Global bifurcations and chaos in the forced oscillations of buckled structures

1978 ◽  
Author(s):  
Philip Holmes
Keyword(s):  
Forced Oscillations ◽  
Global Bifurcations

Study of the dynamics of ТПА 350 automatic mill working stand elements

2020 ◽  
Vol 76 (8) ◽  
pp. 830-840
Author(s):  
S. R. Rakhmanov ◽  
V. V. Povorotnii
Keyword(s):  
Mechanical System ◽  
Dynamic Model ◽  
Maximum Amplitude ◽  
Calculation Scheme ◽  
Dynamic Loads ◽  
Forced Oscillations ◽  
Mass Model ◽  
Automatic Mill ◽  
Hollow Billet ◽  
Oscillation Movement

To form a necessary geometry of a hollow billet to be rolled at a pipe rolling line, stable dynamics of the base equipment of the automatic mill working stand has a practical meaning. Among the forces, acting on its parts and elements, significant by value short-time dynamic loads are the least studied phenomena. These dynamic loads arise during transient interaction of the hollow billet, rollers, mandrel and other mill parts at the forced grip of the hollow billet. Basing of the calculation scheme and dynamic model of the mechanical system of the ТПА 350 automatic mill working stand was accomplished. A mathematical model of dynamics of the system “hollow billet (pipe) – working stand” within accepted calculation scheme and dynamic model of the mechanical system elaborated. Influence of technological load of the rolled hollow billet variation in time was accounted, as well as variation of the mechanical system mass, and rigidity of the ТПА 350 automatic mill working stand. Differential equations of oscillation movement for four-mass model of forked sub-systems of the automatic mill working stand were made up, results of their digital calculation quoted. Dynamic displacement of the stand elements in the inter-roller gap obtained, which enabled to estimate the results of amplitude and frequency characteristics of the branches of the mill rollers setting. It was defined by calculation, that the maximum amplitude of the forced oscillations of elements of the ТПА 350 automatic mill working stand within the inter-roller gap does not exceed 2 mm. It is much higher than the accepted value of adjusting parameters of the deformation center of the ТПА 350 automatic mill. A scheme of comprehensive modernization of the rollers setting in the ТПА 350 automatic mill working stand was proposed. It was shown, that increase of rigidity of rollers setting in the ТПА 350 automatic mill working stand enables to stabilize the amplitude of forced oscillations of the working stand elements within the inter-rollers gap and considerably decrease the induced nonuniform hollow billet wall thickness and increase quality of the rolled pipes at ТПА 350.

CALCULATION OSCILLATIONS OF VARIOUS ELEMENTS OF THE ELASTIC SYSTEM OF THE CENTER-FREE GRINDING MACHINE SASL 5AD

2020 ◽  
pp. 160-165
Author(s):  
Джугурян Т.Г. ◽  
Марчук В.І. ◽  
Марчук І. В.
Keyword(s):  
Horizontal Plane ◽  
Natural Frequencies ◽  
Elastic System ◽  
Experimental Studies ◽  
Piezoelectric Sensors ◽  
Forced Oscillations ◽  
Method Of Calculation ◽  
Vibration Resistance ◽  
Grinding Machine ◽  
Experimental Researches

During the design of operations of centerless intermittent grinding of surfaces there is a need to identify the natural frequencies of oscillations of the elements of the technological system of grinding. The method of calculation of rigidity, vibration resistance and forced oscillations of the elements of the circular grinding machine is offered in the article. Carrying out of experimental researches of rigidity of elastic system of the SASL 5AD grinding machine. We conducted preliminary experimental studies to measure the oscillations of various elements of the elastic system of the SASL 5AD grinding machine in the horizontal plane by piezoelectric sensors during grinding with continuous and discontinuous circles with different geometric parameters.

scholarly journals Forced oscillations of beams with installation (Part II)

2021 ◽  
Vol 1083 (1) ◽  
pp. 012044
Author(s):  
Kh P Kulterbaev ◽  
V A Vodakhova ◽  
L A Baragunova ◽  
M M Shogenova ◽  
A Kh Tsypinova
Keyword(s):  
Forced Oscillations

scholarly journals Damping forced oscillations in power system via interline power flow controller with additional repetitive control

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Shirui Feng ◽  
Xi Wu ◽  
Zhenquan Wang ◽  
Tao Niu ◽  
Qiong Chen
Keyword(s):  
Power Flow ◽  
Forced Oscillation ◽  
Control Method ◽  
Damping Ratio ◽  
Repetitive Control ◽  
Oscillation Amplitude ◽  
Reference Value ◽  
Forced Oscillations ◽  
Flow Controller ◽  
Power Flow Controller

AbstractWith the continuous expansion of power systems and the application of power electronic equipment, forced oscillation has become one of the key problems in terms of system safety and stability. In this paper, an interline power flow controller (IPFC) is used as a power suppression carrier and its mechanism is analyzed using the linearized state-space method to improve the system damping ratio. It is shown that although the IPFC can suppress forced oscillation with well-designed parameters, its capability of improving the system damping ratio is limited. Thus, combined with the repetitive control method, an additional repetitive controller (ARC) is proposed to further dampen the forced power oscillation. The ARC control scheme is characterized by outstanding tracking performance to a system steady reference value, and the main IPFC controller with the ARC can provide higher damping, and further reduce the amplitude of oscillations to zero compared with a supplementary damping controller (SDC). Simulation results show that the IPFC with an ARC can not only greatly reduce the oscillation amplitude, but also actively output the compensation power according to the reference value of the ARC tracking system.

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