بررسي ارتعاشات نانو لوله اي كربني حامل سيال با استفاده از مدل تير و پوسته

چكيده انگليسي :

Vibration Analysis of Carbon Nano Tube CNT Conveying Fluid by Beam and Shell Models Mehran Mirramezani m mirramezani@me iut ac ir 1392 06 16 Department of Mechanical Engineering IsfahanUniversity of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Hamid Reza Mirdamadi hrmirdamadi@cc iut ac ir Abstract Recently carbon nano tubes CNTs have drawn a great deal of attention because CNTs have potential usage as cancer therapy devices or nano vessels for conveying and storing fluids and drug delivery in medicine and bio nanotechnology In this regard a remarkable number of studies have been accomplished to disclose the vibrational behavior and stability responses of such nano structures subjected to fluid flow Several researchers have utilized various theories such as Euler Bernoulli and Timoshenko beam models and elastic shell structure with different boundary conditions for investigating the critical mean flow velocity of CNT conveying fluid In this dissertation we would model the CNT by both Euler Bernoulli and shallow shell Donnell We would utilize Galerkin weighted residual method for discretizing the governing fluid structure interaction FSI equations For analyzing the dynamic response of CNT more accurately we would investigate the size effects of nano structure by using nonlocal and strain inertia gradient theories We would observe that the nonlocal continuum theory could suggest that the pipe conveying fluid could lose its stability sooner and the critical velocity and eigen frequencies would be smaller than that of classical theory However the values of critical mean flow velocities and eigen frequencies predicted by strain gradient theory are greater than that predicted by classical continuum theory Moreover we would consider the size effects of nano flow by using slip flow regime and Kn dependent flow velocity We would utilize a fluid structure interaction model based on the concept of velocity correction factor VCF for modeling slip condition on CNT walls In this model as the value of Kn parameter would increase the values of critical velocity and eigen frequencies could decrease This model would anticipate that considering the slip condition could cause a trivial change in stability response of CNT conveying liquid In contrast for the case of gas nano flow Kn could change noticeably the dynamic responses of CNT and we would observe approximately 95 percent reduction in the value of critical velocities Furthermore we would propose an innovative model based on the Kn dependent slip velocity of nano flow on the CNT walls and size dependent continuum theories for both beam and shell models We would conclude that regardless of the type of size dependent continuum theories the present model would propose a delayed occurrence of divergence for liquid and gas nano flows If the value of Kn could increase significantly the slip velocity of the fluid flow on the CNT walls could become greater and the profile of the velocity distribution become uniform across the cross sectional area of the pipe Consequently the results of this novel model could approach to those obtained by classical FSI governing equation In addition we would reappraise the well known equation of motion for a pipe conveying viscous fluid We would reveal that the viscosity of the fluid flow should not appear explicitly in the equation of motion of Euler Bernoulli conveying fluid Besides we would develop a FSI model for shallow shell Donnell conveying irrotational and viscous flow Finally we would compare the results obtained by Galerkin and wave traveling methods Keywords fluid structure interaction divergence and flutter instabilities Euler Bernoulli beam Donnell shallow shell nonlocal theory of Eringen strain inertia gradient theory slip flow regime viscosity PDF created with pdfFactory trial version www pdffactory com

مير رمضاني، مهران

بررسي ارتعاشات نانو لوله اي كربني حامل سيال با استفاده از مدل تير و پوسته

اندركنش سيال - سازه , ناپايداري ديورژانس و فلاتر , تير اويلر- برنولي , پوسته ي كم عمق دانل , تئوري ناموضعي ارينگن , تئوري گراديان كرنش- اينرسي , رژيم جريان لغزشي , گرانروي