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EN
Stereo photogrammetry has been used in this study to analyse and detect movements within the Lecture theater ofSchool of Environmental Technology of Federal University of Technology Minna via the use of Kalman filter algorithm.The essential steps for implementation of this method are herein highlighted and results obtained indicate Ins. Mov.s(velocity) ranging from±0.0000001 m/epoch to±0.000007 m/epoch with greater movements noticed in the horizontaldirection than in the vertical direction of the building. Because the observed movements were insignificant, the buildinghas been classified as stable. However, a longer period of observation with a bi-monthly observational interval has beenrecommended to enable decision on the rate of rise/sink and deformation of the building
PL
Zarówno podczas eksploatacji samolotów i śmigłowców, jak również w badaniach elementów innych struktur cienkościennych obserwuje się wiele interesujących zjawisk zachodzących w połączeniach nitowych, jak na przykład odkształcenia plastyczne, fretting itp., które wpływają ujemnie na trwałość połączenia, powodując inicjację pękania pokrycia. W artykule zaprezentowano wyniki badań dotyczących wizualizacji pól naprężeń metodami analizy MES oraz optycznymi połączeń nitowanych oraz wskazano na możliwość wykorzystywania tego rodzaju metod w badaniach odkształceń występujących w tych połączeniach.
EN
During the exploitation of aircraft and helicopters, as well as in the study of elements of other thin-walled structures, many interesting phenomena are observed in riveted joints, such as plastic deformations, fretting, etc., which negatively affect the durability of the joint, causing the initiation of cracking of the covering. The paper presents the results of research concerning the visualization of stress fields by FEM analysis methods and optical methods of riveted joints and indicates the possibility of using such methods in studies of deformation occurring in such type of joints.
EN
The paper deals with the study of the deformation, strength, and reservoir properties of rocks under various stress conditions, typical of great depths. The effect of all-round compression causes a change in the elastic, plastic, and strength characteristics of rocks. Some features of fracture formation and development in inhomogeneous solids under tension and compression were determined. The irreversible deformation mechanism of rocks under an uneven volume stress was considered. The irreversible deformation of rocks combines two types of deformation–intergranular slip, which produces the development of micro-fracturing, and intracrystalline slip, which mainly develops only at high pressure. The typical types of rock damage for uneven triaxial compression (transcrystalline and intercrystalline damage) were investigated. The phenomenon of loosening and increasing the volume as a result of irreversible deformations is mainly caused by the simultaneous formation of intergranular micro-cracks and micro-shifts along grain boundaries. As a result of these micro-dislocation combinations, macroscopic shift planes are formed, followed by irreversible deformation. On the surfaces of deformed samples, slip lines often appear; these are the traces of these macroscopic shift planes. Rock samples deformed due to high pressure are presented. The slip plane traces are clearly visible on the samples’ surfaces. It has been stated that under conditions typical of 8–10 km depths, irreversible deformation occurs with decompaction of their structure, increasing the coefficients of porosity and permeability. The effect of rocks deconsolidation caused by stress can be so significant, that in some cases may even increase the volume of voids by 1.5–2 times. The processes of dissolution and leaching of chemically unstable elements are of great importance in determining the filtration capacity and reservoir properties of deep-lying rocks, affected by irreversible deformation changes. Different dependences of volume growth, decompaction intensity coefficient, and permeability coefficient on the overall compression under uneven triaxial stress–which was based on the data of sandstone and marble–have been illustrated. The volume growth is quantitatively determined with the help of the decompaction intensity coefficient, and it is correlated with the collector and filtration capacity of rocks.
PL
Artykuł dotyczy badań odkształcenia, wytrzymałości oraz właściwości zbiornikowych skał w różnych warunkach naprężenia typowych dla znacznych głębokości. Wpływ ściskania obwodowego powoduje zmianę właściwości sprężystych, plastycznych i wytrzymałościowych skał. Określono niektóre cechy tworzenia i rozwoju pęknięć w niejednorodnych ciałach stałych pod wpływem rozciągania i ściskania. Rozważano mechanizm nieodwracalnego odkształcenia skał pod wpływem niejednolitego naprężenia objętościowego. Nieodwracalne odkształcenie skał łączy dwa rodzaje odkształcenia: poślizg międzyziarnowy, powodujący rozwój mikropękania, oraz poślizg międzykrystaliczny, który rozwija się tylko przy wysokim ciśnieniu. Badano rodzaje zniszczenia skał typowe dla niejednolitego trójosiowego ściskania (zniszczenie śródkrystaliczne i międzykrystaliczne). Zjawisko rozluźniania i zwiększenia objętości w wyniku odkształceń nieodwracalnych jest powodowane przez jednoczesne tworzenie mikropęknięć międzyziarnowych oraz mikroprzesunięcia wzdłuż granic ziaren. W wyniku tych kombinacji mikrodyslokacji tworzone są makroskopowe płaszczyzny przemieszczenia, a następnie odkształcenie nieodwracalne. Na powierzchni próbek odkształconych często pojawiają się linie poślizgu, które są śladami tych makroskopowych płaszczyzn poślizgu. Zaprezentowano próbki skalne odkształcone z powodu wysokiego ciśnienia. Na powierzchni próbek widoczne są wyraźnie ślady płaszczyzn poślizgu. Stwierdzono, że w warunkach typowych dla głębokości 8–10 km występuje odkształcenie nieodwracalne z rozgęszczeniem ich struktury, zwiększeniem współczynników porowatości i przepuszczalności. Wpływ dekonsolidacji skał powodowany przez naprężenie może być tak istotny, że całkowicie usuwa konsolidację skał, powodowaną przez naprężenia efektywne, a w niektórych przypadkach może zwiększyć objętość pustek nawet 1,5–2 razy. Procesy rozpuszczania i ługowania elementów niestabilnych chemicznie mają duże znaczenie dla określenia zdolności filtracji oraz właściwości zbiornikowych skał zalegających głęboko pod wpływem nieodwracalnych zmian odkształcenia. Zilustrowano różne zależności wzrostu objętości, współczynnika intensywności dekompakcji i współczynnika przepuszczalności od całkowitego ściskania pod wpływem niejednolitego naprężenia trójosiowego, oparte na danych dla piaskowca i marmuru. Wzrost objętości jest ilościowo określony za pomocą współczynnika intensywności dekompakcji i jest skorelowany z właściwościami filtracyjnymi skał.
6
Content available remote Analiza porównawcza nieskrępowanych i skrępowanych ściskanych ścian z ABK
PL
Mury skrępowane są stosowane dość powszechnie, a mimo to nie prowadzi się zbyt wielu badań dotyczących ich zachowania pod wpływem obciążenia statycznego. W Laboratorium Wydziału Budownictwa Politechniki Śląskiej zostały przeprowadzone kompleksowe badania ścian wykonanych z elementów murowych z betonu komórkowego. Ich głównym celem było określenie wpływu skrępowania, w postaci żelbetowych rdzeni połączonych ryglem, na nośność, odkształcalność oraz rysoodporność ścian murowanych, poddanych ściskaniu w ich płaszczyźnie. Badania pozwoliły również na obserwację mechanizmu zarysowania i zniszczenia elementów próbnych.
EN
Although this type of construction is used quite widely, there is not much research on its behavior under static load. In the Laboratory of the Faculty of Civil Engineering at Silesian University of Technology, masonry walls made of autoclaved aerated concrete were tested under static load. The main purpose of the research was determine the influence of confining masonry walls by reinforced concrete columns and beam on the load-bearing capacity, deformability and scratch resistance of masonry walls subjected to compression in their plane. Indirectly, the research also allowed for observations of the mechanism of scratches and destruction of sample elements.
EN
Basic differences resulting from the use of two types of materials during strengthening of RC structures are described. Attention is drawn to the consequences of using steel flat bars and composite strips or mats in relation to other strain values occurring at failure depending on the material used. Their impact, especially in the case of crack width and automatically shear capacity, makes direct extension of existing models of collapse to elements strengthened with composite materials unjustified.
PL
Opisano podstawowe różnice wynikające z zastosowania dwóch rodzajów materiałów przy wzmacnianiu konstrukcji żelbetowych. Zwrócono uwagę na konsekwencje użycia płaskowników stalowych oraz taśm lub mat kompozytowych w związku z innymi wartościami odkształceń występującymi przy zniszczeniu w zależności od zastosowanego materiału. Ich wpływ, szczególnie w przypadku szerokości rys i automatycznie nośności na ścinanie powoduje, że bezpośrednie rozszerzenie dotychczasowych modeli zniszczenia na elementy wzmocnione materiałami kompozytowymi jest niemożliwe.
EN
Pathological conditions of a male urethra, including fibrosis, have a mechanical background along the entire length of the urethra. They may be caused by excessive deformation of the urethra locally or globally. The condition of prolonged overload causes abnormal tissue remodelling and, consequently, the formation of a thick layer of scar tissue differentiated from the connective tissue of the urethra. This tissue, which has higher mechanical properties, is not highly deformable and therefore, causes a decrease in the diameter of the urethra, which results in conditions that disturb the natural flow of urine. In this paper, it was decided to determine the deformation conditions in the proximal part of the urethra. The study was conducted in three main stages. Transverse sections of the animal urethral tissues were prepared in order to examine mechanical properties and perform histological examinations. On the basis of these examinations, material models which fitted best for the experimental results were sought. Material constants of the Mooney-Rivlin material model with the best fit ratio were determined for further research. On the basis of histological photographs, a geometrical and numerical model of the urethra was developed. The urethra was tested in a flat state of deformation. The strain and stress fields of the Caucha tensor were examined. The methodology of testing the dynamics of the urine flow in the highly deformable urethra was proposed. This is important for the analysis of the influence of at excessive pressure on pathological tissue remodelling leading to fibrosis.
9
Content available Hybrid sandwich panels: a review
EN
A high specific stiffness, high specific strength, and tailoring the properties for specific application hale attracted the attention of the researchers to work in the field of laminated composites and Sandwich structures. Rapid use of these laminated composites and Sandwich structures necessitated the development of new theories that suitable for the bending, buckling and vibration analysis. Many articles were published on free vibration of beams, plates, shells laminated composites and sandwich structures. In this article, a review on free vibration analysis of shear deformable isotropic beams, plates, shells, laminated composites and sandwich structures based on various theories and the exact solution is presented. In addition to this, the literature on finite element modeling of beams, plates, shells laminated composites and sandwich structures based on classical and refined theories is also reviewed. The present article is an attempt to review the available literature, made in the past few decades on free flexural vibration response of Fiber Metal laminated Composites and Sandwich panels using different analytical models, numerical techniques, and experimental methods.
10
EN
The problem of gap estimation for a break of a continuous welded rail is studied. The track is represented as a semi-infinite rod on elastic-based damping. Static and dynamic solutions are obtained. It is shown that during the rail break, the dynamic factor does not exceed 1.5. We derive equations for thermal deformation of the welded rail of jointless track on an elastic foundation in the presence of the insert into the base with another characteristic stiffness. It is shown that the presence of the insertion of up to 20% of the length of the rail, with both large and small stiffness, has a little effect on the stress-strain state (SSS) of the track. The presence of a rigid insert may increase the clearance of an accidental break of the rail, which has a negative effect on traffic safety.
EN
The article presents testing of the mechanical properties of SIKA® polymer adhesives of the type PBM, PMM, PM, and PSM in the aspect of an attempt to determine the parameters of the Mooney-Rivlin hyperelastic model. The article contains a literature review on developed models for hyperelastic materials as well as a description of the author’s own results obtained in monaxial tensile and monaxial compression tests conducted on oars and cylindrical samples, respectively. Furthermore, the results of modeling of Mooney-Rivlin hyperelastic model parameters are shown in relation to the value of average parameters for polymers after both a week and a month-and-a-half of ripening.
EN
This study investigates the flexural strength of simply-supported steel–concrete composite beams under two-point loading. A total of four specimens were tested to failure for varying parameters including type of connectors (stud and channel) and number of connectors (two and four). ANSYS software was used to establish the finite element models that can simulate the flexural behaviour of the composite beam. The test results show that a beam with channel connectors performs better than a beam with stud connectors. The composite beam with two connectors between the beam and slab causes additional deflection due to slippage in the connectors, when compared to the beam with four connectors. The results from the analytical model are in good agreement with the experimental results.
13
Content available Gięcie na zimno dwuteownika HL1100
PL
W artykule opisano badanie w skali naturalnej trójpunktowego zginania na zimno dwuteownika HL1000. Przedstawiono przebieg badania oraz wybrane wyniki odkształceń uzyskane podczas nadawania podniesienia wykonawczego. Podczas badania wykorzystano innowacyjną metodę pomiarów światłowodowych.
EN
The paper presents point cold bending of I-beam HL1100 – full-scale test. The implementation and selected results of deformations during cambering were presented. During The innovative method of measuring by fiber optics were used in research.
EN
Finding effective ways to efficiently drive roadways at depths over 1 km has become a hotspot research issue in the field of mining engineering. In this study, based on the local geological conditions in the Xinwen Mining Area (XMA) of China, in-situ stress measurements were conducted in 15 representative deep roadways, which revealed the overall tectonic stress field pattern, with the domination of the horizontal principal stresses. The latter values reached as high as 42.19 MPa, posing a significant challenge to the drivage work. Given this, a comprehensive set of innovative techniques for efficiently driving roadways at depths over 1 km was developed, including (i) controlled blasting with bidirectional energy focusing for directional fracturing, (ii) controlled blasting with multidirectional energy distribution for efficient rock fragmentation, (iii) wedge-cylinder duplex cuts centered on double empty holes, and (iv) high-strength supports for deep roadways. The proposed set of techniques was successfully implemented in the –1010 west rock roadway (WRR) drivage at the Huafeng Coal Mine (HCM). The improved drivage efficiency was characterized by the average and maximum monthly advances of 125 and 151 m, respectively. The roadway cross-sectional shape accuracy was also significantly improved, with the overbreak and underbreak zones being less than 50 mm. The deformation in the surrounding rock of roadway (SRR) was adequately controlled, thus avoiding repeated maintenance and repair. The relevant research results can provide technical guidance for efficient drivage of roadways at depths over 1 km in other mining areas in China and worldwide.
EN
In this study, the compressive deformation of crushed sandstone was tested using a crushed rock deformation-seepage test system, and the effects of various factors, including crushed rock grade, grade combination, water saturation status, and stress loading method (i.e., continuous loading or cyclic loading and unloading), on the compressive deformation of crushed sandstone was analyzed from four perspectives including stress-strain, bulking coefficient, deformation mechanism and energy dissipation. The results indicate that the stress-strain relations of crushed sandstone are closely associated with all factors considered, and are well represented by exponential functions. The strain observed for a given applied stress increased with increasing crushed rock grade throughout the loading period. Crushed sandstone grades were combined according to a grading index (n), where the proportion of large-grade rocks in the sample increased with increasing n. The bearing capacity of a water-saturated crushed sandstone sample with n = 0.2 was less than that of an equivalent dry sample for a given applied stress. The stress-strain curve of a water-saturated crushed sandstone sample with n = 0.2 under cyclic loading and unloading was similar to that obtained under continuous loading. Observation and discovery, the deformation mechanism of crushed sandstone was mainly divided into four stages, including crushing, rupture, corner detachment and corner wear. And 20% of the work done by testing machine is used for friction between the crushed sandstone with the inner wall of the test chamber, and 80% is used for the closing of the void between the crushed sandstone, friction sliding, crushing damage.
EN
Currently available field rock mass deformability determination methods are rather difficult to perform, due to their complexity and a time-consuming nature. This article shows results of a suitability assessment of a Pen206 borehole jack (a hydraulic penetrometer) for field rock mass deformability measurements. This type of the borehole jack is widely used in Polish hard coal mining industry. It was originally intended only for quick rock mass strength parameters determination. This article describes an analysis and scope of basic modifications performed mainly on a borehole jack head. It includes discussion of results with possible directions for future development of the device.
EN
The article concerns modern, flexible adhesive joints, which might be used in timber construction. The article discusses the test results carried out for timber elements joints using polymeric adhesives produced by Sika®. The scope of the tests includes the analysis of strength criteria, tests of polymer adhesion to the timber with a pull-off method, tests of polymer layer shearing between timber elements as well as examination of bending of timber elements joined with polymer. The conclusions indicate the types of these polymers which are recommended for the creation of polymeric joints of timber-polymeric type in timber constructions.
PL
Dynamiczny rozwój połączeń klejowych, umożliwia ich zastosowanie już nie tylko w naprawach, czy wzmocnieniach głównie konstrukcji żelbetowych oraz murowych. Coraz częściej mówi się o zastąpieniu tradycyjnych łączników przez połączenia klejowe. Szczególnie interesujący jest rozwój połączeń na bazie polimerów w zastosowaniu w konstrukcjach drewnianych, który umożliwia eliminację lub znaczne ograniczenie występowania zjawiska koncentracji naprężeń, jak ma to miejsce w przypadku najbardziej powszechnych połączeń trzpieniowych. Szczególne znaczenie ma eliminacja tego zjawiska w obiektach drewnianych, poddanych oddziaływaniu silnych wiatrów, trzęsień ziemi, czy też dużych gradientów temperaturowych oraz wilgotności. Głównym celem artykułu jest omówienie wyników badań przeprowadzonych dla połączeń elementów drewnianych przy wykorzystaniu podatnych klejów polimerowych produkcji Sika®. Zakres badań obejmuje analizę kryteriów wytrzymałościowych, badania przyczepności polimeru do drewna metodą pull-off (na odrywanie), badania ścinania warstwy polimeru pomiędzy elementami drewnianymi oraz badania zginania elementów drewnianych zespolonych polimerem.
EN
High-pressure jet grouting pile is a kind of stratum reinforcement technology developed in recent years. Due to its characteristics of high solid strength, fast construction, low noise, safety and reliability, low cost, controllable reinforcement diameter, strong adaptability to stratum, and good reinforcement effect for soft soil, loose soil and water-rich stratum, high-pressure jet grouting pile technology has been more and more widely used in foundation treatment, water stop, and seepage prevention, tunnel lining and other fields in recent years. As a country with a relatively late development of underground construction engineering, Vietnam has little research on special geotechnical reinforcement technology, especially on special geotechnical reinforcement technology around urban underground construction engineering, especially on its theoretical analysis and practical application. Therefore, this thesis combines the Vietnam Trung Hoa tunnel project as an example, using the theoretical calculation formula and field monitoring measurement comparing the two methods, the high pressure jet grouting pile system research in Vietnam in the underground engineering reinforcement principle and application effect, get to the actual engineering design and construction has a guiding significance to the research, provides the reference for future similar projects. Finally, the application effect of high-pressure jet grouting pile in underground building reinforcement project is evaluated, which proves that high-pressure jet grouting pile has good applicability and economic benefit in underground building reinforcement project in Vietnam.
EN
Mechanical behavior of a multifunctional titanium alloy Gum Metal was investigated by conducting tensile tests at various strain rates and applying digital image correlation (DIC) technique. Stress–strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength had a tendency to increase, whereas the elongation to the specimen rupture tended to decrease with increasing strain rate. True stress versus strain curves were analyzed using selected lengths of virtual extensometer (VE) placed in the strain localization area. When the initial length of the VE was the same as the gauge length, work hardening was observed macroscopically at lower strain rates, and a softening was seen at higher strain rates. However, the softening effect was not observed at the shorter VE lengths. Evolution of the Hencky strain and rate of deformation tensor component fields were analyzed for various strain rates at selected stages of Gum Metal load-ing. The DIC analysis demonstrated that for lower strain rates the deformation is macroscopically uniform up to the higher average Hencky strains, whereas for higher strain rates the strain localization occurs at the lower average Hencky strains of the deformation process and takes place in the smaller area. It was also found that for all strain rates applied, the maximal values of Hencky strain immediately before rupture of Gum Metal samples were similar for each of the applied strain rates, and the maximal local values of deformation rate were two orders higher when compared to applied average strain rate values.
EN
The paper explores the new method of improving the workability of materials in the dieless drawing processes. The proposed method is based on the implementation of a multi-pass incremental deformation. Moreover, in each pass, strain and strain rate sensitivity of flow stress should be positive and significant. An approach based on the finite element calculation of instability coefficient of plastic deformation and simultaneous modeling of material ductility were applied for prediction of the workability. Two dieless drawing processes have been investigated. The difference was related to the heating system-induction heating and laser heating. FE simulations and experimental tests for three materials, two magnesium alloys (MgCa0.8 and MgNi19) and pure copper were performed. It was shown that the most effective increase in workability by multi-pass deformation can be achieved using laser dieless drawing. This is possible due to the shorter heating area and, as a consequence, the larger strain rate, which leads to better stability of the deformation process.
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