Spatial Electrostrictive Actuation of Circular Cylindrical Tubes

2008 ◽  
Author(s):  
Shih-Lin Huang ◽  
Chin-Chou Chu ◽  
Chien C. Chang ◽  
Horn-Sen Tzou
Keyword(s):  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Input Voltage ◽  
Positive Control ◽  
Design Guidelines ◽  
Design Parameters ◽  
Control Force ◽  
Cylindrical Tubes ◽  
Piping Systems ◽  
Circular Cylindrical Shells

Circular cylindrical shells are common components in aerospace structures and many other engineering systems, e.g., rockets, tubes, piping systems, peristaltic pumps, storage tanks, etc. Electromechanical actuators laminated on the shell surfaces can certainly strengthen the shell when needed. Or, regulated inputs to the surface actuators can introduce prescribed surface waves to control the shell oscillation. This study is to evaluate spatial actuation characteristics of circular cylindrical shells using segmented electrostrictive actuators. Electrostrictive actuations induced by surface laminated electrostrictive actuators are defined first. Governing equations of a hybrid circular cylindrical shell/electrostrictive actuator system are formulated. The total electrostrictive actuation and its contributing circumferential membrane/bending and longitudinal bending components are evaluated with respect to shell modal characteristics, design parameters and control voltages. The actuator’s quadratic behavior only generate a positive control force or moment and thus an actuator patch can suppress (or amplify) the vibration in the positive (or negative) displacement. Accordingly, the quadratic electrostrictive actuation suggests that appropriate input voltage(s) need to be carefully applied to specific actuator(s) or regions in order to control, but not to amplify, the shell oscillations. Based on the spatially distributed modal actuation, generic design guidelines and optimal actuation locations are proposed.

Free Asymmetric Vibrations of Composite Full Circular Cylindrical Shells Stiffened by a Bonded Central Shell Segment

2004 ◽  
Author(s):  
U. Yuceoglu ◽  
V. O¨zerciyes
Keyword(s):  
Cylindrical Shell ◽  
Shell Theory ◽  
Natural Frequencies ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Adhesive Layer ◽  
Shear Stresses ◽  
First Order ◽  
Stress Resultant ◽  
Circular Cylindrical Shells

This study is concerned with the “Free Asymmetric Vibrations of Composite Full Circular Cylindrical Shells Stiffened by a Bonded Central Shell Segment.” The base shell is made of an orthotropic “full” circular cylindrical shell reinforced and/or stiffened by an adhesively bonded dissimilar, orthotropic “full” circular cylindrical shell segment. The stiffening shell segment is located at the mid-center of the composite system. The theoretical analysis is based on the “Timoshenko-Mindlin-(and Reissner) Shell Theory” which is a “First Order Shear Deformation Shell Theory (FSDST).” Thus, in both “base (or lower) shell” and in the “upper shell” segment, the transverse shear deformations and the extensional, translational and the rotary moments of inertia are taken into account in the formulation. In the very thin and linearly elastic adhesive layer, the transverse normal and shear stresses are accounted for. The sets of the dynamic equations, stress-resultant-displacement equations for both shells and the in-between adhesive layer are combined and manipulated and are finally reduced into a ”Governing System of the First Order Ordinary Differential Equations” in the “state-vector” form. This system is integrated by the “Modified Transfer Matrix Method (with Chebyshev Polynomials).” Some asymmetric mode shapes and the corresponding natural frequencies showing the effect of the “hard” and the “soft” adhesive cases are presented. Also, the parametric study of the “overlap length” (or the bonded joint length) on the natural frequencies in several modes is considered and plotted.

scholarly journals Vibration Characteristics of Ring-Stiffened Functionally Graded Circular Cylindrical Shells

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Muhmmad Nawaz Naeem ◽  
Shazia Kanwal ◽  
Abdul Ghafar Shah ◽  
Shahid Hussain Arshad ◽  
Tahir Mahmood
Keyword(s):  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Lagrangian Function ◽  
Dynamical Equations ◽  
Graded Materials ◽  
Present Technique ◽  
Circular Cylindrical Shells ◽  
Stiffened Cylindrical Shells

The vibration characteristics of ring stiffened cylindrical shells are analyzed. These shells are assumed to be structured from functionally graded materials (FGM) and are stiffened with isotropic rings. The problem is formulated by coupling the expressions for strain and kinetic energies of a circular cylindrical shell with those for rings. The Lagrangian function is framed by taking difference of strain and kinetic energies. The Rayleigh-Ritz approach is employed to obtain shell dynamical equations. The axial model dependence is approximated by characteristic beam functions that satisfy the boundary conditions. The validity and efficiency of the present technique are verified by comparisons of present results with the previous ones determined by other researchers.

Aerothermoelastic Stability of Functionally Graded Circular Cylindrical Shells

2010 ◽  
Author(s):  
Farhad Sabri ◽  
Aouni A. Lakis
Keyword(s):  
Finite Element ◽  
Power Law ◽  
Shell Thickness ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Functionally Graded ◽  
Element Formulation ◽  
Power Law Distribution ◽  
Aerodynamic Pressure ◽  
Circular Cylindrical Shells

In this work, a hybrid finite element formulation is presented to predict the flutter boundaries of circular cylindrical shells made of functionally graded materials. The development is based on the combination of linear Sanders thin shell theory and classic finite element method. Material properties are temperature dependent, and graded in the shell thickness direction according to a simple power law distribution in terms of volume fractions of constituents. The temperature field is assumed to be uniform over the shell surface and along the shell thickness. First order piston theory is applied to account for supersonic aerodynamic pressure. The effects of temperature rise and shell internal pressure on the flutter boundaries of FG circular cylindrical shell for different values of power law index are investigated. The present study shows efficient and reliable results that can be applied to the aeroelastic design and analysis of shells of revolution in aerospace vehicles.

Distributed flexoelectric modal signals on circular cylindrical shells

2017 ◽  
Vol 232 (6) ◽  
pp. 952-961 ◽  
Author(s):  
Hua Li ◽  
Kaiming Hu ◽  
HS Tzou
Keyword(s):  
Strain Gradient ◽  
Cylindrical Shells ◽  
Mechanical Strain ◽  
Electric Polarization ◽  
Design Parameters ◽  
Flexoelectric Effect ◽  
Bending Strain ◽  
Longitudinal Bending ◽  
Circular Cylindrical Shells ◽  
Sensing Characteristics

Flexoelectricity exhibits both direct effect and converse effect. For direct flexoelectric effect, mechanical strain gradients induce a homogeneous electric polarization in dielectrics. Thus, the induced electric field between the electrodes can be measured. Compared with the piezoelectric sensors, the main advantage of the flexoelectric sensors is that they are not sensitive to the in-plane strains. This paper presents segmented flexoelectric sensors laminated on circular cylindrical shells, and investigates the electromechanical strain-gradient/signal-generation characteristics and distributed modal flexoelectric signals on the cylindrical shells. The dynamic equations of the proposed flexoelectric sensor are derived based on the direct flexoelectric effect and thin shell assumptions. The model of modal signal is derived to investigate the sensing characteristics. In case studies, the effects of design parameters, i.e. size and thickness of the sensors and geometry of the shells, are evaluated and compared. Numerical results indicate that the contribution of longitudinal bending strain gradient is dominant in the total signals of most evaluated modes, except that in modes 1 and 2, where the contribution of the circumferential bending strain gradient is slightly higher. The amplitudes of the modal signals decrease with the shell radius, but increase with the sensor thickness.

Experimental Study on Pre-Stressed Circular Cylindrical Shell

2012 ◽  
Author(s):  
Antonio Zippo ◽  
Marco Barbieri ◽  
Matteo Strozzi ◽  
Vito Errede ◽  
Francesco Pellicano
Keyword(s):  
Experimental Study ◽  
Cylindrical Shell ◽  
Axial Load ◽  
Nonlinear Vibrations ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Experimental Studies ◽  
Element Model ◽  
Experimental Setup ◽  
Circular Cylindrical Shells

In this paper an experimental study on circular cylindrical shells subjected to axial compressive and periodic loads is presented. Even though many researchers have extensively studied nonlinear vibrations of cylindrical shells, experimental studies are rather limited in number. The experimental setup is explained and deeply described along with the analysis of preliminary results. The linear and the nonlinear dynamic behavior associated with a combined effect of compressive static and a periodic axial load have been investigated for different combinations of loads; moreover, a non stationary response of the structure has been observed close to one of the resonances. The linear shell behavior is also investigated by means of a finite element model, in order to enhance the comprehension of experimental results.

STABILITY ANALYSIS OF AXIALLY COMPRESSED CIRCULAR CYLINDRICAL SHELLS

1998 ◽  
Vol 22 (3) ◽  
pp. 217-230
Author(s):  
J.L. Urrutia-Galicia ◽  
H. Rothert ◽  
U. Jäppelt
Keyword(s):  
Stability Analysis ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Longitudinal Direction ◽  
Wave Number ◽  
Stress Distributions ◽  
Stiffened Shells ◽  
Current Design ◽  
Circular Cylindrical Shells ◽  
Thickness Parameter

Within the range of the bending theory of thin shells, the nomogram and the corresponding formulas for stability analysis of thin simply supported circular cylindrical shells under uniform axial compression are presented. The nomogram provides the first critical load Pcr for m = 1 (m is the number of waves in the longitudinal direction) and the critical circumference wave number “ncr”, which could be used to assess current design methods of cylindrical pipes. The analysis accounts for the influence of the slenderness (l/r), the thickness parameter (t/r) and the deformability parameter [Formula: see text], already correlated with the nonlinearity of stress distributions in internally loaded pipes, in these definitions l, r and t stand for the length, the radius and the thickness of a circular cylindrical shell. To end this presentation it will be seen that when the available experimental data of stringer stiffened shells are grouped and analyzed including all relevant parameters then the results of experimental evidences exhibit the same trends shown by the theoretical results of isotropic shells.

The Effect of Internal Flowing Fluid on the Non-Linear Behavior of Orthotropic Circular Cylindrical Shells

2014 ◽  
Vol 706 ◽  
pp. 54-68 ◽  
Author(s):  
Z.J.G.N. del Prado ◽  
A.L.D.P. Argenta ◽  
F.M.A. da Silva ◽  
Paulo Batista Gonçalves
Keyword(s):  
Dynamic Instability ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Great Influence ◽  
Industrial Applications ◽  
Flowing Fluid ◽  
Non Linear ◽  
Circular Cylindrical Shells ◽  
Lateral Displacements ◽  
Orthotropic Shells

The great use of circular cylindrical shells for conveying fluid in modern industrial applications has made of them an important research area in applied mechanics. Many researchers have studied this problem, however just a reduced number of these works have as object the analysis of orthotropic shells. Although most investigations deal with the analysis of elastic isotropic shells in contact with internal and external quiescent or flowing fluid, several modern and natural materials display orthotropic properties and also stiffened cylindrical shells can be treated as equivalent uniform orthotropic shells. In this work, the influence of internal flowing fluid on the dynamic instability and non-linear vibrations of a simply supported orthotropic circular cylindrical shell subjected to axial and lateral time-dependent loads is studied. To model the shell, the Donnell’s non-linear shallow shell theory without considering the effect of shear deformations is used. A model with eight degrees of freedom is used to describe the lateral displacements of the shell. The fluid is assumed to be incompressible and non-viscous and the flow to be isentropic and irrotational. The Galerkin method is applied to derive the set of coupled non-linear ordinary differential equations of motion which are, in turn, solved by the Runge-Kutta method. The obtained results show that the presence of the internal fluid and material properties have a great influence on the vibration characteristics of the shell.

Creep Buckling of Thin-Walled Circular Cylindrical Shells Subject to Radial Pressure and Thermal Gradients

1971 ◽  
Vol 38 (1) ◽  
pp. 209-216 ◽  
Author(s):  
Y. S. Pan
Keyword(s):  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Radial Pressure ◽  
Temperature Gradients ◽  
Time Dependent ◽  
Thermal Gradients ◽  
Numerical Examples ◽  
Circular Cylindrical Shells ◽  
Thin Walled ◽  
Inelastic Strains

A method of calculating the creep deflections and predicting the creep collapse of a thin-walled circular cylindrical shell, subject to uniform external radial pressure and arbitrary temperature gradients, is shown. This method may also be applied to investigate the behavior of a shell subject to time-dependent temperature gradients and deformations due to other inelastic causes. The set of simultaneous differential equations of equilibrium in terms of creep, thermal, and other inelastic strains is presented. Applications of this method to long cylindrical shells are illustrated by two numerical examples.

Vibrations of Circular Cylindrical Shells With General Elastic Boundary Restraints

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
W. L. Li
Keyword(s):  
Boundary Conditions ◽  
Solution Method ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
Elastic Boundary ◽  
Special Cases ◽  
Ritz Procedure ◽  
Circular Cylindrical Shells ◽  
Elastically Restrained ◽  
Structural Engineers

Vibration of a circular cylindrical shell with elastic boundary restraints is of interest to both researchers and structural engineers. This class of problems, however, is far less attempted in the literature than its counterparts for beams and plates. In this paper, a general solution method is presented for the vibration analysis of cylindrical shells with elastic boundary supports. This method universally applies to shells with a wide variety of boundary conditions including all 136 classical (homogeneous) boundary conditions which represent the special cases when the stiffnesses for the restraining springs are set as either zero or infinity. The Rayleigh–Ritz procedure based on the Donnell–Mushtari theory is utilized to find the displacement solutions in the form of the modified Fourier series expansions. Numerical examples are given to demonstrate the accuracy and reliability of the current solution method. The modal characteristics of elastically restrained shells are discussed against different supporting stiffnesses and configurations.

Creep Buckling Analyses of Circular Cylindrical Shells Under Axial Compression—Bifurcation Buckling Analysis by the Finite Element Method

1987 ◽  
Vol 109 (2) ◽  
pp. 179-183 ◽  
Author(s):  
N. Miyazaki
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cylindrical Shell ◽  
Axial Compression ◽  
Circular Cylindrical Shell ◽  
Cylindrical Shells ◽  
The Finite Element Method ◽  
Bifurcation Buckling ◽  
Creep Buckling ◽  
Circular Cylindrical Shells

The finite element method is applied to the creep buckling of circular cylindrical shells under axial compression. Not only the axisymmetric mode but also the bifurcation mode of the creep buckling are considered in the analysis. The critical time for creep buckling is defined as either the time when a slope of a displacement versus time curve becomes infinite or the time when the bifurcation buckling occurs. The creep buckling analyses are carried out for an infinitely long and axially compressed circular cylindrical shell with an axisymmetric initial imperfection and for a finitely long and axially compressed circular cylindrical shell. The numerical results are compared with available analytical ones and experimental data.

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