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Fatigue Life Predicting for Nitrided Steel - Finite Element Analysis

Sawicki J., Siedlaczek P., Staszczyk A.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

921--927

EN

Thermo-chemical treatments are known to increase the fatigue life of industrial parts. Due to the imprecise consideration of residual stresses in predicting the durability of components subjected to cyclic loading and their effect on the fatigue life, the authors developed a numerical model combining the influence of residual stresses with stresses caused by bending. The authors performed the numerical simulation with the use of Finite Element Method to analyse material behaviour during cyclic loading. The residual stress state developed during nitriding was introduced onto cross-section of the numerical specimen. The goal of this work was better understanding of the real conditions of the nitride steel fatigue processes and improving the knowledge about numerical predicting of the fatigue life for parts with residual stresses. The results of simulation were compared with plane bending fatigue tests. The presented method indicates the possibility of increasing the accuracy of the fatigue analysis of elements after surface treatment, increasing its certainty and the ability to perform better optimization of service life.

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The impact of nozzle configuration on the heat transfer coefficient

Krupanek K., Staszczyk A., Sawicki J., Byczkowska P.

Archives of Materials Science and Engineering

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2018

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Vol. 90, nr 1

16--24

EN

Purpose: The purpose of this paper is to elaborate guidelines regarding geometric configurations of a nozzle manifold that have an impact on the effectiveness of the quenching process and occurrence of quenching distortions. Design/methodology/approach: Within the framework of this study there an optimisation of nozzle manifold geometry was carried out with the help of numerical simulations created using Ansys CFX software. In the first stage, a simplification of the nozzle-sample system reduced to a two-dimensional simulation was employed to determine the most optimal location of the coolant stream. In the second stage, several arrangements of nozzle manifolds were tested in a three-dimensional simulation. The parameters that were taken into account included the rate of sample cooling, the uniformity of cooling with a sample volume and heat coefficient takeover read from its surface. Findings: The different active/inactive nozzle arrangements within the manifold and the impact of the specific arrangements on the uniformity of heat transfer from the sample surface were compared. Research limitations/implications: The simulations carried out within the framework of this study are one of the elaboration stages of a new flow heat treatment technology. Practical implications: The application of an efficient cooling chamber in flow treatment makes it possible to limit quenching distortions to a minimum. An optimal adjustment of cooling parameters and cooling nozzle configuration to the shape of the element in order to make the cooling uniform translate directly into a reduction in distortions. Avoiding the necessity to reduce distortions after quenching means there is a significant reduction in detail production costs (grinding). Originality/value: The concept of single-piece flow in the heat treatment for the mass industry is developing rapidly and constitutes a fully automated element of a manufacturing line, adjusted for the purposes of being included in the production process automatic control system. It also makes it possible to conduct comprehensive and integration quality supervision and management at the level of an individual element, which is not possible in the case of batch heat treatment, which is a gap in the production process.

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Modelling and simulation of core-shell precipitates under tensial loading using the cellular automata method

Staszczyk A., Debyser M., Sawicki J.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 3

443--452

EN

The equivalent truss method has been known for years as a numerical model used in problems with structural optimization. It is often implemented in computational algorithms based on cellular automation (CA). This method (CA) is highly versatile and allows the modelling of phenomena which occur in multiple dimensional scales, including material engineering issues. This paper describes a numerical model used to simulate the stress caused by the external load in a multi-phase material. The authors propose applying the algorithm in modelling the behavior of alloy materials following a thermal treatment which leads to precipitate hardening.

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Application of an equivalent truss model for determining the stress state in multi-phase materials with cellular automata method

Staszczyk A., Sawicki J.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 2

51--57

EN

The Cellular Automata represent a universal method of modelling and simulation. They enable the performance of calculations for even the most complex processes and phenomena. They are also used successfully in mechanical and material engineering. In this paper, the concept of application of the Cellular Automata method for simulating the behaviour of material under stress is presented. The proposed numerical algorithm created performs a number of calculations of local stress states in the structure of precipitation hardened material. The principle of its operation is based on the application of the equivalent truss model, which is often used in the optimisation and design of structures. In this paper, this model was used to simulate a system embodying a section of the material containing various phases with different mechanical properties.