Non-Linearity in Dynamic Tests. I. Vibration Test Methods

1961 ◽  
Vol 34 (2) ◽  
pp. 527-554
Author(s):  
V. E. Gough
Keyword(s):  
Phase Plane ◽  
Dynamic Test ◽  
Test Methods ◽  
Wave Form ◽  
Actual Behavior ◽  
Dynamic Tests ◽  
Important Conclusion ◽  
Single Degree Of Freedom ◽  
Phase Plane Method ◽  
Physical Quantities

Abstract In those cases where dynamic tests are to be interpreted in terms of the molecular structure of rubber, there is a definite need for a method of analysis which is wholly free from mathematical assumptions. Such a method of analysis is possible by the use of phase planes of velocity plotted against displacement. This is so because the slope of the trajectory at any point of the motion of any single degree of freedom system can be written solely in terms of physical quantities, namely, driving force, viscoelastic reaction and momentum. The analysis involves no hidden mathematical assumption. Methods of deriving stress strain relationships from phase plane trajectories are described. This phase plane method is discussed in some detail. Examples are given showing the inadequacy of the usual linear analysis in the case of rubberlike materials. Analysis shows that dynamic test machines should either apply a known motion and record a force-deflection curve or apply a force of known wave form and record the resulting motion as a phase plane trajectory. If force and motion are not kept independent of each other in this manner there is an inbuilt mathematical relationship which, more often than not, influences and falsifies the results. An important conclusion is that only when the nature of the non-linearities, or what is the same thing, the character of the functions which correctly describe the actual behavior of a vibrating system have been established by sound analysis of test data, should the phenomena be ascribed to the physical properties of the material. Because of the important consequence of the acceptance of some common mathematical steps in any analysis, certain of these are critically examined and their relevance discussed.

scholarly journals Concept and Realization of a Novel Test Method Using a Dynamic Test Stand for Detecting Persons by Sensor Systems on Autonomous Agricultural Robotics

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2315
Author(s):  
Christian Meltebrink ◽  
Tom Ströer ◽  
Benjamin Wegmann ◽  
Cornelia Weltzien ◽  
Arno Ruckelshausen
Keyword(s):  
Environmental Conditions ◽  
Dynamic Test ◽  
Test Methods ◽  
Test Stand ◽  
Human Detection ◽  
Test Method ◽  
Sensor Systems ◽  
Functional Safety ◽  
Agricultural Robots ◽  
Agricultural Robotics

As an essential part for the development of autonomous agricultural robotics, the functional safety of autonomous agricultural machines is largely based on the functionality and robustness of non-contact sensor systems for human protection. This article presents a new step in the development of autonomous agricultural machine with a concept and the realization of a novel test method using a dynamic test stand on an agricultural farm in outdoor areas. With this test method, commercially available sensor systems are tested in a long-term test around the clock for 365 days a year and 24 h a day on a dynamic test stand in continuous outdoor use. A test over a longer period of time is needed to test as much as possible all occurring environmental conditions. This test is determined by the naturally occurring environmental conditions. This fact corresponds to the reality of unpredictable/determinable environmental conditions in the field and makes the test method and test stand so unique. The focus of the developed test methods is on creating own real environment detection areas (REDAs) for each sensor system, which can be used to compare and evaluate the autonomous human detection of the sensor systems for the functional safety of autonomous agricultural robots with a humanoid test target. Sensor manufacturers from industry and the automotive sector provide their sensor systems to have their sensors tested in cooperation with the TÜV.

Inspection and Model Experiment of a Damaged Arch Bridge

2007 ◽  
Vol 340-341 ◽  
pp. 223-228
Author(s):  
Ying Fang Fan ◽  
Zhi Qiang Hu ◽  
Jing Zhou
Keyword(s):  
Model Experiment ◽  
Dynamic Test ◽  
Dynamic Responses ◽  
Dynamic Tests ◽  
Arch Bridge ◽  
Mechanical Responses ◽  
Organic Glasses ◽  
Bridge Model ◽  
Static And Dynamic Tests ◽  
Good Agreement

The structural behavior of an old six-span reinforced concrete arch bridge, which has been in service for about 40 years, is investigated. Field monitoring (inclusive of test of material property, static and dynamic test of the bridge) was conducted, static and dynamic responses of the bridge are obtained. Based on the primitive bridge, a scaled one-span bridge model was fabricated by organic-glasses. Both the static and dynamic tests were executed on the bridge model in the laboratory. Since the arch rib is the crucial member for the arch bridge, 7 notches were cut on both arch ribs of the bridge model to simulate different damages of the arch rib. Mechanical responses of the bridge with different damages on the arch ribs were achieved. FEM analyses were preformed on the bridge as well. Numerical results show good agreement with the experimental results.

Detection and quantification of small left-to-right shunts by the phase-plane method

1983 ◽  
Vol 244 (4) ◽  
pp. H622-H627
Author(s):  
A. Fonseca-Costa ◽  
P. Magrassi ◽  
W. A. Zin ◽  
L. J. Romeo
Keyword(s):  
Sampling Method ◽  
Phase Plane ◽  
Sampling Site ◽  
Indicator Dilution ◽  
Terminal Portion ◽  
Systemic Artery ◽  
Anesthetized Dogs ◽  
Phase Plane Method ◽  
High Level ◽  
Dilution Curves

Sixty-five pairs of indicator-dilution curves were obtained in five anesthetized dogs. After the injection of indocyanine dye into the left atrium, blood was simultaneously sampled through dichromatic cuvette densitometers from the femoral artery and the distal pulmonary artery. Dye-dilution curves were recorded from dogs with normal cardiovascular systems and after the surgical production of left-to-right shunts of different magnitudes. The percent of blood shunting was calculated according to the double sampling method and compared with a new method based on the deviation observed in the terminal portion of the indicator-dilution phase-plane loop. A high level of correlation was observed between both methods (r = 0.961). The phase plane shows its utility in the quantification of small left-to-right shunts. The use of only one sampling site at a peripheral systemic artery is an important advantage because there is complete mixture between shunted and unshunted blood.

Analysis and Synthesis of a Fuzzy Controller by the Phase Plane Method

2021 ◽  
Vol 22 (10) ◽  
pp. 507-517
Author(s):  
Y. A. Bykovtsev
Keyword(s):  
Control System ◽  
Automatic Control ◽  
Automatic Control System ◽  
Phase Plane ◽  
Fuzzy Controller ◽  
Piecewise Linear ◽  
Plane Method ◽  
Phase Trajectories ◽  
Analysis And Synthesis ◽  
Phase Plane Method

The article is devoted to solving the problem of analysis and synthesis of a control system with a fuzzy controller by the phase plane method. The nonlinear transformation, built according to the Sugeno fuzzy model, is approximated by a piecewise linear characteristic consisting of three sections: two piecewise linear and one piecewise constant. This approach allows us to restrict ourselves to three sheets of phase trajectories, each of which is constructed on the basis of a second-order differential equation. Taking this feature into account, the technique of "stitching" of three sheets of phase trajectories is considered and an analytical base is obtained that allows one to determine the conditions for "stitching" of phase trajectories for various variants of piecewise-linear approximation of the characteristics of a fuzzy controller. In view of the specificity of the approximated model of the fuzzy controller used, useful analytical relations are given, with the help of which it is possible to calculate the time of motion of the representing point for each section with the involvement of the numerical optimization apparatus. For a variant of the approximation of three sections, a technique for synthesizing a fuzzy controller is proposed, according to which the range of parameters and the range of input signals are determined, at which an aperiodic process and a given control time are provided. On the model of the automatic control system of the drive level of the mechatronic module, it is shown that the study of a fuzzy system by such an approximated characteristic of a fuzzy controller gives quite reliable results. The conducted studies of the influence of the degree of approximation on the quality of control show that the approximated characteristic of a fuzzy controller gives a slight deterioration in quality in comparison with the smooth characteristic of a fuzzy controller. Since the capabilities of the phase plane method are limited to the 2nd order of the linear part of the automatic control system, the influence of the third order on the dynamics of the system is considered using the example of a mechatronic module drive. It is shown that taking into account the electric time constant leads to overshoot within 5-10 %. Such overshoot can be eliminated due to the proposed recommendations for correcting the static characteristic of the fuzzy controller.

Surge Tank Stability by Phase Plane Method

1971 ◽  
Vol 97 (4) ◽  
pp. 489-503
Author(s):  
M. Hanif Chaudhry ◽  
Eugen Ruus
Keyword(s):  
Phase Plane ◽  
Surge Tank ◽  
Plane Method ◽  
Phase Plane Method

scholarly journals Viscoelastic Parameters of Asphalt Mixtures Identified in Static and Dynamic Tests

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2084 ◽  
Author(s):  
Piotr Mackiewicz ◽  
Antoni Szydło
Keyword(s):  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Dynamic Test ◽  
Asphalt Mixtures ◽  
Rheological Parameters ◽  
Dynamic Tests ◽  
Static Test ◽  
Viscoelastic Parameters ◽  
Static Creep ◽  
Asphalt Content

We present two methods used in the identification of viscoelastic parameters of asphalt mixtures used in pavements. The static creep test and the dynamic test, with a frequency of 10 Hz, were carried out based on the four-point bending beam (4BP). In the method identifying viscoelastic parameters for the Brugers’ model, we included the course of a creeping curve (for static creep) and fatigue hysteresis (for dynamic test). It was shown that these parameters depend significantly on the load time, method used, and temperature and asphalt content. A similar variation of parameters depending on temperature was found for the two tests, but different absolute values were obtained. Additionally, the share of viscous deformations in relation to total deformations is presented, on the basis of back calculations and finite element methods. We obtained a significant contribution of viscous deformations (about 93% for the static test and 25% for the dynamic test) for the temperature 25 °C. The received rheological parameters from both methods appeared to be sensitive to a change in asphalt content, which means that these methods can be used to design an optimal asphalt mixture composition—e.g., due to the permanent deformation of pavement. We also found that the parameters should be determined using the creep curve for the static analyses with persistent load, whereas in the case of the dynamic studies, the hysteresis is more appropriate. The 4BP static creep and dynamic tests are sufficient methods for determining the rheological parameters for materials designed for flexible pavements. In the 4BP dynamic test, we determined relationships between damping and viscosity coefficients, showing material variability depending on the test temperature.

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