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EN
Fatigue investigations of two 4XXX0-series aluminum alloys (acc. PN-EN 1706) within a range of fewer than 104 cycles at a coefficient of cycle asymmetry of R = –1 were performed in the current paper. The so-called modified low-cycle test, which provided additional information concerning the fatigue life and strength of the tested alloys, was also performed. The obtained results were presented in the form of diagrams: stress amplitude σa – number of cycles before damage N. On the basis of the microscopic images of sample fractures, the influence of the observed casting defects on the decrease of cycle numbers at a given level of stress amplitude were analyzed. Based on the images and dimensions of the observed defects, stress intensity factor KI was analytically determined for each. Their numerical models were also made, and stress intensity factor KI was calculated by the finite element method (FEM).
EN
Based on the example of the development process of the cast suspension of a special-purpose vehicle the application of the integrated engineering design methodology (ICME – Integrated Computational Materials Engineering) and the development of construction has been presented. Identification of the operating and critical loads, which are guidelines for carrying out the structure strength shaping process, material and technological conversion, are due to the needs and requirements of the suspension system and the purpose and objectives of the special mobile platform. The developed cast suspension element construction includes the use of high-strength AlZnMgCu aluminum alloy. The properties of the used alloy and designed shape allows for the transfer of assumed operating loads in normal exploitation conditions and in the dynamic, critical loads to the susceptibility to damage in the assumed casting areas. For the proposed design, conducted numerical analyzes includes the impact of the shock wave pulse on the occurrence of the destructive stress fields. Based on their distribution, the areas of possible decomposition of the structure of the design element were estimated. The results allowed to devise an element with predicted destructions that allow to absorb a significant part of the impact energy of the shock wave front, which is also the buffer zone for the propagation of destruction for the critical kinematic nodes of the system.
EN
The paper presents the results of the experimental and numerical analysis of material destruction of honeycomb cellular structure. Based on the experimental research, the results of numerical calculations regarding the compression process were verified along with the correctness of used constitutive numerical model. The destruction was analyzed for the casting with no structural defects and for the casting with detected porosities. The results were compared to the structural strength of the honeycomb structure manufactured on the CNC machine. The metallic honeycomb structure was manufactured as a casting of Al alloy in the investment casting technology. For manufacturing purposes the honeycomb model was obtained in additive manufacturing process. The castings and the CNC honeycomb were used in the compression test trials. The process was controlled by the displacement and the results were registered as the changes of the height and the force value. Based on the experimental results the numerical model of honeycombs was introduced for the numerical analysis of the energy absorption and compression process. The results showed good correlation between the experiment and FEM (Finite Element Method) analysis.
EN
The article presents the concept of division of a carbon block into single cathode sections to reduce stresses that occur during thermal shock accompanying the operation of pouring cast iron into a shaped groove in which the current-carrying steel pin is mounted. The temperature field and the state of stress were determined by FEM. Experimental measurements were used to determine the core displacement during pouring operation. The calculations were verified by thermovision and photoelastic method. Based on the temperature field and stress field analysis, a method for the block division into sections has been proposed, resulting in a significant reduction of the stress level.
EN
The ecological meanings clearly indicates the need of reducing of the concentration of the CO2 in the atmosphere, which can be accomplished through the lowering of the fuel consumption. This fact implies the research for the new construction solutions regarding the reduction of the weight of vehicles. The reduced weight of the vehicle is also important in the case of application of the alternative propulsion, to extend the lifetime of the batteries with the reduction of recharge cycles. The use of cast alloy AlZnMgCu compliant of plastic forming class 7xxx alloy, are intended to significantly reduce the weight of the structures, while ensuring high strength properties. The wide range of the solidification temperature, which is more than 150°C, characterizes this alloy with a high tendency to create the micro and macro porosity. The study presents the relationship between the cooling rate and the area of occurrence and percentage of microporosity. Then the results were linked to the local tensile strength predicted in the simulation analysis. The evaluation of the microporosity was performed on the basis of the CT (computed tomography) and the analysis of the alloy microstructure. The microstructure analysis was carried out on test specimen obtained from the varying wall thickness of the experimental casting. The evaluation of the mechanical properties was prepared on the basis of the static tensile test and the modified low cycle fatigue test (MLCF).
EN
Theory and practice of environmental protection in the case of foundries in Europe and Asia. Every specialist dealing with foundry processes and their impact on environmental pollution must have encountered in their professional careers numerous situations in which the theory of environmental protection confronts the stark reality. The discrepancy between theory and practice can particularly be noticed in foundry engineering in developing countries where the contrasts between different countries and casting plants are extremely striking. The comparison of working conditions in European and Asian foundries provides a vast scope for further observations and analyses. Environmental protection seems not only a concern of manufacturers of castings, but also of their customers whose opinion exerts a significant influence on both the acceptability of working conditions and on the approach to environmental pollution adopted in metal casting industry. The article presents a number of examples of various outlooks on environmental issues in foundries manufacturing a wide range of cast steel and cast iron castings, where different technologies and production processes are applied.
EN
This paper discusses the possibility of assessing the quality of materials in terms of their mechanical properties as determined by a modified low-cycle fatigue test applied in these studies. The developed computer program adapted to the needs of an MTS universal testing machine is described, as are the details of an algorithm used by this program. The compatibility of test results obtained by the two methods (i.e., the standard low-cycle fatigue test [LCF] and its modified original version [MLCF]) has been demonstrated on the samples of selected non-ferrous metals alloys.
PL
W niniejszej pracy omówiono możliwość oceny jakości materiałów pod względem ich właściwości mechanicznych, w zmodyfikowanej, niskocyklowej próbie zmęczeniowej. Przedstawiono również opracowany program komputerowy dostosowany do potrzeb uniwersalnej maszyny testującej MTS, a także szczegóły algorytmu używanego przez ten program. Zgodność wyników badań uzyskanych za pomocą dwóch metod: klasycznej niskocyklowej próby zmęczeniowej (LCF) oraz wersji zmodyfikowanej (MLCF) wykazano na przykładzie wybranych metali nieżelaznych stopów.
EN
The article presents various aspects of the analysis of the state of stress in carbon block induced by the effect of temperature when a steel pin is connected to the block by pouring a shaped groove with cast iron. Changes in the temperature and state of stress in the block were examined by FEM (Abaqus program). The numerical model was validated by experimental measurements of pin deflection during pouring of the groove with cast iron.
EN
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.
EN
The development of a novel design for the toothed segment of drive transmission in longwall shearer is expected to significantly reduce the cost of individual components of the feed system and the related work of repair and renovations, increasing at the same time the safety of mine repair teams. The conducted experimental and numerical analysis of the state of stress and strain in the innovative design of the toothed segment has enabled estimating the maximum effort of the developed structure. Based on the results of fundamental mechanical studies of the cast L20HGSNM steel and fatigue tests combined with the numerical stress/strain analysis, the fatigue life curve was plotted for the examined casting of the rack.
EN
The article discusses the weldment to casting conversion process of rocker arm designed for operation in a special purpose vehicle to obtain a consistency of objective functions, which assume the reduced weight of component, the reduced maximum effort of material under the impact of service loads achieved through topology modification for optimum strength distribution in the sensitive areas, and the development of rocker arm manufacturing technology. As a result of conducted studies, the unit weight of the item was reduced by 25%, and the stress limit values were reduced to a level guaranteeing safe application.
EN
The article presents and compares the results of experiments and numerical calculations of fatigue life of the cast lock of scraper conveyor used in the mining industry. The scope of research included determination of the fatigue life characteristics of ADI based on LCF and MLCF tests and fatigue life studies carried out directly on the casting of the lock. The state of stress in casting caused by the effect of forces applied in the test equipment was determined by the finite element method. The obtained results were used in calculation of the fatigue life of the lock applying selected hypotheses of the multiaxial fatigue. The results of calculations were compared with the results of experiments, evaluating at the same time also the validity of the adopted hypotheses.
EN
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.
PL
Konstrukcje szkieletowe są ważnym elementem stosowanym jako absorbery energii w przemyśle zbrojeniowym, lotniczym i samochodowym. Jednoczesne zastosowanie algorytmów optymalizacji topologicznej do kształtowania wytrzymałościowego, programów symulacji krzepnięcia, metod wytwarzania przyrostowego (AM – ang. additive manufacturing) oraz technologii sterujących procesami krzepnięcia, może mieć znaczący wpływ na otrzymanie konstrukcji lekkiej i wytrzymałej. Kształt takiej konstrukcji w sposób optymalny dopasowany jest do przenoszenia obciążeń przy określonym działaniu sił zewnętrznych i sposobach podparcia. Celem niniejszej pracy było przedstawienie możliwości, jakie dają wspólne zastosowanie metod optymalizacji topologicznej oraz metod przyrostowych wykonania oprzyrządowania odlewniczego do wykonania odlewów szkieletowych, odpornych na działanie sił ściskających.
EN
Cellular structures are critical components which perform as energy absorbers in the defense, aerospace and automotive industries. Simultaneous application of topological optimisation algorithms for strength forming, solidification simulation software, additive manufacturing (AM) methods and solidification process control technologies may have a significant impact on building lightweight and strong structures. The shape of such structures is optimally adapted for transmission of loads with certain action of external forces and bearing methods. The purpose of this paper is to present the potential released by joint application of topological optimisation methods and AM methods in building of casting equipment for production of cellular castings which can resist compressive forces.
EN
Rapid development of the methods of additive manufacturing (AM) introduces a number of changes to the design of foundry equipment. AM methods are of particular importance in the development of technology to make small lots of castings or single cast items of complex shapes, such as skeleton castings manufactured also by means of other technologies [1]. AM methods create the possibility of making single-use moulds, cores and wax patterns, as well as patterns made from plastics for repeated use. The development of AM techniques gives theoretically unlimited possibilities in the choice of the designed casting configurations. This fact can be used during the analysis of casting mechanical properties based on the methods of topology optimisation [2], [3], [17], when the said optimisation carried out at the initial stage of design ”matches” the shape of parts to the field of stresses or displacements caused by external load and fixing mode. The article discusses the possibilities and advantages that result from combining the new methods of shaping the casting endurance with AM technologies.
PL
W artykule zaprezentowano możliwości integracji nowoczesnych technologii wykonania oprzyrządowania odlewniczego oraz metod optymalizacji konstrukcji. Systemy przyrostowego wytwarzania (ang. additiv manufacturing, AM) pozwalają na projektowanie bardzo złożonych kształtów konstrukcji, spełniających w znacznie większym stopniu, niż inne metody technologiczne, kryteria kształtowania wytrzymałościowego. Niektóre z szerokiej gamy metod AM, omówione w niniejszym artykule, są szczególnie przydatne w wytwarzaniu form i rdzeni ceramicznych oraz metalowych części oprzyrządowania odlewniczego. Omówiono zastosowanie metod optymalizacji topologicznej w kształtowaniu konstrukcji we wczesnej fazie projektowania, szczególnie w tym przypadku, gdy określone są jedynie założenia dotyczące funkcjonowania podparć i sił działających na obiekt. Przykłady optymalizacji wykonano w oparciu o własny algorytm obliczeniowy, który umożliwia przemieszczanie i eliminowanie masy wewnątrz obszaru projektowego, tak aby przy określonych warunkach brzegowych i sposobie obciążenia, otrzymać najbardziej korzystny stosunek wytrzymałości do masy odlewu. Z reguły w wyniku zastosowania powyższego algorytmu powstają konstrukcje o złożonym kształcie - przestrzenne ramy lub kratownice oraz powierzchnie nie dające się opisać za pomocą prostych jednostek geometrycznych, dla których wykonania właściwe jest stosowanie przyrostowych metod wytwarzania oprzyrządowania odlewniczego.
EN
The article presents the results of experimental and numerical analysis carried out on a variable in time state of stress and strain using the proposed algorithm. Calculations were performed on a model of the scraper conveyor lock used in mining transportation equipment; fatigue tests were performed on samples of the cast L20HGSNM steel.
PL
W artykule przedstawiono najnowocześniejsze tendencje w zakresie wykorzystania symulacji komputerowej w procesie opracowywania nowych rozwiązań, w tym również rozwiązań w branży odlewniczej. Opisano działanie Zintegrowanego Systemu Modelowania Materiałów i Procesów Inżynierskich (ang. Integrated Computational Materials Engineering – ICME) zaakceptowanego w roli wiodącego narzędzia w opracowywaniu nowych materiałów, konstrukcji oraz technologii w przemyśle lotniczym, motoryzacyjnym, okrętowym, energetyce w USA oraz w Unii Europejskiej. Prześledzono funkcjonowanie zintegrowanego systemu w procesie opracowywania konstrukcji odlewanej przez modelowanie stanów naprężeń podczas pracy odlewu, modelowanie właściwości stopu oraz samej technologii. Przedstawiono zagrożenia i korzyści ze stosowania systemu.
EN
This article presents the latest tendencies within the scope of the application of computer simulation in the process of developing new solutions, including solutions in foundry practice. The functioning of Integrated Computational Materials Engineering is described, which is regarded as a leading tool for developing new materials, constructions and technologies in aerospace, automotive and maritime industries in the USA and the European Union. The functioning of ICME was studied in the process of developing a cast construction by modelling stresses of the cast at work, modelling alloy properties and the technology itself. Threats and benefits resulting from the application of ICME are also presented.
EN
Based on the criterion of ductile fracture and progressive degradation of material stiffness, the finite element method (FEM) was used to determine changes in components of the stress state in a numerical model of the spheroidal graphite precipitate and ferritic matrix under the influence of increasing tensile forces leading ultimately to the matrix fracture. For different densities of the graphite precipitates, an increase in the volume of void surrounding the graphite precipitate at an instant of the fracture fonnation was calculated, assuming it to be equal to a critical value fCR of the void volume fraction in the Gurson-Tvergaard-Needelman (GTN) model. Using the GTN yield condition, in which the previously determined values offCR were allowed for, stretching of a cylindrical specimen until rupture was simulated by FEM, comparing the resulting stress-strain curve with the curve determined experimentally for the EN-GJS-400-18 cast iron.
PL
Na podstawie kryterium pękania ciągliwego oraz progresywnej degradacji sztywności materiału, metodą elementów skończonych (MES), wyznaczono zmiany wartości składowych stanu naprężenia w modelu numerycznym wydzielenia grafitu kulkowego i osnowy ferrytycznej pod wpływem rosnącej wartości sił rozciągających, aż do chwili pęknięcia osnowy. Dla różnych gęstości wydzieleń grafitu określono przyrost objętości pustki otaczającej wydzielenie grafitu w momencie powstania pęknięcia, przyjmując założenie, że jest ona równa krytycznej wartości udziału objętościowego pustek fcrz W modelu Gursona-Tvergaarda-Needelmana (GTN). Stosując warunek plastyczności GTN, w którym uwzględniono wcześniej wyznaczone wartości fCR, metodą MES przeprowadzono symulację rozciągania próbki walcowej, aż do chwili zerwania, porównując uzyskane zależności naprężenie-odkształcenie z doświadczalnie wyznaczoną krzywą rozciągania żeliwa EN-GJS-400-18.
EN
The study describes the investigations of fatigue life carried out on selected grades of the G20Mn5 cast steel by two methods, i.e. the standard low-cycle fatigue test (LCF test) and modified low-cycle fatigue test (MLCF). The aim of these investigations was to verify the reliability of tests conducted by the novel method of MLCF [1, 2, 3]. Table 1 shows the results of mechanical tests carried out in accordance with the MLCF methodology on the G20Mn5 cast steel, while Figures 1a-b and 2 show the selected σ = f (ε) curves. Similar studies were carried out for the Mn-Ni cast steel [4]. Low-cycle fatigue tests (LCF) were carried out on an MTS 810 testing machine with control of force exerted on specimens whose dimensions were specified in [2].
PL
W prezentowanej pracy przeprowadzono dla wybranego staliwa G20Mn5 badania trwałości zmęczeniowej dwiema metodami, zarówno zgodnie z procedura LCF (klasyczna, niskocyklowa próba zmęczeniowa), jak i MLCF (zmodyfikowana niskocyklowa próba zmęczeniowa). Badania te miały służyć weryfikacji wiarygodności badań zgodnie z nowatorską metodą MLCF [1, 2, 3]. W tablicy 1 przedstawiono wyniki badań wytrzymałościowych wykonanych zgodnie z metodyką MLCF staliwa w gatunku G20Mn5, a na rysunkach 1a-b i 2, wybrane wykresy σ = f (ε) Podobne badania przeprowadzono dla staliwa Mn-Ni [4]. Badania zmęczeniowe w zakresie małej liczby cykli LCF, to zrealizowano na maszynie wytrzymałościowej MTS 810, przy sterowaniu siła na próbkach o wymiarach przedstawionych w pracy [2].
EN
The aim of the research presented in this paper was to develop an experimental - numerical model for predicting the life of die inserts. For this purpose, using FEM, the temperature and stress fields in the insert during stable operating cycle of a die casting machine were determined. The study of WCL steel, of which inserts are made, included fatigue tests and tests from the range of fracture mechanics. From the results obtained, a relationship was derived between the number of the die casting machine operating cycles and the propagation speed of cracks formed on the insert working surface.
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