An innovative passive control technique for industrial precast frames

2010 ◽  
Vol 32 (4) ◽  
pp. 1123-1132 ◽  
Author(s):  
Paolo Martinelli ◽  
Maria Gabriella Mulas
Keyword(s):  
Passive Control ◽  
Control Technique

scholarly journals Theoretical and Experimental Study of the Vibration Dynamics of a 3D-Printed Sandwich Beam With an Hourglass Lattice Truss Core

2021 ◽  
Vol 7 ◽  
Author(s):  
Zhenkun Guo ◽  
Guobiao Hu ◽  
Jingchao Jiang ◽  
Liuding Yu ◽  
Xin Li ◽  
...  
Keyword(s):  
Theoretical Model ◽  
3D Printing ◽  
Passive Control ◽  
Sandwich Beam ◽  
Control Technique ◽  
Sandwich Beams ◽  
Element Analysis ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Truss Core

3D printing (also known as additive manufacturing) has been developed for more than 30 years. The applications of 3D printing have been increasingly extended to a variety of engineering fields in recent years. The sandwich material with a high strength and overall low density is a kind of artificial material that has been extensively used in various industrial and daily life applications. This paper presents a comprehensive vibration analysis and passive control technique for a cantilevered sandwich beam with an hourglass lattice truss core fabricated with 3D printing technology. The governing equation of the beam is established by using a homogenized model and the Hamilton's principle, from which the natural frequencies are determined. The theoretical model is verified by the results from the existing literature and the finite element analysis. The frequency response of the sandwich beam measured experimentally further validates the proposed model. Subsequently, a non-linear energy sink (NES) is proposed for being employed to passively suppress the vibration of the sandwich beam. A parametric study based on the theoretical model confirms the viability of using NES to effectively control the vibration of the sandwich beam. This work presents a good demonstration of using 3D printing technology for fabricating sandwich beams with a complicated lattice core. More importantly, some guidelines regarding the dynamic analysis of sandwich beams are provided. In addition, the analytical method presented in this work provides a potential means to theoretically explore the advantages of using sandwich beams for energy harvesting in the future.

Suppression of Acoustic Resonance in Rectangular Cavities Using Spanwise Control Cylinder

2015 ◽  
Author(s):  
Ahmed Omer ◽  
Atef Mohany
Keyword(s):  
Shear Layer ◽  
Vortex Shedding ◽  
Passive Control ◽  
Acoustic Resonance ◽  
Control Technique ◽  
Resonance Excitation ◽  
Base Case ◽  
Detached Eddy Simulation ◽  
Free Shear Layer ◽  
Aspect Ratios

Flow over cavities can be a significant source of noise in many engineering applications when a coupling occurs between the flow instabilities at the cavity mouth and one of the acoustic cross-modes in the accommodating enclosure. In this paper, a passive noise control technique using a spanwise cylinder located at the cavity upstream edge is investigated experimentally for two different cavities with aspect ratios of L/D = 1.0 and 1.67, where L is the cavity length and D is the cavity depth. The effect of both the location of the cylinder and its diameter on the flow-excited acoustic resonance is investigated in air flow with Mach number up to 0.45. This passive control technique is found to be effective in suppressing the acoustic resonance excitation when compared to the base case where no cylinder is attached. It is observed that using the optimum cylinder location and diameter reduces the acoustic pressure to less than 140 Pa, compared to the base case with values exceeding 2000 Pa. Moreover, a shift in the onset of acoustic resonance to higher velocities is observed. Localized hot-wire measurements of the free shear layer at the cavity mouth during the off-resonance conditions reveal that attaching a spanwise cylinder at the cavity upstream edge reduces the spanwise correlation of the free shear layer which, in turns, reduces its susceptibility to acoustic excitation. To further understand the interaction between the cylinder’s vortex shedding and the free shear layer at the cavity mouth, a numerical simulation of the flow field using a detached eddy simulation (DES) model has been carried out. The simulation shows that the suppression occurs due to a disturbance of the cavity shear layer by the vortex shedding from the cylinder which results in altering the impingement point at the downstream edge of the cavity, and thereby weakening the feedback cycle that controls the acoustic resonance excitation.

Passive Control of Two-Phase Flow Thermal Instabilities in a Vertical Tube Evaporator

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Ghazali Mebarki ◽  
Samir Rahal
Keyword(s):  
Heat Transfer ◽  
Void Fraction ◽  
Passive Control ◽  
Two Phase Flow ◽  
Tube Wall ◽  
Vertical Tube ◽  
Control Technique ◽  
Control Element ◽  
Phase Flow ◽  
Two Phase

Passive heat transfer techniques are considered to be one of the most important means to enhance heat transfer in heat exchangers that allow also reducing their size and manufacturing cost. Moreover, this passive technique can also be used to control the thermal instabilities caused by the two-phase flow in the evaporators. The thermal instabilities are undesirable because they can lead to a tube failure. For this purpose, a numerical study of the two-phase flow with evaporation in a vertical tube has been performed in this work. The volume of fluid (VOF) multiphase flow method has been used to model the water vapor–liquid two-phase flow in the tube. A phase-change model, for which source terms have been added in the continuity and energy equation, has been used to model the vaporization. The numerical simulation procedure was validated by comparing the obtained results with those given in the literature. The passive control technique used here is a ring element with square cross section, acting as a vortex generator, which is attached to the tube wall at various positions along the tube. Instabilities of temperature and void fraction at the tube wall have been analyzed using fast Fourier transforms (FFTs). The results show that the attachment of the control element has a significant influence on the value and distribution of the void fraction. Higher positions of the control element along the tube allow reducing the magnitude of void fraction oscillations.

On Dynamic Modelling of Compressed Air Engine With Connecting-Rod-Crank to Control Angular Position of Oscillating Rotation

2016 ◽  
Author(s):  
Alexandre C. Alves ◽  
Jose M. Balthazar ◽  
Angelo M. Tusset ◽  
Rodrigo T. Rocha ◽  
Atila M. Bueno
Keyword(s):  
Active Control ◽  
Passive Control ◽  
Angular Position ◽  
Dynamic Modelling ◽  
Rigid Bodies ◽  
Compressed Air ◽  
Control Technique ◽  
Connecting Rod ◽  
Nonlinear Dynamic Model ◽  
Linear Quadratic

In this work is examined the dynamic behavior and the controllability of a compressed air engine with a connecting-rod-crank. The pneumatic motor is composed by a monocylinder, a connecting-rod and a control crank to the oscillating rotation. For the obtainment the nonlinear mathematical model was considered the Lagrange’s method and the components of the physical system in the model are considered as rigid bodies with unilateral restriction. Numerical analysis of the application of the passive control position by a nonconservative pneumatic force with pilot valves in the cylinder showed that it was not possible an exact control to the angular position desired for the output crank. To solve this problem, it is proposed an active control by the Linear Quadratic Regulator method (LQR), to the control of the connecting-rod-crank mechanism. In addition, the robustness of the proposed control technique is tested considering noise measurement in pneumatic external excitation. The numerical simulation results showed the efficiency of the proposed control to the nonlinear dynamic model of the connecting-rod-crank and the sensibility analysis for parametric errors to the control of the oscillating angular positions, demonstrating so that the proposed active control is adequate for this system.

A friction-based passive control technique to mitigate wind induced structural demand to wind turbines

2021 ◽  
Vol 232 ◽  
pp. 111744
Author(s):  
Moira Di Paolo ◽  
Iolanda Nuzzo ◽  
Nicola Caterino ◽  
Christos T. Georgakis
Keyword(s):  
Wind Turbines ◽  
Passive Control ◽  
Control Technique ◽  
Structural Demand

scholarly journals Passive vibration control in a civil structure: Experimental results

2019 ◽  
Vol 52 (7-8) ◽  
pp. 938-946 ◽  
Author(s):  
Josué Enríquez-Zárate ◽  
Hugo Francisco Abundis-Fong ◽  
Ramiro Velázquez ◽  
Sebastián Gutiérrez
Keyword(s):  
Vibration Control ◽  
Structural Control ◽  
Passive Control ◽  
Tuned Mass Damper ◽  
Experimental Results ◽  
Structural Vibration ◽  
Control Technique ◽  
Primary System ◽  
Vibration Absorption ◽  
Mass Damper

The problem of vibrations in civil structures is common; nevertheless, its negative effects can be significantly reduced using structural control methods with intention of maintaining structural welfare as much as possible. This work deals with the study of structural vibration control in a model of a civil-like structure, which consists of three-level building with a tuned mass damper implemented as a passive vibration absorber, mounted on the top of the structure, to attenuate the harmonic vibrations provided by an electromagnetic actuator connected at the base of the primary system. The action of the tuned mass damper is evaluated from an energy approach. The dissipation of energy in the overall system is conducted in an experimental way, where the passive control technique is designed to minimize the undesirable forced dynamic response of the main structure via the tuned mass damper. Experimental results are provided to show the effective performance of the proposed passive vibration absorption scheme to suppress resonant frequency harmonic excitations disturbing the primary system, evaluating the performance energy and contribution of the dissipative device for the energy release in the overall system.

Augmentation of the magnitude of the impulsive wave discharging from a tube

2001 ◽  
Vol 215 (2) ◽  
pp. 191-199 ◽  
Author(s):  
H-D Kim ◽  
T Setoguchi ◽  
H Kashimura ◽  
R S Raghunathan
Keyword(s):  
Passive Control ◽  
Weak Shock ◽  
Control Technique ◽  
Straight Tube ◽  
Governing Equations ◽  
Numerical Result ◽  
Impulsive Wave ◽  
Computational Work ◽  
Sudden Enlargement ◽  
Tube Exit

The present paper describes experimental and computational work to augment the magnitude of the impulsive wave generated at the exit of a pipe. An experiment was performed using a simple shock tube with an open end, and numerical calculations were carried out to solve the unsteady, axisymmetric, inviscid, compressible governing equations that represent the experimental flowfield. The control strategy applied was to alter the exit geometry of a straight tube to a sudden enlargement tube and a flare tube. The effects of the configurations of the tube exit on the magnitude of the impulsive wave were investigated over the range of weak shock Mach numbers from 1.01 to 1.10. Various types of geometric parameter were explored for the configurations of the tube exit. The results obtained were compared with those of the straight tube tests. The numerical result predicted the magnitude of the experimented impulsive waves with a good accuracy. The present passive control technique enabled the magnitude of the impulsive wave to be augmented by about 24 per cent, compared with that of the straight tube with no control.

Passive Control of Flow Induced Vibrations by Splitter Blades

1993 ◽  
Author(s):  
Hsiao-Wei D. Chiang ◽  
Sanford Fleeter
Keyword(s):  
Passive Control ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Control Technique ◽  
Influence Coefficient ◽  
Vibrational Response ◽  
Unsteady Aerodynamic ◽  
Influence Coefficients ◽  
Loading Effects ◽  
Flow Induced Vibrations

Splitter blades as a passive control technique for flow induced vibrations is investigated by developing an unsteady aerodynamic model to predict the effect of incorporating splitter blades into the design of an axial flow blade row operating in an incompressible flow field. The splitter blades, positioned circumferentially in the flow passage between two principal blades, introduce aerodynamic and/or combined aerodynamic-structural detuning into the rotor. The unsteady aerodynamic gust response and resulting oscillating cascade unsteady aerodynamics, including steady loading effects, are determined by developing a complete first-order unsteady aerodynamic analysis together with an unsteady aerodynamic influence coefficient technique. The torsion mode flow induced vibrational response of both uniformly spaced tuned rotors and detuned rotors are then predicted by incorporating the unsteady aerodynamic influence coefficients into a single-degree-of-freedom aeroelastic model. This model is then utilized to demonstrate that incorporating splitters into axial flow rotor designs is beneficial with regard to flow induced vibrations.

Sign in / Sign up

Export Citation Format

Share Document