Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Paweł CYBUŁKA"

Identification of material model for Finite Element Modelling of quenching process DOI:10.15199/24.2017.4.3


  The paper concerns modelling of quenching process using the finite element method. The special emphasis is put on finding the proper material characteristics, in particular for heat transfer coefficient on solid-fluid contact boundary and heat conduction for fluid, in case of highly complex flow close to the solid-fluid boundary. Only heat transfer and fluid flow are considered with solid phase mechanical behaviour neglected. The paper presents an approximate numerical model of the process and technical means by which its implementation is realised. The included numerical examples show how the obtained model allows for fast approximate simulations of quenching.Introduction. Quenching of metals is difficult to model numerically due to the complex character of processes involved, that include multi-phase flows and heat exchange between different phases [2]. Accurate models that try to capture the physics of all these processes are difficult to apply in industrial practice due to excessive requirements of computational resources, related to the necessity of resolving different time scales (e.g. for turbulent flow just after submerging a metal in a cooling agent - with time steps in the range of milliseconds - and heat transfer in the later stages of the process - with time steps in the range of seconds), as well as space scales (thin boundary layers close to the solid-fluid contact surfaces and large dimensions of quenched objects and the machinery used for quenching). The difficulty is additionally augmented by the complex character of computational domains in typical engineering problems. Therefore significant simplifications and the use of experimentally obtained data is necessary in order to provide algorithms that perform simulations with demanded accuracy in a reasonable time. In the paper we propose a finite element model for quenching simulations. In the next section the mathematical model used in finite element simulati[...]

Modelowanie procesu spawania z wykorzystaniem programu adaptacyjnej metody elementów skończonych ModFEM


  W pracy modelowano proces spawania TIG wykorzystując gaussowskie źródło ciepła. Obliczenia przeprowadzono wykorzystując własne oprogramowanie Mod_FEM_met, będące usługą infrastruktury PL-Grid+, przeznaczone między innymi do modelowania procesu spawa- nia za pomocą metody elementów skończonych. Program posiada strukturę modularną, w której wykorzystano moduły do rozwiązywania równań Naviera-Stokesa i transportu ciepła wraz z nadrzędnym modułem sprzęgającym użytym do modelowania spawania. Aby zwiększyć szybkość i dokładność obliczeń, w miejscach o dużym błędzie aproksymacji wykorzystano adaptacyjną siatkę. Obliczenia wykonano dla płytki wykonanej ze stali HS6-5-2. W obliczeniach uwzględniono zależność własności stali HS6-5-2 od temperatury oraz zjawiska termiczne na brzegach i wewnątrz obszaru jeziorka spawalniczego. Wynikiem obliczeń są wymiary i kształt jeziorka spawalniczego, pola prędkości i temperatury. Wyniki obliczeń wskazują, że parametrem optymalizującym dopasowanie wyników obliczeń do danych eksperymentalnych może być sprawność źródła ciepła. The study presents modeling of the TIG welding process using a Gaussian heat source. The calculations were performed using our in-house software Mod_FEM_met, designed for modeling, among others, welding processes using finite element method and employed as a service of PL-Grid+ infrastructure. The program has a modular structure, with the modules for solving the Navier-Stokes and heat transport equations together with a coupling super-module used in welding simulations. To increase computing speed and accuracy in areas with large error of approximation, adaptive meshes were used. Calculations were performed for plate made of HS6-5-2 steel. In the calculations the temperature dependent properties of HS6-5-2 steel, as well as thermal phenomena at the edges and inside the weld pool were taken into consideration. The results of the calculations include the dimensions and shape of the weld pool, as w[...]

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