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Influence of modelling phase transformations with the use of LSTM network on the accuracy of computations of residual stresses for the hardening process

Wróbel Joanna, Kulawik Adam

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 4

art. no. e145681

EN

Replacing mathematical models with artificial intelligence tools can play an important role in numerical models. This paper analyses the modeling of the hardening process in terms of temperature, phase transformations in the solid state and stresses in the elastic-plastic range. Currently, the use of artificial intelligence tools is increasing, both to make greater generalizations and to reduce possible errors in the numerical simulation process. It is possible to replace the mathematical model of phase transformations in the solid state with an artificial neural network (ANN). Such a substitution requires an ANN network that converts time series (temperature curves) into shares of phase transformations with a small training error. With an insufficient training level of the network, significant differences in stress values will occur due to the existing couplings. Long-Short-Term Memory (LSTM) networks were chosen for the analysis. The paper compares the differences in stress levels with two coupled models using a macroscopic model based on CCT diagram analysis and using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) and Koistinen-Marburger (KM) equations, against the model memorized by the LSTM network. In addition, two levels of network training accuracy were also compared. Considering the results obtained from the model based on LSTM networks, it can be concluded that it is possible to effectively replace the classical model in modeling the phenomena of the heat treatment process.

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

Kulawik A., Sczygiol N., Wróbel J

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 1

79--86

EN

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.

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Wyznaczanie odkształceń towarzyszących hartowaniu powierzchniowym wielościegowym źródłem ciepła

Kulawik A., Wróbel J.

Modelowanie Inżynierskie

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2013

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T. 16, nr 47

123--128

PL

W pracy przedstawiono model numeryczny procesu hartowania ruchomym źródłem ciepła elementów stalowych ze średniowęglowej stali konstrukcyjnej. Dokonano analizy zjawisk cieplnych, przemian fazowych w stanie stałym oraz zjawisk mechanicznych towarzyszących obróbce cieplnej elementu stalowego w kształcie rury. Przyjęto, że ruch źródła ciepła odbywał się po ścieżkach kołowych równoległych. Pola temperatury i naprężeń wyznaczono na podstawie opracowanego oprogramowania wykorzystującego metodę elementów skończonych dla zadań 3D. Do wyznaczania udziałów fazowych w stanie stałym wykorzystano model makroskopowy oparty na analizie wykresów CTP.

EN

In the paper a numerical model for the hardening process of surface heat source of steel elements with medium carbon constructional steel have been presented. In this model the relationship occurring between thermal phenomena, phase transformation in the solid state and mechanical phenomena have been taken into account. To solution of the tasks the finite element method is used (three-dimensional tasks). The simulations were performed for the heat source move on the parallel circular path. The presented results of the simulations are the thermal, structural, plastic strains and effective stresses in the hardening steel parts.