Micro-Control Actions of Segmented Actuators on Shallow Paraboloidal Shell Reflectors

2002 ◽  
Author(s):  
S.-S. Lih ◽  
G. Hickey ◽  
J. H. Ding ◽  
H. S. Tzou
Keyword(s):  
Distributed Control ◽  
Design Guidelines ◽  
Shell Structures ◽  
Natural Mode ◽  
Shells Of Revolution ◽  
Control Effect ◽  
Control Cost ◽  
Control Actions ◽  
Control Forces ◽  
Paraboloidal Shell

Shallow paraboloidal shells of revolution are common components for reflectors, mirrors, etc. This study is to investigate the micro-control actions and distributed control effectiveness of precision paraboloidal shell structures laminated with segmented actuator patches. Mathematical models and governing equations of the paraboloidal shells laminated with distributed actuator layers segmented into patches are presented first, followed by formulations of distributed control forces and micro-control actions including meridional/circumferential membrane and bending control components based on an assumed mode shape function and the Taylor series expansion. Distributed control forces, patch sizes, actuator locations, micro-control actions, and normalized control authorities of a shallow paraboloidal shell are then analyzed in a case study. Analysis indicates that 1) the control forces and membrane/bending components are mode and location dependent, 2) the meridional/circumferential membrane control actions dominate the overall control effect, 3) there are optimal actuator locations resulting in the maximal control effects at the minimal control cost for each natural mode. The analytical results provide generic design guidelines for actuator placement on precision shallow paraboloidal shell structures.

Micro-Control Actions of Actuator Patches Laminated on Hemispherical Shells

2002 ◽  
Author(s):  
P. Smithmaitrie ◽  
H. S. Tzou
Keyword(s):  
Distributed Control ◽  
Pressure Vessels ◽  
Control Force ◽  
Control Effect ◽  
Control Effectiveness ◽  
Control Actions ◽  
Spatially Distributed ◽  
Membrane Bending ◽  
Control Forces ◽  
Electromechanical Actuation

Spherical shell-type structures and components appear in many engineering systems, such as radar domes, pressure vessels, storage tanks, etc. This study is to evaluate the micro-control actions and distributed control effectiveness of segmented actuator patches laminated on hemispheric shells. Mathematical models and governing equations of the hemispheric shells laminated with distributed actuator patches are presented first, followed by formulations of distributed control forces and micro-control actions including meridional/circumferential membrane and bending control components. Due to difficulties in analytical solution procedures, assumed mode shape functions based on the bending approximation theory are used in the modal control force expressions and analyses. Spatially distributed electromechanical actuation characteristics resulting from various meridional and circumferential actions are evaluated. Distributed control forces, patch sizes, actuator locations, micro-control actions, and normalized control authorities of a free-floating hemispheric shell are analyzed in a case study. Parametric analysis indicates that 1) the control forces and membrane/bending components are mode and location dependent and 2) the meridional/circumferential membrane control actions dominate the overall control effect.

Actuator Placement and Control Efficiency of Paraboloidal Shell Structures

2001 ◽  
Author(s):  
H. S. Tzou ◽  
J. H. Ding
Keyword(s):  
Distributed Control ◽  
Communication Systems ◽  
Design Parameters ◽  
Control Force ◽  
Shells Of Revolution ◽  
Control Effect ◽  
Membrane Bending ◽  
High Control ◽  
Control Forces ◽  
And Control

Abstract Paraboloidal shells of revolution are commonly used in communication systems, precision opto-mechanical systems and aerospace structures. This study is to investigate the precision distributed control effectiveness of paraboloidal shells laminated with segmented actuator patches. Mathematical models of the paraboloidal shells laminated with distributed actuator layers subjected to mechanical, temperature, and control forces are presented first, followed by formulations of distributed control forces with their contributing meridional/circumferential membrane and bending control components using an assumed mode shape function. Studies of actuator placements, control forces, contributing components, and normalized control authorities of paraboloidal shells are carried out. These forces and membrane/bending components basically exhibit distinct modal characteristics influenced by shell geometries and other design parameters. Analyses suggest that the membrane contributed components dominate the overall control effect. Locations with larger normalized forces indicate the areas with high control efficiencies, i.e., larger induced control force per unit actuator area. With limited actuators, placing actuators at those locations would lead to the maximal control effects.

Micro-Control Actions and Location Sensitivity of Actuator Patches Laminated on Toroidal Shells

2004 ◽  
Vol 126 (2) ◽  
pp. 284-297 ◽  
Author(s):  
H. S. Tzou ◽  
W. K. Chai ◽  
D. W. Wang
Keyword(s):  
Distributed Control ◽  
Piezoelectric Materials ◽  
Spatial Location ◽  
Critical Issue ◽  
Shell Structures ◽  
Toroidal Shell ◽  
Control Actions ◽  
Spatially Distributed ◽  
Control Forces ◽  
Toroidal Shells

Toroidal shell structures have been proposed for components of inflatable telescopes and space structures, etc. over the years. Thus, distributed control of toroidal shells becomes a critical issue in precision maneuver, operation, and reliability. The converse effect of piezoelectric materials has made it one of the best candidates for distributed actuators. The resultant control forces and micro-control actions induced by the distributed actuators depend on applied voltages, geometrical (e.g., spatial segmentation and shape) and material (i.e., various actuator materials) properties of the actuators. The purpose of this analysis is to study the spatial location effects of actuator placement and to evaluate the micro-control actions imposed upon toroidal shell structures. Mathematical models and governing equations of the toroidal shells laminated with distributed actuator patches are presented first, followed by formulations of distributed control forces and micro-control actions including meridional/circumferential membrane and bending control components. Spatially distributed electromechanical microscopic actuation characteristics and control effects resulting from various meridional and circumferential actions of actuator patches at various shell locations are evaluated.

Actuator Placement and Micro-Actuation Efficiency of Adaptive Paraboloidal Shells

2003 ◽  
Vol 125 (4) ◽  
pp. 577-584 ◽  
Author(s):  
H. S. Tzou ◽  
J. H. Ding
Keyword(s):  
Communication Systems ◽  
Design Parameters ◽  
Shells Of Revolution ◽  
Control Effect ◽  
Control Effectiveness ◽  
Membrane Bending ◽  
High Control ◽  
Control Forces ◽  
And Control ◽  
Actuator Placement

Paraboloidal shells of revolution are commonly used in communication systems, precision opto-mechanical systems and aerospace structures. This study is to investigate the precision distributed control effectiveness of adaptive paraboloidal shells laminated with segmented actuator patches. Mathematical models of the paraboloidal shells laminated with distributed actuator layers subjected to mechanical, temperature, and control forces are presented first. Then, formulations of distributed actuating forces with their contributing micro-meridional/circumferential membrane and bending components are derived using an assumed mode shape function. Studies of actuator placements, actuator induced control forces, micro-contributing components, and normalized actuation authorities of paraboloidal shells are carried out. These forces and membrane/bending components basically exhibit distinct modal characteristics influenced by shell geometries and other design parameters. Analyses suggest that the membrane-contributed components dominate the overall control effect. Locations with larger normalized forces indicate the areas with high control efficiencies, i.e., larger induced actuation force per unit actuator area. With limited actuators, placing actuators at those locations would lead to the maximal control effects of paraboloidal shells.

Micro-Control Characteristics of Conical Shell Sections

2003 ◽  
Author(s):  
W. K. Chai ◽  
H. S. Tzou ◽  
K. Higuchi
Keyword(s):  
Distributed Control ◽  
Conical Shell ◽  
Turbine Blades ◽  
Unit Weight ◽  
Solid Rocket Motor ◽  
Control Actions ◽  
Load Carrying ◽  
Spatially Distributed ◽  
Control Forces ◽  
Distributed Actuator

Rocket fairings, turbine blades, load carrying structure for solid rocket motor case, inter-stage joint, satellite-rocket joint etc., usually take the shape of conical shell sections. Conical shell has a large load carrying capacity per unit weight due to its high-strength, high-rigidity and light-weight properties. This paper is to evaluate spatially distributed microscopic control characteristics of distributed actuator patches bonded on conical shell surfaces. The converse effect of piezoelectric materials has been recognized as one of the best electromechanical effects for precision distributed control applications. The resultant control forces and micro-control actions induced by the distributed actuators depend on applied voltages, geometrical (e.g., spatial segmentation and shape) and material (i.e., various actuator materials) properties [8]. Mathematical models and modal domain governing equations of the conical shell section laminated with distributed actuator patches are presented first, followed by the formulations of distributed control forces and micro-control actions which can be refined to longitudinal/circumferential membrane and bending control components. Spatially distributed electromechanical microscopic actuation characteristics and control effects resulting from various longitudinal/circumferential actions of actuator patches are then evaluated.

Spatial Electrostrictive Modal Actuation of Conical Shells

2008 ◽  
Author(s):  
H. S. Tzou ◽  
W. K. Chai
Keyword(s):  
Conical Shell ◽  
Open Loop ◽  
Natural Mode ◽  
Solid Rocket Motor ◽  
Control Effect ◽  
Loop Control ◽  
Modal Expansion ◽  
Control Actions ◽  
Spatially Distributed ◽  
Control Equation

Horns, nozzles and load carrying structures of rockets, e.g., inter-stage joint, satellite-rocket joint, solid rocket motor case, etc., are usually made of circular conical shell sections. This study is to investigate distributed electrostrictive actuation and to evaluate spatially distributed microscopic control actions of distributed electrostrictive actuator segments bonded on conical shell surfaces. Mathematical model and open-loop control equations of a generic conical shell are defined first, followed by simplification to a free-free truncated conical shell section with segmented electrostrictive actuators. Natural mode shape functions are defined based on the Donnell-Mushtati-Vlasov approximation; independent modal control equation is derived by the modal expansion. Distributed control actions induced by the electrostrictive actuator segments are evaluated in the modal domain and the total control effect can be divided into four microscopic control actions: the longitudinal/circumferential membrane and bending control actions. Detailed parametric analyses of two mode groups indicate that 1) magnitudes of control actions comply with the quadratic increase with respect to control voltages and 2) the circumferential membrane control action is the most dominating component in the total shell control effect. Also, the spatially distributed modal actuation plots can be used to locate the most effective locations and/or regions of electrostrictive actuators placed on the shell surface.

Spatial Microscopic Actuations of Shallow Conical Shell Sections

2005 ◽  
Vol 11 (11) ◽  
pp. 1397-1411 ◽  
Author(s):  
W. K. Chai ◽  
J. G. Dehaven ◽  
H. S. Tzou
Keyword(s):  
Distributed Control ◽  
Conical Shell ◽  
High Performance ◽  
Piezoelectric Materials ◽  
Structural Systems ◽  
Solid Rocket Motor ◽  
Control Actions ◽  
Spatially Distributed ◽  
Control Forces ◽  
Distributed Actuator

In recent years there has been an interest in distributed control of shell structures because of its extensive applications in high performance structural systems. Conical shells are relevant to components of structural systems such as engine nozzles, interstage joints, satellite–rocket joints, load carrying structures for solid rocket motor cases, etc. In this paper we evaluate the spatially distributed microscopic control characteristics of distributed actuator patches laminated on conical shell surfaces. Piezoelectric materials have always been utilized for precision distributed control applications due to their converse effect. The resultant control forces and micro-control actions induced by distributed piezoelectric actuators depend on applied voltages, geometrical (e.g. spatial segmentation and shape) and material (i.e. various actuator materials) properties. Mathematical models and modal domain governing equations of the conical shell section laminated with distributed actuator patches are presented first, followed by the formulations of distributed control forces and micro-control actions, which can be refined to longitudinal and circumferential membrane/bending control components. We then evaluate the spatially distributed electromechanical microscopic actuation characteristics and control effects resulting from various longitudinal/circumferential actions of actuator patches.

Micro-Actuations and Location Sensitivity of Actuator Patches Laminated on Toroidal Shells

2002 ◽  
Author(s):  
H. S. Tzou ◽  
W. K. Chai ◽  
D. W. Wang
Keyword(s):  
Distributed Control ◽  
Piezoelectric Materials ◽  
Critical Issue ◽  
Toroidal Shell ◽  
Control Actions ◽  
Spatially Distributed ◽  
Control Forces ◽  
And Control ◽  
Actuator Placement ◽  
Toroidal Shells

Toroidal shell structure has been proposed for components of inflatable space structures and telescope etc. Thus, distributed control of toroidal shells becomes a critical issue in precision maneuver, operation, and reliability. The converse effect of piezoelectric materials has made it one of the best candidates for distributed control actuators. The resultant control forces and micro-control actions induced by the distributed actuators depend on applied voltages, geometrical (e.g., spatial segmentation and shape) and material (i.e., various actuator materials) properties of the actuators. The purpose of this analysis is to study the location effects of actuator placement and to evaluate the micro-control actions imposed upon toroidal shell structures. Mathematical models and governing equations of the toroidal shells laminated with distributed actuator patches are presented first, followed by formulations of distributed control forces and micro-control actions including meridional/circumferential membrane and bending control components. Spatially distributed electromechanical microscopic actuation characteristics and control effects resulting from various meridional and circumferential actions are evaluated.

Micro-Electromechanics of Sensor Patches of Free Paraboloidal Shell Structronic Systems

2002 ◽  
Author(s):  
J. H. Ding ◽  
H. S. Tzou
Keyword(s):  
Shape Control ◽  
Distributed Sensing ◽  
Signal Generation ◽  
Shell Structures ◽  
Shells Of Revolution ◽  
Distributed Sensors ◽  
Free Boundary Conditions ◽  
Parametric Studies ◽  
Paraboloidal Shell ◽  
Sensing Characteristics

Distributed sensing of structural states is essential to vibration control, health monitoring and shape control of precision structronic systems. Paraboloidal shells of revolution are widely used in aerospace, telecommunication, etc. structures. However, distributed sensing of paraboloidal shell structures is rarely investigated over the years. Micro-sensing characteristics, sensor segmentation, sensor placements, shell geometric parameters, etc. of deep/shallow paraboloidal shells are evaluated in this study. Signal generation of generic distributed sensors laminated on paraboloidal shells is defined; microscopic signal components of segmented sensor patches laminated on deep/shallow paraboloidal shells with free boundary conditions are analyzed. Parametric studies of microelectromechanics and microscopic signal generations of segmented sensor patches reveal detailed modal sensing signal generation and efficiency of segmented sensor patches laminated at various shell locations of three paraboloidal shells (i.e., a shallow, a standard, and a deep).

Seismic Control Effect for Nonlinear Benchmark Building Using Passive or Semi-Active Damper

2002 ◽  
Author(s):  
Akira Fukukita ◽  
Tomoo Saito ◽  
Keiji Shiba
Keyword(s):  
Active Control ◽  
Passive Control ◽  
Feedforward Control ◽  
Electrical Power ◽  
Control Device ◽  
Control Effect ◽  
Damping Force ◽  
Active Device ◽  
Seismic Control ◽  
Control Forces

We study the control effect for a 20-story benchmark building and apply passive or semi-active control devices to the building. First, the viscous damping wall is selected as a passive control device which consists of two outer plates and one inner plate, facing each other with a small gap filled with viscous fluid. The damping force depends on the interstory velocity, temperature and the shearing area. Next, the variable oil damper is selected as a semi-active control device which can produce the control forces by little electrical power. We propose a damper model in which the damping coefficient changes according to both the response of the damper and control forces based on an LQG feedback and feedforward control theory. It is demonstrated from the results of a series of simulations that the both passive device and semi-active device can effectively reduce the response of the structure in various earthquake motions.

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