DYNAMIC PROPERTIES OF FILLED RUBBER. PART II: PHYSICAL BASIS OF CONTRIBUTIONS TO THE MODEL

2011 ◽  
Vol 84 (1) ◽  
pp. 24-40 ◽  
Author(s):  
H. R. Ahmadi ◽  
A. H. Muhr
Keyword(s):  
Literature Review ◽  
Simple Shear ◽  
Time Domain ◽  
Dynamic Properties ◽  
Uniaxial Stress ◽  
Domain Model ◽  
Strain Behavior ◽  
Filled Rubber ◽  
Rubber Part ◽  
Analytical Expressions

Abstract A relatively simple time-domain model is proposed with the scope to capture those aspects of the uniaxial stress–strain behavior of filled rubber that are most significant in engineering applications, and is discussed in the context of a literature review. Its performance is investigated in simple shear using analytical expressions. Attention has been given to assembling the model from separate physical contributions, each already established in the literature, so that not only is the number of parameters small but also they may be at least semi-quantitatively related to the formulation of the elastomer. The small number of parameters helps to keep tests for fitting them simple, while their connection to mechanisms also enables a degree of utility of the model even when extrapolated to situations beyond those covered by tests.

Dynamic Properties of Filled Rubber — Part I: Simple Model, Experimental Data and Simulated Results

2008 ◽  
Vol 81 (1) ◽  
pp. 1-18 ◽  
Author(s):  
H. R. Ahmadi ◽  
J. G. R. Kingston ◽  
A. H. Muhr
Keyword(s):  
Dynamic Properties ◽  
Cyclic Stress ◽  
Material Behavior ◽  
Stress Strain ◽  
Viscoplastic Model ◽  
Strain Behavior ◽  
Fitting Procedure ◽  
Filled Rubber ◽  
Constant Rate ◽  
Rubber Part

Abstract A simple “viscoplastic” model is used to capture the stress-strain behavior of a filled SBR vulcanizate; a key objective is to predict dynamic properties, in particular the Fletcher-Gent or Payne effect, from non-cyclic stress-strain data. A simple fitting procedure is described to obtain the parameters of the viscoplastic model from the stress relaxation data and stress-strain loading curves at constant rate. Special attention is given to keeping the numbers of parameters and of characterization tests small. Elastic models are incapable of representing several aspects of the material behavior whereas it is confirmed that the proposed “viscoplastic” approach captures the essence of the behavior.

scholarly journals Efficient reconstruction of dispersive dielectric profiles using time domain reflectometry (TDR)

2005 ◽  
Vol 2 (4) ◽  
pp. 1449-1502 ◽  
Author(s):  
P. Leidenberger ◽  
B. Oswald ◽  
K. Roth
Keyword(s):  
Inverse Problem ◽  
Global Optimization ◽  
Time Domain ◽  
Signal Propagation ◽  
Dielectric Materials ◽  
Time Domain Reflectometry ◽  
Domain Model ◽  
Parallel Circuit ◽  
The Time Domain ◽  
Analytical Expressions

Abstract. We present a numerical model for time domain reflectometry (TDR) signal propagation in dispersive dielectric materials. The numerical probe model is terminated with a parallel circuit, consisting of an ohmic resistor and an ideal capacitance. We derive analytical expressions for the capacitance, the inductance and the conductance of three-wire probes. We couple the time domain model with global optimization in order to reconstruct water content profiles from TDR traces. For efficiently solving the inverse problem we use genetic algorithms combined with a hierarchical parameterization. We investigate the performance of the method by reconstructing synthetically generated profiles. The algorithm is then applied to retrieve dielectric profiles from TDR traces measured in the field. We succeed in reconstructing dielectric and ohmic profiles where conventional methods, based on travel time extraction, fail.

KINEMATIC FEATURES OF THE LAPPING PROCESS AND DETERMINATION OF ITS BASIC PARAMETERS

2020 ◽  
Vol 7 (3) ◽  
pp. 23-28
Author(s):  
EZIZ SARVAN SHIRVAN ◽  
Keyword(s):  
Dynamic Properties ◽  
Cutting Speed ◽  
Equilibrium System ◽  
Technological Parameters ◽  
Kinematic Characteristics ◽  
Angular Velocities ◽  
Basic Parameters ◽  
Grinding Tool ◽  
Mathematical Relationships ◽  
Analytical Expressions

This paper discusses the kinematic characteristics of lapping process and the main parameters of the process. It was determined that the influencing degree of technological parameters to the forming surface and processes. It was projected the construction of the lapping head for processing of internal cylindrical surfaces, scheme of the lapping operation and graphic description of the forces influencing. The relationships between the axial, radial and tangential cutting forces and the effect of the combined force thereof are determined in order to ensure the necessary surface pressure. During the analysis geometric and mathematical relationships were obtained. The extracted analytical expressions can be realized by further experimental researches and can be used in engineering calculations of technological parameters of processing by lapping. Angular velocity, friction force, linear velocity, also the length of the tactile curve and the radius of the part can be considered the main kinematic and dynamic parameters of the process that the formation of the surface, also the course of the process depends on these parameters. Depending on the kinematic parameters, the wear nature of the tool changes and this changes the linear and angular velocities, which have a significant impact on the accuracy, quality and productivity of processing. When examining the technological capabilities of the process, the nature of the movement between the part and the grinding tool, also changes in cutting speed are often considered as a main factor. Analytical expressions were obtained to determine the main parameters of the process, taking into account the kinematic characteristics of the friction process. These expressions can be used in engineering calculations and allow to determine the optimal values of the processing mode. In order to obtain the required micrometric surface cleanliness and measurement accuracy, correlation relationships were established between the main parameters of the process, equations of the equilibrium system of shear forces were compiled and analytical expressions were obtained based on the analysis of kinematic and dynamic properties of the system.

scholarly journals Prediction of deepwater riser VIV with an improved time domain model including non-linear structural behavior

2021 ◽  
Vol 236 ◽  
pp. 109508
Author(s):  
Sang Woo Kim ◽  
Svein Sævik ◽  
Jie Wu ◽  
Bernt Johan Leira
Keyword(s):  
Time Domain ◽  
Domain Model ◽  
Structural Behavior ◽  
Non Linear ◽  
Deepwater Riser

Design and Analysis of Viscoelastic Seismic Dampers

2002 ◽  
Author(s):  
N. Shimizu ◽  
H. Nasuno ◽  
T. Yazaki ◽  
K. Sunakoda
Keyword(s):  
Finite Element ◽  
Constitutive Relation ◽  
Time Domain ◽  
Dynamic Properties ◽  
Design Procedure ◽  
Fe Analysis ◽  
Damping Capacity ◽  
Element Formulation ◽  
Element Analysis ◽  
Equivalent Viscous Damping

This paper describes a methodology of design and analysis of viscoelastic seismic dampers by means of the time domain finite element analysis. The viscoelastic constitutive relation of material incorporating with the fractional calculus has been derived and the finite element formulation based on the constitutive relation has been developed to analyze the dynamic property of seismic damper. A time domain computer program was developed by using the formulation. Dynamic properties of hysteresis loop, damping capacity, equivalent viscous damping coefficient, and equivalent spring constant are calculated and compared with the experimental results. Remarkable correlation between the FE analysis and the experiment is gained, and consequently the design procedure with the help of the FE analysis has been established.

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