Free vibrations of rotating cylindrical shells with both ends clamped

master's thesis

• Title (croatian): Slobodne vibracije rotirajuće cilindrične ljuske s uklještenjem na oba kraja
• Author: Ružica Radoš
• Mentor: Neven Alujević (mentor)
• Mentor: Ziv Brand https://orcid.org/0009-0005-5424-9754 (komentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-07-16, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

In this thesis free vibrations of rotating cylindrical shells with clamped-clamped boundary
conditions are considered. Firstly, an analytical model is developed, which determines the exact
natural frequencies of both stationary shells and shells rotating with a constant angular speed
about its axis. The obtained results are validated by a comparison with the results of an
experimental study and two numerical studies for stationary shells, and two analytical studies
for rotating shells. An excellent agreement is observed. Secondly, an approximate solution
using the Rayleigh-Ritz method is developed. In this solution, exact circumferential mode shape
profiles are kept, but the axial profiles of the mode shapes are approximated by the mode shapes
of a clamped-clamped beam. These results are validated by a comparison with the exact solution
developed here. The Campbell diagrams corresponding to the two solutions practically overlap.
Therefore, a simple and convenient method is developed to determine the natural frequencies
of a rotating shell from those of a stationary shell.

Abstract (croatian)

U ovom radu proučavaju se slobodne vibracije rotirajuće cilindrične ljuske s uklještenjem na
oba kraja. Prvo su egzaktno određene prirodne frekvencije i prirodni oblici za stacionarne
ljuske, kao i za ljuske koje se rotiraju konstantnom kutnom brzinom oko svoje osi. Valjanost
razvijenog analitičkog modela provjerena je usporedbom s eksperimentalnim i dvama
numeričkim rezultatima za stacionarne ljuske, te s dvama analitičkim rezultatima za rotirajuće
ljuske. Uočeno je izvrsno podudaranje rezultata. Povrh toga, razvijeno je i približno rješenje
pomoću metode Rayleigh-Ritz. Kod ovog rješenja zadržani su egzaktni cirkumferencijalni
profili prirodnih oblika, dok su aksijalni profili aproksimirani profilima grede uklještene na oba
kraja. Valjanost ovog rješenja potvrđena je usporedbom s egzaktnim rješenjem. Campbellovi
dijagrami za dva razvijena modela praktički se poklapaju. Dakle, razvijena je jednostavna i
praktična metoda za proračun prirodnih frekvencija rotirajuće ljuske iz poznatih prirodnih
frekvencija stacionarne ljuske.

• Keywords: Theory of plates and shells; Rotating cylindrical shells; Free vibration; Bifurcations of natural frequencies; Rotating modes; Exact solution; Rayleigh-Ritz method
• Keywords (english): Teorija ploča i ljusaka; Rotirajuće cilindrične ljuske; Slobodne vibracije; Bifurkacije prirodnih frekvencija; Rotirajući prirodni oblici; Egzaktno rješenje; Rayleigh-Ritz metoda
• Language: english
• URN:NBN: urn:nbn:hr:235:246552
• Project: Number: IP-2019-04-5402; Title: Dinamika Aktivnih i Rotirajućih KONstrukcija; Title: Dynamics of Active and Rotating Structures; Acronym: DARS; Leader: Neven Alujević; Jurisdiction: Croatia; Funder: Hrvatska zaklada za znanost; Funding stream: Research Projects
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2026-07-16
• Created on: 2024-07-15 11:32:21