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Thermal Properties of Materials used in Dental Medicine

Authors: Blaž Karpe, Mateja Vodlan, Igor Kopač, Igor Budak, Aleš Nagode, Alenka Pavlič, Tatjana Puškar, Borut Kosec

Abstract

Today almost all manufacturers of dental materials in their certificates of material quality describe material chemical composition, mechanical properties, process ability and aesthetic characteristics, while information about thermal properties are not available. Within the interdisciplinary and international teamwork, thermal properties of five selected dental materials were measured, by modern transient plane source method in accordance with standard ISO 22007-2. Thermal properties were measured at temperature interval between 7 °C and 45 °C.

Key words: Dental materials, Thermal properties, Transient plane source (TPS) method, Measurement;

DOI: 10.24867/ATM-2018-1-002

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Impact energy properties of weld joint of high-hardness armor steel

Authors: Aleksandar Čabrilo, Katarina Gerić

Abstract

Welding of armored steel is complicated by the high percentage of carbon in the base metal, the presence of faults in the form of cracks and pores that occur in the weld metal and heat affected zone (HAZ) during the welding process. The crack formed in base metal or HAZ, due to dynamic or impact loads, can easily continue to propagate to the fusion line, after which its accelerated growth may occur. It was demonstrated that the selection of the preheating and interpass temperature is important in terms of the cooling rate and quantity of diffusible and retained hydrogen in the weld joint. Due to the significant interest in quantifying the resistance of material to initiation and propagation of cracks, the impact energy was measured with instrumented pendulum in the zone of base metal, weld metal and HAZ, at temperatures of -40 °C, -20 °C, 0 °C and 20 °C. The impact energy tests showed high energy for initiation as well as crack propagation in weld metal and HAZ zones, while the lowest energy was in the base metal.

Key words: GMAW welding, Armor steels, Austenitic stainless steel and Instrumented Charpy tests.

DOI: 10.24867/ATM-2018-1-003

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Developing and Testing Hybrid Glass to Steel Structural Elements – Flexible Design Approach

Authors: Trajanoska Bojana, Gavriloski Viktor, Doncheva Elisaveta

Abstract

Structural integrity of elements depends on their geometry, function and connections used between them. In this paper new hybrid glass to steel elements are investigated concerning their mechanical behavior and function which directly influences their design and vice versa. Their basic design is tested experimentally and then a flexible design approach including parametrical study is proposed for developing unique structural elements for different application. The concept design takes advantage of the mechanical properties of tempered glass, steel and polymer adhesive and achieves structural geometry which results in high mechanical, structural and architectural potential.

Key words: hybrid elements, glass and steel, design, concept, structural integrity;

DOI: 10.24867/ATM-2018-1-004

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Improvements and materials for production of a magnetic drive micropump: an overview and recommendations

Authors: Ghionea Ionut, Opran Constantin, Ćuković Sašac Pleşa Mihaela

Abstract

This paper presents an overview of an improved solution for an existing micropump model and, also, of the materials recommended to be used in the current stage of the prototype research. This micropump is provided with a closed system for driving and pumping the fluid, obtained by a special constructive solution, where the rotation of the motor shaft is provided by induction of a magnetic field. The micropump system is composed by an external driving and an internal driven magnet, connected to a pair of gears that moves the fluid between the inlet and outlet apertures. These magnets are separated by a metal cover that provides a closed volume for the transported fluid with no need for supplementary sealing, as in the case of classical hydraulic pumps. Due to this constructive solution and to the applicative fields where these magnetic drive micropumps operate, their components are produced from compatible materials to provide a low friction/wear and high efficiency in use

Key words: micropump, magnetic drive, polymeric composite, polymeric, POM, PEEK;

DOI: 10.24867/ATM-2018-1-005

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Development of a self-optimizing baking system

Authors: Lucijano Berus, Simon Klancnik, Timi Karner, Mirko Ficko

Abstract

This study focuses on designing a protocol for optimization of temperature variances inside heating device. Protocol consists of two major parts. First one is the protocol for monitoring temperature distributions and managing heat sources inside an oven. Second part is the optimization scheme, responsible for minimizing the distribution of temperature. Thermocouple J-type sensors are distributed on horizontal plane inside an oven. Digitally operated relay module switch enables heaters manipulation by pulse-width modulation (PWM) signal. Monitoring and operating of the system components is enabled by to data acquisition (DAQ) device and PC, performing the optimization with Particle swarm optimization algorithm. PSO objective function represented as maximum temperature difference recorded by sensors inside heating device is optimized. Included safety protocol serves as an off-switch if temperature inside the oven reaches critical level.

Key words: Oven; Temperature monitoring; Particle swarm optimization algorithm; Latin hypercube sampling;

DOI: 10.24867/ATM-2018-1-006

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Finite Element Modelling of Clinched Joints

Authors: Szabolcs Jónás, Miklós Tisza

Abstract

In this article the clinched joints of DP600 type steel sheets were examined by finite element method. This type of steel is a dual phase (ferritic-martensitic,) advanced high strength steel which is used mainly by the automotive industry. FE analysis was performed for further analysis and for the deeper understanding of the behaviour of the joint. The effects of the planar anisotropy, spring back and different hardening laws were examined by a 2D axisymmetric FE model in ANSYS.

Key words: Clinching; DP600; FEA; Simulation

DOI: 10.24867/ATM-2018-1-001

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