Wpływ oddziaływań mechanicznych między odlewem a formą odlewniczą na warunki oddawania ciepła: model numeryczny

We present a description of the effects of thermal interactions, which take into account formation of a shrinkage gap, that affect the level of stresses in a system casting – mold. Calculations were carried out in our own computer program which is an implementation of the finite element method used to solve the equations describing a thermo-elastic-plastic model of material and the heat conduction, including solidification. In the computing algorithm we use our own criteria for mechanical interaction between the casting and mold domains. Our model of mechanical interactions between the casting and the mold allows efficient modeling of stresses occurring in the casting and an impact of development of the shrinkage gap on cooling course.W artykule przedstawiamy opis oddziaływań cieplnych, uwzględniający tworzącą się szczelinę skurczową, które wpływają na poziom naprężeń w układzie odlew – forma odlewnicza. Obliczenia przeprowadzono we własnym programie komputerowym będącym implementacją metody elementów skończonych użytej do rozwiązania równań opisujących termosprężysto–plastyczny model materiału oraz przewodzenia ciepła z uwzględnieniem krzepnięcia. W algorytmie obliczeniowym wykorzystujemy własne kryteria wzajemnego oddziaływania mechanicznego obszarów odlewu i formy odlewniczej. Opracowany model oddziaływań mechanicznych między odlewem a formą odlewniczą pozwala na efektywne modelowanie naprężeń powstających w odlewie oraz wpływ rozwoju szczeliny skurczowej na przebieg stygnięcia

Determination of stresses in the steel pipe during the superficial heat treatment process with helical path

In the paper a numerical model for the quench hardening process with the moving heat source of steel pipe made of medium carbon steel have been presented. The constant speed rotation and moving of the pipe was assumed to obtain the path of the heat source in the shape of the helical line. In this model the relationship occurring between thermal phenomena, phase transformation in the solid state and mechanical phenomena have been taken into account. The temperature and stress fields are determined using the copyright software based on the finite element method (three-dimensional tasks). To calculate the phase content in the solid state, the macroscopic model based on the analysis of the CTP diagrams is used. The range of the martensite transformations depends on the value of stresses. In the model the tempering phenomena is also taken into account. In the model of mechanical phenomena the elastic, thermal, structural, plastic strains and transformations plasticity are considered

A R C H I V E S O f F O U N D R Y E N G I N E E R I N G Method of efficiency improvement of software used for solidification process simulations

Abstract This paper presents a new method that can be used to improve the efficiency of applications used for simulations of solidification processes. The new approach concentrate on conductivity matrix building process. This operation requires information contained in finite element mesh description. Elements of this matrix depend also on temperature, which is computed in every time-steps. This situation requires multiple repeated building of the conductivity matrix (for each time-step). The new method described in this paper allows to divide the process of matrix building into two parts. The first one is built on the basis of finite element mesh description. It is independent of nodal temperature values determined in successive time-steps and can be performed only once, before first time-step. The second part of the matrix building process is performed on the basis of nodal temperature values, but does not require information about finite element mesh. Such separation of two steps of the conductivity matrix building process allows efficient implementation of simulation software for modern multi-and many-core architectures. This approach can be used to minimize the amount of data that must be transferred to memory of multi-core processors. Conducted research shows that such approach can also reduce time required for computation using sequential implementation for CPU and has no significant effect on the simulation results