Experimentálne stanovenie únavového vrubového súčiniteľa napätia pre vzorky z ocele s355 zvárané technológiou MIG

Joining components by welding is the most widespread method of joining for metal structures. For this reason, fatigue strength assessment of welded joints is of great interest to engineers involved in structure design. The welded joint itself can be considered a notch composed of a technological (inner deffects and material inhomogenities) and a geometrical (surface irregularities) part. Due to stress and strain concentration, such a notch decreases fatigue endurance of a welded construction. This paper shows experimental quantification of the fatigue stress notch factor for butt welded joints manufactured by MIG technology.Technológia zvárania je pri kovových konštrukciách najrozšírenejšou metódou spájania konštrukčných častí. Z tohto dôvodu je problematike posudzovania únavovej životnosti zvarových spojov venovaná zvýšená pozornosť strojných inžinierov. Na zvar ako taký možno pozerať ako na vrub pozostávajúci z technologickej (vnútorné chyby a nehomogenity materiálu) a geometrickej (povrchová členitosť) časti. Tento vrub vplyvom koncentrácie napätia a deformácie znižuje únavovú odolnosť konštrukcie. Obsahom tohoto príspevku je kvantifikácia únavového vrubového súčiniteľa napätia pre tupý zvar vyhotovený technológiou MIG

Experimental Quantification of the Fatigue Stress Concentrator on Mig Butt Welded S355 Steel Specimen

Joining components by welding is the most widespread method of joining for metal structures. For this reason, fatigue strength assessment of welded joints is of great interest to engineers involved in structure design. The welded joint itself can be considered a notch composed of a technological (inner deffects and material inhomogenities) and a geometrical (surface irregularities) part. Due to stress and strain concentration, such a notch decreases fatigue endurance of a welded construction. This paper shows experimental quantification of the fatigue stress notch factor for butt welded joints manufactured by MIG technology

Fatigue strength assessment of bridge dilatation shutter in real operation

In general, the bridge dilatation shutters and their components are dynamically loaded structures and so, the fatigue strength for such bridge joints should be analytically evaluated during design process. Due to difficulties arisen in calculation of acting forces on individual components the bridge shutters were assessed in a real operation. In the article, there will be presented results and diagrams obtained from direct measurements of the time depending strain i.e. stress processes in the critical points for that bridge dilatation joint. In addition, the results obtained from measurements and fatigue strength evaluation will be also confronted with testimonials based on applications of standards

Notch effect of welded joint

In general, the welded joints are multifactorial notches. This study is focused to separate the geometrical influence (when the weld can be seen on the surface) and technological factors (internal defects of the weld, structural changes of the material and residual stress) on its fatigue life. Proposed methodology of this separation comes out from the cyclic test of three specimens – group with existing weld, group without weld joint (base material) and another group where was removed outer geometry of the weld

Notch effect of welded joint

In general, the welded joints are multifactorial notches. This study is focused to separate the geometrical influence (when the weld can be seen on the surface) and technological factors (internal defects of the weld, structural changes of the material and residual stress) on its fatigue life. Proposed methodology of this separation comes out from the cyclic test of three specimens – group with existing weld, group without weld joint (base material) and another group where was removed outer geometry of the weld

Experimental investigation of properties of GFRP foam cored sandwich joints

Presented paper focuses on intermediate outcomes of the bilateral project between the Faculty of Mechanical Engineering, STU in Bratislava, Slovakia and the Institute of Automotive and Transport Engineering, UBFC in Nevers, France. Thus, mechanical properties and behaviour of glass fibre reinforced polymer composite foam cored sandwich panels joints were researched to estimate the best possible joint technology. Three-point bending and four-point bending were used to evaluate flexure strength and static force-flexure curve. Based on such testing, one specific joint composition was chosen to be broadly investigated. Finally, chosen type of joint panels was tested under four-point cyclic loading to obtain its fatigue properties

Simulation of Stress Concentrations in Notches

The fatigue life curves of materials are very sensitive to the magnitude of the stress amplitude. A small change or inaccuracy in the determination of the stress value causes large changes or inaccuracies in the calculated fatigue life estimate. Therefore, the use of computer simulations for fatigue life estimation requires a proper model development methodology. The paper is devoted to the problem of the modeling of components in notches using FEM. The modeling parameters significantly influencing the obtained stress results have been defined. Exact analytical solutions served as a benchmark for comparing the accuracy of the stress values obtained using FEM models. For the selected 2D and 3D notched components, diagrams were created for sensitivity analysis of the influence of the mesh element density at the root of the notch in correlation with the exact analytical solution. The findings from model building were applied to model the stress concentration at the root of a V-weld joint in a gas pipeline

Experimental investigation of properties of GFRP foam cored sandwich joints

Presented paper focuses on intermediate outcomes of the bilateral project between the Faculty of Mechanical Engineering, STU in Bratislava, Slovakia and the Institute of Automotive and Transport Engineering, UBFC in Nevers, France. Thus, mechanical properties and behaviour of glass fibre reinforced polymer composite foam cored sandwich panels joints were researched to estimate the best possible joint technology. Three-point bending and four-point bending were used to evaluate flexure strength and static force-flexure curve. Based on such testing, one specific joint composition was chosen to be broadly investigated. Finally, chosen type of joint panels was tested under four-point cyclic loading to obtain its fatigue properties

Simulation of Stress Concentrations in Notches

The fatigue life curves of materials are very sensitive to the magnitude of the stress amplitude. A small change or inaccuracy in the determination of the stress value causes large changes or inaccuracies in the calculated fatigue life estimate. Therefore, the use of computer simulations for fatigue life estimation requires a proper model development methodology. The paper is devoted to the problem of the modeling of components in notches using FEM. The modeling parameters significantly influencing the obtained stress results have been defined. Exact analytical solutions served as a benchmark for comparing the accuracy of the stress values obtained using FEM models. For the selected 2D and 3D notched components, diagrams were created for sensitivity analysis of the influence of the mesh element density at the root of the notch in correlation with the exact analytical solution. The findings from model building were applied to model the stress concentration at the root of a V-weld joint in a gas pipeline