Parameter Analysis of Vibroimpact Machines Dynamics With Variable Mass and Stiffness
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Дата
2016
ORCID
DOI
Науковий ступінь
Рівень дисертації
Шифр та назва спеціальності
Рада захисту
Установа захисту
Науковий керівник
Члени комітету
Видавець
NTU "KhPI"
Анотація
Vibroimpact machines operate under high repeated loadings. This poses certain requirements with regards to
the strength and durability of their components that have to be met by the design. In order to predict the
magnitude and time distribution of the acting forces the dynamics of the vibroimpact systems need to be
studied. A two-body mechanical system is considered as a model of a shake-out machine designed for
Azovmash company and used for extraction of steel casts from the mold. The first body is the suspended frame
with the shake-out grid driven by an unbalanced vibrator, while the second one is the cast. Its sand mold is
damaged at every impact with the shake-out grid, which results in the gradual loss of mass. The previously
developed rigid body dynamics model is extended in order to account for the variable mass factor. Two
approaches for the time evolution of the cast mass has been taken. The first one suggests that mass is a
predefined linear or piecewise linear function of time. Alternatively the mass is treated as an unknown variable
and was determined in the course of solving the equations of motion. A constitutive law for the mass reduction
based on the energy dissipated at each impact is proposed. It has been shown that this model results in more
adequate description of the shake-out process compared to the fixed-law mass evolution. In addition to the
variable mass the influence of stiffness characteristics has been investigated. Nonlinear double springs with
variable stiffness and length difference suspending the shake-out platform are considered. The survey on the
combined effect of mass and stiffness parameters on the dynamics of the modelled shake-out machine allowed
to determine the loads sustained by its structural elements and to make the rational design with the required
strength. In particular, it has been shown how to detune the machine from resonance frequencies, in particular
from the discovered dangerous subharmonic regimes due to variable mass and stiffness.
Опис
Ключові слова
dynamic processes in machines, strength of machines, vibroimpact system, vibromachine, variable mass, applied theory of oscillations, subharmonic mode
Бібліографічний опис
Parameter Analysis of Vibroimpact Machines Dynamics With Variable Mass and Stiffness / M. M. Tkachuk [et al.] // Nonlinear Dynamics–2016 (ND-KhPI2016) : proceedings of 5th International Conference, dedicated to the 90th anniversary of Academician V. L. Rvachev, September 27-30, 2016 = Нелінійна динаміка–2016 : тези доп. 5-ї Міжнар. конф., 27-30 вересня 2016 р. – Kharkov : NTU "KhPI", 2016. – P. 238-244.