. They do not occur on the mid plane and their locations are different in the same plate for the thick plates. The values of the maximum stress and the strain concentration factor and their locations depend on the distance between the two holes and the plate thickness. The stress and the strain concentration factor are different, even if in an elastic state. The stress concentration factor and the strain concentration factor on the plate surface decrease rapidly with increasing thickness and becomes lower than the values corresponding to the plane stress state and the values of the mid plane. They are too low to reflect the overall stress concentrations as the plate thickness increases. The differences between the maximum value and the surface value of the stress concentration factor, the strain concentration factor increase rapidly and tend to their respective constant values with increasing plate thickness. These constant values depend on the distance between the two holes and the difference of the stress concentration factor is larger than that of the strain concentration factor in the same plate.

scholarly journals A novel thread connection structure of slimehole drilling tool in ultra-deep natural gas well

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110264
Author(s):  
Zhang Ying ◽  
Lian Zhanghua ◽  
Gao Anqi ◽  
Yang Kun
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Sensitivity Coefficient ◽  
Notch Sensitivity ◽  
Sensitivity Factor ◽  
Drilling Tool ◽  
Gas Well ◽  
Thread Connection

The thread connection’s root fillet radius of 0.038″ size is the greatest weakness of the API NC type joints and thread. During the slimehole drilling, especially in the deep and ultra-deep gas well, its stress concentration factor and notch sensitivity factor are very high A novel thread connection design (TM) of a drilling tool is proposed to decrease the fatigue failure of the slimehole drilling tool in the deep and the ultra-deep gas well in the Tarim oilfield China. The novelty in the TM thread structure is, reducing the threads per inch, extending the distance from the last engaged thread to the external shoulder of the pin and adding three threads to the conventional connection. The novel thread connection will improve the slimehole drilling tool’s anti-fatigue life due to its improved elasticity and rigidity. Furthermore, the TM can transfer the maximum stress at the connection root to the loaded surface, which can effectively lower the fatigue notch’s sensitivity coefficient. In this paper, the finite element method (FEM) is applied to carry out the detailed comparative analysis of the TM with existing thread connection NC38, TX60 and TH90. The TM has the lowest stress concentration factor and fatigue notch sensitivity coefficient, so its anti-fatigue life is the highest. In addition, TM is manufactured and is tested at Tarim oilfield in China.

Stress Concentration of Periodic Collinear Square Holes in an Infinite Plate in Tension

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Changqing Miao ◽  
Yintao Wei ◽  
Xiangqiao Yan
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Infinite Plate ◽  
Numerical Approach ◽  
Numerical Examples ◽  
Calculated Stress ◽  
Bueckner’S Principle

A numerical approach for the stress concentration of periodic collinear holes in an infinite plate in tension is presented. It involves the fictitious stress method and a generalization of Bueckner's principle. Numerical examples are concluded to show that the numerical approach is very efficient and accurate for analyzing the stress concentration of periodic collinear holes in an infinite plate in tension. The stress concentration of periodic collinear square holes in an infinite plate in tension is studied in detail by using the numerical approach. The calculated stress concentration factor is proven to be accurate.

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