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PL
Przedstawiono i przedyskutowano wyniki badań popożarowej wytrzymałości konstrukcyjnej stali S355J2+N, niskowęglowej, o ferrytyczno-perlitycznej strukturze wewnętrznej. Wnioskowanie oparto na statycznej próbie rozciągania, prowadzonej na próbkach wystudzonych po ich uprzedniej ekspozycji na oddziaływanie temperatury pożarowej. Rozważono różny czas trwania incydentu pożarowego, różny poziom temperatury wygrzewania materiału i różny sposób jego studzenia. Oddziaływanie pożaru symulowano w scenariuszu badania izotermicznego.
EN
The results of post-fire strength tests performed for samples made of S355J2+N low-carbon structural steel, with ferritic-pearlitic microstructure, have been presented and widely discussed. The conclusion was based on the static tensile tests, carried out on samples cooled down after their prior exposure to fire temperature. Different duration of the fire incidents as well as various temperature levels of the material heating and also differentiated ways of its cooling down after the fire exposure were considered. The fire impact was simulated in an isothermal, steady-state heating regime.
EN
The Zirconium 702 alloy effectively used in nuclear industry at various critical conditions like high temperature and high pressure. This survey is an assessment of insights into the mechanical properties of the metal when exposed to different temperatures along the rolling direction.The main objective of this work is to characterize the tensile properties, and fracture study of broken tensile test samples at various temperatures.The tensile samples tested in our current work are 100°C, 150°C, and 200°C temperatures in different directions (0°, 45°, 90°) along with the rolling direction of the sheet. It is evident from the experimental results that temperatures significantly affect material properties. Temperature increases cause % elongation to increase, and strength decreases. ANOVA analysis revealed that temperature significantly influenced ultimate tensile strength (UTS), and yield strength (YS), as well as % elongation.The temperature contribution for UTS, YS, and % elongation is 41.90%, 31.60%, and 77.80% respectively. SEM fractured images showing the ductile type of behavior for all the temperatures.
PL
Celem pracy jest poznanie możliwości i uwarunkowań stosowania modeli wykonanych w technologii druku 3D do badań dynamicznych. Zaprezentowano metodę i wyniki badań określających parametry fizykomechaniczne polimeru PLA-IMPACT drukowanego z różnymi kątami rastrowania. Badania wykazały, że wartość modułu sprężystości polimeru nie zależy od kąta rastrowania, natomiast na granicę plastyczności ma wpływ kierunek laminacji, co wpływa w istotny sposób na realizację modeli obiektów do badań dynamicznych.
EN
The aim of the work is to identify the possibilities and conditions for the use of models made in 3D printing technology for dynamic experiments. The methodology and results of tests determining the physical and mechanical parameters of the PLA-IMPACT polymer printed with different screening angles are presented. The research showed that the value of the polymer modulus of elasticity does not depend on the rastering angle, while the yield point depends on the direction of lamination, which is of key importance in the implementation of models of objects for dynamic tests.
EN
In this paper, the possibility of replacing tensile extensometers with a non-contacting device for measuring elongation has been analyzed. An example of a non-contacting device is a Digital Image Correlation System (DIC). Such systems are widely used in various areas, for example, biology or modern engineering. DIC systems have several advantages that seem to be promising for testing modern materials. The most important is the fact that there is no physical contact between the sample and the DIC and therefore no additional force is applied during the experiment. On the other hand, a lack of contact with the sample can cause large measurement inaccuracies. Another advantage would be that a DIC can measure strain on the whole surface of the sample in all directions, instead of measuring part of the surface in one direction like in other extensometers. Because of these abilities, the environment impact on test bench (DIC + load device), and differences between conducted experiment with normalized tensile test needed to be investigated. The testing machine was replaced by a DIC system cooperating with a tension-compression module. The proposed method was used to monitor and record the images to determine the basic properties of 13MnSiCr7 grade steel. Twelve tests were performed. The analysis was done by comparing the values of mechanical properties obtained in a static tensile test, such as yield strength, tensile strength, Young’s modulus, elongation of the material; with the values of these properties determined experimentally. For each sample, stress-strain curves were evaluated. To check if the results were correct, a Q-Dixon test was performed in each case, confidence intervals were also calculated. Finally, the obtained properties were compared with those from the standard tensile test acquired from the manufacturer’s material card.
EN
The Mg–6Zn wt.% (MZ-T6) magnesium (Mg) alloy was fabricated after heat treatment (783 K for 6 h and aging at 453 K for 24 h) of an extruded MZ Mg alloy. Later, the alloy was subjected to cross pre-compression along with different directions and strains and obtained MZ-1 and MZ-2Mg specimens. The MZ-1 was pre-compressed along with ED and then TD, whilst MZ-2 was pre-compressed along with ND and TD. Subsequently, the compressive properties were studied of MZ-T6, MZ-1, and MZ-2 specimens. The result displayed that the cross twinning and lenticular twinning significantly altered the < c > axis orientations from c-axes || normal direction (ND) of MZ-T6 Mg specimen towards c-axes || extruded direction (ED) and transverse direction (TD) in MZ-1 and MZ-2Mg specimens, respectively. The compressive yield strength and ultimate compressive strength were significantly increased along with all loading directions, and mechanical anisotropy was significantly reduced. These results are mainly attributed to twin-induced grain refinement and considerable changes in the texture. The concave down curves changed to sigmoidal curves in pre-compressed Mg specimens along with ND, which is the signature of the twinning and de-twinning phenomenon. While loading along ED and TD exhibited almost similar sigmoidal curves in all specimens, however, the curves displayed different deformation behavior and were evaluated based on strain hardening regimes. The hardness of MZ-1 and MZ-2 specimens was increased ~ 18 and ~ 23%, respectively, compared to the MZ-T6 specimen. Thus, cross pre-compression is a convenient technique to further enhance the applications of Mg alloys for industrial development.
EN
Due to the complexity of the marine environment, in deep-sea drilling, all kinds of strings are corroded by different deepsea conditions for a long time, accompanied by high temperature and high pressure, which lead to the continuous change of mechanical properties of materials. In order to solve the problem that the material mechanical parameters cannot be accurately described in the performance analysis of the casing, deep-sea simulated corrosion and material damage experiments of P110 material were carried out in this paper. Mass loss and tensile experiments on corrosion-damaged test pieces were conducted under different corrosion experimental periods. The changes in mechanical properties of the material were analyzed. Equations of the variation of the equivalent yield strength and the equivalent tensile strength were obtained. The results show that the equivalent yield strength and the equivalent tensile strength decrease with the increase of the weight loss rate. Based on the experimental results and finite element analysis, a method for establishing the material corrosion model was proposed in this paper. The deep-sea drilling corrosion performance model of P110 material was established, which greatly reduced the error caused by the material uniformity assumption in finite element analysis. This paper provides a theoretical basis for the analysis of reliability and life of P110 materials in wells.
PL
W artykule omówiono parametry wytrzymałościowe pasów stalowych stosowanych w dźwigarach o falistym środniku na podstawie badań, przeprowadzonych na losowo pobranych próbkach z dwudziestu dźwigarów. Pasy dźwigarów miały grubość 15 mm oraz 20 mm. W wyniku badań oszacowano współczynniki częściowe granicy plastyczności γm oraz współczynniki zmienności VRe. Pokazano uzyskane rozkłady normalne granicy plastyczności. Uzyskane wyniki odniesiono do dostępnych badań blach płaskich i pokazano poziom bezpieczeństwa obliczeń nośności przy zginaniu wynikający ze stosowanych współczynników częściowych granicy plastyczności.
EN
The study presents parameters of strength properties of flanges used in corrugated web girders obtained on the basis of tests. The subject tests were carried out on randomly taken samples from twenty investigated corrugated web girders. The girder flanges were 15 mm and 20 mm thick. As a result of the tests, partial yield factors γm and coefficients of variation VRe were estimated. The normal distribution of yield strength obtained are shown. The obtained results were referred to the available flat sheet tests. Based on the conducted tests, the safety level of bending load calculations resulting from the applied partial factors of the yield strength was shown.
8
Content available remote Stale wysokiej wytrzymałości w konstrukcjach budowlanych
PL
Obecnie normy pozwalają na stosowanie w budownictwie stali wysokiej wytrzymałości o granicy plastyczności do 700 MPa. Efektywne kształtowanie elementów konstrukcyjnych ze stali wysokiej wytrzymałości umożliwia zmniejszenie masy konstrukcji, redukcję gabarytów przekrojów i grubości ich ścianek. W artykule omówiono wybrane aspekty stosowania stali wysokiej wytrzymałości i wskazano zagadnienia istotne z punktu widzenia racjonalnego kształtowania konstrukcji z tego typu stali.
EN
The current standard regulations allow for the use of high-strength steel with a yield strength of 700 mPa in construction. Effective shaping of structural elements from high-strength steel allows for reducing the structure weight, cross-section dimensions and their wall thickness. The article discusses selected aspects of using high-strength steel as well as emphasizes the issues that are important from the point of view of well-balanced shaping of structures from this type of steel.
EN
The article reports the results of research on the influence of the alternate intermittent deformation of specimens by a torsion method on the Bauschinger effect in the Zr-1%Nb zirconium-based alloy. Tests were carried out using an STD 812 torsion plasto-meter. Based on the tests carried out, diagrams have been plotted, which represent the influence of the pre-deformation magnitude, the temperature of heat treatment prior to deformation, and deformation rate on the variation in the values of the flow stress and yield strength of the alloy under study. Conditions have been defined, in which larger magnitudes of plastic deformation of Zr-1Nb% alloy material can be used during its cold plastic working.
EN
In the paper the results of experimental research of the process of flow forming of cylindrical drawpieces were presented. The drawpieces were made of the 3.1 mm thick AMS 5596 sheet by drawing process. Tests were performed on two-roller metal spinning machine of a vertical axis Leifeld SFC 800 V500.The main purpose of this research was to determine the relationship between relative thickness reduction and the mechanical properties of tested material. Knowledge of these dependencies is especially useful in designing machines’ components manufactured by flow forming, in the selection of parameters of realization of this technological process as well. Mechanical properties were determined on the basis of uniaxial tensile of the micro samples obtained from the drawpieces: (I) after cold flow forming, (II) after cold flow forming and in-process heat treatment. Obtained results were shown graphically in the diagrams and their analysis was carried out. In addition, the microstructure of the sheet material tested after drawing and flow forming is presented.
11
Content available remote Structural and mechanical properties of diglycine perchlorate single crystals
EN
Good quality diglycine perchlorate (DGPCL) single crystals were grown by slow evaporation solution growth method using the combination of glycine and perchloric acid in the ratio of 2:1. Single crystal X-ray diffraction and mechanical characterization of the grown single crystals of diglycine perchlorate were analyzed in this article. Lattice parameters, space group and crytal system were found from single crystal X-ray diffraction analysis. All the cell parameters and space group are in a good agreement with the reported values. Mechanical properties, such as Vicker’s microhardness number, work hardening index, standard hardness value, yield strength, fracture toughness, brittleness index and elastic stiffness constant values, were determined using Vicker’s microhardness tester.
PL
Wyznaczone właściwości reologiczne badanego materiału w postaci krzywych zależności naprężenia od odkształcenia są bogatym źródłem informacji na temat procesów wynikających z mechanizmu odkształcenia plastycznego, procesów umocnienia, a także zjawisk aktywowanych cieplnie takich, jak zdrowienie i rekrystalizacja dynamiczna. Wiedza płynąca z prawidłowej interpretacji krzywych umocnienia jest podstawą do optymalnego projektowania procesów kształtowania metali na ciepło i gorąco. Celem pracy była ocena plastyczności stali Orvar Supreme w podwyższonej temperaturze pod kątem możliwości wykonania wykroju w matrycy z tej stali metodą wgłębiania na gorąco. Na wytoczonych próbkach typu Rastigajewa zrealizowano próby ściskania przy temperaturach od 800°C do 1040°C. W celu zminimalizowania wpływu tarcia pomiędzy próbką a kowadłami zastosowano specjalną mieszaninę proszków PbO + 5% B2O3. Badania przeprowadzono ze stałą prędkością ruchu trawersy maszyny wytrzymałościowej (30 mm/min) do wartości odkształcenia logarytmicznego ok. ε = 0,6. W efekcie wykazano istnienie minimum oporu plastycznego przy temperaturze 840°C. Badania za pomocą skaningowego mikroskopu elektronowego pozwoliły określić mikrostrukturę stali, którą tworzył ferryt przy temperaturze 840°C oraz martenzyt w przypadku próbek ściskanych przy temperaturze 1040°C. Wykonano pomiary twardości na przekrojach próbek po ściskaniu oraz próbek poddanych wgłębianiu na gorąco. Na podstawie otrzymanych wyników badań stwierdzono, że możliwe jest wykonanie matryc kuźniczych o wymaganej twardości metodą wgłębiania na gorąco, także z bezpośrednim hartowaniem w oleju po wgłębianiu.
EN
Determined rheological properties of the tested material, in the form of stress-strain curves, are a rich source of information about processes arising from the mechanism of plastic deformation, hardening processes, as well as thermally activated phenomena such as recovery and dynamic recrystallization. The knowledge stemming from proper interpretation of flow curves is the basis for optimal design of warm and hot metal forming processes. The goal of this study was to assess the plasticity of Orvar Supreme steel at elevated temperature from the perspective of the possibility of making an impression in a die made from this steel using the hot hobbing method. Compression tests were conducted on rolled Rastigaiev samples at temperatures from 800°C to 1040°C. In order to minimize the influence of friction between the sample and anvils, a special mixture of powders, PbO + 5% B2O3, was applied. Tests were conducted at a constant speed of the testing machine’s crosshead (30 mm/min), up to a logarithmic strain value of approx. ε = 0.6. In consequence, minimum plastic resistance was demonstrated at 840°C. Scanning electron microscope examinations allowed for identification of the steel’s microstructure, which formed ferrite at 840°C, and martensite in the case of samples compressed at 1040°C. Hardness measurements were performed on cross-sections of samples after compression and of hot-hobbed samples. Based on obtained test results, it was determined that it is possible to produce forging dies of the required hardness by hot hobbing, including with direct quenching in oil after hobbing.
EN
The article examines the effect of the change in the speed of deformation on the mechanical properties of AW 6060 alloy specimens, characterized by high mechanical strength, which is a material used in the shipbuilding industry. The theoretical basis for the influence of load speed on the mechanical properties of materials is presented. Static and dynamic tensile test was conducted on a universal testing machine. Dynamic stretching was performed on samples at 10–1 s–1 – 102 s–1. Done charts and tables showing results. Calculated in accordance with DIN EN ISO 6892-1 2010P total elongation and contraction of the sample. Comparison of the results of the study with the current knowledge of the subject. Material studies have shown that increasing the deformation rate results in an increase in the yield point and tensile strength. On the basis of calculations of the narrowing and elongation of the total sample, the material can be strengthened. The rate of deformation of the materials is favourable for their strengthening by increasing the limit of tensile strength. Given that most of the design is subject to dynamic loads and the aluminum alloy AW 6060 finds extensive use in shipbuilding and beyond, these are satisfactory results.
PL
W artykule przeanalizowano wpływ wysokiej temperatury na wytrzymałość współcześnie stosowanej w Polsce stali zbrojeniowej. Sprawdzono, czy szacowanie cech wytrzymałościowych na bazie rekomendacji PN-EN 1992-1-2 nadal można uważać za prawidłowe. Analizę przeprowadzono na bazie wyników badań własnych wykonanych na próbkach prętów gatunku B500SP, zarówno w warunkach ustalonej, jak i nieustalonej wysokiej temperatury. Wyniki badań współczynnika redukcji wytrzymałości stali na rozciąganie (ks,θ) okazały się zgodne z wartościami oszacowanymi na podstawie wymagań Eurokodu. Nie zaobserwowano też, aby wyniki badań prętów o średnicy 10, 12 i 16 mm istotnie się od siebie różniły. Analiza wyników prowadzi do wniosku, iż model podany w PN-EN 1992-1-2 może nadal stanowić wiarygodną podstawę prognozowania zmniejszenia wytrzymałości stali zbrojeniowej w warunkach pożarowych
EN
In this paper the influence of high temperature on strength of the reinforcing steel currently used in Poland was analysed. It was investigated whether steel strength properties estimated according to EN 1992-1-2 are still valid. The analysis was based on tests performed on samples of B500SP reinforcing bars in steady and unsteady (increasing) high temperature conditions. Obtained values of the steel strength reduction factor (ks,θ) have been found to be in accordance with Eurocode. Additionally, no significant differences between result obtained for bars 10, 12 and 16 mm in diameter were observed. Obtained results show that the EN 1992-1-2 recommendations can provide an adequate prediction of steel strength reduction factor in fire conditions.
PL
Zaprezentowano algorytm wyznaczania temperatury eksponowanej ogniowo stalowej nośnej ramy portalowej, skojarzonej z aktywowaniem się w niej krytycznego mechanizmu zniszczenia plastycznego. Zaproponowano zastosowanie uogólnionego podejścia kinematycznego z wykorzystaniem identyfikacji chwilowego środka obrotu. Miarodajna temperatura jest najniższą spośród uzyskanych ze szczegółowej analizy poszczególnych kinematycznie dopuszczalnych mechanizmów zniszczenia.
EN
Calculation algorithm helpful in the specific temperature assessment for steel load-bearing portal frame exposed to fire, being associated with the activation in such a structure of critical plastic failure mechanism, is presented and discussed in detail. It is proposed to apply to do this a generalized kinematic approach using the identification of the instantaneous centre of rotation. The lowest of the values obtained from a detailed study of all kinematically admissible collapse mechanisms can be recognized to be the conclusive temperature value related to the whole considered frame.
EN
The subject of the study is martensitic 22MnB5 steels, which are used in the automotive industry. The main purpose of the performed analyses is a study of strength differences in heat affected zones of the spot welding. For the needs of the strength decrease assessment, the critical layer of the heat affected area was experimentally simulated. The aim of the work is to determine the most suitable methodology for evaluating the local changes of the elastic-plastic material response. The aim of this work is to determine the optimal methods for the determination of the yield strength and to find a firming trend in these zones.
Logistyka
|
2014
|
nr 3
3335--3345
PL
Jednym z zadań logistyki jest zapewnienie efektywnego przepływu surowców z punktu pochodzenia do punktu konsumpcji. Realizacja tych zadań wiąże się z użytkowaniem maszyn roboczych. Oprócz maszyn realizujących transport surowców użytkowane są także maszyny realizujące załadunek jak np. koparki. Wytwarzanie węzłów konstrukcyjnych maszyn roboczych wymaga zastosowania procesu spawania łukowego, które wprowadza do konstrukcji naprężenia własne mogące przekraczać granicę plastyczności. W artykule przedstawiona została metoda zmniejszania naprężeń własnych w spoinach połączeń przegubowych przez przeciążenie. Naprężenia własne po spawaniu osiągające 1.14 Re udało się zmniejszyć do 0.81 Re po przeciążeniu siłą 106 kN oraz do 0.58 Re po przeciążeniu siłą 150 kN. Przeciążenie wpływa najbardziej na zmniejszenie się składowej wzdłużnej tensora naprężeń. Obliczenia procesu spawania oraz przeciążenia wykonane zostały przy użyciu oprogramowania MSC Marc oraz MSC Patran z wykorzystaniem metody elementów skończonych.
EN
One of the tasks of logistics is to ensure the effective flow of raw materials from point of origin to point of consumption. Realization of these tasks involves the use of building machines. In addition to the machines performing transportation of raw materials, loading machines such as excavators are also used. Production of construction joints of building machines require the use of arc welding processes. Welding causes high level residual stresses which can exceed the yield stress. This article presents method of decreasing residual stresses in welds of the articulated excavator joints by overloading. Residual stresses after welding process, which reach 1.14 Re have been reduced to 0.81 Re after overloading with force 106 kN and to 0.58 Re after overloading with force 150 kN. Overloading influence the most decrease of longitudinal residual stress. Analysis of welding process and overloading has been performed using MSC Marc and MSC Patran finite element software.
EN
In the present investigation, the effects of processing parameters, such as roughing, finishing and coiling temperatures, on the strain hardening exponent and yield strength of a Nb-microalloyed steel has been studied by Taguchi method. In order to achieve maximum n-value and yield strength, tests were done in a laboratorial pilot considering a L16 orthogonal array of Taguchi method under following condition: roughing temperature of 1000, 1050, 1100, 1150°C, finishing temperature of 800, 850, 900, 950°C, coiling temperature of 550, 600, 650, 700°C. Then, analysis of variance and signal to noise ratios are performed on the measured data. The results indicated that the finishing and coiling temperatures were the major factor affecting the mechanical properties. The confirmation tests at optimal conditions approve the effectiveness of this robust design methodology in investigating the hot rolling process of the microalloyed steels.
PL
W niniejszej pracy, metodą Taguchi badano wpływ parametrów obróbki takich jak temperatura obróbki zgrubnej, wykańczającej i zwijania na wykładnik utwardzenia i granicę plastyczności stali niskostopowej. W celu uzyskania maksymalnej wartości wykładnika n i granicy plastyczności, badania przeprowadzono w skali laboratoryjnego pilota uwzględniając ortogonalną macierz L16 metody Taguchi pod następującymi warunkami: temperatura obróbki zgrubnej: 1000, 1050, 1100, 1150° C, temperatura obróbki wykańczającej: 800, 850, 900, 950° C, temperatura zwijania: 550, 600, 650, 700° C. Następnie dokonano analizy wariancji stosunku sygnału do szumu na zmierzonych danych. Wyniki wskazują, że temperatury obróbki wykończeniowej i zwijania były głównym czynnikiem wpływającym na własności mechaniczne. Testy przeprowadzone w optymalnych warunkach potwierdziły skuteczności zaprojektowanej metodologii w badaniach procesu walcowania na gorąco stali niskostopowych.
PL
Uderzeniowy test Taylora jest jedną z najbardziej popularnych technik badawczych. Umożliwia on wyznaczanie charakterystyk mechanicznych materiałów w warunkach deformacji plastycznych zachodzących z szybkościami odkształcenia obejmującymi zakres od 103 do 104 s-1. Test ten w pierwotnej postaci, zaproponowanej przez Taylora w 1948 roku, polega na wystrzeleniu cylindrycznego pocisku wykonanego z materiału badanego do twardej i masywnej tarczy w celu wywołania deformacji plastycznej w jej czołowej części. W trakcie testu rejestrowana jest prędkość zderzenia, natomiast po teście wykonywane są pomiary kształtu próbki. Na podstawie tak otrzymanych danych doświadczalnych możliwe jest oszacowanie wartości dynamicznej granicy plastyczności Y za pomocą równania przedstawionego na rys.1.
20
Content available remote The effect of yield strength on inelastic buckling of reinforcing bars
EN
The paper presents the results of numerical analyses of inelastic buckling of reinforcing bars of various geometrical parameters, made of steel of various values of yield strength. The results of the calculations demonstrate that the yield strength of the steel the bars are made of influences considerably the equilibrium path of the compressed bars within the range of post yielding deformations. Comparative diagrams of structural behaviour (loading paths) of thin-walled sections under investigation for different strain rates are presented. Some conclusions and remarks concerning the strain rate influence are derived.
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