How to search?
advanced search

Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 64
items per page: 25 50 75
Sort by:

A pre-protection method for a pipe-jacking channel over shield tunnels

Yunliang Cui Xukun Yang Xinquan Wang Hongguo Diao Xiao Li Yuanyuan Gao
Bulletin of the Polish Academy of Sciences Technical Sciences | 2024 | 72 | 2 | e148443 | DOI: 10.24425/bpasts.2023.148443
Keywords shield pipe jacking numerical simulation
Download PDF Download RIS Download Bibtex

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.
Go to article

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

Application of Numerical Simulation for Analysis and Optimization of Forging Manufacturing Process

M. Sobociński M. Nabrdalik
Archives of Metallurgy and Materials | 2024 | vol. 69 | No 2 | 733-738 | DOI: 10.24425/amm.2024.149804
Keywords physical parameters numerical simulation FEM
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the use of numerical modeling results for multivariate simulation of the manufacturing process of a wheel hub forging made of 20 HG alloy. The QForm 3D program was used to analyze the issue, which allowed to analyze the forging process without the need for expensive tools and technological tests. Based on insights from several variants of numerical calculations, new technology solutions were proposed, reducing the number of deficiencies found in industrial practice. In order to obtain full information about the phenomena occurring in the deformation process, numerical calculations were carried out in the areas of material flow, the degree of filling of blanks, the distribution of deformations and stresses in the various stages of the forging process in the die, and the elimination of defects in products. The information obtained formed the basis for proposing the optimal technology for forging wheel hubs.
Go to article

Authors and Affiliations

M. Sobociński
1
ORCID: ORCID
M. Nabrdalik
1
ORCID: ORCID
  1. Czestochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, Department of Technology and Automation, 21 Armii Krajowej Av., 42-201 Czestochowa, Poland

Analysis of the inadequacy of determining the spectral characteristics of optical fibre periodic structures by way of numerical modelling

Piotr Stępniak Piotr Kisała
Metrology and Measurement Systems | 2020 | vol. 27 | No 1 | 33-50 | DOI: 10.24425/mms.2020.131713
Keywords numerical simulations fibre Bragg grating numerical modelling
Download PDF Download RIS Download Bibtex

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.

Go to article

Authors and Affiliations

Piotr Stępniak
Piotr Kisała

High performance optical shutter design with scalable aperture

Piotr Pokryszka Mateusz Wośko Wojciech Kijaszek Regina Paszkiewicz
Bulletin of the Polish Academy of Sciences Technical Sciences | 2021 | 69 | 5 | e138236 | DOI: 10.24425/bpasts.2021.138236
Keywords optical shutter numerical simulation current source jitter
Download PDF Download RIS Download Bibtex

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.
Go to article

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).
Go to article

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

Vibrations of the non-linear three-body wheeled vehicle model. Bifukatoins and chaotic

Ryszard Andrzejewski Jerzy Werner
Archive of Mechanical Engineering | 2002 | vol. 49 | No 1 | 81-95
Keywords vibrations bifurkation numerical simulation vehicle suspension
Download PDF Download RIS Download Bibtex

Abstract

The paper presents theoretical analysis of excited vibrations of the vehicle in a wide range of excitation frequencies (from I to 80 Hz). The mathematical model and calculations were prepared for the accepted physical model of the vehicle. The model was used to simulate the excited vertical vibrations. The bifurcation figures with an excitation frequency as a bifurcation parameter were determined on the basis of the simulation results - the changes of kinematics values in time. Bifurcation diagrams give a picture of vehicle vibrations. This picture gives the possibility of identification of characteristic parameters of sprigs and dumping elements and can be used for control, diagnostic aims, and for making technical investigations of vehicle suspension.
Go to article

Authors and Affiliations

Ryszard Andrzejewski
Jerzy Werner

Numerical Evaluation of the Impact of Riser Geometry on The Shrinkage Defects Formation in the Solidifying Casting

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Metallurgy and Materials | 2022 | vol. 67 | No 1 | 181-187 | DOI: 10.24425/amm.2022.137487
Keywords numerical simulations solidification casting defects FEM
Download PDF Download RIS Download Bibtex

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.
Go to article

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

Calculations of Non-Metallic Particles Removal from Liquid Aluminium to Top Slag

P.L. Żak K. Kuglin M. Szucki D. Kalisz N. Mrówka E. Dand
Archives of Foundry Engineering | 2024 | vol. 24 | No 2 | 60-68 | DOI: 10.24425/afe.2024.149272
Keywords Numerical simulation Liquid aluminium Particle motion Inclusions
Download PDF Download RIS Download Bibtex

Abstract

In the paper, the results of a numerical analysis of KCl and KF particles present in liquid aluminium assimilation to the slag are presented. The authors analysed particle movement in the slag model, which is based on buoyant, capillary, viscosity, Newton and repulsion forces, interfacial tensions at the interface of phases and surface energy during the particle movement through phases boundary. On the basis of the mathematical model, a computer programme was written to make simulations under different conditions. The results of particle position in the slag are presented for different particle radiuses: 1, 5, 10, 20 μm, and constant viscosity of the slag including velocity evolution of the velocity. Another approach was used to indicate the influence of slag viscosity on particle and slag penetration depth. During computations, selected viscosities of slag of 0.0012, 0.0015, 0.0018 [kg/m·s] were taken into account. Different comparisons were made for the chosen particle sizes. Each examination takes into account the impact of the particle type. The results clearly show that for larger particles the penetration depth is greater and viscosity of the slag has an impact on the velocity evolution during assimilation process.
Go to article

Bibliography


[1] Instone, S., Buchholz, A. & Gruen, G. U. (2008). Inclusion transport phenomena in casting furnaces. Light Metals (TMS). 811-816 .

[2] Prillhofer, B., Antrekowitsch, H., Böttcher, H. & Enright, P. (2008). Non-metallic inclusions in the secondary aluminium industry for the production of aerospace alloys. Light Metals (TMS). 603-608.

[3] Johansen, S.T., Gradahl, S. & Myrbostad, E. (1996). Experimental determination of bubble sizes in melt refining reactors. Light Metals (TMS). 1027-1031.

[4] Johansen, S.T., Robertson, D.G.C., Woje, K. & Engh, T.A. (1988). Fluid dynamics in bubble stirred ladles: Part I. Experiments. Metallurgical Transactions B 19, 745-754, DOI: https://doi.org/10.1007/BF02650194.

[5] Nakaoka, T., Taniguchi, S., Matsumoto, K. & Johansen, S. T. (2001). Particle size grouping method of inclusion agglomeration and its application to water model experiments. ISIJ International. 41, 1103-1111. DOI: https://doi.org/10.2355/isijinternational.41.1103.

[6] Saffman, P.G. & Turner, J.S. (1956). On the collision of drops in turbulent clouds. Journal of Fluid Mechanics. 1, 16-30. DOI: https: //doi.org/10.1017/S0022112056000020.

[7] Wang, L., Lee, H. G. & Hayes, P. (1996). Prediction of the optimum bubble size for inclusion removal from molten steel by flotation. ISIJ International. 36, 7-16, DOI: https://doi.org/10.2355/isijinternational.36.7.

[8] Schulze, H. J. (1989). Hydrodynamics of bubble-mineral particle collisions. Mineral Processing and Extractive Metallurgy Review. 5, 43-76. https://doi.org/10.1080/08827508908952644.

[9] Bouris, D. & Bergeles, G. (1998). Investigation of inclusion re-entrainment from the steel-slag interface. Metallurgical and Materials Transactions B. 29, 641-649. DOI: https://doi.org/10.1007/s11663-998-0099-6.

[10] Strandh, J., Nakajima, K., Eriksson, R. & Jonsson, P. (2005). Solid inclusion transfer at a steel-slag interface with focus on tundish conditions. ISIJ International. 45, 1597-1606, DOI: https://doi.org/10.2355/isijinternational.45.1597

[11] Votava, I. & Matiašovský, K. (1973). Measurement of viscosity of fused salts. II. viscosity of molten binary mixtures on the cryolite basis. Chemical Papers. 27(5), 582-587.

[12] Suchora-Kozakiewicz, M. & Jackowski, J. (2017). Evaluation of interfacial tension in the liquid aluminum alloy – liquid slag system. Journal of Casting & Materials Engineering. 1(1), 11-14. DOI: https://doi.org/10.7494/jcme.2017.1.1.11.

[13] Zhang, L. & Taniguchi, S. (2000). Fundamentals of inclusion removal from liquid steel by bubble flotation. International Materials Reviews. 45(2), 59-82. DOI: https://doi.org/10.1179/095066000101528313.

[14] Żak, P. L., Kalisz, D., Lelito, J., Szucki, M., Gracz, B., & Suchy, J. S. (2015). Modelling of non-metallic particles motion process in foundry alloys. Metalurgija. 54(2), 357-360.

[15] Dewing, E.W. (1972). Thermodynamics of the system NaF-AlF3. part III: Activities in liquid mixtures. Metallurgical Transactions B. 3, 499-505, DOI: https://doi.org/10.1007/BF02642055.

[16] Dewing, E. (1970). Thermodynamics of the system NaF-AlF3 part I: The equilibrium 6NaF(s) + Al = Na3AlF6(s) + 3Na. Metall. Transactions. 1, 1691-1694, DOI: https://doi.org/10.1007/BF02642018.

[17] Ransley, C.E. & Neufeld, H. (1950). The solubility relationships in the Al-Na and Al-Si systems. Journal of Institute of Metals. 78, 25-46.

[18] Kvande, H. (1980) Solubility of aluminium in NaF-AlF3-Al2O3 melts. Light Metals. 171-182.

[19] Dewing, E.W. (1980). Thermodynamic functions for LiF-AlF3 mixtures at 1293 k. Metallurgical Transactions B. 11, 245–249, DOI: https://doi.org/10.1007/BF02668408.

[20] Wang, L.T., Zhang, Q.Y., Deng, C.H. & Li, Z.B. (2005). Mathematical model for removal of inclusion in molten steel by injecting gas at ladle shroud. ISIJ International. 45, 1138-1144, DOI: https://doi.org/10.2355/isijinternational. 45.1138.

[21] Suchora-Kozakiewicz, M. & Jackowski, J. (2017). The way of estimating interphase tension in the liquid aluminum alloy – liquid slag. Composites Theory Practice. 17(2), 73-78.

Go to article

Authors and Affiliations

P.L. Żak
1
K. Kuglin
2
M. Szucki
3
ORCID: ORCID
D. Kalisz
1
ORCID: ORCID
N. Mrówka
E. Dand
  1. AGH University of Krakow, Krakow, Poland
  2. NPA Skawina Sp. z o. o., Poland
  3. Technische Universität Bergakademie Freiberg, Germany

Numerical simulation of the influencing factors of array jet shock cooling

Nianyong Zhou Youxin Zhou Yingjie Zhao Qingguo Bao Guanghua Tang Wenyu Lv
Bulletin of the Polish Academy of Sciences Technical Sciences | 2024 | 72 | 4 | e150200 | DOI: 10.24425/bpasts.2024.150200
Keywords array jet enhanced heat exchange numerical simulation
Download PDF Download RIS Download Bibtex

Abstract

Array jet impingement cooling is a significant technology of enhanced heat dissipation which is fit for high heat flux flow with large area. It is gradually applied to the cooling of electronic devices. However, The research on the nozzle array mode and the uniformity of the cooling surface still has deficiencies. Therefore, the influence of heat flux, inlet temperature, jet height, array mode, and diversion structure on jet impingement cooling performance and temperature distribution uniformity is analyzed through numerical calculation. The results show that the heat transfer coefficient of jet impingement cooling increases linearly with the increment of heat flux and inlet temperature. With the increment of the ratio of jet height to nozzle diameter (H/d), the heat transfer coefficient increases first and then decreases, that is, there is an optimal H/d, which makes the heat transfer performance of the array jet impact cooling best. The temperature uniformity of array jet impact cooling is greatly affected by array mode. The improvement effect of nozzle array mode on temperature uniformity is ranked as sequential >staggered >shield >elliptical array. The overall temperature uniformity and heat transfer coefficient are increased by 5.88% and 7.29% compared with the elliptical array. The heat transfer performance can be further improved by adding a flow channel to the in-line array layout, in which the heat transfer coefficient is increased by 6.53% and the overall temperature uniformity is increased by 1.45%.
Go to article

Authors and Affiliations

Nianyong Zhou
1
ORCID: ORCID
Youxin Zhou
1
Yingjie Zhao
1
Qingguo Bao
1
Guanghua Tang
1
Wenyu Lv
1
  1. College of Urban Construction, Changzhou University, Changzhou, China

Influence of Liquid Metal Movements on the Casting Creation

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Metallurgy and Materials | 2021 | vol. 66 | No 2 | 489-495 | DOI: 10.24425/amm.2021.135883
Keywords numerical simulations solidification Navier-Stokes equations
Download PDF Download RIS Download Bibtex

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.
Go to article

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

The Influence of Riser Shape on Feeding Effectiveness of Solidifying Casting

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Foundry Engineering | 2019 | vol. 19 | No 4 | 91-94 | DOI: 10.24425/afe.2019.129636
Keywords Solidification process Castings defects Numerical simulation Liquid metal flow
Download PDF Download RIS Download Bibtex

Abstract

The mathematical model and numerical simulations of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity by liquid metal and feeding the casting through the riser during its solidification, are presented in the paper. Mutual dependence of thermal and flow phenomena were taken into account because have an essential influence on solidification process. The effect of the riser shape on the effectiveness of feeding of the solidifying casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of riser shape was made, which is important for foundry practice. Numerical calculations of the solidification process of system consisting of the casting and the conical or cylindrical riser were carried out. The velocity fields have been obtained from the solution of momentum equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. Changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.

Go to article

Authors and Affiliations

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

Quantitative Prediction of Air Entrainment Defects in Casting Filling Process

Yajun Yin Yao Xie Yingchen Song Xu Shen Xiaoyuan Ji Jianxin Zhou
Archives of Foundry Engineering | 2023 | vol. 23 | No 4 | 117-126 | DOI: 10.24425/afe.2023.146686
Keywords Casting Numerical simulation Gas entrainment defect Filling process
Download PDF Download RIS Download Bibtex

Abstract

Air entrainment defect is a common type of defect in the casting process, which will seriously affect the quality of the casting. Numerical simulation technology can predict the occurrence of casting defects according to the evolution law of liquid metal in the process of fill ing and solidification. The simulation of air entrainment process is a hot and difficult issue in the field of numerical simulation. The evolution law of air entrainment and the tracking of induced bubbles in the process of metal filling are still lacking. So is the quantitative prediction of trained gas. In this paper, based on the numerical simulation software of Inte CAST, this paper proposes an algorithm for air entrainment search and tracking, which is used to develop a quantitative prediction system for air entrainment. The feasibility of the system is verified through the simulation calculation of the typical test pieces of the air entrainment and the prediction of air entrainment defects of the casting in the process of filling is obtained through the simulation calculation of the actual casting, which can provide a certain guiding role for the optimization of the process in the production practice.
Go to article

Bibliography

[1] Hu, L., Feng, Z.P., Feng, L., Duan, S.P. & Liang, S.P. (2016). Numerical simulation of porosity defects in casting filling process. DOI:10.16410/j.issn1000-8365.2016. 02.030. (in Chinese)
[2] Bi, C. (2016). Study on numerical simulation of gas entrapment and external solidified crystals during mold filling of high pressure die casting process. Doctoral dissertation, Tsinghua University. (in Chinese).
[3] Yu, M.Q., Xia, W., Cao, W.J. & Zhou, Z.Y. (2010). Numerical simulation of filling process and air entrapment condition of Al alloy die-casting. Hot Working Technology. 01, 36-39. DOI:10.14158/j.cnki.1001-3814.2010.01.039. (in Chinese).
[4] Hernández-Ortega, Juan, J., Zamora, Rosendo, & Palacios, et al. (2007). Experimental and numerical study of air entrapment during the filling of a mould cavity in die casting. In 10th Esaform Conference on Material Forming, 18-20 April 2007 (1430-1435). Zaragoza, Spain.
[5] Guerra, F.V., Archer, L., Hardin, R.A & Beckermann C. (2019). Measurement of air entrainment during pouring of an aluminum alloy. Shape Casting. 80, 31-40. https://doi.org/10.1007/s11663-020-01998-3.
[6] Chen, Y.X., Chen, Z. & Liao, D.M. (2021). Prediction of air entrapment defect in casings based on gas phase tracking and bubble breaking criterior. Foundry. 70(07), 806-812.
[7] Caboussat, A., Picasso, M. & Rappaz, J. (2005). Numerical simulation of free surface incompressible liquid flows surrounded by compressible gas. Journal of Computational Physics. 203(2), 626-649. https://doi.org/10.1016/ j.jcp.2004.09.009.
[8] Kimatsuka, A., Ohnaka, I., Zhu, J.D., Sugiyama, A. & Kuroki, Y.(2006). Mold filling simulation for predicting gas porosity. IHI Engineering Review. 40(2), 83-88.
[9] Yang, X., Huang, X., Dai, X., Campbell, J. & Tatler, J. (2004). Numerical modelling of entrainment of oxide film defects in filling of aluminium alloy castings. International Journal of Cast Metals Research, 17(6), 321-331. https://doi.org/10.1179/136404604225022748.
[10] Dai, X., Jolly, M., Yang, X., & Campbell, J. (2012). Modelling of liquid metal flow and oxide film defects in filling of aluminium alloy castings. IOP Conference Series Materials Science and Engineering, 33(1), 2073.
[11] Reilly, C., Green, N.R., Jolly, M.R. & Gebelin, J.C. (2013). The modelling of oxide film entrainment in casting systems using computational modelling. Applied Mathematical Modelling, 37(18-19), 8451-8466. https://doi.org/10.1016/j.apm.2013.03.061.
[12] Reilly, C., Green, N.R. & Jolly, M.R. (2013). The present state of modeling entrainment defects in the shape casting process. Applied Mathematical Modelling. 37(3), 611-628. https://doi.org/10.1016/j.apm.2012.04.032.
[13] Majidi, Hojjat, S., Beckermann, & Christoph. (2017). Modelling of air entrainment during pouring of metal castings. International Journal of Cast Metals Research. 30(5), 301-315. https://doi.org/10.1080/13640461.2017. 1307624.
[14] Cao, LiuLiao, DunmingSun, FeiChen, TaoTeng, ZihaoTang, Yulong. (2018). Prediction of gas entrapment defects during zinc alloy high-pressure die casting based on gas-liquid multiphase flow model. The International Journal of Advanced Manufacturing Technology. 94, 807-815. https://doi.org/10.1007/s00170-017-0926-5.
Go to article

Authors and Affiliations

Yajun Yin
1
Yao Xie
2
Yingchen Song
1
Xu Shen
1
Xiaoyuan Ji
1
Jianxin Zhou
1
  1. Huazhong University of Science and Technology, China
  2. State Key Laboratory of Special Rare Metal Materials, China

Casting Quality Improvement by Gating System Optimization

M. Bruna M. Galčík
Archives of Foundry Engineering | 2021 | vo. 21 | No 1 | 132-136 | DOI: 10.24425/afe.2021.136089
Keywords Reoxidation Gating system Numerical simulation Aluminium alloys Mechanical properties
Download PDF Download RIS Download Bibtex

Abstract

One of the main reason for decreased internal homogeneity of aluminium alloy castings is reoxidation. The resulting products of reoxidation are doubled oxides, so called "bifilms". Submitted paper deals with optimization of gating system design in order to reduce reoxidation processes taking place in mold cavity. Experimental work compares and evaluates three gating systems designs based on non-pressurized and naturally pressurized principles. Unconventional spin trap extension of runner was used in third design. Among the evaluated aspects were: mechanical properties, hot tearing index, visual inspection of average porosity amount, numerical simulation of velocity, turbulence and oxide amount. Paper aim is also to clarify the reoxidation phenomenon by visualization with the aid of ProCAST numerical simulation software. Results of mechanical properties and hot tear index clearly confirmed the positive effect of the naturally pressurized gating system with applied element for velocity reduction.
Go to article

Bibliography

[1] Svoboda, J.M., Monroe, R.W., Bates, C.E. & Griffin, J. (1987). TAFS. 95, 187-202.
[2] Campbell, J. (2006). Entrainment defects. Materials Science and Technology. 22(2), 127-145. ISSN 0267-0836. https://doi.org/10.1179/174328406X74248.
[3] Campbell, J. (1993). Invisible Macrodefects in castings. Journal de Physique Archives. 03(C7), 861-872. https://doi.org/10.1051/jp4:19937135.
[4] Dojka, R. Jezierski, J. & Campbell, J. (2018) Optimized gating system for steel castings. Journal of Materials Engineering and Performance. 10. DOI: 10.1007/s11665-018-3497-1.
[5] Sladek, A., Patek, M. & Mician, M. (2017). Behavior of steel branch connections during fatigue loading‎. Archives of Metallurgy and Materials. 62 (3), 1597-1601‏.
[6] Brůna, M., Bolibruchová, D. & Pastirčák, R. (2017). Archives of Foundry Engineering. 17, 23-26. https://doi.org/10.1515/afe-2017-0084.
[7] Lin, S., Aliravci, C. & Pekguleryuz, N.I.O. (2007). Hot-tear susceptibility of aluminum wrought alloys and the effect of grain refining. Materials Science and Engineering. A Sci. 38A, 1056-1068. https://doi.org/10.1007/s11661-007-9132-7.
[8] Campbell, J. (2006). An overview of the effects of bifilms on the structure and properties of cast alloys. Metallurgical and Materials Transaction B. 37, 857-863. https://doi.org/ 10.1007/BF0273500.

Go to article

Authors and Affiliations

M. Bruna
1
ORCID: ORCID
M. Galčík
1
  1. Department of Technological Engineering, University of Zilina, Univerzitna 1, 010 26 Zilina, Slovakia

Impact of thermal backfill parameters on current-carrying capacity of power cables installed in the ground

Seweryn Szultka Stanisław Czapp Adam Tomaszewski
Bulletin of the Polish Academy of Sciences Technical Sciences | 2023 | 71 | 3 | e145565 | DOI: 10.24425/bpasts.2023.145565
Keywords current-carrying capacity numerical simulations power cables thermal analysis
Download PDF Download RIS Download Bibtex

Abstract

Proper design of power installations with the participation of power cables buried in homogeneous and thermally well-conductive ground does not constitute a major problem. The situation changes when the ground is non-homogeneous and thermally low-conductive. In such a situation, a thermal backfill near the cables is commonly used. The optimization of thermal backfill parameters to achieve the highest possible current-carrying capacity is insufficiently described in the standards. Therefore, numerical calculations based on computational fluid dynamics could prove helpful for designers of power cable lines. This paper studies the influence of dimensions and thermal resistivity of the thermal backfill and thermal resistivity of the native soil on the current-carrying capacity of power cables buried in the ground. Numerical calculations were performed with ANSYS Fluent. As a result of the research, proposals were made on how to determine the current-carrying capacity depending on the dimensions and thermal properties of the backfill. A proprietary mathematical function is presented which makes it possible to calculate the cable current-carrying capacity correction factor when the backfill is used. The research is expected to fill the gap in the current state of knowledge included in the provisions of standards.
Go to article

Authors and Affiliations

Seweryn Szultka
1
ORCID: ORCID
Stanisław Czapp
1
ORCID: ORCID
Adam Tomaszewski
2
ORCID: ORCID
  1. Faculty of Electrical and Control Engineering, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
  2. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk, Poland

Frequency of free vibration in systems with power-law restoring force

Ivan Grega Robert Grega Jaroslav Homisin
Bulletin of the Polish Academy of Sciences Technical Sciences | 2021 | 69 | 2 | e136723 | DOI: 10.24425/bpasts.2021.136723
Keywords power-law restoring force nonlinear vibration dimensional analysis numerical simulations
Download PDF Download RIS Download Bibtex

Abstract

To model the nonlinear behaviour of vibrating systems, Taylor expansion with integer powers is often used. Some systems, however, are inherently nonlinear. In the case of a non-integer real exponent, the power-law system cannot be linearised around the equilibrium position using Taylor expansion. The approach presented here provides a simple estimate of the principal frequency of free vibration in systems with power-law restoring force. Without seeking the precise mathematical form of the output waveform, we only focus on the principal frequency. The first step is the use of dimensional analysis to reduce the number of parameters. Two independent non-dimensional groups are formed and functional dependence between them is sought using numerical simulations. Once this dependence is known, the principal frequency of free vibration can be readily determined for any system properties and any initial conditions. Finally, we compare the numerical results to analytical expressions for a few restoring force exponents.
Go to article

Bibliography

  1.  M. Moravec et al., “Development of psychoacoustic model based on the correlation of the subjective and objective sound quality assessment of automatic washing machines”, Appl. Acoust. 140, 178–182 (2018).
  2.  M. Puškar et al., “Possibilities for reducing combustion engine fuel consumption and gas emissions”, Pol. J. Environ. Stud. 27(4), 1691–1698 (2018).
  3.  L. Jakubovičová et al., “Impact analysis of mutual rotation of roller bearing rings on the process of contact stresses in rolling elements”, Manuf. Technol. 13(1), 50–54 (2013).
  4.  Y. Li et al., “Analysis on electromechanical coupling vibration characteristics of in-wheel motor in electric vehicles considering air gap eccentricity”, Bull. Pol. Acad. Sci. Tech. Sci. 67(5), 851–862 (2019).
  5.  B. Błachowski and W. Gutkowski, “Graph based discrete optimization in structural dynamics”, Bull. Pol. Acad. Sci. Tech. Sci. 62(1), 91–102 (2014).
  6.  M.P. Kazmierkowski, “Power Electronics in Renewable Energy Systems and Smart Grid: Technology and Applications”, IEEE Ind. Electron. Mag. 13(4), 138–138 (2019).
  7.  W. Jarzyna, “A survey of the synchronization process of synchronous generators and power electronic converters”, Bull. Pol. Acad. Sci. Tech. Sci. 67(6), 1069–1083 (2019).
  8.  M. Wieczorek, M. Lewandowski, and W. Jefimowski, “Cost comparison of different configurations of a hybrid energy storage system with battery-only and supercapacitor-only storage in an electric city bus”, Bull. Pol. Acad. Sci. Tech. Sci. 67(6), 1095–1106 (2019).
  9.  R. Grega et al., “Failure analysis of driveshaft of truck body caused by vibrations”, Eng. Fail. Anal. 79, 208–215 (2017).
  10.  THE AA: European emission standards, Limits to improve air quality and health, (2017).
  11.  L. Jakubovičová et al., “Transport Duty Cycle Measurement of Hybrid Drive Unit for Mixing Drum”, Adv. Intell. Syst. Comput. 393, 219–224 (2016).
  12.  P. Charles et al., “Detecting the crankshaft torsional vibration of diesel engines for combustion related diagnosis”, J. Sound Vib. 321, 1171–1185 (2009).
  13.  M. Sága et al., “Modeling and experimental analysis of the aluminium alloy fatigue damage in the case of bending – torsion loading”, Procedia Eng. 48, 599–606 (2012).
  14.  L. Konieczny et al., “Determination of the effect of tire stiffness on wheel accelerations by the forced vibration test method”, J. Vibroengineering 17, 4469–4477 (2005).
  15.  A. Wedin, “Reduction of Vibrations in Engines using Centrifugal Pendulum Vibration Absorbers”, Chalmers University of Technology, 2011.
  16.  W. Sun et al., “Nonlinear Characteristics Study and Parameter Optimization of DMF-RS”, SAE Int. J. Passeng. Cars – Mech. Syst. 4(2), 1050–1057 (2011).
  17.  M. Zink and M. Hausner, “LuK clutch systems and torsional dampers”, Schaeffler Symposium, 2010, pp. 8–27.
  18.  R. Grega et al., “The Reduction Of Vibrations In A Car – The Principle Of Pneumatic Dual Mass Flywheel”, Zeszyty naukowe Politechniki Śląskiej 84, 21–28 (2014).
  19.  J. Krajňák et al., “The analysis of the impact of vibrations on noisiness of the mechanical system”, Pneumatyka 17, 21–26 (2016).
  20.  J. Homisin et al., “Removal of systematic failure of belt conveyor drive by reducing vibrations”, Eng. Fail. Anal. 99, 192‒202 (2019).
  21.  J. Krajnak et al., “Effect of helium on mechanical properties of flexible pneumatic coupling”, Sci. J. Sil. Uni. Tech. – Ser. Trans. 73, 63–69 (2011).
  22.  P. Baran and R. Grega, “Comparison of dynamic properties of dual mass flywheel”, Diagnostyka 16, 29–33 (2015).
  23.  J. Homisin et al., “Continuous tuning of ship propulsion system by means of pneumatic tuner of torsional oscillation”, Int. J. Mar. Eng.: Trans. R. Inst. Nav. Arch. 158 (A3), 231–238 (2016).
  24.  Ye-Wei Zhang et al., “Nonlinear energy sink with inerter”, Mech. Sys. Sig. Proc. 125, 52–64 (2019).
  25.  D. Qiu et al., “Design of cubic stiffness for the absorber of Nonlinear Energy Sink”, CFA/VISHNO, 2016.
  26.  A. Haris et al., “A study on torsional vibration attenuation in automotive drivetrains using absorbers with smooth and non-smooth nonlinearities”, Appl. Math. Model 46, 674–690 (2017).
  27.  D. Maffiodo et al., “Finite life fatigue design of spiral springs of dual-mass flywheels: Analytical estimation and experimental results”, AIME 10(6), 1–13 (2018).
  28.  J. Homisin, “Characteristics of pneumatic tuners of torsional oscillation as a result of patent activity”, Acta Mech. Autom. 10(4), 316–323 (2016).
  29.  R. Grega and J. Krajnak, “The pneumatic dual-mass flywheel”, Sci. J. Sil. Uni. Tech. – Ser. Trans. 76, 19–24 (2012).
  30.  I. Grega and R. Grega, “Simple approach for pure cubic nonlinear vibrating systems”, Proj. bad. eks.: Tom 1. – Bielsko-Biała 91–100 (2019).
  31.  I. Kovacic and M. Brennan, “The Duffing Equation: Nonlinear Oscillators and their Behaviour”, Wiley, Chichester, 2011.
  32.  Z. Rakaric and I. Kovacic, “Approximations for motion of the oscillators with a non-negative real-power restoring force”, J. Sound Vib. 330(2), 321–336 (2011).
  33.  E. Buckingham, “On Physically Similar Systems; Illustrations of the Use of Dimensional Equations”, Phys. Rev. 4(4), 345–376 (1914).
  34.  I. Grega et al., “The potential for use of cubic nonlinear systems in internal combustion engine drivetrains”, XXV Polish-Slovak Scientific Conference on Machine Modelling and Simulations, 2020.
Go to article

Authors and Affiliations

Ivan Grega
1
Robert Grega
2
ORCID: ORCID
Jaroslav Homisin
2
  1. Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
  2. Faculty of Mechanical Engineering, Technical University of Kosice, Letna 9, 042 00 Kosice, Slovakia

Numerical Simulations of Metallic Foam Safeguarded RC Square Columns under Lateral Soft Impact

Z.Y. Xie
Archives of Civil Engineering | Vol. 66 | No 2 | 3-17 | DOI: 10.24425/ace.2020.131792
Keywords metallic foams RC columns Impact resistance numerical simulation
Download PDF Download RIS Download Bibtex

Abstract

When a truck impacts on a reinforced concrete (RC) column such as a bridge pier at a high velocity, a large reaction force would generate which would damage the truck, hurt the passengers and destroy the column. Lightweight foams with excellent energy absorbing performance are often used as safeguard constructions to resist impact. The impact behavior can be divided into soft and hard impact. In the case of soft impact, the impacted structure deformation is predominant. In the paper, metallic foam safeguarded RC square columns impacted by a rigid block are simulated using the ABAQUS code software, and the influential characteristic of foam density on the peak impact force and ultimate energy absorption is focused on. The simulated results indicate that the foam safeguard constructions play remarkable role on impact resistance. It is exciting that there appears almost an identical critical foam density corresponding to the minimum peak force and the ultimate energy absorption, which is of great significance for engineering design of this type of safeguard constructions to resist impact.

Go to article

Authors and Affiliations

Z.Y. Xie

Analysis of uniaxial compression of rock mass with parallel cracks based on experimental study and PFC2D numerical simulation

Jie Yang Haijun Chen Xiong Liangxiao Zhongyuan Xu Tao Zhou Changheng Yang
Archives of Civil Engineering | 2022 | vol. 68 | No 1 | 111-128 | DOI: 10.24425/ace.2022.140159
Keywords uniaxial compression parallel cracks numerical simulation mechanical properties failure characteristics
Download PDF Download RIS Download Bibtex

Abstract

In this study, the uniaxial compression test and the numerical simulation of the twodimensional particle flow code (PFC2D) were used to study the mechanical properties and failure laws of rock masses with parallel cracks. The experiment considers the influences of crack length (��º, crack angle (��1, ��2), and numerical changes in the rock bridge length (ℎ) and bridge angle (��) on failures of rock-like specimens. The results indicate that the uniaxial compressive strength (UCS) of the rock-like specimens with parallel cracks decreases with increasing �� under different �� values. The smaller angle between the preset crack and the loadinging direction (��) resulting in higher UCS. In addition, a larger ℎ results in higher UCS in the specimen. When ��1 or ��2 is fixed, the UCS and elastic modulus of the specimen show an ‘M’ shape with an increase in ��. Moreover, the crack growth or failure mode of samples with different �� values is similar. When ��1 or ��2 is small, the failure of the specimen is affected by the development and expansion of wing cracks. If one of ��1 and ��2 is large, the failure of the specimen is dominated by the expansion and development of the secondary cracks which is generated at the tip of the prefabricated crack. Furthermore, when the angle between the prefabricated crack and the loading direction is ��1 = 0°, the rock bridge is less likely to reach penetration failure as ℎ increases. Secondary crack connections between the prefabricated cracks occur only when �� is small.
When �� ¡ 30°, the failure mode of the specimen is crack tip cracking which leads to penetration failure of the specimen, or the overall splitting failure.
Go to article

Authors and Affiliations

Jie Yang
1
ORCID: ORCID
Haijun Chen
2
ORCID: ORCID
Xiong Liangxiao
3 4
ORCID: ORCID
Zhongyuan Xu
5
ORCID: ORCID
Tao Zhou
1
ORCID: ORCID
Changheng Yang
3
ORCID: ORCID
  1. College of Environment and Civil Engineering, Chengdu University of Technology, Chengdu, 610059, PR China
  2. Geotechnical Engineering Department, Nanjing Hydraulic Research Institute, Nanjing, Jiangsu Province, 210029, PR China
  3. School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, PR China
  4. Hunan Provincial Key Laboratory of Hydropower Development Key Technology, HydroChina Zhongnan Engineering Corporation, Changsha 410014, PR China
  5. Department of Earth Sciences, University of Delaware, Delaware 19716, United States

Effect of surface energy on the contamination characteristics of porcelain double umbrella insulators

Yukun Lv Qian Wang Zeze Chen Jiawen Wang
Archives of Electrical Engineering | 2024 | vol. 73 | No 1 | 235-250 | DOI: 10.24425/aee.2024.148867
Keywords contamination characteristics numerical simulation surface energy XWP2-160 insulator
Download PDF Download RIS Download Bibtex

Abstract

To explore the influence of surface energy on the contamination characteristics of insulators, COMSOL Multiphysics software was used to simulate the contamination characteristics of XWP 2-160 insulators under wind tunnel conditions, and the rationality of the modified expression of the dynamic deposition model of the contaminated particles was verified. The change of contamination characteristics before and after changing the surface energy of insulators under natural conditions was simulated and analyzed. The results show that under the original surface energy (72 mJ/m 2) and low surface energy (6.7 mJ/m 2) with the increase in particle size, the contamination amount of an insulator surface area decreases first and then increases. When the wind speed is 2 m/s, the change in the particle size has the most pronounced effect on the amount of contamination. The amounts of contamination for the low surface energy are 64–75%, 60–95%, 55–91% and 54–78% lower than those for the original surface energy for particle sizes of 10, 15, 20 and 25 μm, respectively. For the same wind speed, when the size of contamination particles increases, the difference between the ratio of DC and AC contamination accumulation is gradually increasing because of the influence of the electric field force. From the perspective of the insulator preparation process, the development of low surface energy insulators can improve their anti-fouling performance.
Go to article

Authors and Affiliations

Yukun Lv
1
Qian Wang
1
Zeze Chen
1
ORCID: ORCID
Jiawen Wang
1
  1. Department of Power Engineering, North China Electric Power University

Numerical research of combustion with a minimum boiler load

Bartłomiej Hernik Wiesław Zabłocki
Archives of Thermodynamics | 2020 | vol. 41 | No 4 | 93-114 | DOI: 10.24425/ather.2020.135855
Keywords numerical simulations Ultra-supercritical boiler coal combustion Minimum boiler load
Download PDF Download RIS Download Bibtex

Abstract

Power boilers should be characterized by high flexibility in terms of loads, which results from the demand for electricity. In addition to the flexibility of the boiler, it is also important for the boiler to operate under technical minimum conditions while maintaining harmful emissions standards. A boiler operating with a technical minimum should also exhibit a stable combustion process. The paper presents the results of numerical combustion research for the minimum load of the two-pass ultrasupercritical boiler with front wall swirl burners system. The combustion stability for the minimum boiler load of 40% for the three mill system configurations has been demonstrated. Based on the numerical tests carried out in terms of obtaining the most favourable combustion conditions and the emission of harmful substances, the most favourable of them cases was indicated.

Go to article

Authors and Affiliations

Bartłomiej Hernik
Wiesław Zabłocki

Experimental and numerical analysis of vortex generators designed for utility vehicles

Ramesh Kumar Chidambaram Rajesh Kanna Poomanandan Gopal Senthil Kumar Arumugam
Archives of Thermodynamics | 2023 | vol. 44 | No 3 | 217-240 | DOI: 10.24425/ather.2023.147545
Keywords Vortex generator Pressure coefficient Numerical simulation drag force
Download PDF Download RIS Download Bibtex

Abstract

The main goal of today’s car designers is to minimize fuel consumption in all possible ways at the same time maintaining the vehicle’s performance as usual. The goal of this work is to study the effect of adding a vortex generator (VG) on the aerodynamics of the vehicle and fuel economy. Both theoretical and experimental works were carried out and the outcomes of the numerical simulations are contrasted with those of the experimental results. A utility vehicle model with a scale ratio of 1:15 was used as a test model. Experimental research has been done on the fluctuation of the coefficient of pressure, dynamic pressure, and coefficients of lift and drag with and without VG on the roof of a utility vehicle. The delta-shaped VG was put to the test both numerically and experimentally. At a velocity of 2.42 m/s, it is observed that the addition of VG can raise the pressure coefficient by about 17%. When compared to the vehicle model without vortex generators, the velocity profile of the ccomputational fluid dynamics analysis shows that at the back end of the vehicle, the wake has been minimized with VG.
Go to article

Authors and Affiliations

Ramesh Kumar Chidambaram
1
Rajesh Kanna
2
Poomanandan Gopal
3
Senthil Kumar Arumugam
4
  1. Vellore Institute of Technology, Automotive Research Centre, Vellore – 632014, India
  2. Vellore Institute of Technology, CO2 Research and Green Technologies Center, Vellore – 632014, India
  3. Anna University, Department of Automobile Engineering, BIT Campus, Tiruchirappalli, 620024, India
  4. VIT Bhopal University, Bhopal, 466114, India

Ground settlement and estimation of maximum settlement value in adjacent foundation pit excavation

Yan Wu
Archives of Civil Engineering | 2024 | vol. 70 | No 1 | 605-619 | DOI: 10.24425/ace.2024.148931
Keywords double foundation pit numerical simulation maximum settlement position maximum settlement
Download PDF Download RIS Download Bibtex

Abstract

The excavation of adjacent pits following the initial foundation pit excavation can significantly influence ground settlement. Using a foundation pit excavation project in Changzhou as a prototype, this study employed the numerical simulation method in conjunction with the HSS model to analyze the settlement deformation characteristics of the original excavation and compare them with the recorded monitoring values. In this study, the analysis focused on the ground settlement between two pits by varying the spacing between them at different excavation depths. The findings revealed that the ground settlement does not exhibit a significant increase when the new pit is excavated at a shallow depth. However, it rapidly increases when the excavation depth of the new pit surpasses that of the existing pit. Furthermore, an increase in the distance between the two pits causes the maximum settlement position to shift towards the edge of the new pit. The maximum ground settlement is found to have a linear relationship with both the maximum horizontal displacement of the two pits and the spacing between them.
Go to article

Authors and Affiliations

Yan Wu
1
ORCID: ORCID
  1. Changzhou University Huaide College, Architecture and Environmental Engineering Department, Tiazhou, Jiangsu, China

Static liquefaction as a form of material instability in element test simulations of granular soil

Krzysztof Sternik
Archives of Civil Engineering | 2024 | vol. 70 | No 2 | 309-322 | DOI: 10.24425/ace.2024.149865
Keywords constitutive model element test numerical simulation static liquefaction
Download PDF Download RIS Download Bibtex

Abstract

Static liquefaction is a form of unstable behaviour of granular soil. It is most common in saturated loose sands under monotonically loaded undrained conditions. Predicting static liquefaction using an elastic-plastic model that incorporates the non-associated plastic flow rule and strain hardening is possible. The article briefly describes the unstable behaviour of saturated sand in undrained conditions under a monotonic load. A simple elastic-plastic model with deviatoric hardening and a Drucker–Prager load surface is presented. The constitutive relationships were programmed in a Python script. Simulations of triaxial tests under mixed stress-strain control demonstrated the model’s ability to predict various undrained sand responses, including fully stable responses (no liquefaction) and partial and complete liquefaction under triaxial compression and tension. Predicting static liquefaction is possible by properly selecting the proportions of the parameters involved in plastic potential and loading functions and the parameter A used in the deviatoric hardening rule of hyperbolic type.
Go to article

Authors and Affiliations

Krzysztof Sternik
1
ORCID: ORCID
  1. Silesian University of Technology, Faculty of Civil Engineering, ul. Akademicka 5, 44-100 Gliwice,Poland

Damage diagnostics of turbine blades

Jerzy Madej
Archive of Mechanical Engineering | 2003 | vol. 50 | No 1 | 69-87
Keywords damage mechanizms turbine blades diagnostic methods thermovisional diagnosis numerical simulations
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the most frequently encountered types and mechanism of damage of turbines' flow elements. The methods used nowadays for diagnosis of the damage are presented. A new possibility of localisation of damaged areas of turbine blades based upon the analysis of isotherm layout is proposed.
Go to article

Authors and Affiliations

Jerzy Madej

Time parameters verification of a numerical simulator of an automated store warehouse

Sebastian Rzydzik Piotr Kroczek
Bulletin of the Polish Academy of Sciences Technical Sciences | 2024 | 72 | 3 | e149816 | DOI: 10.24425/bpasts.2024.149816
Keywords automated store warehouse vending machine numerical simulator digital twin
Download PDF Download RIS Download Bibtex

Abstract

The intelligent automated store warehouse (iZMS) research and development project was created to meet the expectations of a modern automatic store. The project concerns the development of the concept and pilot implementation of an automated store warehouse adapted to the autonomous and automatic sales of goods selected by retail chains. One of the aims of the iZMS project is to develop a scalable solution that allows for the simple adaptation of the iZMS to the needs of a potential customer, considering their requirements in terms of the quantity and variety of assortment offered within the iZMS. An important requirement in the use of the iZMS system is minimizing the customer waiting time for purchased products. This problem is related, among others, to the placement of products on the shelves of racks and will be solved in the optimizing process. Running optimization tasks requires a simulator that will mimic the features of a physical device faster than in real time to generate many proposals of the allocation of goods on storage racks in the shortest possible time and choose the best one, guaranteeing the shortest picking time of a representative basket of goods. A numerical simulator was developed to model the physical structures of food storage equipment and then simulate the sales process. Among the results obtained, the most important are the time parameters of individual operations,which will be used to optimize the placement of goods on storage racks. After analyzing the needs resulting from the usage of the iZMS system, we decided to develop a dynamic, deterministic simulator with discrete objects and perform the simulation with a controlled time increment and, in some cases, utilize elements of event-driven simulation, in which the flow of goods is simulated with first-in, first-out (FIFO) queues. Finally, verification of the numerical simulator with a physical model confirmed that it could be employed in optimization processes.
Go to article

Authors and Affiliations

Sebastian Rzydzik
1
ORCID: ORCID
Piotr Kroczek
2
  1. Faculty of Mechanical Engineering, Silesian University of Technology, ul. Konarskiego 18A, 44-100 Gliwice, Poland
  2. HemiTech sp. z o.o., ul. Piastowska 2, 44-122 Gliwice, Poland

Study on the Three-Phase Flow of the Water Transfer Export Elbow of Natural Gas Hydrate

Wei Chen Hai-liang Xu Bo Wu Fang-qiong Yang
Archives of Mining Sciences | 2022 | vol. 67 | No 2 | 239-258 | DOI: 10.24425/ams.2022.141456
Keywords deep-sea mining natural gas hydrates three-phase flow numerical simulation
Download PDF Download RIS Download Bibtex

Abstract

The Euler multiphase flow and population equilibrium model were used to simulate the three-phase flow field in the bubble expansion stage of the outlet curved pipe section. The influence of the ratio of the bending diameter and the volume fraction of the gas phase on the pressure loss is revealed, and the safety range of the optimum bending diameter ratio and the volume fraction of the outlet gas phase is determined. The results show that the three-phase flow in the tube is more uniformly distributed in the vertical stage, and when the pipe is curved, the liquid-phase close to the pipe wall gathers along the pipe flank to the outside of the pipe, the solid phase is transferred along the pipe flank to the inside of the pipe, and the gas phase shrinks along the pipe flank to the inner centre. The maximum speed of each phase of the three-phase flow in the elbow is at the wall of the tube from 45° to 60° inside the elbow, and the distribution law along the axial direction of the pipe is about the same as the distribution law of volume fraction. The pressure loss of the elbow decreases with the increase of the bend diameter ratio, when the bend diameter ratio increases to 6, the pressure loss of the pipe decreases sharply, and the pressure loss decreases slowly with the increase of the bend diameter ratio. When the gas phase volume score in the elbow reaches 70%, there will be an obvious wall separation phenomenon, to keep the system in a stable working state and prevent blowout, the gas phase volume score should be controlled within 60%.
Go to article

Authors and Affiliations

Wei Chen
1 2 3
ORCID: ORCID
Hai-liang Xu
2 3
ORCID: ORCID
Bo Wu
2 3
ORCID: ORCID
Fang-qiong Yang
2 3
ORCID: ORCID
  1. Hunan University of Humanities, Department of Energy and Electrical Engineering, Science and Technology, Loudi, Hunan 417000, China
  2. Central South University, School of Mechanical and Electrical Engineering, Changsha, Hunan 410083, China
  3. State Key Laboratory of High Performance Complex Manufacturing, Changsha, Hunan 410083, China

This page uses 'cookies'. Learn more