Experimental Investigation of Sloshing Dynamics Coupled With Barge Responses

2009 ◽  
Author(s):  
T. Nasar ◽  
S. A. Sannasiraj ◽  
V. Sundar
Keyword(s):  
Experimental Investigation ◽  
Wave Height ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Wave Excitation ◽  
The Third ◽  
Sloshing Frequency ◽  
Sloshing Dynamics ◽  
Liquid Depth ◽  
Cover Up

An experimental work has been carried out to study the phenomena of sloshing of liquid in a partially filled tank with aspect ratio (hs/l, where hs is the static liquid depth and l is the tank length) of 0.585. The sloshing tank was rigidly fixed in to a barge and was exposed to regular beam waves. The wave excitation frequencies (fw) ranging from 0.70Hz to 1.54Hz that cover up to the third mode natural sloshing frequency (f3) are considered. The incident wave height (Hi) is 0.10m. The effects of wave excitation frequency and wave height on the sloshing oscillation are studied. Attempts are made to evaluate the harmonics present in the sloshing oscillation and compare with the results of earlier studies. The barge responses such as sway, heave and roll are measured and it is found that the barge responses at their natural frequencies are insensitive to induce sloshing oscillation inside the tank.

Effect of Porous Baffle on Sloshing Dynamics in a Barge Mounted Container Subjected to Wave Excitation

2017 ◽  
Author(s):  
Nasar Thuvanismail ◽  
Akshay P. Shah ◽  
Deepak J. Surahonne ◽  
Sannasiraj S. Annamalaisamy
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
Water Level ◽  
Excitation Frequency ◽  
Experimental Setup ◽  
Regular Wave ◽  
Wave Excitation ◽  
Regular Waves ◽  
Sloshing Dynamics

An experimental investigation was carried out to determine the effect of porous baffle walls on sloshing dynamics of a sloshing tank that is partially filled with liquid and rigidly mounted in a barge. The experimental setup is subjected to beam sea regular wave excitations and hence the barge experiences combined sway heave and roll excitations. An aspect ratio (hs/l, where hs is still water level and l is length of tank) of 0.488 is considered which corresponds to 75% fill condition with respect to tank height. Three porosities of 15%, 20%, and 25% are considered. The barge system was subjected to regular waves of frequency (fw) ranging from 0.45Hz to 1.54Hz. The effectiveness of porous baffles on the dissipation of sloshing energy is studied in comparison with without baffle condition. The effect of wave excitation frequency on the sloshing dynamics has also been analysed and the prominent results are here in reported.

Liquid Sloshing Dynamics in a Container Subjected to Coupled Mode Excitation

2008 ◽  
Author(s):  
T. Nasar ◽  
S. A. Sannasiraj ◽  
V. Sundar
Keyword(s):  
Excitation Frequency ◽  
Qualitative Assessment ◽  
Floating Body ◽  
Nonlinear Behaviour ◽  
Wave Excitation ◽  
Coupled Mode ◽  
Sloshing Dynamics ◽  
Time Histories ◽  
Fill Level ◽  
The Individual

An experimental work has been carried out to study the phenomena of sloshing of liquid in a partially filled tank mounted on a barge exposed to regular beam waves. Liquid fill level with aspect ratio (hs/l, where hs is the static liquid depth and l is the tank length) of 0.325 is studied. The time histories of sloshing oscillation are measured along the length of container at predefined locations. The nonlinear behaviour of sloshing oscillation is observed for the regular wave excitation. The spectra of the sloshing oscillation and their qualitative assessment are reported. The individual sway and heave analytical model have been studied in order to substantiate the importance of coupled mode of excitation. Attempts are made to evaluate the harmonics present in the sloshing oscillation and compare with the results of earlier studies. In the present interaction study, it was found that the nonlinear response of the floating body also plays a role to induce violent sloshing oscillation. The effects of wave excitation frequency on the sloshing oscillation are reported.

scholarly journals Liquid sloshing dynamics in a barge carrying container subjected to random wave excitation

2012 ◽  
Vol 9 (1) ◽  
pp. 43-65 ◽  
Author(s):  
Nasar Thuvanismail ◽  
Sannasiraj Sannasi ◽  
Sundar Vallam
Keyword(s):  
Excitation Frequency ◽  
Primary Resonance ◽  
Peak Frequency ◽  
Experimental Program ◽  
Random Wave ◽  
Wave Excitation ◽  
Excitation Peak ◽  
Sloshing Dynamics ◽  
Sloshing Mode ◽  
Marine Engineering

The sloshing phenomenon of liquid in a partially filled tank mounted rigidly on a barge exposed to random beam waves has been investigated through a well controlled experimental program. Four relative liquid depths, (liquid depth, hs/ length of tank, l) of 0.163, 0.325, 0.488 and 0.585 were considered for the tests. The sloshing oscillation was measured along the length of the tank at predefined locations. The effect of variation of the peak wave excitation frequency on the sloshing oscillation in the frequency domain is studied. The dominant energy is found to be concentrated around lowest nth sloshing mode frequency and, secondary peaks are observed at higher order sloshing frequencies. Odd modes contributions are dominating even modes irrespective of the excitation peak frequency. The sacrifice of second mode is observed while the excitation peak frequency is closer to its primary resonance. DOI: http://dx.doi.org/10.3329/jname.v9i1.7600 Journal of Naval Architecture and Marine Engineering 9(2012) 43-65

Nonlinear Resonances in a Flexible Cantilever Beam

1994 ◽  
Vol 116 (4) ◽  
pp. 480-484 ◽  
Author(s):  
T. J. Anderson ◽  
B. Balachandran ◽  
A. H. Nayfeh
Keyword(s):  
Natural Frequency ◽  
Cantilever Beam ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Continuous Systems ◽  
Modal Interactions ◽  
The Third ◽  
First Case ◽  
Second Mode ◽  
Band Limited

An experimental investigation into the response of a nonlinear continuous systems with many natural frequencies in the range of interest is presented. The system is a flexible cantilever beam whose first four natural frequencies are 0.65 Hz, 5.65 Hz, 16.19 Hz, and 31.91 Hz, respectively. The four natural frequencies correspond to the first four flexural modes. The fourth natural frequency is about fifty times the first natural frequency. Three cases were considered with this beam. For the first case, the beam was excited with a periodic base motion along its axis. The excitation frequency fe was near twice the third natural frequency f3, which for a uniform isotropic beam corresponds to approximately the fourth natural frequency f4. Thus the third mode was excited by a principal parametric resonance (i.e., fe ≈ 2f3) and the fourth mode was excited by an external resonance (i.e., fe ≈ f4) due to a slight curvature in the beam. Modal interactions were observed involving the first, third, and fourth modes. For the second case, the beam was excited with a band-limited random base motion transverse to the axis of the beam. The first and second modes were excited through nonlinear interactions. For the third case, the beam was excited with a base excitation along the axis of the beam at 138 Hz. The corresponding response was dominated by the second mode. The tools used to analyze the motions include Fourier spectra, Poincare´ sections, and dimension calculations.

scholarly journals A numerical study: liquid sloshing dynamics in a tank due to uncoupled sway, heave and roll ship motions

2013 ◽  
Vol 10 (2) ◽  
pp. 119-138 ◽  
Author(s):  
Nasar Thuvanismail ◽  
Sannasiraj Sannasi ◽  
Sundar Vallam
Keyword(s):  
Numerical Study ◽  
Energy Spectra ◽  
Qualitative Assessment ◽  
Ship Motions ◽  
Theoretical Studies ◽  
Sloshing Dynamics ◽  
Tank System ◽  
Liquid Depth ◽  
Sloshing Phenomenon ◽  
Heave Motion

In order to explore the physics implicated with the sloshing phenomenon subjected to independent regular sway, heave and roll excitations of the liquid tank system, theoretical studies are carried out. Four liquid fill levels with static liquid depth, hs, to the length, l of aspect ratio (hs/l) 0.163, 0.325, 0.488 and 0.585, are considered. The energy spectra of sloshing oscillation, their qualitative assessment and the harmonics present in the sloshing oscillation are studied. Frequency –Response amplitude has also been presented. The study reveals that sway excites a particular mode of sloshing (primary harmonic) by fulfilling the resonance conditions and also excites secondary modes. However, the roll motion excites the first mode of sloshing irrespective of the excitation frequencies. The heave motion excites the particular mode which is assumed as an initial perturbation.DOI: http://dx.doi.org/10.3329/jname.v10i2.16215 

scholarly journals Analysis of Timoshenko beam with Koch snowflake cross-section and variable properties in different boundary conditions using finite element method

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110609
Author(s):  
Hossein Talebi Rostami ◽  
Maryam Fallah Najafabadi ◽  
Davood Domiri Ganji
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Cross Section ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Variable Properties ◽  
The Third ◽  
Koch Snowflake

This study analyzed a Timoshenko beam with Koch snowflake cross-section in different boundary conditions and for variable properties. The equation of motion was solved by the finite element method and verified by Solidworks simulation in a way that the maximum error was about 2.9% for natural frequencies. Displacement and natural frequency for each case presented and compared to other cases. Significant research achievements illustrate that if we change the Koch snowflake cross-section of the beam from the first iteration to the second, the area and moment of inertia will increase, and we have a 5.2% rise in the first natural frequency. Similarly, by changing the cross-section from the second iteration to the third, a 10.2% growth is observed. Also, the hollow cross-section is considered, which can enlarge the natural frequency by about 26.37% compared to a solid one. Moreover, all the clamped-clamped, hinged-hinged, clamped-free, and free-free boundary conditions have the highest natural frequency for the Timoshenko beam with the third iteration of the Koch snowflake cross-section in solid mode. Finally, examining important physical parameters demonstrates that variable density from a minimum value to the standard value along the beam increases the natural frequencies, while variable elastic modulus decreases it.

An Experimental Investigation of Desensitization in Phobic Patients

1974 ◽  
Vol 124 (581) ◽  
pp. 392-401 ◽  
Author(s):  
P. Gillan ◽  
S. J. Rachman
Keyword(s):  
Experimental Investigation ◽  
Clinical Outcome ◽  
Laboratory Studies ◽  
Comparative Efficacy ◽  
Fear Reduction ◽  
The Third

The investigation had three major aims. We attempted to repeat and extend the findings of the Gelder, Marks and Wolff (1967) study of the comparative efficacy of desensitization and psychotherapy in the treatment of phobic patients. Our second aim was to isolate the effects of various components of desensitization treatment, in the manner employed in laboratory studies of fear-reduction (e.g. Davison, 1968; Rachman, 1965; Rachman, 1968). The third aim was to collect data on the relationships between psychophysiological changes and clinical outcome.

Nonlinear Combination Resonances in Cantilever Composite Plates

1995 ◽  
Author(s):  
Kyoyul Oh ◽  
Ali H. Nayfeh
Keyword(s):  
Natural Frequencies ◽  
Excitation Frequency ◽  
Power Spectra ◽  
Low Frequency ◽  
Composite Plates ◽  
High Amplitude ◽  
Mode Shapes ◽  
Laser Vibrometer ◽  
Combination Resonance ◽  
Response Curves

Abstract We experimentally investigated nonlinear combination resonances in a graphite-epoxy cantilever plate having the configuration (–75/75/75/ – 75/75/ – 75)s. As a first step, we compared the natural frequencies and mode shapes obtained from the finite-element and experimental modal analyses. The largest difference in the obtained frequencies was 2.6%. Then, we transversely excited the plate and obtained force-response and frequency-response curves, which were used to characterize the plate dynamics. We acquired time-domain data for specific input conditions using an A/D card and used them to generate time traces, power spectra, pseudo-state portraits, and Poincaré maps. The data were obtained with an accelerometer monitoring the excitation and a laser vibrometer monitoring the plate response. We observed the external combination resonance Ω≈12(ω2+ω5) and the internal combination resonance Ω≈ω8≈12(ω2+ω13), where the ωi are the natural frequencies of the plate and Ω is the excitation frequency. The results show that a low-amplitude high-frequency excitation can produce a high-amplitude low-frequency motion.

Natural frequency modulation of a kinematically redundant planar parallel robot

2021 ◽  
pp. 095440622110524
Author(s):  
Jiawei Gu ◽  
Zhijiang Xie ◽  
Jian Zhang ◽  
Yangjun Pi
Keyword(s):  
Natural Frequency ◽  
Frequency Modulation ◽  
Natural Frequencies ◽  
Vibration Suppression ◽  
Excitation Frequency ◽  
Parallel Robot ◽  
Modulation Method ◽  
Kinematic Redundancy ◽  
Resonance Amplitude ◽  
Searching Method

When a parallel robot is equipped with kinematic redundancy, it has sufficient capabilities of natural frequency modulation through adjusting geometric configuration. To reduce resonance of a mechanism, this paper investigates the natural frequency modulation of a kinematically redundant planar parallel robot. A double-threshold searching method is proposed for controlling the inverse kinematics solution and keeping the natural frequencies away from the excitation frequency. The effectiveness of modulating the natural frequencies is demonstrated by comparing it with a non-modulation method. The simulation results indicate that, in all directions, the responses are coupled, and every order should be taken into consideration during natural frequency modulation. Compared to the non-modulation method, the proposed method can reduce the resonance amplitude to a certain extent, and the effect of vibration suppression is remarkable.

Sign in / Sign up

Export Citation Format

Share Document