Seminar
MECHANICS OF MACHINES AND MECHANISMS - MODELS AND MATHEMATICAL METHODS

 

PROGRAM

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Plan rada Seminara Mehanika mašina i mehanizama - modeli i matematičke metode za MART 2021.

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UTORAK, 16.03.2021. u 17:00, Live stream Beograd
Danilo Karličić, Mathematical Institute of the Serbian Academy of Sciences and Arts, Belgrade, Serbia
APPLICATION OF THE INCREMENTAL HARMONIC BALANCE METHOD IN NONLINEAR VIBRATION PROBLEM OF NONLINEAR ENERGY SINK
Structural vibrations are very common in aerospace and mechanical engineering systems, where dynamic analysis of modern aerospace structures and industrial machines has become an indispensable step in their design. Suppression of unwanted vibrations and their exploitation for energy harvesting at the same time would be the most desirable scenario. The main property of nonlinear energy sink (NES) is the transfer of vibration energy from the main structure to the tuned vibration absorber. It was demonstrated that nonlinear vibration absorbers are more effective in vibration absorption than the linear ones since they can cover a wider frequency range. To explore complex dynamical behaviour of the presented models, periodic solutions and their bifurcations are found by using the incremental harmonic balance and continuation methods. For the detection of unstable periodic orbits, the Floquet theory is applied and an interesting harmonic response of the presented nonlinear dynamical system is detected. The main advantage of the presented approach is its ability to obtain approximated periodic responses in terms of Fourier series for a system with strong nonlinearity. The accuracy of the presented methodology is verified by comparing the results obtained in this work with those obtained by a standard numerical integration method and results from the literature. Numerical examples show the effects of different physical parameters on amplitude-frequency response, where a qualitative change is explored and studied in detail.

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UTORAK, 30.03.2021. u 17:00, Live stream Beograd
Maja Čavić, Faculty of Technical Sciences, University of Novi Sad, Serbia
MECHANISMS FOR ACHIEVING DIFFERENT WAYS OF POWER TRANSMISSION AND MOTION OF THE ANTHROPOMORPHIC ROBOTS UPPER BODY
In the near future, anthropomorphic robots will work actively in the immediate human environment that is dynamic and unpredictable, and will have to perform numerous and complex tasks. Such robots must be absolutely safe for the humans and objects from environment.
The human body is musculoskeletal and viscoelastic structure that has variable flexibility and approximately 350 degrees of freedom (DOFs). On the other hand, almost all humanoids that have been developed have rigid bodies and their mobility is therefore limited and unnatural. Flexible spine is essential for achieving human-like movements. Thanks to its flexible spine, humanoids can absorb mechanical impacts and shocks, and therefore are safer in physical contacts with humans or objects. Spine allows the upper body movements without moving the lower body, so the higher assortment of movements is achieved and the range of the robot arms reach is increased. Besides that, humanoids that have more DOF in the torso area when walking require less energy compared to humanoids with rigid torso. In addition, the robot will have two anthropomorphic arms, neck and human-like lumbar structure to increase mobility.
Beside the fact that these robots have to be absolutely safe for humans and objects from the environment, it is expected from them to realize nonverbal communication in an intuitive and transparent manner. Nonverbal communication is extremely powerful mean of communication which can transmit a large amount of information in a short period of time. Even 55% of communication between humans refers to nonverbal communication, 38% to the intonation – paraverbal communication and only 7% to the content of the message – verbal communication. Paraverbal and nonverbal messages sent clear signals regardless to the meaning of spoken words. Today there is a lot of work on improving the interactive elements of the robot. For expressing facial expressions biologically inspired eyes and eyelids are going to be used. To extend the range of nonverbal communication the robot is going to shrug when the answer is confusing or the robot does not know what to answer.

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Obavezno je nošenje maski i održavanje distance. Broj prisutnih na predavanju ograničen na najviše 10 (uključujući i predavača).

Seminar Mehanika mašina i mehanizama - modeli i matematičke metode započeo je sa radom u junu 2018.god. Seminar se održava do dva puta mesečno, utorkom u periodu od 17.00 - 19.00 u Matematičkom institutu SANU.

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