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Number of results: 160
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Abstract

Redundant constraints in MBS models severely deteriorate the computational performance and accuracy of any numerical MBS dynamics simulation method. Classically this problem has been addressed by means of numerical decompositions of the constraint Jacobian within numerical integration steps. Such decompositions are computationally expensive. In this paper an elimination method is discussed that only requires a single numerical decomposition within the model preprocessing step rather than during the time integration. It is based on the determination of motion spaces making use of Lie group concepts. The method is able to reduce the set of loop constraints for a large class of technical systems. In any case it always retains a sufficient number of constraints. It is derived for single kinematic loops.

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Authors and Affiliations

Andreas Müller
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Abstract

As part of the work, the error level of simulations of uniform optical-fibre Bragg gratings was determined using the transitionmatrixmethod. The errorswere established by comparing the transmission characteristics of the structures obtained by simulation with the corresponding characteristics arrived at experimentally. To compile these objects, elementary properties of the characteristics were specified, also affecting the applications of Bragg gratings, and compared with each other. The level of error in determining each of these features was estimated. Relationships were also found between the size of the physical properties of Bragg gratings and the level of errors obtained. Based on the findings, the correctness of the simulation of structures with the said method was verified, giving satisfying results.

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Authors and Affiliations

Piotr Stępniak
Piotr Kisała
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Abstract

Exploitation of hard coal seams by roadway system is applied by two coal mines in southern Poland in Upper Silesian Basin. It is a secondary mining exploitation carries out in safety pillars of urban areas and shafts within mining areas of closed coal mines. Roadway system is the excavation process of gateways which are made in parallel order leaving coal pillars between them. An optimal width of coal pillar makes roadway stable and reduces subsidence of terrain surface. The article presents results of subsidence simulation caused by partial extraction using empirical and numerical methods on the example of one exploitation field of “Siltech” coal mine. The asymptotic state of subsidence was considered after mining ceased in the study area. In order to simulate of subsidence, numerical model of rock mass and model of Knothe-Budryk theory were calibrated. Simulation of vertical displacements in numerical method was carried out using RS3 program by Rocscience based on finite element method. The assumption was made that model of rock mass is transversely isotropic medium, in which panels were designed according to order of extraction of coal seams. The results of empirical and numerical methods were compared with measured values of subsidence at benchmarks along drawn lines (subsidence profiles).

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Authors and Affiliations

Piotr Polanin
Andrzej Kowalski
ORCID: ORCID
Andrzej Walentek
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Abstract

With the improvement of the planning level of underground space, the location of the planned under-crossing tunnel can be known in advance when constructing the upper-span tunnel. Therefore, pre-protection measures can be taken in advance during the construction of the upper-span tunnel. A new pre-protection method of a pipe-jacking channel was proposed to reduce the adverse effects of under-crossing shield tunnels. Numerical simulations of different pre-protection schemes were carried out using the finite element method to analyze its deformation control effect. The simulation results show that the deformation control effect of the gantry reinforcement scheme is the most significant. It is shown that the displacement of the pipe-jacking channel is more significantly suppressed with pre-protection measures than without preventive protection measures. The vertical displacement curve of the pipe-jacking channel exhibits a “W” shape after the construction of the double-lane shield underpass. By comparing the three different working conditions, it is found that the maximum vertical displacement and surface settlement of the pipe-jacking channel greatly reduced the gantry reinforcement pre-protection. Compared with Case 3, the effect of the pre-protection measures adopted in Case 2 was less obvious, which indicated that the form of the pre-protection had an important influence on controlling the deformation of the pipe-jacking channel.
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Authors and Affiliations

Yunliang Cui
1 2
Xukun Yang
1 2
ORCID: ORCID
Xinquan Wang
1 2
Hongguo Diao
1 2
Xiao Li
1 2
Yuanyuan Gao
1 2

  1. School of Engineering, Hangzhou City University, Hangzhou 310015, PR China
  2. Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province, Hangzhou 310015, PR China
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Abstract

The approach to numerical analyses was changed by the introduction of Eurocodes . The EN 1993-1-6 standard allows taking into account imperfections on the shape of a buckling form from a linear elastic bifurcation analysis. The article analyses the first ten forms of imperfection from a linear elastic bifurcation analysis on the reduction of the capacity of a cylindrical shell. Calculations were made using finite element methods.

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Authors and Affiliations

K. Schabowicz
Ł. Zawiślak
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Abstract

This article presents the results of a numerical analysis of the road acoustic screen deterioration. Due to the fact that road noise barriers are located in an environment of very high corrosivity, the problem is the rusting of the metal cladding of component panels. The presented case study was, therefore, verified to fulfill the requirements presented in the Eurocode EN 1794-1. Static analysis for wind load and dynamic analysis for the load induced from vehicles was carried out. The analysis presented in the article proved the design errors and their contribution to the formation of severe corrosion, as well as demonstrating the importance of dynamic analysis in the design of acoustic screens.

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Authors and Affiliations

P. Stempin
W. Sumelka
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Abstract

The residual stress analysis is discussed in the paper. However, the author has not intended to present, even partially, all aspects of this very broad problem. The aim of this work has been limited to a review of conternporarily used experimental, numerical and hybrid methods, and to outline the directions of possible developments.
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Authors and Affiliations

Marek Bijak-Żochowski
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Abstract

In this work we provide a method for approximating the separable numerical range of a matrix. We also recall the connection between restricted numerical range and entanglement of a quantum state. We show the possibility to establish state separability using computed restricted numerical range. In particular we present a method to obtain separability criteria for arbitrary system partition with use of the separable numerical range.

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Authors and Affiliations

Piotr Gawron
Przemysław Sadowski
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Abstract

The stability of gateroads is one of the key factors for the mining process of hard coal by a longwall system. Wrong designed and applied the gateroad support at the stage of drilling, may adversely affect the functionality of the gateroad and the safety of the crew throughout its existence.

The article presents the results of the underground tests and observations such as: convergence of the gateroad, stratification and the fractured zone range in the roof rocks, carried out in four longwall gateroads at the stage of their drilling.

The obtained test results were the basis for the assessment of the possibility of using a convergence control method in the design of the gateroad support. The method is based on three interdependent relationships, such as: Ground Reaction Curve (GRC), Longitudinal Displacement Profile (LDP), and a Support Characteristic Curve (SCC). All calculations were performed using numerical modeling in the Phase2 program, based on the finite element method (FEM).

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Authors and Affiliations

Andrzej Walentek
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Abstract

On the basis of corpus-derived data, the present paper examines the collocational patterns of the singular and the plural forms of a pair of etymologically and semantically related quantifying nouns (QNs), namely English heap and its Polish equivalent kupa ‘heap’. The primary aim is to determine their respective levels of numeralization, operationalized as the frequency of co-occurrence with animate and abstract N2-collocates in purely quantificational uses, in an attempt to establish whether, and to what extent, the addition of the plurality morpheme bears on the grammaticalization of a nominal of this kind into an indefinite quantifier. Following the observations arrived at by Brems (2003, 2011), the hypothesis is that pluralization should yield a facilitating effect on the numeralization of nouns referring to large quantities by amplifying their inherent scalar implications. The results demonstrate that whereas heaps indeed exhibits a higher percentage of such numeralized uses than heap, kupy ‘heaps’ has turned out to be grammaticalized in the quantifying function to a markedly lesser degree than kupa ‘heap’. It is argued that this apparently aberrant behaviour of kupy ‘heaps’ can nonetheless be elucidated in terms of the specificity of numeralization in Polish, since at its advanced, morphosyntactic stage, the process in question affects solely the singular (accusative) forms of QNs.

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Authors and Affiliations

Damian Herda
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Abstract

In this paper, a class of linear Boolean functions is analyzed. The Boolean function can be represented as disjoint cubes or in the form of a truth vector. The primary purpose of this analysis is to decide whether an incompletely defined function can be extended to a complete linear form. A simple algorithm for generating all states of this function has been proposed if the Boolean function can have a full representation. The algorithm is beneficial for large functions. The proposed approach can be applied to completely and incompletely defined Boolean functions.
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Authors and Affiliations

Piotr Porwik
1

  1. Faculty of Science and Technology, University of Silesia, Bedzinska 39, 41-200 Sosnowiec, Poland
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Abstract

In this study, a theoretical model is presented to investigate the performance of a thermoelectric (TE) radiant cooling system combined with photovoltaic (PV) modules as a power supply in a building with an ambient temperature reaching more than 45ºC. The combined system TE/PV performance is studied under different solar radiation by using the hourly analysis program and photovoltaic system software. The thermal and electric characteristics of TE are theoretically investigated under various supplied voltages using the multi-paradigm programming language and numerical computing environment. Also, a theoretical analysis of heat transfer between the TE radiant cooling system and an occupied zone from the side, and the other side between the TE radiant cooling system and duct zone is presented. The maximum power consumption by TE panels and building cooling load of 130 kW is predicted for May and June. The 145 units of PV panels could provide about 50% of the power required by TE panels. The thermal and electric characteristics of TE panels results show the minimum cold surface temperature of 15ºC at a supplied voltage between 6 V and 7 V, and the maximum hot surface temperature of 62ºC at a supplied voltage of 16 V. The surface temperature difference between supplied current and supplied power increases as supplied voltage increases. At a higher supplied voltage of 16 V, the maximum surface temperature difference between supplied current, and supplied power of 150ºC, 3.2 A, and 48 W, respectively. The cooling capacity increases as supplied voltage increases, at a surface temperature difference of –10ºC and supplied voltage of 16 V, the maximum cooling capacity is founded at about 60 W. As supplied voltage decreases the coefficient of performance increases. The maximum coefficient of performance is about 5 at the surface temperature difference of –10ºC and supplied voltage of 8 V.
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Authors and Affiliations

Israa Ali Abdulghafor
1
Mohannad Jabbar Mnati
1

  1. Middle Technical University, Institute of Technology Baghdad, Al-Za’franiya, 10074, Baghdad, Iraq
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Abstract

The aim of the presented investigations was to irnprovc the quality of CFO numerical modeling of the propagation of gaseous contaminations in a test laboratory with a tracer gas source and a local exhaust in general mixing ventilation. The investigations were carried out making use of experimental identification of the flow. Concise information is presented concerning the CFO method applied in the modeling of the airflow and gaseous contaminant. The tested object has been characterized, as well as its respective experimental data. The ways of generating its simulation model has been described, paying special attention to the simulation of the diffuser. TI1e results of prediction have been compared with the results of measurements of the air velocity and the concentration of gaseous contaminant. Attempts have been made to improve the quality of the obtained results of prediction of the distribution of tracer gas concentration by increasing the accuracy simulating the diffuser, the jct leaving the diffuser and the airflow pattern in surrounding the contarninant source and suction nozzle. It has also been tried to utilize the results of numerical prediction for the purpose of determining the effectiveness of the local exhaust.
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Authors and Affiliations

Barbara Lipska
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Abstract

The work concerns of modeling the process of manufacturing machine parts by casting method. Making a casting without internal defects is a difficult task and usually requires numerous computer simulations and their experimental verification at the prototyping stage. Numerical simulations are then of priority importance in determining the appropriate parameters of the casting process and in selecting the shape of the riser for the casting fed with it. These actions are aimed at leading shrinkage defects to the riser, so that the casting remains free from this type of defects. Since shrinkage defects usually disqualify the casting from its further use, this type of research is still valid and requires further work. The paper presents the mathematical model and the results of numerical simulations of the casting solidification process obtained by using the Finite Element Method (FEM). A partial differential equation describing the course of thermal phenomena in the process of 3D casting creating was applied. This equation was supplemented with appropriate boundary and initial conditions that define the physical problem under consideration. In numerical simulations, by selecting the appropriate shape riser, an attempt was made to obtain a casting without internal defects, using a simple method of identifying their location. This is the main aim of the research as such defects in the casting disqualify it from use.
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Authors and Affiliations

L. Sowa
1
ORCID: ORCID
T. Skrzypczak
1
ORCID: ORCID
P. Kwiatoń
1
ORCID: ORCID

  1. Czestochowa University of Technology, Department of Mechanics and Machine Design Fundamentals, Dąbrowskiego 73, 42-200 Częstochowa, Poland
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Abstract

Knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.
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Authors and Affiliations

L. Sowa
1
ORCID: ORCID
T. Skrzypczak
1
ORCID: ORCID
P. Kwiatoń
1
ORCID: ORCID

  1. Czestochowa University of Technology, Department of Mechanics and Machine Design Fundamentals, 73 Dąbrowskiego Str., 42-200 Częstochowa, Poland
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Abstract

The article presents the results of model research concerning the change of technology of argon blowing into liquid steel at the ladle furnace, using the dual plug system. The results of numerical simulations were verified with experimental data carried out on the water model device. The verified model was used to perform numerical simulations to predict the impact of using a new gas injection technology – with different flow rates – on the time to achieve the assumed degree of metal chemical homogenization after alloy addition. Simulation results show that argon blowing metal bath in dual plug mode can effectively reduce mixing time compared to conventional technology with the same gas flow rates. Generally, the use of the dual plug system is beneficial for reducing the bath mixing time, however, the assumed optimal proportion of gas blown through individual plug should be followed. Finally, numerical predictions were used to perform experimental melt under industrial conditions. Industrial verification has clearly confirmed the validity of numerical modeling and showed that also in industrial conditions, a shorter time of chemical homogenization was obtained for the dual plug system.
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Authors and Affiliations

M. Warzecha
1
A. Hutny
1
P. Warzecha
1
Z. Kutyła
2
T. Merder
3

  1. Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology, 19 Armii Krajowej Av., 42-200 Czestochowa, Poland
  2. CMC Poland Sp. z o.o., 82 Piłsudskiego Str., 42-400 Zawiercie, Poland
  3. Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, 8 Krasinskiego Str., 40-019 Katowice, Poland
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Abstract

In this paper, design, construction and switching parameters of a self-made optical shutter with scalable aperture were reported. The aim of the study was to obtain the shortest possible switching times, minimum shutter open time and comparable with commercial shutter, the switch-on and switch-off times. For this purpose, numerical simulations were performed using Comsol Multiphysics 5.4. The design of the shutter and the control system have been optimized accordingly to the obtained results of numerical simulations. The optimized design was fabricated in a professional mechanical workshop and operational parameters of the constructed device were investigated. The switching parameters of the shutter, such as opening time, closing time, minimum shutter open time and other parameters were measured. The values of the parameters were determined from a statistical analysis of a sample consisting of 10,000 measurement results. The performed characterization showed that the tested device has the opening time of 0.8 ms, while the closing time is approximately 1 ms. The designed device is characterized by the minimum shutter open time of 6.4 ms.
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Bibliography

  1.  H. Jo and D. Kim, “Observations of in vivo laser tissue ablation in animal models with different chromophores on the skin and modulating duration per laser exposure,” Lasers Med. Sci., vol. 34, no. 5, pp. 1031–1039, 2019.
  2.  T. Osuch, P. Gąsior, K. Markowski, and K. Jędrzejewski, “Development of fiber bragg gratings technology and their complex structures for sensing, telecommunications and microwave photonics applications,” Bull. Pol. Acad. Sci. Tech. Sci., vol. 62, no. 4, pp. 627–633, 2014.
  3.  W. Lamperska, J. Masajada, S. Drobczyński, and P. Gusin, “Two-laser optical tweezers with a blinking beam,” Opt. Lasers Eng., vol. 94, pp. 82–89, 2017.
  4.  H. Kim, W.-K. Lee, D.-H. Yu, M.-S. Heo, C. Park, S. Lee, and Y. Lee, “Atom shutter using bender piezoactuator,” Rev. Sci. Instrum., vol. 88, no. 2, 2017.
  5.  C. Colquhoun, A. Di Carli, S. Kuhr, and E. Haller, “Note: A simple laser shutter with protective shielding for beam powers up to 1 w,” Rev. Sci. Instrum., vol. 89, no. 12, 2018.
  6.  Thorlabs, “Optical shutters,” https://www.thorlabs.com/ newgrouppage9.cfm?objectgroup_id=927, (Accessed on 20/02/2021).
  7.  K. Singer, S. Jochim, M. Mudrich, A. Mosk, and M. Weidemüller, “Low-cost mechanical shutter for light beams,” Rev. Sci. Instrum., vol. 73, no. 12, pp. 4402–4404, 2002.
  8.  L.P. Maguire, S. Szilagyi, and R. E. Scholten, “High performance laser shutter using a hard disk drive voice-coil actuator,” Rev. Sci. Instrum., vol. 75, no. 9, pp. 3077–3079, 2004.
  9.  W. Bowden, I.R. Hill, P.E.G. Baird, and P. Gill, “Note: A highperformance, low-cost laser shutter using a piezoelectric cantilever actuator,” Rev. Sci. Instrum., vol. 88, no. 1, p. 016102, 2017.
  10.  P.-W. Huang, B. Tang, Z.-Y. Xiong, J.-Q. Zhong, J. Wang, and M.-S. Zhan, “Note: A compact low-vibration high-performance optical shutter for precision measurement experiments,” Rev. Sci. Instrum., vol. 89, no. 9, 2018.
  11.  G.H. Zhang, B. Braverman, A. Kawasaki, and V. Vuletić, “Note: Fast compact laser shutter using a direct current motor and threedimensional printing,” Rev. Sci. Instrum., vol. 86, no. 12, p. 126105, 2015.
  12.  S. Martínez, L. Hernández, D. Reyes, E. Gomez, M. Ivory, C Davison, and S. Aubin, “Note: Fast, small, and low vibration mechanical laser shutters,” Rev. Sci. Instrum., vol. 82, no. 4, p. 046102, 2011.
  13.  Newport, “Electronic fast shutters,” https://www.newport.com/f/electronic-fast-shutters, (Accessed on 20/02/2021).
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Authors and Affiliations

Piotr Pokryszka
1
ORCID: ORCID
Mateusz Wośko
1
ORCID: ORCID
Wojciech Kijaszek
1
ORCID: ORCID
Regina Paszkiewicz
1
ORCID: ORCID

  1. Wrocław University of Science and Technology, wybrzeze Stanislawa Wyspianskiego 27, 50-370 Wroclaw, Poland
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Abstract

In the ironmaking, sizes of raw materials such as iron ores and coke must be adjusted for subsequent process in the blast furnace. The depletion of high grade iron ore in recent years necessitates a technology that can utilize low-grade fine iron ores. Thus, steelmakers have been studying the sinter-briquette complex firing process that employs a method of charging the sinter feed together with briquettes made of fine iron ore. In this process, larger briquettes increase the briquette productivity per unit time but decrease the green strength of briquettes and they can break during transportation and charging. Thus, the briquette shape is very important.

Therefore, in this study, we simulate a twin roll briquetting process using the DEM analysis and compared the compressive force distributions in the briquette for different aspect ratios. This study is a new attempt, because research cases by numerical methods on the same or similar systems are very rare. Consequently, the optimal aspect ratio is 0.5 at briquette height 20 mm, 2.0 at 30 mm, and 1.5 at 40 mm. Also, the average compressive force increased in proportion with the pocket height at the same aspect ratio. Therefore, to increase the pocket depth for high productivity, the pocket height must also be increased for obtaining high strength briquettes.

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Authors and Affiliations

Kang-Min Kim
Jong-Ho Bae
Jeong-Whan Han
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Abstract

The paper presents analysis of the vibrational environment on scaffoldings. It is based on the results obtained in the project considering workers safety on scaffoldings. The total number of 120 façade scaffoldings was analysed over a period of two years. One of the issues considered in this project was the vibrations influence on scaffoldings and workers safety. The values of natural frequencies were obtained based on in-situ measurements of free vibrations. Analysis of the tests results made it possible to verify the elaborated numerical models. Values of natural frequencies and displacements in mode shaped from numerical modal analyses were compared with test results. Measurements of forced vibrations were also made with various sources of vibrations active at scaffoldings. The detailed numerical dynamic analysis was performed considering excitation forces variable in time. The obtained results were compared with allowable values according to the appropriate Polish standards. Most influential sources of vibrations for human comfort were indicated in the conclusions.

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Authors and Affiliations

Jarosław Bęc
ORCID: ORCID
Ewa Błazik-Borowa
ORCID: ORCID
Paulina Jamińska-Gadomska
Tomasz Lipecki
ORCID: ORCID
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Abstract

The main aim of the study is an assessment of models suitability for steel beams made of thin-walled cold-formed sigma profiles with respect to different numerical descriptions used in buckling analysis. The analyses are carried out for the sigma profile beam with the height of 140 mm and the span of 2.20 m. The Finite Element (FE) numerical models are developed in the Abaqus program. The boundary conditions are introduced in the formof the so-called fork support with the use of displacement limitations. The beams are discretized using S4R shell finite elements with S4R linear and S8R quadratic shape functions. Local and global instability behaviour is investigated using linear buckling analysis and the models are verified by the comparison with theoretical critical bending moment obtained from the analytical formulae based on the Vlasow beam theory of the thin-walled elements. In addition, the engineering analysis of buckling is carried out for a simple shell (plate) model of the separated cross-section flange wall using the Boundary Element Method (BEM). Special attention was paid to critical bending moment calculated on the basis of the Vlasov beam theory, which does not take into account the loss of local stability or contour deformation. Numerical shell FE models are investigated, which enable a multimodal buckling analysis taking into account interactive buckling. The eigenvalues and shape of first three buckling modes for selected numerical models are calculated but the values of critical bending moments are identified basing on the eigenvalue obtained for the first buckling mode.
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Authors and Affiliations

Katarzyna Rzeszut
1
ORCID: ORCID
Ilona Szewczak
2
ORCID: ORCID
Patryk Różyło
3
ORCID: ORCID
Michał Guminiak
4
ORCID: ORCID

  1. Poznan University of Technology, Institute of Building Engineering, Marii Skłodowskiej-Curie 5, 60-965 Poznan
  2. Lublin University of Technology, Faculty of Civil Engineering and Architecture, ul. Nadbystrzycka 38D,20–618 Lublin, Poland
  3. Lublin University of Technology, Faculty of Mechanical Engineering, ul. Nadbystrzycka 38 D, 20–618 Lublin, Poland
  4. Poznan University of Technology, Institute of Structural Analysis, Marii Skłodowskiej-Curie 5, 60-965 Poznan, Poland
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Abstract

The author analyses the structure of the predicative expression, i.e. a mor-phosyntactic construction functioning as the so-called constitutive predicate of the proposition in question. She illustrates her analysis with examples from Polish and from Macedonian – two languages whose grammatical systems are maximally typologicaly opposed in the frame of the Slavic linguistic group. She states that the predicative expression is composed of 1) constitutive form of verbum finitum and 2) its adjuncts formalized as adverbia and/or adverbialia responding to the questions: when? how long? how? in which mood? in which way? and carrying supplementary information from the semantic domains of the grammatical categories characteristic of the finite verb, such as ‘time’, ‘aspect’, or ‘mood’; most numerous are those informing (a) on the location of the referred to event on the time-axis or (b) on the procedure leading to the realization of that event.

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Authors and Affiliations

Zuzanna Topolińska
ORCID: ORCID
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Abstract

Biskupin is one of the most recognizable archaeological site in Poland and Central Europe. The origins of the excavations dates back to year 1934 and had lasted almost continuously until 1974. In the framework of the grant from the Ministry of Culture and National Heritage interdisciplinary team of scientists from Archaeological Museum in Biskupin and Warsaw University of Technology performed multi-dimensional analysis of the settlement. Based on the integrated vector documentation, resulting from the photographic documentation, numerical models of structural systems of main types of buildings and defensive rampart were prepared. The aim of the analysis was a verification of the earlier findings of archaeological and architectural researches. The analysis allowed to verify both the arrangement of individual parts of structure of buildings, their work and the interconnection, as well as the possible dimensions of the individual components.

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Authors and Affiliations

Wojciech Terlikowski
ORCID: ORCID
Martyna Gregoriou-Szczepaniak
ORCID: ORCID
Ewa Sobczyńska
ORCID: ORCID
Kacper Wasilewski
ORCID: ORCID
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Abstract

The paper presents the results of laboratory tests of SCB (semi-circular beam) samples of asphalt concrete, subjected to the destructive effect of water and frost as well as the aging processes. The determined values of material parameters show significant dispersions, which makes the design of mixtures difficult. Statistical analysis of the test results supplemented by computer simulations made with the use of the proprietary FEM model was carried out. The main distinguishing feature of the model is the assignment of material parameters of coarse aggregate and bituminous mortar to randomly selected finite elements. The parameters of the mortar are selected by trial and error to match the numerical results to the experimental ones. The stiffness modulus of the bituminous mortar is, therefore, a substitute parameter, taking into account the influence of many factors, including material degradation resulting from the aging and changing environmental conditions, the influence of voids, and contact between the aggregate and the bituminous mortar. The use of the Monte Carlo method allows to reflect the scattering of the results obtained based on laboratory tests. The computational algorithm created in the ABAQUS was limited only to the analysis of the global mechanical bending response of the SCB sample, without mapping the failure process in detail. The combination of the results of laboratory tests usually carried out on a limited number of samples and numerical simulations provide a sufficiently large population of data to carry out a reliable statistical analysis, and to estimate the reliability of the material designed.
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Authors and Affiliations

Cezary Szydłowski
1
ORCID: ORCID
Łukasz Smakosz
2
ORCID: ORCID
Marcin Stienss
1
ORCID: ORCID
Jarosław Górski
2
ORCID: ORCID

  1. Gdansk University of Technology, Faculty of Civil and Environmental Engineering, Department of Highway and Transportation Engineering, 11/12 Gabriela Narutowicza Street, 80-233 Gdansk, Poland
  2. Gdansk University of Technology, Faculty of Civil and Environmental Engineering, Department of Structural Mechanics, 11/12 Gabriela Narutowicza Street, 80-233 Gdansk, Poland
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Abstract

In the article the effects of backfilling an underground, flexible pipeline, using natural materials (ground backfill) and modified materials, so called Lightweight Backfilling Materials (LBMs) were analyzed. These materials, thanks their lower density, have a positive effect on reducing the loads on the underground pipeline and, consequently, reducing deformations and stresses in its wall. LBMs include lightweight expanded clay aggregates, recycled tire chips used directly in the trench or mixed with the soil, foam concrete, foam glass (granules or plates), and expanded polystyrene, embedded in the ground in the form of blocks. The assessment of the effects of modifying the backfill of the underground pipeline was carried out by means of multi-variant numerical analysis in which models of the pipe-soil system in a plane strain state (2D model) were tested. In these models PEHD pipes were represented, with differential of their diameter (DN315, DN600) and stiffness (SDR), as well as trenches of various shapes (trench with vertical walls and with sloping walls). In the numerical calculations, two variants of trench filling were analyzed: full filling with soil and filling with selected LBMs (expanded clay aggregates, expanded polystyrene, tire chips mixed with soil) in layers separated in the backfill. The results of numerical calculations for particular variants of the models were analyzed in terms of the distribution of vertical displacements and stresses in the soil and pipe deformation. The received pipe deflections and circumferential stresses in their wall were related to the permissible values for PEHD pipes.
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Authors and Affiliations

Barbara Kliszczewicz
1
ORCID: ORCID

  1. Silesian University of Technology, Faculty of Civil Engineering, Akademicka 5,44-100 Gliwice, Poland

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