Laser welding technology is applied to many types of welded joints. The determination of the influence of technological parameters on the properties of resulting joint is a significant problem for ...technologists. Numerical estimation of the shape of the weld and its deformation is important in the initial stage of construction design. The paper concerns computer analysis of thermal and mechanical phenomena in laser welded lap joint made of austenitic steel. Three dimensional discrete model of analyzed lap joint is created in Abaqus FEA engineering software. Numerical analysis takes into account temperature dependent thermomechanical properties of austenitic steel. The movable heat source power distribution is modelled using Gaussian distribution. Computational model takes into account the gap between the joined plates. Temperature distribution in analysed joints is presented on the basis of performed numerical simulations. The shape and size of the fusion zone as well as deformation of the joint are estimated.
Laser beam cutting technology is becoming increasingly popular in various industries. Advantages of this method is a very high cutting speed and a precision of edges of cut elements. Good quality ...depends on many technological parameters. Numerical prediction of the effect of cutting process parameters on the quality of the surface can be useful for technologists. The work concerns the numerical analysis of the laser cutting process of sheet made of steel. The influence of selected parameters on the energy efficiency of the heat source and the cutting speed are analyzed. Numerical calculations are performed in Abaqus software. Three-dimensional discrete model of the analyzed system is developed. The standard material parameters of austenitic steel changing with the temperature are taken into account. Gauss model describing the distribution of movable heat source of a laser beam power are assumed in the solution algorithms. The influence of various parameters of the laser beam on obtained temperature field and shape of cut zone is estimated on the basis of numerical calculations. The results are compared with the results of the experiment.
We develop a new method to measure source proper motions in microlensing events, which can partially overcome problems due to blending. It takes advantage of the fact that the source position is ...known precisely from the microlensing event itself. We apply this method to the event MOA-2011-BLG-262, which has a short timescale t {sub E} = 3.8 day, a companion mass ratio q = 4.7 × 10{sup –3}, and a very high or high lens-source relative proper motion μ{sub rel} = 20 mas yr{sup –1} or 12 mas yr{sup –1} (for two possible models). These three characteristics imply that the lens could be a brown dwarf or a massive planet with a roughly Earth-mass 'moon'. The probability of such an interpretation would be greatly increased if it could be shown that the high lens-source relative proper motion was primarily due to the lens rather than the source. Based on the long-term monitoring data of the Galactic bulge from the Optical Gravitational Lensing Experiment, we measure the source proper motion that is small, μ{sub s}=(−2.3,−0.9)±(2.8,2.6) mas yr{sup −1} in a (north, east) Galactic coordinate frame. These values are then important input into a Bayesian analysis of the event presented in a companion paper by Bennett et al.
This work concerns mathematical and numerical modelling of temperature field during Yb:YAG laser heating of sheets made of S355 steel with the motion of liquid steel in the fusion zone taken into ...account. Laser power distribution and the caustics are determined on the basis of the geostatistical kriging method. Temperature field and melted material velocity field in the fusion zone are obtained from the numerical solution of continuum mechanics equations using projection method and finite volume method. Numerical algorithms are implemented into computer solver using ObjectPascal programming language. Computer simulations of Yb:YAG laser heating process are performed for different process parameters. Characteristic zones of experimentally obtained cross sections of heated elements are compared to numerically predicted fusion zone and heat affected zone.
The numerical analysis of laser welding process with consideration analytical methods determining phase transformations and mechanical properties of welded joints are presents in this paper. The ...analytical CCT diagram and final structural composition of S355 steel are presented. The empirical relations presents in paper are determined by chemical compositions investigated steel and cooling rate between temperatures 800-500°C (t
8/5
). Phase composition and mechanical properties each of structures of steel in weld and heat affected zone (HAZ) are determined on the basis of analytical methods. Laser welded flat is used in numerical simulations in ABAQUS. Mathematical modes of volumetric welding source are used in the calculations. Temperature fields, shape and size of melting zone for selected points in the cross-section of the joint are determined on the basis of thermal cycles obtained numerical.
The COVID-19 pandemic affected the elderly in a special way. On the one hand, it contributed to the increase in health deficits and those related to social isolation. On the other hand, it also had a ...significant impact on the level and methods of support provided to seniors. The pandemic situation turned out to be a particular challenge for local governments and non-governmental organisations operating in various areas of senior policy. The general aim of the article was to analyse the state’s initiatives aimed at counteracting the effects of the COVID-19 pandemic addressed to seniors and examples of activities of the local government and the civil sector cooperating with it for the benefit of this group of people. In turn, the specific objective was to identify and understand the greatest difficulties that seniors had during the pandemic and the role played by the non-governmental organisation (both during the pandemic and as an entity of potential support in the future, which was particularly interesting given the European Union promoting services provided in the local environment). In connection with the specific objective, qualitative research was carried out using the in-depth interview method. The interviews were based on scripts that concerned four areas: problems and experiences of the elderly during the pandemic, help and support, communication, health, and well-being.
The paper concerns numerical analysis of thermal phenomena occurring in the butt welding of two different materials by a laser beam welding. The temperature distribution for the welded butt-joint is ...obtained on the basis of numerical simulations performed in the ABAQUS program. Numerical analysis takes into account the thermophysical properties of welded plate made of two different materials. Temperature distribution in analysed joints is obtained on the basis of numerical simulation in Abaqus/Standard solver, which allowed the determination of the geometry of laser welded butt-joint.
The paper deals with the implementation of the chosen fatigue damage criterions into FE analysis. Our study considers a shell finite element structural analysis in conjunction with the multiaxial ...rainflow counting and the fatigue damage prediction. The computational analysis considers stochastic response under random excitation in time domain and damage calculation based on so called critical plane approach (CPA).
The paper concerns numerical simulations of progressive hardening include phase transformations in solid state of steel. Abaqus FEA software is used for numerical analysis of temperature field and ...phase transformations. Numerical subroutines, written in fortran programming language are used in computer simulations where models of the distribution of movable heat source, kinetics of phase transformations in solid state as well as thermal and structural strain are implemented. Model for evaluation of fractions of phases and their kinetics is based on continuous heating diagram and continuous cooling diagram. The numerical analysis of thermal fields, phase fractions and strain associated progressive hardening of elements made of steel were done.
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