System Representations of Dynamics of Mechanical Oscillatory Structures Based on Frequency Function and Damping Function

2021 ◽  
pp. 335-347
Author(s):  
Sergey Eliseev ◽  
Andrey Eliseev ◽  
Nikolai Kuznetsov
Keyword(s):  
Frequency Function ◽  
Damping Function

scholarly journals SYSTEM REPRESENTATIONS OF DYNAMIC PROCESSES IN MECHANICAL OSCILLATORY SYSTEMS WITH SPECIAL FEATURES

2020 ◽  
Author(s):  
А.В. Елисеев
Keyword(s):  
System Analysis ◽  
Viscous Friction ◽  
Frequency Function ◽  
Dissipative Function ◽  
Dynamic Features ◽  
Friction Forces ◽  
Damping Function ◽  
Oscillatory Systems ◽  
Frequency Functions ◽  
Damping Functions

Рассматриваются подходы в формировании методологического базиса системного анализа колебательных структур на примере упруго-диссипативных механических систем с двумя степенями свободы. Целью исследования является разработка метода оценки свойств механических колебательных систем с учетом сил вязкого трения на основе частотных функций и функции демпфирования в зависимости от коэффициентов форм связности. Для построения математических моделей используется формализм Лагранжа, матричные методы, элементы теории функций комплексной переменной. Представлены понятия частотной функции и функции демпфирования, отражающие особенности соотношения потенциальной, кинетической энергии системы с учетом сил вязкого трения, представленных диссипативной функцией. Разработан метод построения частотной функции и функции демпфирования, отражающих динамические особенности свободных движений с учетом сил трения в зависимости от коэффициента форм связности. На основе полученных общих аналитических выражений частотных функций и функций демпфирования проведен анализ особенных вариантов механических колебательных систем, представляющих интерес на начальном этапе исследования. Разработанный метод построения частотной функции и функции демпфирования может быть использован для отображения динамических форм связности движений механических колебательных систем. Предложенный метод построения частотной функции и функции демпфирования может быть обобщен на механические колебательные системы, рассматриваемые в различных системах координат. Approaches to the formation of a methodological basis for the system analysis of oscillatory structures on the example of elastic-dissipative mechanical systems with two degrees of freedom are considered. The aim of the study is to develop a method for evaluating the properties of mechanical oscillatory systems with account for viscous friction forces based on frequency functions and damping functions depending on the coefficients of connectivity forms. To build mathematical models, we use Lagrange formalism, matrix methods, and elements of the theory of functions of a complex variable. The concepts of the frequency function and the damping function are presented, which reflect the features of the ratio of the potential and kinetic energy of the system, taking into account the viscous friction forces represented by the dissipative function. A method is developed for constructing the frequency function and damping function that reflect the dynamic features of free movements, taking into account the friction forces depending on the coefficient of connectivity forms. Based on the obtained General analytical expressions of frequency functions and damping functions, special variants of mechanical oscillatory systems that are of interest at the initial stage of research are analyzed. The developed method for constructing the frequency function and the damping function can be used to display dynamic forms of connectivity of movements of mechanical oscillatory systems. The proposed method for constructing the frequency function and the damping function can be extended to mechanical oscillatory systems considered in different coordinate systems.

Adhesives fulfil a damping function

2013 ◽  
Vol 10 (3) ◽  
pp. 12-17
Author(s):  
Anke Büscher ◽  
Christian Schäfers ◽  
Norbert Austerhoff
Keyword(s):  
Damping Function

STRESS RELAXATION OF MAGNETORHEOLOGICAL FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2655-2661
Author(s):  
W. H. LI ◽  
G. CHEN ◽  
S. H. YEO ◽  
H. DU
Keyword(s):  
Stress Relaxation ◽  
Viscoelastic Model ◽  
Relaxation Modulus ◽  
Damping Function ◽  
Mr Fluids ◽  
Large Step ◽  
Linear Viscoelastic ◽  
Predicted Values ◽  
Two Parameters ◽  
Step Strain

In this paper, the experimental and modeling study and analysis of the stress relaxation characteristics of magnetorheological (MR) fluids under step shear are presented. The experiments are carried out using a rheometer with parallel-plate geometry. The applied strain varies from 0.01% to 100%, covering both the pre-yield and post-yield regimes. The effects of step strain, field strength, and temperature on the stress modulus are addressed. For small step strain ranges, the stress relaxation modulus G(t,γ) is independent of step strain, where MR fluids behave as linear viscoelastic solids. For large step strain ranges, the stress relaxation modulus decreases gradually with increasing step strain. Morever, the stress relaxation modulus G(t,γ) was found to obey time-strain factorability. That is, G(t,γ) can be represented as the product of a linear stress relaxation G(t) and a strain-dependent damping function h(γ). The linear stress relaxation modulus is represented as a three-parameter solid viscoelastic model, and the damping function h(γ) has a sigmoidal form with two parameters. The comparison between the experimental results and the model-predicted values indicates that this model can accurately describe the relaxation behavior of MR fluids under step strains.

Adaptive Elastic SMA Elements for Damping Applications

2013 ◽  
Author(s):  
Alexander Czechowicz ◽  
Peter Dültgen ◽  
Sven Langbein
Keyword(s):  
Boundary Conditions ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Smart Materials ◽  
Electrical Resistance ◽  
Thermal Activation ◽  
Hysteretic Behavior ◽  
Damping Function ◽  
Actual Shape ◽  
Elastic Elements

Shape memory alloys (SMA) are smart materials, which have two technical usable effects: While pseudoplastic SMA have the ability to change into a previously imprinted actual shape through the means of thermal activation, pseudoelastic SMA show a reversible mechanical elongation up to 8% at constant temperature. The transformation between the two possible material phases (austenite and martensite) shows a hysteretic behavior. As a result of these properties, SMA can be used as elastic elements with intrinsic damping function. Additionally the electrical resistance changes remarkably during the material deformation. These effects are presented in the publication in combination with potential for applications in different branches at varying boundary conditions. The focus of the presented research is concentrated on the application of elastic elements with adaptive damping function. As a proof for the potential considerations, an application example sums up this presentation.

scholarly journals ‘Where’ Questions and Their Responses in Duna (Papua New Guinea)

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Lila San Roque
Keyword(s):  
Papua New Guinea ◽  
High Frequency ◽  
New Guinea ◽  
Direct Reference ◽  
Space And Place ◽  
Frequency Function ◽  
Data Set ◽  
Functional Flexibility ◽  
Information Gap ◽  
Question Formation

AbstractDespite their central role in question formation, content interrogatives in spontaneous conversation remain relatively under-explored cross-linguistically. This paper outlines the structure of ‘where’ expressions in Duna, a language spoken in Papua New Guinea, and examines where-questions in a small Duna data set in terms of their frequency, function, and the responses they elicit. Questions that ask ‘where?’ have been identified as a useful tool in studying the language of space and place, and, in the Duna case and elsewhere, show high frequency and functional flexibility. Although where-questions formulate place as an information gap, they are not always answered through direct reference to canonical places. While some question types may be especially “socially costly” (Levinson 2012), asking ‘where’ perhaps provides a relatively innocuous way of bringing a particular event or situation into focus.

Reabsorption kinetics of albumin from pleural space of dogs

1988 ◽  
Vol 255 (2) ◽  
pp. H375-H385 ◽  
Author(s):  
M. Miniati ◽  
J. C. Parker ◽  
M. Pistolesi ◽  
J. T. Cartledge ◽  
D. J. Martin ◽  
...  
Keyword(s):  
Control Mechanism ◽  
Mean Transit Time ◽  
Input Function ◽  
Pleural Space ◽  
Frequency Function ◽  
Liquid Pressure ◽  
Physiological Conditions ◽  
Transit Times ◽  
The Mean ◽  
Kinetics Of

The reabsorption of albumin from the pleural space was measured in eight dogs receiving 0.5 ml intrapleural injection of 131I-labeled albumin and a simultaneous intravenous injection of 125I-labeled albumin. Plasma curves for both tracers were obtained over 24 h. The 125I-albumin curve served as input function of albumin for interstitial spaces, including pleura, whereas the 131I-albumin curve represented the output function from pleural space. The frequency function of albumin transit times from pleural space to plasma was obtained by deconvolution of input-output plasma curves. Plasma recovery of 131I-albumin was complete by 24 h, and the mean transit time from pleura to plasma averaged 7.95 +/- 1.57 (SD) h. Albumin reabsorption occurred mainly via lymphatics as indicated by experiments in 16 additional dogs in which their right lymph ducts or thoracic ducts were ligated before intrapleural injection. A pleural lymph flow of 0.020 +/- 0.003 (SD) ml.kg-1.h-1 was estimated, which is balanced by a comparable filtration of fluid into the pleural space. This suggests that, under physiological conditions, the subpleural lymphatics represent an important control mechanism of pleural liquid pressure.

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