Bio-inspired aquatic propulsion using piezoelectric effect

Underwater propulsion of fishes have inspired many biomimetic structures. Generally, the bio-inspired structures mimics the flapping behaviour of various control surfaces/fins in fishes. The present study mimics the flapping behaviour using a piezoelectric structure. The system is analyzed as a fluid structure interaction problem. The dynamic behaviour of a cantilever beam surrounded by a bounded fluid domain open at top is analyzed. The structure is modeled as a Euler-Bernoulli beam and the fluid is modeled using potential flow theory. The influence of domain size on the wet natural frequencies of the system was analyzed. The dimensions of the fluid domain wherein the variation in wet natural frequencies becomes insensitive were determined. The influence of added mass on the wet natural frequency was parametrized based on Non-dimensional Added Mass Increment (NAVMI) factor. The NAVMI factors were observed to be relatively higher for lower wet modes of the structure. Therefore, the peizo-beam was analyzed by exciting the lower wet modes. The thrust generated at different excitation frequencies were determined using tip velocity of the cantilever beam following Lighthill’s analogy. The results from the study indicated that higher propulsive thrust was produced for lower modes of excitation of the structure.

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Free Vibration of a Carbon Nanotube-Based Mass Sensor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.403-408.1163 ◽

2011 ◽

Vol 403-408 ◽

pp. 1163-1167 ◽

Cited By ~ 3

Author(s):

Payam Soltani ◽

Omid Pashaei ◽

Mohammad Mehdi Taherian ◽

Anoushiravan Farshidianfar

Keyword(s):

Boundary Condition ◽

Carbon Nanotube ◽

Natural Frequencies ◽

Dynamical Behavior ◽

Beam Theory ◽

Added Mass ◽

Mass Sensor ◽

Bernoulli Beam ◽

Single Walled Carbon Nanotube ◽

Euler Bernoulli Beam

In this paper, nonlocal Euler-Bernoulli beam theory is applied to investigate the dynamical behavior of a single-walled carbon nanotube (SWCNT) with an extra added nanoparticle. The SWCNT is assumed to be embedded on a Winkler-type elastic foundation with cantilever boundary condition. This configuration can be used as a nano-mass sensor which works on the basis of the changing the natural frequencies. The results show that the added mass causes an obvious increase in sensitivity of SWCNT-based nano-mass sensor, especially for stiff mediums, small nonlocal parameters, and stocky SWCNTs.

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Type and number of elements effect on the calculation of cantilever beam free natural frequencies using the finite element method

2019 2nd International Conference on Electrical, Communication, Computer, Power and Control Engineering (ICECCPCE) ◽

10.1109/iceccpce46549.2019.203747 ◽

2019 ◽

Author(s):

Iesam J. Hasan

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Cantilever Beam ◽

Natural Frequencies ◽

The Finite Element Method ◽

Element Method

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Fluid Added Mass Effect in the Modal Response of a Pump-Turbine Impeller

Volume 1: 22nd Biennial Conference on Mechanical Vibration and Noise, Parts A and B ◽

10.1115/detc2009-86830 ◽

2009 ◽

Cited By ~ 4

Author(s):

Eduard Egusquiza ◽

Carme Valero ◽

Quanwei Liang ◽

Miguel Coussirat ◽

Ulrich Seidel

Keyword(s):

Natural Frequencies ◽

Experimental Tests ◽

Mass Effect ◽

Added Mass ◽

Mode Shapes ◽

Pump Turbine ◽

Modal Response ◽

Surrounding Fluid ◽

Turbine Impeller ◽

Good Agreement

In this paper, the reduction in the natural frequencies of a pump-turbine impeller prototype when submerged in water has been investigated. The impeller, with a diameter of 2.870m belongs to a pump-turbine unit with a power of around 100MW. To analyze the influence of the added mass, both experimental tests and numerical simulations have been carried out. The experiment has been performed in air and in water. From the frequency response functions the modal characteristics such as natural frequencies and mode shapes have been obtained. A numerical simulation using FEM (Finite Elements Model) was done using the same boundary conditions as in the experiment (impeller in air and surrounded by a mass of water). The modal behaviour has also been calculated. The numerical results were compared with the available experimental results. The comparison shows a good agreement in the natural frequency values both in air and in water. The reduction in frequency due to the added mass effect of surrounding fluid has been calculated. The physics of this phenomenon due to the fluid structure interaction has been investigated from the analysis of the mode-shapes.

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Nondestructive Detection of a Crack in a Triangular Cantilever Beam Based on Frequency Measurement

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.2285 ◽

2007 ◽

Vol 353-358 ◽

pp. 2285-2288

Author(s):

Fei Wang ◽

Xue Zeng Zhao

Keyword(s):

Cantilever Beam ◽

Natural Frequencies ◽

Frequency Measurement ◽

Crack Size ◽

Force Sensors ◽

Rotational Spring ◽

Cantilever Deflection ◽

Crack Location ◽

Small Force ◽

Point Of Intersection

Triangular cantilevers are usually used as small force sensors in the transverse direction. Analyzing the effect of a crack on transverse vibration of a triangular cantilever will be of value to users and designers of cantilever deflection force sensors. We present a method for prediction of location and size of a crack in a triangular cantilever beam based on measurement of the natural frequencies in this paper. The crack is modeled as a rotational spring. The beam is treated as two triangular beams connected by a rotational spring at the crack location. Formulae for representing the relation between natural frequencies and the crack details are presented. To detect crack details from experiment results, the plots of the crack stiffness versus its location for any three natural modes can be obtained through the relation equation, and the point of intersection of the three curves gives the crack location. The crack size is then calculated using the relation between its stiffness and size. An example to demonstrate the validity and accuracy of the method is presented.

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Effect of Dynamic Shear Force on Fastener Loosening in Assemblies

Volume 1C: 16th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc97/vib-3904 ◽

1997 ◽

Author(s):

Yubo Dong ◽

Daniel P. Hess

Keyword(s):

Cantilever Beam ◽

Static Load ◽

Nodal Line ◽

Shear Stresses ◽

Dynamic Shear ◽

Bernoulli Beam ◽

Cyclic Shear ◽

Nodal Lines ◽

Inertial Loading ◽

Euler Bernoulli Beam

Abstract Placement and orientation of fasteners in assemblies is generally based on convenience or static load and strength considerations. Vibration and other dynamic loads can result in loosening of threaded product, particularly when cyclic shear stresses are present. This paper investigates the placement of a bolt and nut on a compound cantilever beam subjected to dynamic inertial loading. Calculations for an inertial loaded, cantilever, Euler-Bernoulli beam show that the dynamic shear stress is maximum near the dynamic nodal lines, and essentially vanishes near the anti-nodes. Experiments with a compound cantilever beam assembly with one fastener reveal that loosening occurs more readily when the bolt and nut are placed near a nodal line. Data presented include time to loosen, break-away torque, and acceleration level. The data shows that fastener integrity is maintained for longer periods of time and with lower tightening torques, when the bolt and nut are positioned away from nodal lines where shear stresses are lower, even though acceleration levels are higher.

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Vibration of Triangular Cantilever Plates by the Ritz Method

Journal of Applied Mechanics ◽

10.1115/1.4010935 ◽

1954 ◽

Vol 21 (4) ◽

pp. 365-370

Author(s):

B. W. Andersen

Keyword(s):

Cantilever Beam ◽

Natural Frequencies ◽

Ritz Method ◽

Plan View ◽

Modes Of Vibration ◽

Accuracy Of Results ◽

Isosceles Triangles

Abstract Using the method published by Ritz in 1909, natural frequencies and corresponding node lines have been determined for two symmetric and two antisymmetric modes of vibration of isosceles triangular plates clamped at the base and having length-to-base ratios of 1, 2, 4, and 7 and for the two lowest modes of right triangular plates clamped along one leg and having ratios of the length of the free leg to that of the clamped one of 2, 4, and 7. A nonorthogonal co-ordinate system was used which gave constant limits of integration over the area of the triangle. The co-ordinate transformation made it necessary to modify the functions used by Ritz in approximating deflections and to consider cross products in the integration. The integration was done numerically, using tables compiled by Young and Felgar in 1949. To check the accuracy of results, a solution was obtained to the problem of a vibrating cantilever beam of uniform depth and triangular plan view. The results obtained were found to be consistent with those obtained for the plates by using an eight-term series to approximate the deflections of the symmetric plates (isosceles triangles) and a six-term series to approximate the deflections of the unsymmetric plates (right triangles).

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Cantilever Beam Metastructure for Active Broadband Vibration Suppression

University of the Future: Re-Imagining Research and Higher Education ◽

10.29117/quarfe.2020.0087 ◽

2020 ◽

Author(s):

Ratiba Fatma Ghachi ◽

Wael Alnahhal ◽

Osama Abdeljaber

Keyword(s):

Cantilever Beam ◽

Natural Frequencies ◽

Vibration Suppression ◽

Research Work ◽

Peak Frequency ◽

Experimental Frequency ◽

Transmission Frequency ◽

Vibration Attenuation ◽

The Masses ◽

Zigzag Structure

This paper presents a beam structure of a new metamaterial-inspired dynamic vibration attenuation system. The proposed experimental research presents a designed cantilevered zigzag structure that can have natural frequencies orders of magnitude lower than a simple cantilever of the same scale. The proposed vibration attenuation system relies on the masses places on the zigzag structure thus changing the dynamic response of the system. The zigzag plates are integrated into the host structure namely a cantilever beam with openings, forming what is referred to here as a metastructure. Experimental frequency response function results are shown comparing the response of the structure to depending on the natural frequency of the zigzag structures. Results show that the distributed inserts in the system can split the peak response of the structure into two separate peaks rendering the peak frequency a low transmission frequency. These preliminary results provide a view of the potential of research work on active-controlled structures and nonlinear insert-structure interaction for vibration attenuation.

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NONLINEAR NATURAL FREQUENCIES OF A TAPERED CANTILEVER BEAM

10.18057/ijasc.2009.5.3.3 ◽

2009 ◽

pp. 259-272

Author(s):

M. Abdel-Jaber ◽

◽

A.A. Al-Qaisia ◽

M.S. Abdel-Jaber ◽

◽

...

Keyword(s):

Cantilever Beam ◽

Natural Frequencies ◽

Tapered Cantilever Beam

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Structural seismic characteristics assessment of LMFR fuel assembly hexagonal wrapper over operational temperature range

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp1904313k ◽

2019 ◽

Vol 34 (4) ◽

pp. 313-324

Author(s):

M. Khizer ◽

Zhang Yong ◽

Yang Guowei ◽

Wu Qingsheng ◽

Wu Yican

Keyword(s):

Fuel Assembly ◽

Fast Reactor ◽

Natural Frequencies ◽

Mass Effect ◽

Added Mass ◽

Reactor Fuel ◽

Temperature Range ◽

Fast Reactor Fuel ◽

Lead Bismuth Eutectic ◽

Reactor Fuel Assembly

In this study, the structural integrity of liquid metal fast reactor fuel assembly has been established for different parameters considering the optimum fuel design. Analytical calculation of added mass effect due to lead bismuth eutectic and verification through previously presented theories, has been established. The integrity of the hexagonal wrapper of fuel assembly has been guaranteed over the entire operating temperature range. Effect of temperature on the density of lead bismuth eutectic, the subsequent change in added mass of lead bismuth eutectic, the effect on natural frequencies and effect on stresses on wrapper, has been studied in detail. A simple empirical relationship is presented for estimation of added mass effect for lead bismuth eutectic type fast reactors for any desired temperature. An approach for assessment of fast reactor fuel assembly performance has been outlined and calculated results are presented. Nuclear seismic rules require that systems and components which are important to safety, shall be capable of bearing earthquake effects and their integrity and functionality should be guaranteed. Mode shapes, natural frequencies, stresses on wrapper and seismic aspect has also been considered using ANSYS. Modal analysis has been compared in vacuum and lead bismuth eutectic using the calculated added mass.

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