Dynamic Analysis of Partially Filled Non-circular Cylindrical Shells with Liquid Sloshing

2016 ◽  
Vol 08 (03) ◽  
pp. 1650027 ◽  
Author(s):  
Sergey A. Bochkarev ◽  
Sergey V. Lekomtsev ◽  
Valery P. Matveenko
Keyword(s):  
Ideal Liquid ◽  
Harmonic Excitation ◽  
Compressible Liquid ◽  
Liquid Sloshing ◽  
Vibration Frequencies ◽  
Linearized Euler Equations ◽  
Finite Element Procedure ◽  
Deformed State ◽  
Free Surface Oscillations

The paper investigates the dynamic behavior of thin-walled reservoirs containing an ideal liquid taking into account the effects of hydroelastic interaction and sloshing. A mathematical statement of the problem is based on the principle of virtual displacements, which accounts for the pre-stressed non-deformed state of the shell caused by various force factors. The behavior of compressible liquid is described by linearized Euler equations, which are transformed by the Bubnov–Galerkin method. The dynamics of partially filled circular and elliptical cylindrical reservoirs are investigated numerically using a finite element procedure. It has been shown that allowing for sloshing considerably reduces eigenfrequencies of vibrations of the examined systems but has inessential effect on the displacements of the structure under non-stationary loads. Based on the modal analysis we present a classification of eigenmodes of free surface oscillations of a liquid in vertical tanks. It has been found that due to consideration of the sloshing effect, the frequency spectrum of the system can split into two parts in the case when the vibration frequencies of liquid differ from the vibration frequencies of an empty shell. Moreover, under harmonic excitation consideration of liquid sloshing leads to a more complicated amplitude-frequency curve characterized by displacement jumps.

Resolving wave and laminar boundary layer scales for gap resonance problems

2019 ◽  
Vol 866 ◽  
pp. 759-775 ◽  
Author(s):  
H. Wang ◽  
H. A. Wolgamot ◽  
S. Draper ◽  
W. Zhao ◽  
P. H. Taylor ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Second Harmonic ◽  
Critical Role ◽  
Harmonic Excitation ◽  
Resonant System ◽  
Primary Interest ◽  
Wave Groups ◽  
Laminar Boundary Layers ◽  
Gap Resonance ◽  
Free Surface Oscillations

Free surface oscillations in a narrow gap between elongated parallel bodies are studied numerically. As this represents both a highly resonant system and an arrangement of relevance to offshore operations, the nature of the damping is of primary interest, and has a critical role in determining the response. Previous experimental work has suggested that the damping could be attributed to laminar boundary layers; here our numerical wave tank successfully resolves both wave and boundary layer scales to provide strong numerical evidence in support of this conclusion. The simulations follow the experiments in using wave groups so that the computation is tractable, and both linear and second harmonic excitation of the gap are demonstrated.

Vibration Control of Horizontally Excited Structures Utilizing Internal Resonance of Liquid Sloshing in Nearly Square Tanks

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Takashi Ikeda ◽  
Yuji Harata
Keyword(s):  
Frequency Response ◽  
Internal Resonance ◽  
Passive Control ◽  
Harmonic Excitation ◽  
Liquid Sloshing ◽  
Maximum Efficiency ◽  
System Response ◽  
Response Curves ◽  
System Parameters ◽  
Theoretical Results

Passive control of vibrations in an elastic structure subjected to horizontal, harmonic excitation by utilizing a nearly square liquid tank is investigated. When the natural frequency ratio 1:1:1 is satisfied among the natural frequencies of the structure and the two predominant sloshing modes (1,0) and (0,1), the performance of a nearly square tank as a tuned liquid damper (TLD) is expected to be superior to rectangular TLDs due to internal resonance. In the theoretical analysis, Galerkin's method is used to determine the modal equations of motion for liquid sloshing considering the nonlinearity of sloshing. Then, van der Pol's method is used to obtain the expressions for the frequency response curves for the structure and sloshing modes. Frequency response curves and bifurcation set diagrams are shown to investigate the influences of the aspect ratio of the tank cross section and the tank installation angle on the system response. From the theoretical results, the optimal values of the system parameters can be determined in order to achieve maximum efficiency of vibration suppression for the structure. Hopf bifurcations occur and amplitude modulated motions (AMMs) may appear depending on the values of the system parameters. Experiments were also conducted, and the theoretical results agreed well with the experimental data.

Dynamic Analysis Subject to Displacement Harmonic Excitation of Liquid Storage Tank with 20000m3

2014 ◽  
Vol 552 ◽  
pp. 47-50
Author(s):  
Guang Hao Zhang ◽  
Ping Huo ◽  
Li Wen Chen
Keyword(s):  
Wave Height ◽  
Storage Tank ◽  
Horizontal Displacement ◽  
Relative Displacement ◽  
Harmonic Excitation ◽  
Liquid Sloshing ◽  
Tank Wall ◽  
Element Analysis ◽  
Maximal Stress ◽  
Height Increase

The isolation storage tank with 20000m3 responded to seismic is calculated by using the finite element analysis (FEA) program ANSYS, and horizontal displacement harmonic excitation is considered for investigation of the relative displacement of tank wall, liquid sloshing wave height, and the stress of tank wall. The analysis show that, with isolation, the maximal relative displacement, the maximal liquid sloshing wave height, and the maximal stress of tank wall are reduced obviously compared with tank that without isolation, and as site become soft, the maximal relative displacement of the tank wall at the top and the maximal wave height increase gradually, but the maximal stress of tank wall change little.

scholarly journals Physical basis of rolling bearing vibration formation of structural

2020 ◽  
Vol 220 ◽  
pp. 01046
Author(s):  
Mikolay Hruntovich ◽  
Nadzeya Hruntovich ◽  
Aliaksei Kapanski ◽  
Larisa Markaryants ◽  
Elena Gracheva
Keyword(s):  
Rolling Bearing ◽  
Vibration Frequencies ◽  
Rolling Bearings ◽  
Bearing Defects ◽  
Rolling Elements ◽  
Different Dimensions ◽  
Bearing Vibration ◽  
Bearing Rings ◽  
Rotor Mass

The problem of increasing the reliability of detecting defects, both in new rolling bearings and the ones having already been in operation is current. The article describes the physical foundations of vibration of rolling bearings, caused by the different dimensions of the rolling elements and increased microwaves of the rings. A classification of rolling bearing defects was proposed, as well as calculation formulas for vibration frequencies corresponding to the indicated defects. It is shown that the vibration level at the overturning frequency depends on the gap size and the rotor mass. As an example, possible defects of rolling bearing No.310 were considered and their vibration frequencies were calculated. The frequency range in which defects of the rings and rolling elements appear was installed. An explanation of the reasons for the occurrence of high-frequency vibration was given. The combination of defects in the rolling elements of different dimensions and imbalance in the rotor causes the intensive development of microshells on the rolling bearing rings. Examples of experimental vibroacoustic characteristics were given to illustrate the physical processes of vibration in rolling bearings with various defects.

Vibration Suppression of Flexible Structures Utilizing Internal Resonance of Liquid Sloshing in a Nearly Square Tank

2010 ◽  
Author(s):  
Takashi Ikeda
Keyword(s):  
Frequency Response ◽  
Internal Resonance ◽  
Vibration Suppression ◽  
Equations Of Motion ◽  
Flexible Structures ◽  
Harmonic Excitation ◽  
Liquid Sloshing ◽  
Maximum Efficiency ◽  
Tuned Liquid Damper ◽  
Response Curves

This paper proposes a new idea to utilize the internal resonance of two different sloshing modes in a nearly square tank when used as a tuned liquid damper (TLD). This idea results in achieving higher efficiency of vibration suppression for flexible structures subjected to horizontal harmonic excitation. Namely, the two sloshing modes (1, 0) and (0, 1) in a nearly square tank are degenerated and hence their natural frequencies are nearly equal with each other. Because the two predominant sloshing modes are nonlinearly coupled, internal resonance is expected to occur. Galerkin’s method is used to determine the modal equations of motion for liquid sloshing. Then, van der Pol’s method is used to determine the expressions of the frequency response curves. Frequency response curves and bifurcation sets are numerically calculated. From these results, the optimal values of the size and instillation angle of the tank can be determined in order to achieve maximum efficiency of vibration suppression in a flexible structure. Experiments confirmed the validity of the theoretical analysis.

Design of the Flexible Container for Control of Sloshing

2013 ◽  
Vol 365-366 ◽  
pp. 62-65
Author(s):  
Marija Gradinscak
Keyword(s):  
Free Surface ◽  
Design Parameter ◽  
Liquid Sloshing ◽  
The Other ◽  
Effective Control ◽  
Numerical Predictions ◽  
Other Hand ◽  
Design Alternatives ◽  
Free Surface Oscillations

The inherent flexibility of a liquid container is usually treated as a problem since achieving a perfectly rigid container is practical impossibility. On the other hand container flexibility may be used as design parameter in control of free surface oscillations. Intentional container flexibility has been employed in this research to suppress excessive levels of liquid sloshing. This paper outlines numerical predictions for simulation of liquid sloshing in a flexible container and its design alternatives while maintaining effective control.

scholarly journals EXPERIMENTAL STUDY OF LIQUID SLOSHING FORCE CHARACTERISTICS IN RECTANGULAR TANK OF SPRAYER UNDER HARMONIC EXCITATION

2020 ◽  
pp. 125-132
Author(s):  
Jizhou Zheng ◽  
Xiang Han ◽  
Haoran Guo ◽  
Jialin Hou ◽  
Xinyu Xue
Keyword(s):  
Passive Control ◽  
Practical Method ◽  
Excitation Amplitude ◽  
Harmonic Excitation ◽  
Liquid Sloshing ◽  
Factors Affecting ◽  
Rectangular Tank ◽  
The Stability ◽  
Violent Sloshing ◽  
Force Characteristics

The stability of the boom system of sprayers is easily affected by the liquid sloshing force and the uniformity of droplet deposition deteriorates. Therefore, the liquid sloshing forces in the rectangular tank were measured through experiments. Three main factors affecting the sloshing forces were examined. Experimental results reveal that the sloshing forces measured fit well with the theoretical curve and the maximum sloshing force is independent of the excitation amplitude for a violent sloshing. Based on these characteristics, a practical method was proposed which can approximately calculate the maximum sloshing force based on the linear model, and can be used for the sprayer chassis design and active and passive control of boom attitude.

Note on the spectral classification of carbon stars in the photographic infrared region

1966 ◽  
Vol 24 ◽  
pp. 21-23
Author(s):  
Y. Fujita
Keyword(s):  
Infrared Region ◽  
Spectral Classification ◽  
Carbon Stars

We have investigated the spectrograms (dispersion: 8Å/mm) in the photographic infrared region fromλ7500 toλ9000 of some carbon stars obtained by the coudé spectrograph of the 74-inch reflector attached to the Okayama Astrophysical Observatory. The names of the stars investigated are listed in Table 1.

Diagnostic Value of Electron Microscopy in Soft Tissue Tumors

1970 ◽  
Vol 28 ◽  
pp. 220-221
Author(s):  
Gerald Fine ◽  
Azorides R. Morales
Keyword(s):  
Cardiac Myxoma ◽  
Osteogenic Sarcoma ◽  
Diagnostic Value ◽  
Soft Tissue Tumors ◽  
Amelanotic Melanoma ◽  
Growth Patterns ◽  
Light Microscopic Level ◽  
Mesenchymal Tumors ◽  
Good Agreement

For years the separation of carcinoma and sarcoma and the subclassification of sarcomas has been based on the appearance of the tumor cells and their microscopic growth pattern and information derived from certain histochemical and special stains. Although this method of study has produced good agreement among pathologists in the separation of carcinoma from sarcoma, it has given less uniform results in the subclassification of sarcomas. There remain examples of neoplasms of different histogenesis, the classification of which is questionable because of similar cytologic and growth patterns at the light microscopic level; i.e. amelanotic melanoma versus carcinoma and occasionally sarcoma, sarcomas with an epithelial pattern of growth simulating carcinoma, histologically similar mesenchymal tumors of different histogenesis (histiocytoma versus rhabdomyosarcoma, lytic osteogenic sarcoma versus rhabdomyosarcoma), and myxomatous mesenchymal tumors of diverse histogenesis (myxoid rhabdo and liposarcomas, cardiac myxoma, myxoid neurofibroma, etc.)

Ultrastructure of mesotheliomas

1984 ◽  
Vol 42 ◽  
pp. 98-101
Author(s):  
Irving Dardick
Keyword(s):  
Electron Microscopy ◽  
Latent Period ◽  
Spindle Cell ◽  
Spindle Cell Sarcoma ◽  
Metastatic Adenocarcinoma ◽  
Cell Sarcoma ◽  
Cytological Features ◽  
Industrial Use ◽  
Degree Of Differentiation

With the extensive industrial use of asbestos in this century and the long latent period (20-50 years) between exposure and tumor presentation, the incidence of malignant mesothelioma is now increasing. Thus, surgical pathologists are more frequently faced with the dilemma of differentiating mesothelioma from metastatic adenocarcinoma and spindle-cell sarcoma involving serosal surfaces. Electron microscopy is amodality useful in clarifying this problem.In utilizing ultrastructural features in the diagnosis of mesothelioma, it is essential to appreciate that the classification of this tumor reflects a variety of morphologic forms of differing biologic behavior (Table 1). Furthermore, with the variable histology and degree of differentiation in mesotheliomas it might be expected that the ultrastructure of such tumors also reflects a range of cytological features. Such is the case.

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