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EN
The aim of the article was to present issues related to the determination of the influence of the surface preparation method on the strength of adhesive joints made of three types of construction materials: structural steel C45, aluminium alloy EN AW-1050A and stainless steel 1.4401. The surfaces of the analysed materials were prepared by machining with three different abrasive tools of different gradations: P120, P220, P400. Adhesive joints were prepared using the E53/Z-1/100:10 epoxy adhesive composition. After the process of adhesive joint curing, destructive tests were carried out on the Zwick/Roell Z150 strength machine, in accordance with PN-EN 1465 standard, which determined the shear strength of the analyzed joints. During the tests it was observed that the most advantageous method of surface preparation is treatment using P220 grit abrasive.
PL
Celem artykułu było zaprezentowanie zagadnień związanych z określeniem wpływu sposobu przygotowania powierzchni na wytrzymałość połączeń klejowych wykonanych z trzech rodzajów materiałów konstrukcyjnych: stali konstrukcyjnej C45, stopu aluminium EN AW-1050A oraz stali nierdzewnej 1.4401. Powierzchnie analizowanych materiałów zostały przygotowane poprzez obróbkę trzema różnymi narzędziami ściernymi różnej gradacji: P120, P220, P400. Połączenia klejowe przygotowano z użyciem kompozycji klejowej epoksydowej E53/Z-1/100:10. Po procesie utwardzania spoiny klejowej przeprowadzono badania niszczące na maszynie wytrzymałościowej Zwick/Roell Z150, zgodnie z normą PN-EN 1465, dzięki którym wyznaczono wytrzymałość na ścinanie analizowanych połączeń. W trakcie badań zaobserwowano, że najkorzystniejszym sposobem przygotowania powierzchni jest obróbka wykorzystująca ścierniwo ziarnistości P220.
EN
The paper presents the results of experimental studies determining the effect of temperature on the shear strength of the adhesive joint between the layers of the fiber metal laminate (FML). The tests were carried out for composites being a combination of 2024-T3 aluminum alloy sheet and Glass Fiber-Reinforced Polymer (GFRP) made in the autoclave process. The key factor determining the quality of layered composites is the high strength adhesive joint between the layers. Due to the possibility of extreme temperature conditions during utilization of the composite structure, tests were carried out at reduced temperatures, i.e. -60°C, as well as elevated temperatures, i.e. 80°C. The obtained results were related to the results obtained at a room temperature (RT). The study showed that at the elevated temperature the shear strength increased by approx. 10% compared to the result obtained at room temperature. There is also a significant reduction in the stiffness of the joint as the temperature increases. In turn, a slight increase in joint stiffness was demonstrated for the reduced temperature.
PL
W pracy przedstawiono wyniki badań eksperymentalnych określających wpływ temperatury na wytrzymałość na ścinanie połączenia adhezyjnego pomiędzy warstwami składowymi hybrydowego kompozytu metalowo-włóknistego (FML). Próby przeprowadzono dla kompozytów będących połączeniem blachy ze stopu aluminium 2024-T3 oraz kompozytu szklanego polimerowo-włóknistego (ang. Glass Fiber-Reinforced Polymer - GFRP) wykonanych w procesie autoklawowym. Kluczowym czynnikiem determinującym jakość kompozytów warstwowych jest wysokiej wytrzymałości połączenie adhezyjne pomiędzy warstwami. Ze względu na możliwość występowania różnych warunków temperaturowych w procesie eksploatacyjnym struktury kompozytowej, zrealizowano badania w temperaturach obniżonej tj. -60°C, a także podwyższonej tj. 80°C. Uzyskane rezultaty odniesiono do wyników uzyskanych w temperaturze pokojowej. W pracy wykazano, że w podwyższonej temperaturze dochodzi do wzrostu wytrzymałości na ścinanie o ok. 10% w stosunku do rezultatu uzyskanego w temperaturze pokojowej. Dochodzi tu także do znacznego obniżenia sztywności połączenia wraz ze wzrostem temperatury. Dla obniżonej temperatury wykazano z kolei nieznaczny wzrost sztywności połączenia.
EN
This article concerns the assessment of selected physical and mechanical properties of a dump soil. The dump soil is a specific soil with a very heterogeneous internal structure. Next to each other, there may be lumps and crumbs of cohesive soils mixed with non-cohesive soils accompanied by a very diverse admixture of organic substance. In addition, the soil in the waste dump, in spatial terms, may significantly differ in consistency and density. This is the result of the process of forming a dump soil, which takes place in three stages: excavation, transport and dumping. A heterogeneous soil deposited within the waste dump is subject to further processes: consolidation, compaction and creeping. Changes occurring in the course of these processes have a significant impact on the development of the properties of the dump soil. Due to the large diversity of the tested soils, the results of their properties were divided into two groups, based on type and consistency of soil. This allows us to estimate the selected properties of the dump soil only on the basis of their macroscopic analysis.
PL
W artykule przedstawiono badania nośności na ścinanie płyt z betonu zwykłego oraz lekkiego zbrojonego prętami kompozytowymi GFRP (ang. Glass Fibre Reinforced Polymer), w schemacie czteropunktowego zginania. Wykonano i poddano obciążeniu statycznemu łącznie 7 płyt betonowych o długości 2,8 m, szerokości 1,0 m i grubości 18 cm. Analizowano wpływ takich czynników, jak rodzaj betonu (zwykły, lekki), stopień zbrojenia i jego konfiguracja, obecność zbrojenia górnego a zachowanie się badanych płyt pod obciążeniem oraz ich nośność na ścinanie. Weryfikowano wybrane normowe modele obliczeniowe do określania nośności na ścinanie elementów zbrojonych prętami kompozytowymi. Stwierdzono brak wystarczająco wiarygodnej procedury obliczeniowej do wyznaczania nośności na ścinanie płyt z betonu lekkiego zbrojonego prętami GFRP.
EN
This paper evaluates the shear behaviour of simply supported normal-weight and lightweight concrete slabs reinforced with glass fibre reinforced polymer (GFRP) rebars and subjected to four-point static loading. A total of seven concrete slabs of 2.8 m long, 1.0 m wide and 0.18 m deep, were constructed and tested. Different parameters like type of concrete (normal – and lightweight), reinforcement ratio, reinforcement configuration and the existence of top reinforcement are considered in order to assess their influence on static behaviour and shear strength of concrete slabs. Furthermore several codes and theoretical models applied for predicting shear strength of concrete members reinforced with GFRP rebars have been compared with test results, and the discrepancies and compatibilities have been established and discussed. The lack of code models to predict accurately shear strength of LW concrete slabs reinforced with GFRP has been revealed.
EN
This research investigates the mechanical behavior of artificially cemented sandy soils formed by lime alkali activation of natural zeolite under saturation settings. In order to verify the bar capability of cemented sands with this new method, an analysis of the undrained shear strength of the soil with pore water pressure ratio measurements was performed from the interpretation of the results of unconfined compression tests. The effect of zeolite-lime blend on treated sands was also visualized by scanning electron microscopy. For the studied soils, it was concluded from the unconfined compression stress values that the soil is fully capable of withstanding compressions due to overburden pressure. Additionally, this study seeks to evaluate the effect of the void ratio on the pore space and undrained shear strength. The results showed that pore water B-ratio increases with the decrease of the void ratio. Moreover, with the increase of zeolite content, confining pressure, and curing age, the peak failure strength increases. The results indicated a promising consistency of treated samples with lime and zeolite under various values of undrained shearing and B-ratios, making this method an ideal treatment for loose sand deposits.
EN
A paste containing Cu(II) formate rods was prepared, and characteristics of sinter bonding at 250°C under a pressure of 10 MPa were investigated to accomplish a high-speed die attachment for wide-bandgap power chips on Cu finish in air. Synthesisn of the plate-type Cu formate particles from CuO was accomplished through a wet reaction for 180 min. Cu, formed in situ in the bondline by pyrolysis of the formate during heating for the attachment, was sufficiently active to lead high-speed sintering within a carbon dioxide-hydrogen atmosphere derived from the pyrolysis, and the oxide layer on the Cu finish was reduced by the hydrogen. As a result, sinter bonding for 10 min formed a robust bonding with a shear strength approaching 27 MPa.
EN
This paper examines the experimental performance of ultra-high-performance steel fibre-reinforced concrete (UHPSFRC) beams subjected to loads at relatively low shear span-to-depth ratios. The results and observations from six tests provide a detailed insight into the ultimate response including shear strength and failure mode of structural elements incorporating various fibre contents. The test results showed that a higher fibre content results in an increase in ultimate capacity and some enhancement in terms of ductility. Detailed nonlinear numerical validations and sensitivity studies were also undertaken in order to obtain further insights into the response of UHPSFRC beams, with particular focus on the influence of the shear span-to-depth ratio, fibre content and flexural reinforcement ratio. The parametric investigations showed that a reduction in shear span-to-depth ratio results in an increase in the member capacity, whilst a reduction in the flexural reinforcement ratio produces a lower ultimate capacity and a relatively more flexible response. The test results combined with those from numerical simulations enabled the development of a series of design expressions to estimate the shear strength of such members. Validations were performed against the results in this paper, as well as against a collated database from previous experimental studies.
EN
The combined effect of extrusion and multi-directional forging (MDF) was investigated on microstructure and mechanical properties of aluminum-based composite with 10, 15, and 20 wt% Mg2Si. In the casted Al–Mg2Si composites, the primary and eutectic Mg2Si particles are generally coarse which lead to decreasing their mechanical properties and formability. Extrusion process was utilized to overcome this shortcoming by breakage of the eutectic structure, reduction of Mg2Si size, and the decrease of casting defects. Then, MDF process was applied up to failure on the extruded composites at room temperature. It led to the morphological modification of primary and eutectic Mg2Si phases and the reduction of their size. It was found that the MDF process resulted in a considerable improvement in hardness and shear strength of materials. This may be related to the reduction in the average size of Mg2Si particles with their uniform distribution. In addition, ultimate shear strength is, respectively, increased from 94, 99, and 81 MPa to 119, 116, and 117 MPa for the 10, 15, and 20 wt% Mg2Si aluminum composites after the final pass of MDF. Meanwhile, the normal displacement of composites is reduced at initial passes and increased by the addition of more pass numbers.
EN
The paper evaluates the effect of the surface treatment on the strength of the single‑lap adhesive joints made of the C45 steel. The samples were joined using an adhesive composition consisting of Epidian 57 epoxy resin and PAC curing agent. The study also used Greinplast mosaic plaster with a grain size of 1.0–1.6 mm as coating. The experiment was carried out for 3 variants of joints: sheet/sheet, sheet+plaster/sheet+plaster, sheet/sheet+plaster. Each variant was divided into 3 methods of surface treatment. The strength tests were carried out on the Zwick/Roell Z150 testing machine. The roughness parameters of the surface’s samples were measured using a HOMMEL TESTER T1000 profilometer.
EN
This article presents adhesive shearing test methods, focusing especially on the ASTM D5656 method. These methods will be briefly characterized and compared. The most important concerns about the D5656 method are described. With the use of ASTM D1002 and D5656 methods, the influence of adherend surface preparation on shearing properties of the bond is evaluated. Compared to sandblasting only, sandblasting followed by the FPL process (sulfochromate etching of aluminum) increased shear strength of joints by 35 % for ASTM D1002 tests and by 48% for D5656 tests. Comparing these two methods, shear strength obtained in D5656 tests is about two times higher than in D1002 tests. The cause for this phenomena is much larger adherend thickness in the D5656 method, which provides the coupons with increased stiffness. Shear modulus, calculated with 3 different calculation methods, showed differences in obtained results, which points to necessary actualization of D5656 standard.
PL
W niniejszym artykule opisano metody badań wytrzymałości na ścinanie klejów, ze szczególnym uwzględnieniem metody ASTM D5656. Dokonano porównania tych metod i krótkiej ich charakterystyki. Opisano najważniejsze problemy związane ze stosowaniem metody ASTM D5656. Zbadano również wpływ przygotowania powierzchni aluminium na otrzymywane wartości wytrzymałości spoiny na ścinanie, mierzone metodami ASTM D1002 i ASTM D5656. Porównując z piaskowaniem, połączenie piaskowania aluminium z procesem FPL (chromianowanie aluminium) zwiększyło wytrzymałość spoin na ścinanie o 35 % dla prób według normy ASTM D1002 i o 48 % dla metody D5656. Spośród tych dwóch metod, wytrzymałość na ścinanie uzyskiwana w badaniach wg normy D5656 jest średnio dwukrotnie wyższa, niż ta uzyskiwane w badaniach wg normy D1002. Przyczyną jest użycie znacznie grubszych substratów i większa sztywność spoiny w normie D5656. Przeprowadzenie obliczeń modułu ścinania kleju z uwzględnieniem 3 różnych metod wykazało różnice w otrzymywanych wynikach, co wskazuje na konieczność aktualizacji normy D5656.
PL
W artykule opisano wpływ wybranych czynników konstrukcyjnych takich jak długość złącza, grubość warstwy kleju, wielkości fazy w otworze tulei oraz chropowatość powierzchni na wytrzymałość na ścinanie klejowych połączeń czopowych walcowych. Do przeprowadzenia niezbędnych obliczeń w pracy użyto programu Minitab.
EN
The article describes the influence of selected structural factors such as joint length, thickness of the adhesive layer, the size of the phase in the bushing opening and the surface roughness on the shear strength of adhesivly bonded cylindrical joints. The Minitab program was used to carry out the necessary analyzes.
EN
Waste material such as used tires is increasing every year, which poses environmental problems. However, such material has been used in several geotechnical applications as alternative lightweight backfill in highway embankments and/or behind retaining walls, providing environmental, economic and technical benefits. These applications require knowledge of engineering properties of soil-tire rubber mixtures. The present study aims to show the possibility of tire rubber usage in sand by evaluating the shear strength and deformability of sand mixed with granulated rubber, in weight percentages between 0 and 50%. The tire rubber content was found to influence the stress-strain and deformation behavior of the mixtures. The shear strength of sand mixed with 10% or 20% tire rubber was higher than that measured for sand only. However, the trend for TRC = 30–50% was different. Samples with a rubber content of 30-50% exhibited a rapid decrease in the stress ratio compared with that of sand. The major principal strain at maximum stress ratio was found to increase with increasing tire rubber content. However, it was observed that the lateral strains (minor and intermediate principal strains) of samples reduced significantly with the addition of tire rubber to the sand.
EN
The inclusions of geosynthetic materials (fibers, geomembranes and geotextiles) is a new improvement technique that ensures uniformity in the soil during construction. The use of tension resisting discreet inclusions like polypropylene fibers has attracted a significant amount of attention these past years in the improvement of soil performance in a cost-efficient manner. A series of direct shear box tests were conducted on unreinforced and reinforced Chlef sand with different contents of fibers (0, 0.25, 0.5 and0.75%) in order to study the mechanical behavior of sand reinforced with polypropylene fibers. Samples were prepared at three different relative densities 30%, 50% and 80% representing loose, medium dense and dense states, respectively, and performed at normal stresses of 50, 100 and 200 kPa. The experimental results show that the mechanical characteristics are improved with the addition of polypropylene fibers. The inclusion of randomly distributed fibers has a significant effect on the shear strength and dilation of sandy soil. The increase in strength is a function of fiber content, where it has been shown that the mechanical characteristics improve with the increase in fiber content up to 0.75%, this improvement is more significant at a higher normal stress and relative density.
15
Content available remote Wytrzymałość niezbrojonych połączeń ścian z ABK
PL
Artykuł przedstawia syntezę wyników własnych badań niezbrojonych połączeń ścian wykonanych z autoklawizowanego betonu komórkowego. Omówiono zależności obciążenie – przemieszczenie niezbrojonych połączeń z klasycznym wiązaniem murarskim. Wykorzystując normowe procedury, podano parametry umożliwiające projektowanie połączeń.
EN
The article presents a synthesis of own results of unreinforced joints of walls made of autoclaved aerated concrete masonry units. The relationships of the load displacement of unreinforced joints with the classical masonry bond are discussed. Using the standard procedures, parameters enabling the design of joint were given.
PL
W artykule podano wyniki badań próbek murowych z autoklawizowanego betonu komórkowego (ABK) na zaprawie z piany poliuretanowej prowadzonych na Białorusi. Ustalono wytrzymałość muru na ściskanie, ścinanie i rozciąganie przy zginaniu. Porównano te wyniki z otrzymanymi podczas badań próbek na spoinach cementowo-polimerowych oraz z wynikami badań prowadzonych na Politechnice Śląskiej.
EN
The article presents the results of tests of masonry samples of autoclaved aerated concrete (AAC) on polyurethane mortar carried out in Belarus. Compressive strength, shear and tensile strength during bending of the masonry samples were determined. The test results were compared with sample tests on thin cement-polymer as well as with the research results conducted at the Silesian University of Technology.
EN
Ag and Cu powders were mechanically alloyed using high-energy planetary milling to evaluate the sinter-bonding characteristics of a die-attach paste containing particles of these two representative conductive metals mixed at atomic scale. This resulted in the formation of completely alloyed Ag-40Cu particles of 9.5 μm average size after 3 h. The alloyed particles exhibited antioxidation properties during heating to 225°C in air; the combination of high pressure and long bonding time at 225°C enhanced the shear strength of the chip bonded using the particles. Consequently, the chips sinter-bonded at 225°C and 10 MPa for 10 min exhibited a sufficient strength of 15.3 MPa. However, an increase in bonding temperature to 250°C was detrimental to the strength, due to excessive oxidation of the alloyed particles. The mechanically alloyed phase in the particle began to decompose into nanoscale Ag and Cu phases above a bonding temperature of 225°C during heating.
EN
Ti–48Al–2Cr–2Nb and TiC/Ti matrix composites were successfully joined using Ti–28Ni eutectic filler metal at different brazing temperatures. Microstructure and mechanical properties of the joints were systematically studied. The results showed that the joints all showed integral interfaces and the microstructures of the joints for 980 8C/15 min were detected as Ti-48Al-2Cr-2Nb/a2-Ti3Al + t3-Al3NiTi2/a2-Ti3Al/Ti(s,s) + d-Ti2Ni + TiC/Ti matrix composites. As brazing temperature increased, continuous Ti2Ni layer diminish and Ti2Ni phase became more discrete. However, a2-Ti3Al rich layer has thickened which deteriorates the properties of the joints. The highest shear strength achieved 469.5 MPa as the joint brazed at 1010 8C for 15 min. The evolution of microstructures brazed with different tem-peratures was studied and its relationship with the shear strength was also revealed in details.
EN
This paper investigates experimentally the shear strength behavior of reinforced concrete (RC) beams cast with Lava lightweight aggregates as a replacement of normal coarse aggregates. A total of 24 shear deficient RC beams were fabricated and cast with normal (NWC) and lightweight (LWC) concrete and tested under three-point bending after 28 and 56 days. The variables of the experimental program include type of aggregate, concrete compressive strength, and beam size. The experimental results include load–deflection response curves along with failure mode for each beam specimen. The experimental result showed that all beams failed in a similar fashion, due to diagonal tension shear crack. However, a larger number of cracks with less spacing occurred in the LWC beams as compared to NWC specimens. Based on the experimental results, it can be also concluded that LWC specimens tested after 56 days achieved comparable shear strength results to that of NWC beams. In addition, the strength reduction factor (l) for LWC specimens was in the range of 0.69–0.98. The concrete shear strength (Vc) was also predicted using different shear design provisions and the results has shown that Eurocode 2 provisions yielded the lowest C. O.V. of 2.3 and 10.2% for NWC and LWC specimens, respectively.
EN
A systematic approach to measure the differences between Mohr-Coulomb (MC) and Drucker-Prager (DP) shear strength criteria used commonly in soil and rock mechanics is presented. It is shown that the DP criterion generates a shear strength between 0.6 and 3 times the MC strength, for the same friction angle and cohesion parameters. The appropriate conditions for obtaining equal shear strengths are given. Moreover, some new DP failure surfaces are proposed which minimize the differences relative to the MC predictions. The equivalence of the DP and MC criteria under plane strain conditions is also examined.
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