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  1. 7 Archives of Civil and Mechanical Engineering
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1
Content available Resonance of a structure with soil elastic waves released in non-linear hysteretic soil upon unloading
Kowalczyk Piotr
Studia Geotechnica et Mechanica
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2022
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Vol. 44, nr 4
253--266
EN
High-frequency motion is often observed in small-scale experimental works carried out in flexible containers under simplified seismic loading conditions when single harmonic sine input motions are introduced at the base of a soil specimen. The source of the high-frequency motion has often been sought in experimental inaccuracies. On the other hand, the most recent numerical studies suggested that high-frequency motion in the steady-state dynamic response of soil subjected to harmonic excitation can also be generated as a result of soil elastic waves released in non-linear hysteretic soil upon unloading. This work presents an example of a finite element numerical study on seismic soil–structure interaction representative of an experimental setup from the past. The results show how high-frequency motion generated in soil in the steady-state response, apparently representative of soil elastic waves, affects the steady-state response of a structure, that is, it is presented how the structure in the analysed case resonates with the soil elastic waves. The numerical findings are verified against the benchmark experimental example to indicate similar patterns in the dynamic response of the structure.
2
Content available Optimization of technological measures increasing the safety of the Żelazny Most tailings pond dams with the combined use of monitoring results and advanced computational models
Łydżba Dariusz, Różański Adrian, Sobótka Maciej, Stefanek Paweł
Archives of Civil Engineering
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2022
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Vol. 68, nr 1
503--518
EN
The paper presents the approach for optimization of preventive/technological measures increasing the safety of tailings pond dams. It is based on the combined use of monitoring results as well as advanced 3D finite element (FE) modeling. Under consideration was the eastern dam of Żelazny Most Tailings Storage Facility (TSF). As part of the work, four numerical models of the dam and the subsoil, differing in the spatial arrangement of the soil layers, were created. For this purpose, the kriging technique was used. The numerical models were calibrated against the measurements from the monitoring system. In particular the readings acquired from benchmarks, piezometers and inclinometers were used. The optimization of preventive measures was performed for the model that showed the best general fit to the monitoring data. The spatial distribution and installation time of relief wells were both optimized. It was shown that the optimized system of relief wells provides the required safety margin.
PL
W artykule przedstawiono podejście do optymalizacji zabiegów technologicznych zwiększających bezpieczeństwo zapór zbiorników odpadów wydobywczych. Opiera się ono na jednoczesnym wykorzystaniu wyników monitorowania oraz modelowania numerycznego 3D w ujęciu metody elementów skończonych. Rozpatrywana jest wschodnia zapora OUOW Żelazny Most. W ramach pracy stworzono cztery modele numeryczne zapory i podłoża, różniace się przestrzennym układem warstw gruntowych. W tym celu wykorzystano technikę krigingu. Na podstawie wyników monitoringu skalibrowano modele numeryczne i wybrano ten, dla którego przeprowadzono procedurę optymalizacji. Zoptymalizowano zarówno rozkład przestrzenny, jak i czas instalacji studni odciążających. Wykazano, że takie rozwiązanie zapewnia, wymagany stosownymi rozporządzeniami, zapas bezpieczeństwa.
3
Content available Anti-overturning safety performance investigation for single column pier bridge
Ji Yongcheng, Liu Wenchao, Li Wei, Wang Pixiang
Archives of Civil Engineering
|
2022
|
Vol. 68, nr 3
221--240
EN
Under eccentric load, a single column pier bridge often overturns. In order to study the anti overturning performance of a single column pier bridge, taking the accident bridge in Wuxi as an example, a finite element model is established based on ABAQUS. According to the model simulation results, the relationship between the ultimate rotational load and overturning load of the accident bridge is obtained, and the ratio of the latter to the former is 1.75. Based on the model, the stress state, displacement state, and support state of the accident bridge under dead load, highway class I vehicle load, and accident vehicle load are obtained. Whether the strength and stability of the accident bridge under each load meet the service requirements is analyzed. In order to explore the differences among China, United States, and Japan specifications, the lateral stability of accident bridges is checked. It is found that the safety of the United States and Japan specifications is conservative, but the utilization rate of bridge traffic capacity is low. The safety of China specifications is slightly lower, but it can maximize the bridge’s traffic capacity and judge the ultimate overturning state of the bridge more accurately. The research results can provide technical references for the design and application of a single-column pier bridge.
4
Content available remote Flexural behavior of square hollow steel-reinforced concrete members
Ren Qingxin, Ding Jinan, Wang Qinghe, Liang Hui
Archives of Civil and Mechanical Engineering
|
2022
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Vol. 22, no. 1
art. no. e34, 2022
EN
This paper presents an experimental investigation on the flexural behavior of the square hollow steel-reinforced concrete (HSRC) members. A total of six specimens with different hollow ratios and steel tube ratios were prepared, and their failure modes, strain distributions, the mid-span deflection, and bending moment were recorded. The obtained results showed that the HSRC specimen fails in a ductile mode and no local buckling occurs in the inner steel tube. The increase of steel tube ratio leads to the improvements of the ultimate bending moment, the flexural stiffness and the ductility coefficient. The ultimate bending moment can be increased by 52.8% when the steel tube ratio increases from 0 to 2.96%. To expand the ranges of parameters, a finite element model (FEM) was developed and benchmarked against the test results from this study. Then, a parametric study was conducted to quantify various influential factors on the flexural behavior of the square HSRC members, and the key influential factors were further determined. Based on the parametric investigation, a simplified design method on the prediction of the ultimate bending moment for the square HSRC members was provided to account for the contribution of the incompletely full-section yielded steel tube, and the predicted results from the simplified design method were satisfactorily in accordance with the experimental and numerical results.
5
Content available Sliding of spherical ball on solid lubricating coating combined with wear process
Białas Marcin, Maciejewski Jan, Kucharski Stanisław
Welding Technology Review
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2021
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R. 93, nr 1
39--50
EN
In present paper we show results of ball-on-disk wear experiment of MoS2 film deposited on Ti6Al4V substrate. The ball material is aluminium oxide. The tests are performed for different surrounding temperature conditions: 20°C, 200°C and 350°C. It is shown that depth of the wear groove increases with increasing surrounding temperature. A finite element modelling approach is next developed to mimic the experimental observations of ball-on-disk wear process. It is based on the assumption of steady state condition developed during short time scale at contact region. The steady state results can next be applied to long time scale in which wear process is numerically simulated. Model results are compared with experimentally obtained wear groove and show satisfactory agreement.
PL
Artykuł prezentuje wyniki testu zużycia powłoki samosmarującej MoS2 nałożonej na podłoże wykonane z materiału Ti6AI4V. Powłoka obciążona jest kulką szafirową w ruchu rotacyjnym. Badania wykonano w trzech różnych temperaturach otoczenia: 20°C, 200°C oraz 350°C. Wykazano, że głębokość rowka zużyciowego wzrasta wraz ze wzrostem temperatury otoczenia. Zaproponowano model metody elementów skończonych za pomocą którego zasymulowany został proces zużycia warstwy. Punktem wyjścia dla tej części pracy było założenie stanu ustalonego, powstającego w obszarze kontaktu pomiędzy kulą a warstwą. Warunki odpowiadające temu stanowi przyjęto do matematycznego opisu procesu zużycia z wykorzystaniem równań Archarda. Na zakończenie eksperymentalny profil zużycia porównany został z wynikami otrzymanymi metodą elementów skończonych.
6
Content available remote Investigation of finite element (FE) modelling of composite materials: shell, solid and solid layered composite modelling – comparison of impact on simulation results
Gojny Katarzyna, Dacko Adam
Composites Theory and Practice
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2021
|
R. 21, nr 1-2
29--39
EN
Composites materials have attracted a great deal of interest for use in various fields e.g. the transport industry, construction, sport equipment and even home applications. This is due to the excellent properties of composite materials such as their high strength/stiffness to mass ratio. Nowadays, finite element (FE) modelling allows investigation of the behaviour of composite materials subjected to loading before the production stage. This paper compares the available ways of FE modelling of composite materials: shell, solid shell and solid layered composite modelling in MSC Patran/Nastran software. The aim of this research work was a comparative analysis and determination of the influence of the applied modelling type on the simulation results. Numerous finite element analyses (FEAs) (tensile and bending) of different narrow plate (resembling a slender, beam-like structural member) structure models were performed, i.e. laminated beam and sandwich beam models, with different layups of layers. The obtained numerical results allow the authors to conclude that shell composite finite element modeling can be considered a practically optimal choice due to reduction of the modelling effort and time, as well as due to obtaining consistent simulation results, especially when having only the basic manufacturer’s set of material constants.
PL
Materiały kompozytowe cieszą się dużym zainteresowaniem w różnych dziedzinach, np. przemysł transportowy, budownictwo, sprzęt sportowy i nawet zastosowania domowe. Wynika to z doskonałych właściwości materiałów kompozytowych, takich jak wysoki stosunek wytrzymałości/sztywności do masy. Obecnie modelowanie metodą elementów skończonych (MES) pozwala na badanie zachowania się materiałów kompozytowych poddanych obciążeniu przed etapem produkcji. W artykule porównano dostępne sposoby modelowania MES materiałów kompozytowych: modelowanie powłokowe, bryłowe i bryłowo-warstwowe w oprogramowaniu MSC Patran/Nastran. Celem pracy badawczej była analiza porównawcza i określenie wpływu zastosowanego modelowania na wyniki symulacji. Przeprowadzono liczne analizy MES (zginanie i rozciąganie) dla różnych modeli wąskiej płyty (przypominającej smukły, belkowy element konstrukcyjny), tj. dla modelu materiału laminatu warstwowego oraz struktury przekładkowej, z różnymi układami warstw. Uzyskane wyniki numeryczne pozwalają stwierdzić, że modelowanie powłokowe materiałów kompozytowych jest praktycznie optymalnym wyborem ze względu na zmniejszenie nakładu pracy i czasu oraz uzyskanie spójnych wyników symulacji, zwłaszcza gdy dysponuje się tylko podstawowym zestawem stałych materiałowych producenta.
7
Content available remote Coupled FEM-microstructural X-ray examination of a controlled internal damage approach for concrete samples
Sidiq Amir, Robert Dilan, Gravina Rebecca, Giustozzi Filippo
Archives of Civil and Mechanical Engineering
|
2021
|
Vol. 21, no. 2
350--369
EN
One of the critical factors that govern the technology of concrete self-healing evaluation at laboratory scale is the crack induction pattern within the concrete sample. Within the various techniques of inducing artificial cracks, such as the flexural testing or splitting testing methods, there are limitations of inducing the microcracks homogenously throughout the entire volume of the concrete sample. In this study, an innovative technique is utilised to induce the microcracks at a controlled damage level to further study the self-healing phenomena in concrete at the laboratory scale. By placing a concrete sample into an ad-hoc fabricated steel mould and applying fractional compressive strength, the axial-circumferential pressure induces microcracks in the concrete sample, homogenously. A Finite Element Model was also built to investigate the hypothesis on the cracking pattern at various damage levels; jointly, experimental work was conducted with X-ray µCT images to reconstruct the three-dimensional sections at the various damage levels. Qualitative analyses in relation to the two test methods were conducted. Furthermore, quantitative analyses on the individual-artificially generated-cracks were conducted in terms of the crack size crack geometry variation and the orientation of the newly formed cracks. Results revealed that the proposed crack-inducing methodology is highly efficient to induce uniform cracks in the sample, assisting for the evaluation of concrete self-healing process. The novel method can be adapted to identify the optimised strategies for enhancing the structural performance of concrete, thus facilitating the safe operation of concrete infrastructure.
8
Content available Numerical and experimental modelling of slope stability and seepage water of earthfill dam
El-Hazek Alaa N., Abdel-Mageed Neveen B., Hadid Mohammed H.
Journal of Water and Land Development
|
2020
|
no. 44
55--64
EN
In this paper, finite element modelling is employed for simulating and analysing seepage and slope stability of earthfill dam via GeoStudio software. Two products are employed, which are SLOPE/W for slope stability and SEEP/W for seepage analysis. The behaviour of earthfill dam with four different types of sandy soils having different values of hydraulic conductivity (K) has been studied. Different upstream (US) slopes of 1:2, 1:2.5, 1:3 and 1:3.5 for the earthfill dam are simulated. The downstream (DS) slope is constant at 1:2. The results showed for all the four types of soils that when the US slope is increased, the amount of seepage from the dam increases and the factor of safety (F) decreases. For each US slope, when K (type of soil) increases, both seepage and F increase. Fine sand soil is associated with less seepage and less F. Sixteen equations are obtained to predict both seepage and F with respect to US slope for each type of soil and K of the soil for US slope. An experimental model for earthfill dam is constructed in the laboratory of hydraulics, Benha University to investigate the seepage of water through earthfill dams. It is concluded that seepage decreased when K decreased, and when the US slope for each type of soil decreased. The seepage increased when K increased for each US slope. Seven equations are obtained to predict seepage with respect to US slope for each type of soil, and K for each US slope.
9
Content available Seismic Behavior of Earth Dams With Different Reservoir Water Levels Under Near-Field and Far-Field Earthquakes
Asadi Masoud, Soltani Fazlollah, Sinvandi-Pour Abbas, Noroozinejad Farsangi Ehsan
Civil and Environmental Engineering Reports
|
2020
|
Vol. 30, no. 4
125--141
EN
The height of reservoir water is one of the important factors affecting the seismic behaviour of earth dams. A large number of earth dams have been constructed in different countries that are sometimes located in a high-risk geographical zone. The studies on the seismic behaviour of earth dams have been conducted for several decades. However, this study, considering the importance of the subject, it investigates the seismic behaviour of Sumbar rock-fill embankment dam under near- and far-field earthquakes with variation in the water level behind the dam. The ratio of water height of the dam to dam height is considered as an important indicator to investigate the seismic performance of these structures. The analyses were performed using the ABAQUS finite element platform, under 7 near-field and 7 far-field earthquake records. In this research, the changes in dam stresses, displacements, and failure of the dam have been discussed. The results indicated that the effect of near-field earthquakes on the seismic behaviour of earth dams is more significant than far-field earthquakes.
10
Content available Numerical simulations of ductile fracture in steel angle tension members connected with bolts
Bernatowska Edyta
Civil and Environmental Engineering Reports
|
2020
|
Vol. 30, no. 2
32--54
EN
Numerical simulations of ductile fracture in steel angle tension members connected with bolts
11
Content available Surface based cohesive behavior implementation for the strength analysis of glued-in threaded rods in Glulam
Gečys T., Šaučiuvėnas G., Ustinovichius L., Miedzialowski C., Sulik P.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2020
|
Vol. 68, nr 5
1149--1157
EN
The paper presents the analysis of strength and stiffness of metric threaded steel rods glued in glulam obtained by using two different gluing methods. The first method is used when the threaded steel rod is glued into a groove larger than the rod’s diameter, while the second method is applied when the diameter of the groove is smaller than the diameter of the threaded steel rod. The steel rod is covered with glue before it is inserted into the smaller diameter groove. The first method investigates the 2-mm-thick glue-line, while the second method analyses the contact when the groove’s diameter is 2 mm smaller than the outer diameter of the rod. Epoxy-type resin is used for both gluing methods. Different gluing methods present different interactions between the steel rod and glulam which result in different failure modes. The second method presents a plastic failure between the steel rod and glulam caused by the local compression and shear of glulam. The presented studies are made using metric threaded steel rods of diameters M12 and M16. In total, 20 specimens are experimentally tested in tension-to-tension tests performed according to EN 26891. The interaction between glulam and glued steel rods is also investigated using the 3D finite element modelling. The results obtained using the proposed 3D finite element model with different contact conditions between steel and glulam and the failure criterion for timber shear are well in line with the experimental findings.
12
Content available Stability analysis of drilling rigs moving on a weak subsoil. Selected case studies
Urbański A., Richter M.
Archives of Civil Engineering
|
2020
|
Vol. 66, nr 2
303--319
EN
This article presents results of the numerical analysis of the interaction between heavy caterpillar tracks system and subsoil. The main goal of the article is to present an algorithm to design working platforms - temporary structures enabling the work of heavy construction equipment on weak subsoils. A semi-analytical method is based on the results of the numerical analysis performed with use of the finite element method (FE software ZSoil.PC [12]). The calculations were carried out for the piling rig machine - Bauer BH20H (BT60). Three ground models were adopted: Model 1: one layer - weak cohesive soil (clay); Model 2: two layers: weak cohesive soil (clay) and cohesionless working platform (medium sand); Model 3: one layer: strong cohesionless subsoil (medium sand). The following problems were solved: I) entry of the machine on the ground with various geotechnical parameters under each caterpillar tracks II) detection of the maximum permissible angle of ground slope.
PL
Nabierająca tempa dynamika produkcji budowlanej wymusza na inwestorach konieczność zagospodarowania nieruchomości gruntowych których przeznaczenie na cele budowlane było wcześniej nieopłacalne (niskie parametry gruntowe, wysoki poziom wód gruntowych, występowanie zwartej zabudowy itp.). W związku z tym, grunty na których posadowienie są budynki coraz częściej charakteryzują się niskimi parametrami wytrzymałościowymi. Dlatego geotechnicy mają trudne zadanie projektowania i wykonywania budowli na terenach wymagających podjęcia szczególnych środków ostrożności. W celu odpowiedniego przenoszenia obciążeń pomiędzy budynkiem a podłożem gruntowym o niskich parametrach wytrzymałościowych projektanci decydują się na wykonanie fundamentów pośrednich. Ich wykonanie wymaga zastosowania specjalistycznych maszyn roboczych (palownic, wiertnic itp.). Przed dopuszczeniem maszyny roboczej do pracy należy sprawdzić, czy podłoże gruntowe ma wystarczającą nośność. W przypadku jej niedoboru, należy odpowiednio wzmocnić podłoże poprzez wykonanie platformy roboczej. W niniejszym artykule przedstawiono analizę współpracy maszyna budowlane - podłoże gruntowe. Podstawową analizę przeprowadzono metodą elementów skończonych 3D (oprogramowanie FE ZSoil.PC). Jej wyniki zostały opracowane w formie formuł umożliwiających rozwiązanie problemu interakcji maszyna budowlana – podłoże gruntowe. Szczegółowe obliczenia przeprowadzono dla palownicy - Bauer BH20H (BT60).
13
Content available remote Microstructure evolution and property analysis of commercial pure Al alloy processed by radial-shear rolling
Gamin Yu. V., Akopyan T. K., Koshmin A. N., Dolbachev A. P., Goncharuk A. V.
Archives of Civil and Mechanical Engineering
|
2020
|
Vol. 20, no. 4
674--683
EN
The features of microstructure formation and properties of commercial pure aluminum alloy (Al 99.5%) obtained by radial-shear rolling (RSR) method at the different heating temperatures of 25, 200, 250, 300 and 350 °C were examined. In this paper, the rods with diameter of 14 mm were obtained from initial billet with diameter of 60 mm in five passes. The microstructure analysis with electron backscatter diffraction (EBSD), measurements of microhardness HV over cross-section, and tension test for determination of mechanical properties were carried out for these rods. The FEM simulation of RSR process and calculation of Zener–Hollomon parameter (Z) were carried out with Software QFORM. The obtained rods have the gradient microstructure typical of RSR characterized by surface layer with ultrafine grain structure (UFG) and grain size from 0.3 to 5 µm. In the central part of rod, the fiber deformed structure with minimal fraction of recrystallized grains (< 5%) is formed. This combination is optimal for simultaneous achievement of high strength (UTS ~ 107–110 MPa; YS ~ 100–109 MPa; ~ 35–40 HV) and ductility (El ~ 15–30%). The most intensive growth of plastic properties is observed at rolling temperatures close to the temperature of the onset of recrystallization, it is associated with additional deformational heating of surface layers and the formation of partially recrystallized structure. The obtained distribution dependences of average size of dynamic recrystallized grain on Zener–Hollomon parameter showed that the decrease in parameter Z leads to the increase in size of recrystallized grain for RSR process.
14
Content available Application of the finite element method in the milling process stability diagnosis
Dunaj Paweł, Marchelek Krzysztof, Chodźko Marcin
Journal of Theoretical and Applied Mechanics
|
2019
|
Vol. 57 nr 2
353--367
EN
The article presents results of both experimental and FEM model-based investigations on chatter phenomena that occur in the end milling process. On the basis of chatter symptoms observed during machining, the mechanism of its occurrence has been identified. Then, a FEM model has been built to indicate machine tool elements responsible for loss of stability. Afterwards, experimental modal analysis has been conducted in order to validate the FEM model. Finally, on the basis of the validated model, the structural changes have been proposed and applied in the real object resulting in increased stability.
15
Content available remote Novel shearhead reinforcement for slab-column connections subject to eccentric load and fire
Al-Hamd Rwayda Kh. S., Gillie Martin, Cunningham Lee S., Warren Holly, Albostami Asad S.
Archives of Civil and Mechanical Engineering
|
2019
|
Vol. 19, no. 2
503--524
EN
Traditional means of reinforcing concrete flat slab-column connections against punching shear, such as increasing slab thickness, or provision of shear links, all have drawbacks. This paper proposes a novel type of punching shear reinforcement in the form of a shearhead to enhance connection strength and ductility. The structural behaviour of the connection is explored experimentally by testing nine specimens under various loading conditions including eccentric loads that produce combined axial and bending effects. Specimens with and without shearheads are compared. This is followed by a detailed numerical investigation using finite element analysis to obtain more in-depth insights into the connection behaviour when shearheads are present. The performance of the proposed system is also investigated under fire conditions for the first time. It is found that the proposed shearheads improve the performance of slab-column connections in all conditions and particularly under concentric loading and in fire conditions.
16
Content available Simplified design equation for web tapered I-sections using finite element modeling
Rameshbabu C., Prabavathy S.
Archives of Civil Engineering
|
2018
|
Vol. 64, nr 3
57--66
EN
The web-tapered I-columns have the capacity to resist the flexural buckling and lateral torsional buckling at a particular location where as in the rest of the member the capacity is lower. There needs a focusing on the nonprismatic members, to find the buckling capacity and standard procedures are to be framed in Indian Code IS 800:2007. This exploratory research explores simulated finite element models covering a total of 60 web tapered column sections having taper ratios (h2/h1) from 1.0 to 3.0 using FEA software ANSYS17.2. With an elaborate Eigenvalue buckling analysis, this research has come up with newer design equation for calculating the buckling load of web tapered I columns. This novel equation could predict the buckling stress for any taper ratio of web tapered I column of any length.
17
Content available Oil pipeline leak detection using GPR method - simple case study
Fąfara Z., Lewandowska-Śmierzchalska J., Matuła R.
AGH Drilling, Oil, Gas
|
2018
|
Vol. 35, no. 1
165--171
EN
Modelling experiment was used to investigate the abilities of using ground penetrating radar (GPR) to detect oil leaks in the underground pipeline system. Leaks not only waste precious natural resources but also create substantial damage to the transportation system within urban environments. Surface geophysical methods are noninvasive tools used to characterize the changes in the physical properties of the subsurface material. This characterization, in consequence, is used to interpret the geological and hydrogeological conditions of the strata. GPR is a reflection-based technique which uses high frequency electromagnetic waves to acquire subsurface information. GPR responds to changes in electrical properties, which are a function of soil and rock material and moisture content. A simple experiment was conducted to determine the validity and effectiveness of GPR technology in detecting leakage in metal pipelines. Initially, a prototype model was designed to simulate a pipe leak. A 1.5 GHz antenna modeling mode was used to collect GPR data. The test was modelled using sandy soil material that is representative for pipelines construction. Also model simulations are being used to select an appropriate equipment configuration (frequency band, type of antenna and real-time imaging software) prior to data acquisition.
18
Content available Stability Problems of Compressed Thin-Walled Structures
Dębski Hubert
Advances in Science and Technology. Research Journal
|
2018
|
Vol. 12, no 4
190--198
EN
The object of this study involves thin-walled columns made of carbon-epoxy composite with open top-hat cross-section. The material used comprised a composite of epoxy matrix reinforced with carbon fiber (system HexPly M12, Hexcel). The M12 system is used above all in aircraft structures. It exhibits high fatigue durability and good maintenance properties at relatively low specific gravity. The research was carried out as the FEM numerical analyses and experimental tests in buckling and post-buckling state. The numerical tool used was the ABAQUS software.
19
Content available Modifying the Shape of Blades of a Flexible Reed in a Vibration Beat-up Mechanism – Theoretical Investigation
Kuchar M.
Fibres & Textiles in Eastern Europe
|
2017
|
Vol. 25, no. 6 (126)
114--118
EN
The beat-up mechanism of a loom with exciters for vibrating motion of the reed is presented. With the placing of exciters at regular distances across the width of the reed, certain differences can be observed in the amplitudes of the vibratory motion of individual blades. Undercutting is proposed here as a method of reducing these differences. The permissible distance between the exciters was determined taking into account the undercut reed. The undulation of the reed in the process of thickening of the wefts is shown to be a consequence of undercutting. For a distance between the exciters of L = 200 mm and relative depth of the undercut h0/h = 0.8, differences in the amplitudes of individual blades do not exceed 10%.
PL
Przedstawiono mechanizm bidłowy krosna ze wzbudnikami ruchu wibracyjnego płochy. Umieszczając wzbudniki w regularnych odstępach na szerokości płochy istnieją różnice w amplitudach ruchu wibracyjnego poszczególnych trzcinek. Zaproponowano podcięcie trzcinek jako sposób na zmniejszenie tych różnic. Biorąc pod uwagę płochę podciętą określono dopuszczalną odległość pomiędzy wzbudnikami. Jako konsekwencje podcięcia ujawniono pofalowanie płochy podczas zagęszczania wątków. Biorąc po uwagę odległość pomiędzy wzbudnikami L = 200 mm oraz względną głębokość podcięcia h0/h = 0,8 różnice w amplitudach ruchu wibracyjnego poszczególnych trzcinek nie przekraczają 10%.
20
Content available remote Synergetic approach to die wear modelling in hot forging process
Wilkus M., Szeliga D., Rauch Ł., Pietrzyk M.
Computer Methods in Materials Science
|
2017
|
Vol. 17, No. 4
193--204
EN
A proposition of the hybrid model of the tool wear in hot forging is described in the paper. The idea of the model was based on distinguishing various mechanisms of the tool wear and evaluation of the mutual influence of these mechanisms. The analysis of factors, cumulative wear of which is mutually dependent, confirmed that all mechanisms influence each other in some way. To cover this, the hybrid die wear model was proposed which includes significance of each mechanism and the mutual relation between them. Additionally, to include change of material parameters, modification of these parameters was account for by a feedback, passing modified die geometry and optionally material parameters into the next iteration of die wear modelling. Developed model consists of the FE simulation to which the following process parameters are supplied by the user: wear mechanisms blocks containing adequate models, significance models and extrapolation routines for results or input parameters, component to apply computed wear value as a die geometry and control the computation of multi-iteration wear prediction. Some mechanisms blocks contain additional components for computing correction of surface parameters altered by thermomechanical fatigue, cracks or increased porosity. Numerical tests of the model were performed for the second operation in the forging of clutch wheel. Comparison of predictions and measurements confirmed improvement of the model predictive capability when synergy of the three mechanisms was accounted for.
PL
W pracy opisano hybrydowy model zużycia narzędzi w procesie kucia na gorąco. Idea modelu bazuje na rozróżnieniu mechanizmów degradacji narzędzi i ocenie ich wpływu na siebie. Analiza czynników, których sumaryczne zużycie jest wzajemnie zależne, wykazała, że wszystkie mechanizmy wpływają na siebie. Aby to wziąć pod uwagę, opracowano hybrydowy model uwzględniający istotność każdego z mechanizmów oraz ich synergię. Dodatkowo uwzględniono zmianę własności materiału narzędzia w czasie kucia kolejnych odkuwek. Zrealizowano to poprzez sprzężenie zwrotne przekazujące nowy kształt narzędzia i własności materiału do następnej iteracji. Opracowany model obejmuje symulację metodą elementów skończonych z następującymi parametrami wprowadzanymi przez użytkownika: blok mechanizmów zużycia zawierający odpowiednie modele, procedury ekstrapolacji dla parametrów wejściowych i wyjściowych, modele istotności, komponenty' przeliczające zużycie na kształt narzędzia oraz blok sterowania iteracyjnymi obliczeniami zużycia. Niektóre bloki dla mechanizmów zużycia zawierają dodatkowe składniki pozwalające korygować parametrów powierzchni uwzględniając wpływ termomechanicznego zmęczenia, mikro- pęknięć i wzrostu porowatości. Numeryczne testy modelu zostały przeprowadzone dla drugiej operacji kucia kola czołowego sprzęgła. Porównanie wyników obliczeń i pomiarów potwierdziło poprawę dokładności kiedy zastosowano model uwzględniający synergię trzech mechanizmów.
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