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Vladimír Liška, Zuzana Šútova and Dušan Pavliak

Abstract

In this paper we analyze the sensitivity of solutions to a nonlinear singularly perturbed dynamical system based on different rewriting into a System of the First Order Differential Equations to a numerical scheme. Numerical simulations of the solutions use numerical methods implemented in MATLAB.

Open access

Catalina Raluca Mocanu and Liviu Valentin Balanescu

Abstract

To reduce the negative effects of eutrophication processes in water bodies it is necessary to improve water quality by ensuring the necessary oxygen concentration. The paper proposes a new innovative solution for the improvement of lake water quality. The premises for the implementation of the experimental floating platform which will aerate the lake waters will be presented. To give a specific view over the oxygen dispersion into the lake, numerical simulations in CFD software will be presented in different cases.

The protection of drinking water resources against pollution is a common task of outstanding importance for the water management and environment protection sectors. To prevent water supply problems arising from the short and medium-term quality deterioration of resources caused by pollution incidents, it is vital to develop methods for monitoring the quality of resources as well as methods for monitoring and predicting serious pollution events to protect water users. In the case of vulnerable drinking water resources, the establishment and maintenance of an early warning monitoring system is important. Emergency treatment technologies are also needed by the waterworks to treat the water for periods when the quality of the water has temporarily deteriorated.

Innovative solutions for the improvement of water quality consist in using a floating platform equipped with aeration systems. The equipment used to aerate the lake waters is powered by the area renewable energy (solar, wind). So, this platform can be used in isolated area, where there is no energy supply from the national network.

Open access

Grzegorz Porembski and Janusz Kozak

Simulation of damage process of containership's side structure due to collision with a rock

This paper presents methods and results of a simplified numerical simulation of collision process of containership's side structure and a rock. Analysis of results of the modeling makes it possible to draw conclusions as to a character of the event as well as to estimate area and depth of damage caused by the penetrating rock, in order to select geometry of a filler and impermeable layer of 2nd protection barrier.

Open access

P. Chabera, A. Boczkowska, A. Morka, T. Niezgoda, A. Oziębło and A. Witek

Abstract

The paper presents numerical and experimental results in the study of composite armour systems for ballistic protection. The modelling of protective structures and simulation methods of experiment as well as the finite elements method were implemented in LS DYNA software. Three armour systems with different thickness of layers were analyzed. Discretization for each option was built with three dimensional elements guaranteeing satisfactory accuracy of the calculations. Two selected armour configurations have been ballistically tested using the armour piercing (AP) 7.62 mm calibre. The composite armour systems were made of Al2O3 ceramics placed on the strike face and high strength steel as a backing material. In case of one ballistic structure system an intermediate ceramic- elastomer layer was applied. Ceramic- elastomer composites were obtained from porous ceramics with porosity gradient using pressure infiltration of porous ceramics by elastomer. The urea-urethane elastomer, as a reactive liquid was introduced into pores. As a result composites, in which two phases were interconnecting three-dimensionally and topologically throughout the microstructure, were obtained. Upon ballistic impact, kinetic energy was dissipated by ceramic body The residual energy was absorbed by intermediate composite layer. Effect of the composite shell application on crack propagation of ceramic body was observed.

Open access

Daria Wotzka, Andrzej Cichoń and Tomasz Boczar

Abstract

A verification study of ultrasound transmission numerical simulation results with experiment results is presented in this paper. The work considers a model of a transformer tank which is filled with electro insulating oil. In the experiment, performed under laboratory conditions, an ultrasound wave is generated by a piezoelectric transducer that is fixed in the centre of the tank and measured by another transducer mounted inside the tank at three distances: 10, 20 and 30 cm from the sound source. The transducer is able to measure and generate acoustic waves in the ultrasound frequency band up to 1 MHz. The simulation considers numerical calculation of acoustic pressure distribution inside the tank in which acoustic source emits waves with frequency equal to 100 kHz. Verification analysis has confirmed consistency of the numerically calculated values with the measurement results.

Open access

Dongqiao Zhang, Yajun Yin, Jianxin Zhou and Zhixin Tu

Abstract

Eutectoid growth, as the important reaction mechanism of the carbon steel heat treatment, is the basis to control the microstructure and performance. At present, most studies have focused on lamellar growth, and did not consider the nucleation process. Mainly due to the nucleation theory is inconclusive, a lot of research can support their own theory in a certain range. Based on the existing nucleation theory, this paper proposes a cooperative nucleation model to simulate the nucleation process of eutectoid growth. In order to ensure that the nucleation process is more suitable to the theoretical results, different correction methods were used to amend the model respectively. The results of numerical simulation show that when the model is unmodified, the lateral growth of single phase is faster than that of longitudinal growth, so the morphology is oval. Then, the effects of diffusion correction, mobility correction and ledges nucleation mechanism correction on the morphology of nucleation and the nucleation rate were studied respectively. It was found that the introduction of boundary diffusion and the nucleation mechanism of the ledges could lead to a more realistic pearlite.

Open access

J. Adamus and P. Lacki

In the paper the results of investigation of sheet-titanium forming with flexible tool are presented. Titanium alloy sheets belong to a group of materials which are very hard to deform at ambient temperature. To improve sheet formability forming technology using a semi-flexible tool was implemented. Experiments were carried out on a specially designed for this purpose device. Due to the application of a rubber pad the stress state similar to triaxial compression was produced in the deformed material. Such a stress state made it possible to obtain higher material deformation without risk of fracture. The numerical simulations were used for analysing the flexible forming process. The ADINA System basing on the Finite Element Method (FEM) was applied.

Open access

K. Sołek and L. Trębacz

Thermo-Mechanical Model of Steel Continuous Casting Process

In the paper a numerical model of heat and mass transfer in the mould zone in the steel continuous casting technology was presented. The model has been developed using ProCAST software designed for simulation of casting processes. It allows to determine temperature and stress distribution in continuous castings in order to optimize the most important process parameters. In this work calculations were executed for low carbon steel grades casted in the industry. In the simulations the real rheological properties measured in the experimental work and the boundary conditions determined on the basis of the industrial data were used.

Open access

A. Cwudziński

Abstract

This paper presents the results of computer simulations (Ansys-Fluent) and laboratory experiments (physical water model) carried out to describe the motion of steel flow in the tundish. The facility under investigation is a single-nozzle slab tundish. The internal geometry of consider object was changed by flow control device i.e. subflux turbulence controller (STC). In order to obtain a complete hydrodynamic picture in the tundish furniture variants tested, the computer simulations were performed for both isothermal and non-isothermal conditions. From the performed computer simulations and laboratory experiments (physical modeling) it can be found that, the non-isothermal conditions occurring during continuous steel casting will definitely influence the hydrodynamic pattern forming in the tundishes with STC.

Open access

A. Cwudziński

Abstract

This paper presents the results of computer simulations and laboratory experiments carried out to describe the motion of steel flow in the tundish. The facility under investigation is a single-nozzle tundish designed for casting concast slabs. For the validation of the numerical model and verification of the hydrodynamic conditions occurring in the examined tundish furniture variants, obtained from the computer simulations, a physical model of the tundish was employed. State-of-the-art vector flow field analysis measuring systems developed by Lavision were used in the laboratory tests. Computer simulations of liquid steel flow were performed using the commercial program Ansys-Fluent¯. In order to obtain a complete hydrodynamic picture in the tundish furniture variants tested, the computer simulations were performed for both isothermal and non-isothermal conditions.