تحليل ارتعاشات آزاد ورق هاي دايره اي سوراخ دار غير چرخان و چرخان ساخته شده از مواد با عملكرد درجه بندي شده ي چند-جهته

چكيده انگليسي :

Free Vibration Analysis of Non Rotating and Rotating Multi Directional Functionally Graded Annular Plates Iman Davoodi kermani i davoodikermani@me iut ac ir May 3rd 2011 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor M Ghayour Assoc Prof ghayour@cc iut ac ir AbstractThe free vibration of non rotating and rotating multi directional functionally graded annular plates are studied in thisthesis The concept of functionally graded materials was first introduced in 1984 as ultrahigh temperature resistantmaterials for aircrafts space vehicles and other engineering applications The functionally graded materials arecomposite materials that are microscopically inhomogeneous and their mechanical properties vary continuously inone or more directions This is achieved by gradually varying the volume fraction of the constituent materials Thecontinuity of the material properties reduce the influence of the presence of interfaces and avoid high interfacialstresses Furthermore functionally graded materials can be designed to achieve particular desired properties and thegradation in properties of material can optimize stress distribution Non rotating and rotating annular plates are usedin many engineering applications so that using the functionally graded materials in these structures is useful Thevibration analysis of circular and annular plates are presented in two parts non rotating and rotating First the three dimensional free vibration of non rotating multi directional functionally graded plates is studied The three dimensional elasticity theory is used to analyze the free vibration of the plate It is assumed that the materialproperties vary in both thickness and radial directions so that the plate is made of bi directional functionally gradedmaterial The governing equations are solved by a semi analytical numerical method which is the state space baseddifferential quadrature method This method solves the problem analytically in thickness direction by the state spacemethod and useing the differential quadrature method to solve the problem in radial direction numerically Theaccuracy and convergence of method are studied and the natural frequencies of these plates are determined fordifferent kind of functionally graded materials and different type of boundary conditions is obtained The influenceof various parameters such as inner radius to outer radius ratio thickness to outer radios ratio and graded indiceson natural frequencies are demonstrated It is shown that the increase of inner radius to outer radius ratio andthickness to outer radios ratio increase the natural frequencies of non rotating functionally graded plates The effectsof graded indices on natural frequencies are different The increase of the absolute value of thickness graded index decreases the natural frequencies and the variations of radial graded index have different effects on naturalfrequencies of plates with different kind of boundary conditions The corresponding displacements mode shapes aredrawn In the second part the free vibration analysis of rotating functionally graded annular plates is discussed Thetransverse motion equation is obtained by the classical plate theory In this case the material properties is variable inonly radial direction and the differential quadrature method is used to solve the vibration problem for determiningthe natural frequencies It is illustrated that the increase of inner radius to outer radius ratio increases the naturalfrequencies and the variation of the thickness to outer radius ratio is not effective on natural frequencies The naturalfrequencies via the different radial grade indices are determined and the transverse displacement mode shapes aredrawn It is found that the increasing rotating speed increases the forward natural frequencies and decreases thebackward frequencies The critical rotating speeds occur when the backward natural frequencies vani

داودي كرماني، ايمان

تحليل ارتعاشات آزاد ورق هاي دايره اي سوراخ دار غير چرخان و چرخان ساخته شده از مواد با عملكرد درجه بندي شده ي چند-جهته

روش نيمه-تحليلي , روش انتگرال گيري ديفرانسيلي