تحليل كمانش و ارتعاشات آزاد نانو و ماكرو صفحات مستطيل شكل بر روي بستر الاستيك در تماس با سيال

چكيده انگليسي :

The Buckling and Free Vibration Analysis of Nano and Macro Rectangular Plate Resting on an Elastic Medium in Contact with Fluid Azadeh Hosseini a hoseininogourani@me iut ac ir Date of Submission 2013 01 13 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Alireza shahidi shahidi@cc iut ac ir Abstract Plates have wide applications in areas such as modern construction engineering aerospace and aeronautical industries aircraft construction shipbuilding and the components of nuclear power plants It is therefore very important that the static and dynamic behavior of plates when subjected to different loading conditions be clearly understood so that they may be safely used in these industrial applications The present study is concerned with the free vibration and buckling analysis of a horizontal rectangular plate on elastic foundations either immersed in fluid or floating on its free surface The governing equations for a thin rectangular plate are analytically derived based on the classical plate theory CLPT and the higher order employed to obtain the fluid pressure applied on the free surface of the plate by using the minimum The effect of elastic medium is expressed with Winkler and Pasternak foundation It is well known that the natural frequencies of structures in contact with fluid are different from those in vacuum In addition the existence of the fluid around the plate causes the kinetic energy to considerably increase Subsequently the natural frequencies of plate coupled with fluid decrease significantly in comparison to those of the plate in the air Therefore the prediction of changes natural frequency due to the presence of the fluid is important for designing structures which are in contact with or immersed in fluid So the effect of fluid motion on vibration and stability of plate under uniaxial and biaxial loading is studied and the critical velocity of fluid that leads to zero natural frequency is obtained The Galerkin and Rayleigh Ritz method are applied to solve the equations of motion The natural frequencies of rectangular plates are presented in tabular and graphical forms for different fluid levels fluid velocity foundation parameters aspect ratios thickness to width ratios and boundary conditions The result shows that increasing fluid velocity and stiffness parameter respectively increasing and decreasing natural frequency Also in recent years Nanomaterials are among the most important topics discussed in the scientific community due to their unique mechanical chemical thermal and electrical properties since the invention of carbon nanotubes CNTs Therefore the exact knowledge of the physical and mechanical properties and their effect on production efficiency and ability to applications is necessary Thus the buckling and vibration analysis of single layered graphene sheet and doubled layered nanoplate is studied based on theory The van der Waals vdW forces between two layers are taken into account based on the Lennard Jones model Results indicate that the small scale parameter elastic medium and temperature change have significant effects on the dimensionless natural frequency and critical fluid velocity Natural frequencies of the plate are presented in graphical forms for different temperature change aspect ratio fluid level stiffness parameter and fluid velocity for different boundary conditions It is demonstrated that some properties of vibrations of double layered nanoplates are dependent on the change of temperature Keywords Rectangular plates Buckling analysis Vibrational frequencies Solid Fluid Interaction Graphene nanosheets PDF created with pdfFactory trial version www pdffactory com

حسيني، آزاده

تحليل كمانش و ارتعاشات آزاد نانو و ماكرو صفحات مستطيل شكل بر روي بستر الاستيك در تماس با سيال

آناليز كمانش , فركانس ارتعاشي , اندركنش جامد-سيال , نانو صفحات گرافين