Fatigue Strength Evaluation of the Load-Carrying Cruciform Fillet Welded Joints Using Hot-Spot Stress

2006 ◽  
pp. 1281-1284
Author(s):  
Byeong Wook Noh ◽  
Jung Il Song ◽  
Sung In Bae
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Hot Spot ◽  
Hot Spot Stress ◽  
Strength Evaluation ◽  
Load Carrying

Fatigue Strength Evaluation of the Load-Carrying Cruciform Fillet Welded Joints Using Hot-Spot Stress

2006 ◽  
Vol 324-325 ◽  
pp. 1281-1284 ◽  
Author(s):  
Byeong Wook Noh ◽  
Jung I. Song ◽  
Sung In Bae
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Hot Spot ◽  
Plate Thickness ◽  
Structural Stress ◽  
Leg Length ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Load Carrying ◽  
Weld Toe

In this study, fatigue strength of load-carrying cruciform fillet welded joints were evaluated using a new method proposed by Yamada, for geometric or structural stress in welded joint, that is, one-millimeter stress below the surface in the direction corresponding to the expected crack path. Validity of the method is verified by analyzing fatigue test results for load-carrying cruciform welded specimens has different size of weld toe radius, leg length and plate thickness reported in literature. Structural stress concentration factor for 1mm below the surface was calculated by finite element analysis for each specimen respectively. When compared to the basic fatigue resistance curve offered by BS7608, the one-millimeter stress method shows conservative evaluation for load-carrying cruciform fillet welded joints.

FATIGUE STRENGTH ASSESSMENT OF THE FILLET WELDED CRUCIFORM JOINTS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4225-4230
Author(s):  
DAE-JIN KIM ◽  
CHANG-SUNG SEOK ◽  
JAE-MEAN KOO
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Hot Spot ◽  
Fatigue Tests ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Cruciform Joints ◽  
Strength Assessment ◽  
Load Carrying ◽  
Cruciform Joint

In this study, fatigue tests to obtain S - N curves and FE analyses to obtain structural stress concentration factors were conducted for two types of fillet welded cruciform joints, that is, load-carrying and non load-carrying types. The obtained S - N curve of the load-carrying joint was changed to that based on hot-spot stress. As a result, the S - N curve of the load-carrying joint based on hot-spot stress almost coincided with that of the non load-carrying joint based on nominal stress. The fatigue strength of a welded joint which has a different geometry from that of the non load-carrying cruciform joint but the same bead profile as that of the non load-carrying cruciform joint could be estimated by using both the structural stress concentration factor at the weld toe position obtained from FEM and the nominal S - N curve of the non load-carrying cruciform joint from experiment.

A Comparative Study on the Fatigue Evaluation for Weldments under Out-of Plane Bending Load Using Structural Stress and Hot Spot Stress

2006 ◽  
Vol 326-328 ◽  
pp. 995-998
Author(s):  
Myung Hyun Kim ◽  
Chung In Ha ◽  
Sung Won Kang ◽  
Jeong Hwan Kim ◽  
Jae Myung Lee
Keyword(s):  
Fatigue Strength ◽  
Hot Spot ◽  
Mesh Size ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Strength Assessment ◽  
Bending Load ◽  
Load Carrying ◽  
Out Of Plane ◽  
Plane Bending

Fatigue strength assessments with two types of load carrying fillet weldment under out-of-plane bending load have been carried out by using both hot spot stress and structural stress methods. Basis for the derivation of structural stress method is discussed in detail. Finite element analyses using shell elements models have been performed for the fatigue strength assessment of weldments. As a result of the fatigue strength evaluation for load carrying transverse fillet weldment, hot spot stress method is found to be consistent with structural stress method as well as measurement. Hot spot stress, however, estimated for the load carrying longitudinal fillet weldment exhibit large variation with respect to mesh size and element type while the calculated structural stress for the longitudinal fillet weldment is relatively independent of mesh size. The fatigue life estimation according to structural stress has been introduced with the master S-N curve.

Hot Spot Stress Fatigue Evaluation to Duplex Stainless Steel Welded Joints

2006 ◽  
Vol 324-325 ◽  
pp. 779-782
Author(s):  
Fa Yong Jia ◽  
Li Xing Huo ◽  
Gang Chen ◽  
Qun Peng Zhong
Keyword(s):  
Stainless Steel ◽  
Fatigue Strength ◽  
Duplex Stainless Steel ◽  
Test Data ◽  
Welded Joints ◽  
Hot Spot ◽  
Engineering Application ◽  
Hot Spot Stress ◽  
Flat Side ◽  
Stress Fatigue

Fatigue strength of duplex stainless steel welded joints with longitudinal fillet welded guess and with longitudinal flat side guess welded on plate was evaluated by hot spot stress, hot spot stress S-N curves were produced and compared with normal stress S-N curves. The results show that the hot spot stress fatigue strength of the two kinds welded joints should be expressed by only single S-N curve while nominal stress S-N curves can only be regressed respectively. The test data are greatly above the S-N curves with slope m=3, recommended by IIW, which indicates that the slope m=3(IIW) has great safety factor in practical engineering application. But there is no appreciable difference in fatigue strength between duplex stainless steel and common structural steel with similar welded joints when fixed the test data to slope m=3.

Re-evaluation of weld root fatigue strength for load-carrying fillet welded joints using the notch stress concept

2021 ◽  
Vol 144 ◽  
pp. 106076
Author(s):  
Hamidreza Rohani Raftar ◽  
Mohammad Dabiri ◽  
Antti Ahola ◽  
Timo Björk
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Notch Stress ◽  
Load Carrying ◽  
Weld Root

Fatigue Assessment of Welded Joints Taking Into Account Effects of Residual Stress

2010 ◽  
Author(s):  
Nur Syahroni ◽  
Stig Berge
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Fatigue Testing ◽  
International Association ◽  
Hot Spot ◽  
Mean Stress ◽  
Element Analysis ◽  
Structural Rules ◽  
Fatigue Design

Residual stress may have a significant effect on the fatigue strength of welded joints. As a non-fluctuating stress, it has an effect similar to that of the mean stress. Recently the International Association of Ship Classification Societies (IACS) has issued Common Structural Rules (CSR) for respectively tankers (IACS 2006a) and bulk carriers (IACS 2006b). The effect of mean stress in fatigue design is taken into account in both sets of rules. However, the treatment is quite different, in particular with regard to residual stress and shakedown effects. In the present paper a comparative study of fatigue design procedures of the IACS rules is reported, with emphasis on residual stress effects. Testing was carried out with longitudinal attachment welds in the as-welded condition. The initial residual stress was measured by a sectioning method using strain gages. Hot spot stress was determined experimentally by strain gauges and numerically by finite element analysis using different types of elements. Fatigue testing was carried out and SN-curves were plotted according to the relevant stress as specified by the rules. In order to investigate the shake-down effect of residual stress, testing was performed for several pre-load conditions which could be taken to represent maximum load levels in a load history. The aim of the study is to contribute towards better understanding of the effect of residual stress and shakedown on fatigue strength of welded joints.

scholarly journals Improvement of trawler hull structure under condition of ensuring fatigue strength

2021 ◽  
Vol 4 (7(112)) ◽  
pp. 50-59
Author(s):  
Leontii Korostylov ◽  
Dmytro Lytvynenko ◽  
Hryhorii Sharun ◽  
Ihor Davydov
Keyword(s):  
Fatigue Strength ◽  
Fatigue Damage ◽  
Hot Spot ◽  
Fatigue Cracks ◽  
Bending Moment ◽  
Theoretical Method ◽  
Corrosive Wear ◽  
Hot Spot Stress ◽  
Hull Structure ◽  
Internal Forces

The structure of the hull of the project 1288 trawler in a region of fore hold was improved to ensure fatigue strength of assemblies of the intersection of main frames with the second bottom. To this end, a study of the fatigue strength of these assemblies was carried out for the original side structure and two versions of its modernization. Values of internal forces at the points of appearance of fatigue cracks in the compartment have been determined for three design versions of the side. It was found that the greatest forces act in the middle of the fore half of the compartment. Calculations of parameters of the long-term distribution of magnitudes of ranges of total equivalent operating stresses according to the Weibull law in the points of occurrence of fatigue cracks for different design versions of the side grillage have been performed. These parameters were determined for the middle of the fore hold of the vessel and for the areas in which maximum values of bending moment ranges are in effect with and without corrosive wear. Values of total fatigue damage and durability of the studied assemblies were determined. Calculations were carried out by nominal stress method, hot spot stress method, and experimental and theoretical method. It was shown that in order to ensure fatigue strength of the assembly under consideration, it is necessary to extend the intermediate frames of the original version of the side structure to the level of the second bottom fixing them to the deck. It is also necessary to attach a cargo platform to the side thus reducing the frame span. As a result, the level of fatigue damage over 25 years of operation will decrease by about 3.5 times. As it was found, approximate consideration of the slamming effect does not significantly increase the amount of fatigue damage to the assembly. The results of the development of recommendations for modernization of the side structure can be implemented both on ships of the 1288 project and on other ships with a transverse side framing system.

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