The paper presents the results of research work on linear FSW (Friction Stir Welding) joining aluminum alloys AA2024-T3 of 0.5 mm in thickness. The study was conducted on properly adapted numerical controlled 3 axis milling machine using a ceramic tool and special designed fastening device. The tool dimensions have been estimated according to the algorithm shown in the literature [4]. All joints were made of end-to end (butt) configuration under different welding speed. The rotational speed of the tool and tool offset was constant. The effect of selected technological parameters on the quality of the joint was analyzed. Produced butt joint have been subjected to a static tensile testing to identify mechanical features of the materials of joints compared to parent materials. Measurements of micro hardness HV in the plastically formed stir zone of joint and in the parent material have been carried out. Axial and radial welding forces in the joining region were recorded during the tests and their dependency from the welding parameters was studied. Based on the results of strength tests the efficiency of joints for sheets of 0.5 mm in thicknesses oscillated up to 96% compared to the parent material. It has been found that for given parameters the correct, free of defects joints were obtained. The paper also presents the results of low-cycle fatigue tests of obtained FSW joints. The use of a ceramic tool in the FSW process allows to obtain welds with higher strength than conventional tools. The results suggests that FSW can be potentially applied to joining aluminum alloys.
The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn) aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075) was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.
The paper examines various issues related to the state of stress occurring in the connection of graphite electrodes during their lifetime when operating in electric arc furnaces. It also discusses the impact of graphitization process on the electrode strength. Based on the results of numerical calculations supported by experimental studies, the effect on the connection durability of its design and technological process parameters was determined.
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The article describes the mechanical properties determined from an optimised program of modified low-cycle fatigue test (MLCF) using ductile iron as a test material. The results were compared with the results obtained from standard low-cycle fatigue test (LCF). The investigations are particularly interesting in all those cases when obtaining the required repeatability of properties of the investigated material poses some problems, even if samples are taken from the same melt, or the same variant of heat treatment is applied.
PL
W artykule zaprezentowano właściwosci mechaniczne określone w oparciu o zoptymalizowany program zmodyfikowanej niskocyklowej próby zmęczeniowej (MLCF) dla żeliwa sferoidalnego i porównano je z wynikami uzyskanymi zgodnie z procedurą klasycznej wersji niskocyklowej próby zmęczeniowej LCF. Badania te są szczególnie interesujące w tych wszystkich przypadkach, w których trudno jest uzyskać powtarzalność właściwości materiału badawczego, pochodzącego nawet z tego samego wytopu, czy wariantu obróbki cieplnej.
W pracy opisano matematycznie zjawisko cyklicznego pełzania cementu chirurgicznego, jakie zaobserwowano podczas badań zmęczeniowych niskocyklowych. Badaniom poddano cement chirurgiczny o nazwie Palamed oraz cement Palamed modyfikowany węglem szklistym w postaci proszku o granulacji 60 μm i udziale 3,2% mas. Wykorzystując model reologiczny standardowy, oceniono wpływ domieszki węgla szklistego na wielkość odkształcenia w warunkach cyklicznego pełzania. Stwierdzono korzystny wpływ tej domieszki na zachowanie się cementu w warunkach obciążeń zmiennych. Obliczenia przeprowadzono przy wykorzystaniu programu matematycznego „Mathcad 14”.
EN
Mathematically description of cyclic creep phenomena in surgical cement which occurred at low cycle fatigue tests has been attempted in this paper. It has been examined bone cement Palamed and Palamed modified with glassy carbon powder of 60 µm granulation and 3,2% in mass fraction. Calculation of deformation changes in time for the elaborated model of cyclic creep has been done. It was stated that glassy carbon has advantageous influence on behavior bone cement in conditions of changeable loadings. Calculations have been made by using program Mathcad 14.
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