تحليل پايدري ديناميكي ارتعاشات تير انعطاف پذير تحت اثر عبور متوالي جرم هاي متحرك

چكيده انگليسي :

Dynamic Stability Analysis of a Flexible Beam Under the Effect of Successive Passage of Moving Masses Mehran Ghomeshi Bozorg m ghomeshibozorg@me iut ac ir February 2014 Department of mechanical Emngineering Isfahan University of Technology Isfahan 84156 83111 IranMehdi keshmiri mehdik@cc iut ac ir Supervisor Saeed Ziaei Rad1 szrad@cc iut ac ir Advisor Department Graduate Program CoordinatorAbstract In this thesis stability analysis of an Euler Bernoulli beam subjected to the periodic passage of vehicles isinvestigated The beam moving mass interaction causes dynamic stability issue in the beam vibration It isstudied using Floquet theory Homotopy perturbation metod HPM and Homotopy analysis method HAM The results are presented in the form of stability maps All the methods are able to determine boundary of thestable and unstable region in the map However HAM and HPM determine the boundary analytically whileFloquet theory does it numerically In addition to the stable unstable boarder line HAM and HPM determineresonant curves on the map Effects of modelling approach for the beam and moving mass on the stable unstableboarder line are investigated using Floquet theory The results show that modelling approach has a significantinfluence on the results and inappropriate modelling leads to inaccurate results The similarity of the HAM andHPM perturbation methods permits to pursue a common trend and compare the results The results areconfirmed through numerical simulations Keywords Beam moving mass Stability analysis Resonant conditions Floquet theory Homotopy analysismethod Homotopy perturbation method INTRODUCTIONI Analyzing dynamic interaction between structural flexibility and inertia loading hasreceived increasing attention due to the design of low weight structures augmented by thetransition of heavier loads Dynamic stability of such systems and conditions which cause thegrowth of vibrations is an issue that has been studied from different aspects by researchers The research community focused on this subject some neglected inertia terms of the vehicleand considered it as a moving load 1 Only a restricted number of them included allcomponents of moving mass acceleration in their analysis 2 In many of these cases vehicletransition recurrence equal to the beam natural frequencies are presented as trigger toresonance In the present research a different approach based on Floquet theory is followed contributing to a comprehensive evaluation of the influence of modelling methods ondynamic stability of the beam vibrations To the best of authors knowledge stability analysiswith respect to aforementioned aspects has not been done yet The results are presented asstability maps in mass velocity diagrams which show that the modelling method and value ofthe model parameters have significant effect on the system stability Also in the presentresearch adopting the HAM and HPM for the time varying beam moving mass problem performance of these two methods on predicating the edges of instability and locus ofresonance conditions are compared Solutions obtained through the methods split theparametric mass velocity plane of moving mass into two distinct stable and unstable regions Associated professor Mechanical Engineering Department Isfahan university of Technology Iranj Professor Mechanical Engineering Department Isfahan university of Technology Iran

قمشي بزرگ، مهران

تحليل پايدري ديناميكي ارتعاشات تير انعطاف پذير تحت اثر عبور متوالي جرم هاي متحرك

تير-جرم متحرك , آناليز پايداري , شرايط تشديد , تئوري فلاكه , روش آناليز هموتوپي , روش اختلال هموتوپي