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Harmonic analysis of the wind-loaded bar dome at the Satellite Services Centre in Psary

W. Szaniec K. Zielińska
Archives of Civil Engineering | 2016 | No 1 | 37-50
Keywords wind load harmonic analysis resonance natural vibrations forced vibrations
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Abstract

The research paper presents the results of the dynamic analysis of an existing bar dome subjected to wind loads. The calculation model of the structure was constructed using the finite element method. The dome was subjected to the standard wind pressure, assuming that it is operates in a harmonic manner. The numerical analyses were performed with the application of Autodesk Robot and MES3D. The analysis focused on the impact of selected factors such as the frequency of forcing, wind gustiness coefficient and structural damping on the behaviour of structures.

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Authors and Affiliations

W. Szaniec
K. Zielińska

An Improved MSA Model for Evaluating the Sound Transmission Loss of a Rectangular Plate for Diffuse Field Incidence

Myong-Jin Kim Kyong-Su Won Chol-Su Ri
Archives of Acoustics | 2019 | vol. 44 | No 2 | 259-265 | DOI: 10.24425/aoa.2019.128489
Keywords transmission loss low frequency range natural vibration mode diffuse field incidence
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Abstract

This paper presents an approximate analytical model for estimating the transmission loss (TL) of a finite rectangular plate in the low frequency range, which is based on the modal summation approach (MSA) taking into account the modal radiation impedance and fluid loading. The mode-dependent radiation resistance is calculated using the Rayleigh integral. The fluid loading is taken into account through the natural frequency modified by the added mass. The results are compared with the ones of Statistical Energy Analysis (SEA) coupled with FEM and FEM coupled with BEM. In addition, the effects of the various vibration modes and the fluid loading on TL, and a way for reducing the calculation time are discussed.

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Authors and Affiliations

Myong-Jin Kim
Kyong-Su Won
Chol-Su Ri

Forecasting the Natural Frequency of the Brake Disc casting

Andrzej Zyska Mariusz Bieroński
Archives of Foundry Engineering | 2023 | vol. 23 | No 4 | 87-92 | DOI: 10.24425/afe.2023.146682
Keywords Gray cast iron Brake discs ultrasonic method Elastic property Natural vibrations
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Abstract

The paper presents the results of calculations and measurements of the first natural frequency of castings of solid and ventilated brake discs made of gray cast iron of the EN-GJL-200 class. The tests were carried out for three types of chemical composition, taking into account the permissible minimum and maximum content of alloying elements. Numerical simulations of natural vibrations were carried out on the basis of our own production material databases. To determine the elastic properties of cast iron, the ultrasonic method with the measurement of the propagation velocity of longitudinal and transverse waves was used. Measurements were made directly on casts of raw discs of various thicknesses. The values of Young's modulus and Poisson's number calculated from ultrasonic measurements were used to define the stiffness matrix in the equilibrium equation, which is solved by the solver of the MSC Nastran program. A high compatibility between the results of numerical simulations and the results of experimental FRF frequency analysis was obtained. The differences between the calculated and actual values were at the level of several hertz, while the estimated average error of numerical simulations was 0.76%. It was also found out that cast iron melts for brake discs must be subject to strict control in terms of chemical composition. Slight deviations of the eutectic saturation coefficient from the optimal value cause a significant change in the first natural frequency of the brake discs, regardless of their geometry.
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Bibliography

[1] Zagrajek, T., Krzesiński, G., Marek, P. (2006). Finite element method in structural mechanics. Warszawa: Oficyna Wydawnicza Politechniki Warszawskiej. (in Polish).
[2] Qatu, M.S., Abdelhamid, M.K., Pang J. & Sheng, G. (2009). Overview of automotive noise and vibration. International Journal of Vehicle Noise and Vibration. 5(1-2), 1-35. https://doi.org/10.1504/IJVNV.2009.029187.
[3] Lü, H. & Yu, D. (2014). Brake squeal reduction of vehicle disc brake system with interval parameters by uncertain optimization. Journal of Sound and Vibration. 333(26), 7313-7325. https://doi.org/10.1016/j.jsv.2014.08.027.
[4] Yoon, J., Park, J. & Min, S. (2022). Optimal disc brake design for reducing squeal instability using slip-dependent complex eigenvalue analysis. Mechanical Systems and Signal Processing. 177, 109240. https://doi.org/10.1016/j.ymssp. 2022.109240.
[5] Liu, P., Zheng, H., Cai, C., Wang, Y.Y., Lu, C., Ang, K.H. & Liu G.R. (2007). Analysis of disc brake squeal using the complex eigenvalue method. Applied Acoustics. 68(6), 603-615. https://doi.org/10.1016/j.apacoust.2006.03.012.
[6] Sinou, J.-J. (2010). Transient non-linear dynamic analysis of automotive disc brake squeal – On the need to consider both stability and non-linear analysis. Mechanics Research Communications. 37(1), 96-105. https://doi.org/10.1016/ j.mechrescom.2009.09.002.
[7] Nouby, M., Mathivanan, D. & Srinivasan, K. (2009). A combined approach of complex eigenvalue analysis and design of experiments (DOE) to study disc brake squeal. International Journal of Engineering, Science and Technology. 1(1), 254-271. DOI: 10.4314/ijest.v1i1.58084 .
[8] Armstrong, P.E., in: R.F. Bunshan (Ed.) (1971). Measurement of Mechanical Properties, Techniques of Metals Research. vol. V (Part 2). New York: Wiley.
[9] Radovic, M., Lara-Curzio, E., Riester, L. (2004). Comparison of different experimental techniques for determination of elastic properties of solids. Materials Science and Engineering A. 368(1-2), 56-70. https://doi.org/10.1016/ j.msea.2003.09.080.
[10] Migliori, A., Sarrao, J.L. (1997). Resonant Ultrasound Spectroscopy: Applications to Physics. Materials Measurements and Nondestructive Evaluation. , New York: Wiley.
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[14] Konopka, Z., Łągiewka, M. & Zyska, A. (2020). Influence of cast iron modification on free vibration frequency of casting. Archives of Foundry Engineering. 20(1), 23-26. DOI: 10.24425/afe.2020.131277.
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Authors and Affiliations

Andrzej Zyska
1
ORCID: ORCID
Mariusz Bieroński
2
ORCID: ORCID
  1. Department of Metallurgy and Metal Technology, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Częstochowa, Poland
  2. Brembo Poland Sp. z o.o., ul. Roździeńskiego 13, 41-308 Dąbrowa Górnicza

Numerical models for the evaluation of natural vibration frequencies of thermo-modernized building walls

K. Kuźniar M. Zając
Archives of Civil Engineering | 2018 | Vol. 64 | No 4/I | 3-14
Keywords numerical models thermo-modernized walls natural vibration frequencies finite element method
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Abstract

As a result of the necessity to improve energy properties of prefabricated buildings, their thermo-modernizations are performed. In the paper various approaches to the modelling of prefabricated load bearing walls before and after thermo-modernization are presented. Simple one layer models with extra mass from ceilings and equivalent stiffness as well as multilayer ones are taken into consideration using the finite element method software. Values of the natural frequencies of the wall horizontal vibrations calculated using the various models, are compared. It was proved that even the very simple model with equivalent stiffness allows to compute natural vibration frequencies of wall with acceptable accuracy for engineering practice.

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Authors and Affiliations

K. Kuźniar
M. Zając

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