Nonlinear oscillations in machines and mechanisms theory

Půst, L.; Peterka, F.; Stépàn, Gábor; Tomlinson, G.R.; Tondl, A.

doi:10.1016/s0094-114x(98)00068-8

Cited by 8 publications

(6 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the beginning, in Model 1 the stiffness ratio

is assumed to be 0.96, because some researchers claim that the ligaments and tendons should be treated as collagen fibres and the surrounding proteoglycan-rich matrix [ 10 , 23 , 24 , 25 ]. Thus, the mechanics of these tissues is also modelled using the Maxwell-type viscoelastic material, where the elastic modulus of the matrix and the fibre is

= 130.4 MPa and

= 3500 MPa, respectively.…”

Section: Materials and Methodsmentioning

confidence: 99%

Biomechanics of the Human Middle Ear with Viscoelasticity of the Maxwell and the Kelvin–Voigt Type and Relaxation Effect

2020

View full text Add to dashboard Cite

The middle ear is one of the smallest biomechanical systems in the human body and is responsible for the hearing process. Hearing is modelled in different ways and by various methods. In this paper, three-degree-of-freedom models of the human middle ear with different viscoelastic properties are proposed. Model 1 uses the Maxwell type viscoelasticity, Model 2 is based on the Kelvin–Voigt viscoelasticity, and Model 3 uses the Kelvin–Voigt viscoelasticity with relaxation effect. The primary aim of the study is to compare the models and their dynamic responses to a voice excitation. The novelty of this study lies in using different models of viscoelasticity and relaxation effect that has been previously unstudied. First, mathematical models of the middle ear were built, then they were solved numerically by the Runge–Kutta procedure and finally, numerical results were compared with those obtained from experiments carried out on the temporal bone with the Laser Doppler Vibrometer. The models exhibit differences in the natural frequency and amplitudes near the second resonance. All analysed models can be used for modelling the rapidly changing processes that occur in the ear and to control active middle ear implants.

show abstract

“…At the beginning, in Model 1 the stiffness ratio

= 130.4 MPa and

= 3500 MPa, respectively.…”

Section: Materials and Methodsmentioning

confidence: 99%

Biomechanics of the Human Middle Ear with Viscoelasticity of the Maxwell and the Kelvin–Voigt Type and Relaxation Effect

2020

View full text Add to dashboard Cite

show abstract

“…Knowing the synchronous generator's rotative speed the time intervals can be converted into rotative speed intervals and then into variations of the angle by which the rotor's axis departs from its centre position [7][8][9]. Let α denote the angle by which the rotor's axis wanders from its centre position after a short-circuit occurred [7].…”

Section: Data Processingmentioning

confidence: 99%

“…where J is the rotative moment of the rotative components, p is the synchronous generator's number of pole pairs, M m is the driving torque of the synchronous spindle motor after the working and the ventilation losses were deducted, since they are considered to be constant, and M sc is the synchronous generator's electromagnetic couple during the short-circuit conditions [7][8][9].…”

Section: Data Processingmentioning

confidence: 99%

Experimental measurements of the rotor oscillations in an synchronous generator during the three-phased sudden short-circuit test

Piroi

Spunei

Piroi

2014

2014 International Conference on Applied and Theoretical Electricity (ICATE)

View full text Add to dashboard Cite

This work presents a method to determine rotor oscillations during a three-phased sudden short-circuit test of a synchronous generator. To our best current knowledge, no such similar method is yet published in the technical literature. During the periodic and non-periodic component separation of the three phase currents, it was found that the time difference between the currents' extreme values, for any of the three phase currents, does not have a 10 ms constant value, as in the stationary phase. Investigating why this happens we found that these variations are caused by the rotor oscillations. Certain parameters of a synchronous generator's rotor and of the rotor's oscillations are measured during the sudden three-phased short-circuit test. Based on these readings, with the method presented in this paper, we can compute the rotor's mechanical oscillation amplitudes and the transient process durations. Using the measured values, the equation describing the rotor's mechanical oscillations, independent of its power, can be re-written. Knowledge of the oscillation amplitudes and their durations is necessary for a correct loop control design and in establishing the generator's performance.

show abstract

“…An analysis of the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14] showed that a large number of works are devoted to both the general issues of synchronization of oscillations in different fields of physics and the synchronization of engines with unbalanced rotors. At the same time, the analysis revealed the absence of works devoted to the influence of synchronization of electric motors on the electromagnetic and thermal processes occurring in them and the assessment of electrical losses due to frequency locking.…”

Section: Introductionmentioning

confidence: 99%

Reduction of electrical power at mechanical synchronization of induction electric motors in a multi-motor unit

Ermolaev,

Okhulkov,

Plekhov

et al. 2024

Third International Conference on Optics, Computer Applications, and Materials Science (CMSD-III 2023)

View full text Add to dashboard Cite

The article proposes mathematical and simulation models for studying mechanical synchronization processes that occur in asynchronous electric motors with unbalanced rotors, as well as models for studying power losses and thermal processes. As a result, dependencies were obtained that describe the relationship between power losses in the windings of vibration exciter motors, changes in rotor slip and the steady-state temperature of the motor on the one hand, and the eccentricity radius and the rigidity of the oscillating base on the other hand. As the rotor eccentricity radius increased, the phenomenon of frequency locking and the Sommerfeld effect were observed. It has been established that in these modes the total power losses can exceed the losses in the nominal mode by 2-3 times, and the current in the stator winding by 1.5-2.5 times. Experimental studies of the synchronization of oscillations of two engines on a single basis confirmed the good accuracy of the proposed models.

show abstract

Nonlinear oscillations in machines and mechanisms theory

Cited by 8 publications

References 65 publications

Biomechanics of the Human Middle Ear with Viscoelasticity of the Maxwell and the Kelvin–Voigt Type and Relaxation Effect

Biomechanics of the Human Middle Ear with Viscoelasticity of the Maxwell and the Kelvin–Voigt Type and Relaxation Effect

Experimental measurements of the rotor oscillations in an synchronous generator during the three-phased sudden short-circuit test

Reduction of electrical power at mechanical synchronization of induction electric motors in a multi-motor unit

Contact Info

Product

Resources

About