Theory and Application of Localized Vibration Control Strategy in Cable-Suspended Membrane Space Structures

Aerospace ◽  
2005 ◽  
Author(s):  
Hiraku Sakamoto ◽  
K. C. Park
Keyword(s):  
Controller Design ◽  
Low Frequency ◽  
Space Structures ◽  
Membrane Structures ◽  
Flexible Support ◽  
Low Frequency Vibration ◽  
And Control ◽  
Structural Mass ◽  
The Web ◽  
Frequency Harmonic

The present study explores both structural and controller design to attenuate vibration in large membrane structures especially due to low-frequency harmonic excitations. It is very difficult for membrane structures to suppress the low-frequency vibration induced by flexible support structures, because a lightly pre-stressed membrane has extremely low mode frequencies and little damping effect. The present study proposes the use of web-like perimeter cables around a membrane, and the application of simple and lightweight active controllers only along the web cables. This strategy successfully suppresses the membrane vibration when the web-cable configuration is appropriately tailored. Both linear and nonlinear finite-element analyses exhibit a clear tradeoff between structural mass and control efficiency.

Localized Vibration Isolation Strategy for Low-Frequency Excitations in Membrane Space Structures

2006 ◽  
Vol 128 (6) ◽  
pp. 790-797 ◽  
Author(s):  
Hiraku Sakamoto ◽  
K. C. Park
Keyword(s):  
Vibration Isolation ◽  
Controller Design ◽  
Low Frequency ◽  
Space Structures ◽  
Membrane Structures ◽  
Low Frequency Vibration ◽  
And Control ◽  
Structural Mass ◽  
The Web ◽  
Frequency Harmonic

The present study explores both structural and controller design to attenuate vibration in large membrane space structures, especially due to low-frequency harmonic excitations. It is very difficult for membrane structures to suppress the low-frequency vibration induced by flexible support structures, because a lightly prestressed membrane has extremely low mode frequencies and little damping effect. The present study proposes the use of weblike perimeter cables around a membrane, and the application of simple and lightweight active controllers only along the web cables in order to isolate the membrane from vibration. This strategy successfully reduces the membrane vibration when the web-cable configuration is appropriately tailored. Both linear and nonlinear finite-element analyses exhibit a clear tradeoff between structural mass and control efficiency.

The Wide World of Translating Webs

1997 ◽  
Author(s):  
C. D. Mote ◽  
Eric Mockensturm
Keyword(s):  
Material Handling ◽  
Problem Area ◽  
Space Structures ◽  
Magnetic Media ◽  
Membrane Structures ◽  
Polymer Sheets ◽  
The Rich ◽  
Machine Systems ◽  
Experimental Findings ◽  
The Web

Abstract Our webs are wide, very thin, two-dimensional, continua arising commonly as a material in transport in machine systems. Though they are thin, webs often require modeling as plates or shells, albeit very thin and flexible ones, because even small bending stiffness distinguishes their behaviors from membranes in critical ways. Technological applications generating interest in web mechanics include the manufacture and handling of paper where wide sheets are transported by rollers at the highest possible speed, thereby maximizing productivity. Material handling problems of a similar type also arise with tissues, films, magnetic media, textiles, fabrics, polymer sheets, and the like. In a technical world pressing for ever higher speeds of stable transport, the web instabilities of wrinkling and flutter commonly bound the productivity of a technological process. These instabilities can result in permanent damage or rupture of the material and disruption of the manufacturing process. Consequently, the presentation today addresses some findings on webs that relate to their modeling, the prediction and causes of wrinkling, and the effect of roller misalignment on web behavior during transport. To allow us to maintain this focus, the rich collection of works on membrane structures, including modeling of inflated membranes, space structures and fiber reinforced membranes will not be part of our discussion. For attention to interesting membrane developments readers might examine Reissner (1938), Steigmann and Pipkin (1989), Jenkins and Leonard (1991), Li and Steigmann (1993), and Haseganu and Steigmann (1994). The most important topic of web flutter caused by air flows over the web surfaces will not be addressed, though recent experimental findings can be found in Chang and Moretti (1992) and Nguyen (1993). Theories modeling the flow and web in these coupled problems tend to underestimate the flutter speeds. This problem area is one of great importance.

System Identification for Boring Bar Chatter Control

1993 ◽  
Author(s):  
Jonathan A. Embry ◽  
Suzanne Weaver Smith ◽  
Bruce L. Walcott
Keyword(s):  
Aerospace Industry ◽  
Low Frequency ◽  
Structure Identification ◽  
Space Structures ◽  
Modal Interactions ◽  
Element Analysis ◽  
Flexible Space Structures ◽  
Boring Bar ◽  
Low Frequency Vibration ◽  
Chatter Control

Abstract The boring bar is used to provide smooth, accurate cuts in materials. However, when the length to diameter (L/D) ratio of the boring bar becomes large, low-frequency vibration, or chatter, results. Initial attempts to control this unwanted vibration with an active absorber have been successful, but in some configurations problems remain. In this paper, algorithms for flexible structure identification widely used in the aerospace industry are applied to a number of boring bar setups to identify the vibration characteristics of each system. Emphasis is placed on one class of methods which includes the Eigensystem Realization Algorithm (ERA), developed for identification of flexible space structures. The resulting identified characteristics are compared and contrasted. Results are also compared to finite element analysis predictions. From the current identification results, implications for chatter control are discussed, including the possibility of nonlinear modal interactions.

Cause analysis of low frequency vibration of flexible support stator frame for giant hydro generator

2014 ◽  
Vol 22 (14) ◽  
pp. 3151-3156
Author(s):  
Li Jianwei ◽  
Xiao Liangyu ◽  
Tian Chao ◽  
Li Yongheng ◽  
Que Guangqing
Keyword(s):  
Low Frequency ◽  
Cause Analysis ◽  
Flexible Support ◽  
Low Frequency Vibration

scholarly journals Vibration Excitation and Control of a Pedestrian Walkway by Individuals and Crowds

2005 ◽  
Vol 12 (5) ◽  
pp. 333-347 ◽  
Author(s):  
James Mark William Brownjohn ◽  
Tao Neng Fu
Keyword(s):  
Force Plate ◽  
Low Frequency ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Low Frequency Vibration ◽  
Lateral Response ◽  
Single Mass ◽  
The Subject ◽  
Mass Spring ◽  
And Control

As part of a continuing study on effects of humans on loading and dynamic response of footbridges, a steel frame walkway has been the subject of studies on the effects of multiple pedestrians with respect to loading and response mitigation. Following finite element modeling and experimental modal analysis to identify the low frequency vibration modes likely to be excited by normal walking, the variation of response with pedestrian density and of system damping and natural frequency with occupancy by stationary pedestrians were both studied. The potentially mitigating effect of stationary occupants is still not well understood and the study included direct measurement of damping forces and absorbed energy using a force plate. The various tests showed that energy dissipation measured directly was consistent with the observed change in damping, that vertical and lateral response both varied approximately with square root of number of pedestrians, and that the simple model of a human as a single mass-spring-damper system may need to be refined to fit observed changes in modal parameters with a crowd of humans present. Modal parameter changes with moving pedestrians were small compared to those with stationary pedestrians indicating that within limits, modal parameters for the empty structure could be used in analysis.

scholarly journals A Generic Control-Oriented Model Order Reduction Approach for High Step-Up DC/DC Converters Based on Voltage Multiplier

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1971
Author(s):  
Binxin Zhu ◽  
Qingdian Zeng ◽  
Mahinda Vilathgamuwa ◽  
Yang Li ◽  
Yao Chen
Keyword(s):  
Control System ◽  
System Design ◽  
Controller Design ◽  
Low Frequency ◽  
Order Reduction ◽  
Control System Design ◽  
Model Order ◽  
Modeling And Control ◽  
Simulation Results ◽  
And Control

The modeling and control system design of high step-up DC/DC converters based on voltage multipliers (VMs) are difficult, due to the various circuit topologies and the presence of large number of capacitors in VMs. This paper proposes a generic approach to reduce the model order of such converters by replacing the VM capacitors with voltage sources controlled by the output voltage of the converter. Theoretical analysis and simulation results show that the derived models can accurately represent the low frequency response of the converter which is valuable for obtaining a small-signal AC model for control system design. The detailed modeling and controller design process are demonstrated for the converter, and the obtained simulation results are verified experimentally on a 400 W prototype.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Rancang Bangun Sistem Penerimaan Dan Mutasi Barang Pada PDAM Tirta Kerta Raharja

Sensi Journal ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 236-246
Author(s):  
Ilamsyah Ilamsyah ◽  
Yulianto Yulianto ◽  
Tri Vita Febriani
Keyword(s):  
System Analysis ◽  
Object Oriented ◽  
Analysis Method ◽  
Web Based ◽  
Visual Modeling ◽  
Long Time ◽  
The Right ◽  
And Control ◽  
Web Based System ◽  
The Web

The right and appropriate system of receiving and transferring goods is needed by the company. In the process of receiving and transferring goods from the central warehouse to the branch warehouse at PDAM Tirta Kerta Raharja, Tangerang Regency, which is currently done manually is still ineffective and inaccurate because the Head of Subdivision uses receipt documents, namely PPBP and mutation of goods, namely MPPW in the form of paper as a submission media. The Head of Subdivision enters the data of receipt and mutation of goods manually and requires a relatively long time because at the time of demand for the transfer of goods the Head of Subdivision must check the inventory of goods in the central warehouse first. Therefore, it is necessary to hold a design of information systems for the receipt and transfer of goods from the central warehouse to a web-based branch warehouse that is already database so that it is more effective, efficient and accurate. With the web-based system of receiving and transferring goods that are already datatabed, it can facilitate the Head of Subdivision in inputing data on the receipt and transfer of goods and control of stock inventory so that the Sub Head of Subdivision can do it periodically to make it more effective, efficient and accurate. The method of data collection is done by observing, interviewing and studying literature from various previous studies, while the system analysis method uses the Waterfall method which aims to solve a problem and uses design methods with visual modeling that is object oriented with UML while programming using PHP and MySQL as a database.

Sign in / Sign up

Export Citation Format

Share Document