Mechanics Colloquium

 

PROGRAM

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MATEMATIČKI INSTITUT SANU
ODELJENJE ZA MEHANIKU

PROGRAM ZA DECEMBAR 2017.

Pozivamo Vas da učestvujete u radu sednica Odeljenja i to:

SREDA, 6.12.2017 u 18:00, Sala 301f, MI SANU, Kneza Mihaila 36
Si Mohamed Sah, Danish Technical University (DTU)
ASSESSING BOLTED JOINTS TIGHTNESS WITH MEASURED NATURAL FREQUENCY
Abstract: Structural health monitoring techniques based on vibration measurements have been receiving large attention in the last decades, in particular techniques used for estimating bolted joints tightness and detecting loosened bolts. Due to the exposure of bolted joints to external forces, the bolts may loosen and therefore affect the healthy functioning of the bolted structure. In this work, a technique is proposed to assess the level of bolt tightness and to quantify the tension based on the measured natural frequencies. An experiment is performed on two structure specimen where each one is clamped with a bolt. The excited natural frequencies are recorded as the bolts are gradually tightened. The measured frequencies trends were described by a one dimensional beam model with elastic supports. The sensitivity of the measured transverse frequency showed the reliability of this frequency-based technique in assessing bolt tightness. This technique can also quantify the bolt tension using the analytical model, which gave an excellent agreement with the experimental data for high bolt tension.

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SREDA, 13.12.2017 u 18:00, Sala 301f, MI SANU, Kneza Mihaila 36
Dragomir Zeković, Mašinski fakultet, Beograd
DINAMIKA MEHANIČKIH SISTEMA SA NELINEARNIM NEHOLONOMNIM VEZAMA - III ANALIZA KRETANJA
Rezime: Analizira se kretanje neholonomnih mehaničkih sistema, sastavljenih od dve materijalne tačke kojima se nameću različita nelinearna ograničenja na brzine tih tačaka – paralelnost brzine, jednakost intenziteta brzina i upravnost brzina. Za takve sisteme se analiziraju: jednačine veza, reakcije veza tj. način variranja takvih veza, trajektorije tačaka sistema, linearni integrali po generalisanim brzinama tj. ciklične koordinata. Na ovim modelima se jasno pokazuje da u slučaju nelinearnih neholonomnih veza Hamiltonovo dejstvo u opštem slučaju nema stacionarnu vrednost. Na kraju su izvedene jednačine brahistohronog kretanja opisanih sistema i određene brahistohrone određenih tačaka.

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SREDA, 20.12.2017 u 18:00, Sala 301f, MI SANU, Kneza Mihaila 36
Ván Péter, Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics
INTERNAL VARIABLES IN THERMOMECHANICS: A SIMPLE APPROACH TO MEMORY AND WEAK NONLOCALITY
Abstract: The role of internal variables is to improve the performance and extend the validity of theories of mechanics and thermodynamics. However, their mechanical and thermodynamical appearance, the related theoretical structures are different and seemingly incompatible. In the presentation I show a unified treatment and shortly survey the various experimental and theoretical efforts of our group to develop and validate the theory.

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SREDA, 27.12.2017 u 18:00, Sala 301f, MI SANU, Kneza Mihaila 36
Vladimir Dragović, Matematički institut SANU
NOVOGODIŠNJI KOKTEL MATEMATIKE I MEHANIKE

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Predavanja su namenjena širokom krugu slušalaca, uključujući studente redovnih i doktorskih studija. Održavaju se sredom sa početkom u 18 sati u sali 301f na trećem spratu zgrade Matematičkog instituta SANU, Knez Mihailova 36.

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