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Open access

Michał Grenda

Abstract

Demand for thin-walled structures has been increasing for many years. Cold- formed, thin-walled channel beams are the subject of presented research. The local elastic buckling and limit load of these beams subjected to pure bending are investigated. This study includes numerical investigation called the Finite Strip Method (FSM). The presented results give a deep insight into behaviour of such beams and may be used to validate analytical models. The number of works devoted to the theory of thin-walled structures has been steadily growing in recent years. It means that is an increasing interest in practical methods of manufacturing cold-formed thin-walled beams with complicated cross-sections, including also beams with web stiffeners. The ratio of transverse dimensions of beam to its wall-thickness is high, therefore, thin-walled beams are prone to local buckling that may interact with other buckling modes. The stability constraints should be always considered when using cold-formed thin-walled beams.

Open access

Ráthy Istvánné, Pinke Péter and Huszák Csenge

Abstract

The wide use of composite materials is mainly due to their excellent strength / mass ratio, corrosion resistance and relatively low price. Approximately 35-40% of the fibre-reinforced composites are made of thermoplastic polymers in which fibreglass, carbon or natural fibres are most often used as reinforcement, while the remaining 60 – 65% is made up of high-tech carbon or glass fibre-reinforced thermosetting composites. Most of them are used in the transport and electronics industries. New processing technologies not only improve the properties of the products but also contribute to reducing costs.

In this paper, we compare the results of mechanical tests with molded standard specimens with polypropylene matrix and test results from cut-outs from injection molded products.

Open access

Attila Zsolt Kenéz and Gyula Bagyinszki

Abstract

Segments containing diamond particles are fixed to replaceable inserts or to steel tool bodies for cost-effectiveness. The joining technology used should meet both environmental and technical requirements. The joining zone is subjected to high mechanical and significant thermal loads during use. In the event of an improper joint, the segments may detach from the base and fly away causing injury. Nowadays, many methods of welding or brazing are used to fix diamond segments. Among the possible segment fixing technologies, laser beam welding has been investigated. The microstructure of the joints has been examined by optical and scanning electron microscopy and chemical element maps have been recorded. Joints have been subjected to fracture and hardness testing. The mechanical properties and composition changes of the joints with different joining technologies have been evaluated and compared.

Open access

Klaudia Kulcsár and János Kónya

Abstract

The material used for manufacturing of dental implantation prostheses is cobalt-chromium alloy. The following study presents a new heat treatment technology for dental implantation prostheses. Specimens were created with the innovative technology of 3D printing. The brittleness of specimens subjected to heat treatment with parameters recommended by the manufacturer made it necessary for us to reconsider the heat-treating process. After changing given heat treatment processes, tensile and hardness tests were performed. From these tests, the optimal heat treatment process technology was chosen.

Open access

Dávid Miklós Kemény and Dóra Károly

Abstract

Additive manufacturing (AM) is becoming increasingly important, making it possible to produce a product in a short time, to specific individual requirements, and even in the presence of the customer. This research is related to direct metal laser sintering of additive manufacturing. This new technology is increasingly being used in more sectors, for example in biomedical industry, where a damaged product can potentially endanger human life. Corrosion tests were carried out during our research. Cyclic voltammetry curves and corrosion rates were determined with a potentiostat. Two typical biocompatible implant materials were compared, a cobalt chromium alloy (powder metallurgy) and a titanium alloy (3D printed). The results will help in specifying the corrosion properties of additively manufactured materials.

Open access

Enikő Bitay, Irén Kacsó, Szilamér Péter Pánczél and Erzsébet Veress

Abstract

Iron slag samples unearthed at the eastern border of Roman Dacia, in the auxiliary fort and the military settlement of Călugăreni (Mikháza) are investigated by macroscopic inspection, optical microscopy (OM) and FTIR spectroscopy in order to comparatively characterize their macro- and microstructure as well as their mineralogical composition. During the recent archaeological excavations, a large number of iron artefacts were discovered together with a great quantity of iron slag fragments. The present paper focuses on the data obtained from 17 slag samples.

Open access

Tünde Kovács, Zoltán Nyikes and Lucia Figuli

Abstract

In the current century, building protection is very important in the face of terrorist attacks. The old buildings in Europe are not sufficiently resilient to the loads produced by blasts. We still do not fully understand the effects of different explosives on buildings and human bodies. [1–3] Computing blast loads are different from that of traditional loads and the material selection rules for this type of impact load are diverse. Historical and old buildings cannot be protected simply by new walls and fences. New ways need to be found to improve a building’s resistance to the effects of a blast. It requires sufficiently thin yet strong retrofitted materials in order to reinforce a building’s walls [4–6].

Open access

Gergő Richárd Fejes, Viktor Gonda and Károly Széll

Abstract

Severe plastic deformation (SPD) is a well-established methodology for the processing of bulk ultrafine grained materials. Among various methods, equal channel angular pressing (ECAP) is the most popular way of creating ultrafine grained materials. The stored energy after ECAP in these substances highly influences the microstructural processes: recovery and recrystallization of the processed materials. We analyzed the recrystallization kinetics of room and elevated temperature ECAP processed copper samples using differential scanning calorimetry (DSC). For the processing of the measurement data we developed a MATLAB processing routine.

Open access

Kónya János and Kulcsár Klaudia

Abstract

The following study analyses the use of modern 3D printing technology in dentistry with its necessary manufacturing and machining processes. Fitting of the manufactured metal structures is examined depending on their use, in terms of conventional adhesion-based denture designs and screw-fixed dentures on implants. Influencing factors and effects of the required post-processing steps are examined. Aspects such as sand-blasting, heat treatment, equipment and tools required for cutting are analyzed. The aim of this study is to create a manufacturing process that enables the required precision fitting of the created frame structure types.