Fatigue Analysis of a Welded Lap Joint Under Bending Load

2002 ◽  
Author(s):  
Kenny Koay ◽  
Brad Bracht ◽  
Vance Browne
Keyword(s):  
Hot Spot ◽  
Lap Joints ◽  
Cycle Life ◽  
Test Machine ◽  
Lap Joint ◽  
Joint Work ◽  
Hot Spot Stress ◽  
Actual Structure ◽  
Welded Structure ◽  
Bending Load

Welded lap joints subject to cyclic loading are used in industrial vehicles and equipment. Cyclic bending loads can result in fatigue failure of these joints. It is desirable to predict the expected life of the joint as a function of a load-stress parameter. To predict the life of a typical welded structure, additional types of weld joints and loads must also be considered. The lap joint work covered here provides a building block for the structure life prediction. For the work reported here, lap joints were formed by an industrial manufacturing wire feed weld process by certified welders. Strain gages were applied to one of the joint members. A fixture was designed and built to apply a pure bending load to the welded members at the joints, and this was installed in a fatigue test machine. A number of fully reversed tests were run to failure at various loads and some were run to effective infinite life. A resulting set of stress life curves was generated based on mean life and mean life less one and two standard deviations as a function of the “hot spot” stress. This hot spot is the region near the weld toe where the stress distribution starts to deviate from linearity due to the geometric stress riser of the weld fillet and joint geometry. Measurements show that this stress can be approximated by the calculated beam bending stress for the specimens and loads used in the tests. The results of this work provide guidelines for design of welded lap joints for a desired cycle life and for predicting the expected cycle life of an existing joint including uncertainties in life due to weld and test variables. The stress needed to predict the life of a joint is obtained by strain measurements on the actual structure. For design, the stress may be approximated by calculated stresses.

Assessment of Fatigue Crack Growth in Imperfect Lap Joint: Part 2 — Crack Propagation Analysis Using “SCANP”

2012 ◽  
Author(s):  
Satoshi Igi ◽  
Yasushi Morikage ◽  
Masaru Wakasa ◽  
Shoichi Yoshida ◽  
Kazuyoshi Sekine ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Tensile Load ◽  
Lap Joints ◽  
Software System ◽  
Lap Joint ◽  
Crack Face ◽  
Deck Plate ◽  
Bending Load

The deck plates of single-deck-type floating roofs for large oil storage tanks are joined by single-welded Full-fillet lap joints. In areas with frequent strong winds, fatigue cracks sometimes occur in the welds of the deck plate. The aim of the present study is to investigate the effect of the gap imperfection of the lap joints on the fatigue life. In the case that tensile load acted on Full-fillet lap joints, the stress at the crack face becomes larger by gap imperfection of the lap joint. The authors have developed a software system called “SCANP (Surface Crack Analysis Program)”, a software system to evaluate the stress intensity factor, K, and to simulate fatigue crack propagation for surface cracks for arbitrarily distributed surface stresses. The fatigue life of a lap joint was predicted by the “SCANP” using the calculated stresses at the root crack face and the toe crack face. The number of loading cycles to penetration for arbitrary bending load amplitudes and tensile load amplitudes are obtained.

Numerical Investigation on the Fatigue Behavior of the Multi-Planar Tubular DX-Joint under Combined Loads

2014 ◽  
Vol 1006-1007 ◽  
pp. 11-17
Author(s):  
Gui Jie Liu ◽  
Yu Zhang ◽  
Basit Farooq
Keyword(s):  
Finite Element ◽  
Hot Spot ◽  
Fatigue Behavior ◽  
Combined Loading ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Bending Load ◽  
Weld Toe ◽  
Plane Bending ◽  
Stress Concentration Factors

The stress concentration factors (SCFs) is used in the fatigue design for calculating hot-spot stress. However a major issue can be noted that the majority of research results are focused on the SCF distribution of uni-planar tubular joints subjected to the single basic load. By aiming to find the solution of this problem, the distribution of SCFs at the weld toe of a multi-planar tubular DX-joint which is subjected to the two set of the balanced combined loading components at the end of in-plane braces is studied by the finite element method. Thus it is concluded that for the axial plus in-plane bending load case, hot-spot stress location varies between saddle and crown position; while the location is invariably at the saddle position under combined axial plus out-of-plane bending loads. At last the API RP2A equation for predicting hot-spot stress is used for comparison with the finite element analysis results. Meanwhile the distribution of SCFs is also provided, that information indicates the-hot spot location along the weld toe affects the crack initiation.

scholarly journals Definition of hot spot Stress in welded structure for fatigue assessment (2nd Report)

1991 ◽  
Vol 1991 (170) ◽  
pp. 705-721
Author(s):  
Susumu Machida ◽  
Masaaki Matoba ◽  
Hitoshi Yoshinari ◽  
Ryuichi Nishimura
Keyword(s):  
Hot Spot ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Welded Structure ◽  
Definition Of

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.

scholarly journals Definition of Hot Spot Stress in Welded Structure for Fatigue Assessment (3rd Report)

1992 ◽  
Vol 1992 (171) ◽  
pp. 477-484 ◽  
Author(s):  
Susumu Machida ◽  
Masaaki Matoba ◽  
Hitoshi Yoshinari ◽  
Ryuichi Nishimura
Keyword(s):  
Hot Spot ◽  
Hot Spot Stress ◽  
Fatigue Assessment ◽  
Welded Structure ◽  
Definition Of

scholarly journals Effect of Pressure Distribution on the Energy Dissipation of Lap Joints under Equal Pre-tension Force

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 320-328
Author(s):  
Delin Sun ◽  
Minggao Zhu
Keyword(s):  
Energy Dissipation ◽  
Pressure Distribution ◽  
Theoretical Basis ◽  
Lap Joints ◽  
Power Exponent ◽  
Lap Joint ◽  
Stick Slip ◽  
Pressure Distributions ◽  
Hysteretic Characteristics ◽  
Effective Use

Abstract In this paper, the energy dissipation in a bolted lap joint is studied using a continuum microslip model. Five contact pressure distributions compliant with the power law are considered, and all of them have equal pretension forces. The effects of different pressure distributions on the interface stick-slip transitions and hysteretic characteristics are presented. The calculation formulation of the energy dissipation is introduced. The energy dissipation results are plotted on linear and log-log coordinates to investigate the effect of the pressure distribution on the energy distribution. It is shown that the energy dissipations of the lap joints are related to the minimum pressure in the overlapped area, the size of the contact area and the value of the power exponent. The work provides a theoretical basis for further effective use of the joint energy dissipation.

Hot spot stress investigation on rib-to-deck-to-floor beam connections in UHPC reinforced OSDs

2021 ◽  
Vol 179 ◽  
pp. 106517
Author(s):  
Bin Cheng ◽  
Hesham Abdelbaset ◽  
Liang Tian ◽  
Hai-Ting Li ◽  
Qingtian Su
Keyword(s):  
Hot Spot ◽  
Hot Spot Stress

Experimental comparison in hot spot stress between CFCHS and CHS K-joints with gap

2008 ◽  
pp. 389-395 ◽  
Author(s):  
L Tong ◽  
C Sun ◽  
Y Chen ◽  
X Zhao ◽  
C Liu ◽  
...  
Keyword(s):  
Hot Spot ◽  
Experimental Comparison ◽  
Hot Spot Stress

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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