Effect of details of vertical stiffener on fatigue behavior of welding plate beams

The design of the vertical stiffener details is important in the anti-fa- tigue design of the welded steel plate beams.There still exist different opinions on the selection of the design parameters and the effect of the shear stress.In the present study,the effects of the welding process(semi-automatic welding, manual welding)and the connecting location of vertical stiffener(welded to the web or to the flange)on the fatigue behaviour in the regions subjected to the pure bending and subjected to the bending and shearing are investigated by test- ing the simulation beams of large scale.The analysis of the fatigue test results shows that the normal bending stress is the governing factor to the fatigue strength.

Semi-analytic Solution of Steady Temperature Fields During Thin Plate Welding

Usually, it is very difficult to find out an analytical solution to thermal conduction problems during high temperature welding. Therefore, as an important numerical approach, the method of lines （MOLs） is introduced to solve the temperature field characterized by high gradients. The basic idea of the method is to semi-discretize the governing equation of the problem into a system of ordinary differential equations （ODEs） defined on discrete lines by means of the finite difference method, by which the thermal boundary condition with high gradients are directly embodied in formulation. Thus the temperature field can be obtained by solving the ODEs. As a numerical example, the variation of an axisymmetrical temperature field along the plate thickness can be obtained.

Penetration of the Stiffener Web to Deck Plate Weld in Orthotropic Plated Bridge Decks

This paper reports the results of experimental research the longitudinal stiffeners in an orthotropic plated bridge deck on concerning the connection between the deck plate and the web of a microscopic scale. An important number of test specimens of a weld are studied with the help of a video microscope, to detect the efficiency of the root of the weld. The second part of the paper is concerned with parametric analysis of the lack of weld penetration by using accurate finite element modelling. The results demonstrate that the weld quality often required can not always be assured, which surely has important consequence on the stresses in the weld and the fatigue resistance.

Inhomogeneity of microstructure and mechanical properties in the nugget of friction stir welded thick 7075 aluminum alloy joints

In this study, 20 mm thick AA7075-T6 alloy plates were joined by friction stir welding. The microstructure and mechanical properties of the nugget zone along the thickness direction from the top to the bottom was investigated. The results showed that the microstructure including the grain size, the degree of dynamic recrystallization, the misorientation angle distribution and the precipitation phase containing its size, type and content exhibited a gradient distribution along the thickness direction. The testing results of mechanical properties of the slices showed that the nugget was gradually weakened along the depth from the top to the bottom. The maximum ultimate tensile strength, yield strength and elongation of the slice in the nugget top-middle are obtained, which are 415 MPa, 255 MPa and 8.1%, respectively.

Lower limit law of welding windows for explosive welding of dissimilar metals

The influence of explosive charge thickness on the quality of explosive welding of dissimilar metals was investigated.The lower limit law should be followed in the course of explosive welding.Three welding experiments of stainless steel（410S）and steel（Q345R）were carried out in three different kinds of explosive charge thicknesses,namely 15,25and 35mm.Interfaces of morphology and mechanical properties of three samples were observed and tested.It was found that micro and small wavy bonding is mainly formed for charge thickness of 15mm whose strength is the highest with minor deformation and few defects in the interface;small and middle wavy bonding are mainly formed for charge thickness of 25 mm whose strength is comparatively mediocre;big wavy bonding is mainly formed for charge thickness of 35 mm whose strength is the lowest.The cause of high bonding strength of the micro and small wavy interface was analyzed and verified on the basis of the results of Electron Probe Micro-Analyzer（EPMA）tests of three selected samples.