Primena nelokalne teorije kontinuuma u analizi dinamičkog ponašanja i stabilnosti sistema spregnutih nano-struktura
Докторанд
Karličić, Danilo Z.Ментор
Kozić, PredragЧланови комисије
Pavlović, RatkoJovanović, Dragan
Janevski, Goran
Simić, Srboljub
Метаподаци
Приказ свих података о дисертацијиСажетак
This dissertation investigates vibration and stability behavior of complex
nano-scale systems composed of single and multiple carbon nanotubes and
graphene sheets. Based on the assumptions introduced through the nonlocal
continuum theory, the nanotubes are modeled as nanobeams and graphene
sheets are represented as nanoplates where the influence of inter-atomic
forces and the discrete nature of nanomaterials are introduced as material
parameters. To such mechanical models of nanostructures one can apply the
second Newton’s law of motion or Hamilton’s principles to derive the
governing equation of motion of the system. In order to obtain solutions of
partial differential equations, the analytical and approximation methods will
be employed. Special attention is devoted to determining the analytical
solutions for natural frequencies and critical buckling load of systems with
multiple nanostructures (nanorods, nanobeams and nanoplates) and special
cases of such systems. Thus o...btained analytical solutions are validated by
using the numerical methods as well as the results from molecular dynamics
simulations, where excellent agreement of the results is confirmed. In
addition, the longitudinal vibration of systems with a single or multiple
coupled nanorods will be analyzed using nonlocal elasticity and
viscoelasticity theories. What should be noted are the effects of temperature
changes and magnetic fields on the dynamic behavior of a cracked carbon
nanotube embedded in an elastic medium. It is shown that the possibility of
change in the overall system stiffness by changing the parameters of external
physical fields leads to certain changes in natural frequencies without any
change in other parameters of the model. The case of the free nonlinear
vibration and dynamic stability of carbon nanotubes subjected to variable
axial force and external magnetic field will be presented in the example of a
single nanobeam embedded in a viscoelastic medium by considering the
geometric nonlinearity. Analytical approximation results are determined for
nonlinear frequencies, amplitude-frequency curve by using the multiple
scales method. It is shown that it is possible to avoid resonant states as well
as changes in stability and instability regions by changing the external
magnetic field parameter without any change in other parameters of the
system. A parametric study is performed for all presented systems, and effects
of different physical and geometrical parameters on the dynamic behavior and
stability are examined in detail.
Факултет:
Универзитет у Нишу, Машински факултетДатум одбране:
03-10-2016Пројекти:
- Динамичка стабилност и нестабилност механичких система под дејством стохастичких поремећаја (RS-MESTD-Basic Research (BR or ON)-174011)