پديد آورنده :
علينقيان جوزداني، حسين
عنوان :
تحليل كمانش الاستيك - پلاستيك صفحه ي مستطيلي مدرج تابعي تحت بارگذاري دومحوره
مقطع تحصيلي :
كارشناسي ارشد
گرايش تحصيلي :
طراحي كاربردي
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مكانيك
صفحه شمار :
هفت، 69ص.: مصور
استاد راهنما :
مهدي سلماني تهراني
استاد مشاور :
عليرضا شهيدي
توصيفگر ها :
مواد هدفمند , نظريه نموي , نظريه تغيير شكل
استاد داور :
محمدرضا فروزان، مهران مرادي
تاريخ ورود اطلاعات :
1395/07/17
چكيده فارسي :
1 چكيده در پژوهش حاضككر براي يك صككفحهي ضككخيم مسككتطيلي از جنس مواد مدرج تابعي هدفمند كه تحت بار دو محوره قرار دارد تحليل كمانش االسكتيك پالستيك انجام شده است اين تحليل براساس دو نظريهي رايج در حوزهي پالستيسيته نظريهي نموي و نظريهي تغييرشكل انجام شدهاست پس از ارايهي روابط كمانش االستيك پالستيك براي صفحات از جنس همگن اين روابط براي مواد هدفمند نيز رابطه بندي شكده اند پس از تعريف مادهي هدفمند با استفاده از روابط استخراج شده براي مادهي هدفمند مورد مطالعه تحليل كمانش انجام شكده اسكت براي يافتن بار بحراني كمانش از روش كمينهسازي انرژي پتانسيل و براي كمينهسازي انرژي پتانسيل از روش ريلي ريتز اسكتفاده شكدهاسكت مادهي هدفمند اسكتفاده شكده از نوع فلز فلز بوده و خواص فيزيكي از جمله مدول االسكتيسكيته چگالي و نماي مادهي كك ك ك كك ك رامبرگ ازگود بكهصكككورت تكابعي تواني تغيير ميكنكد در اين پژوهش ابتكدا نتكايج بكا مراجع و سكككبس بكا يكي از فلزات تشككككيكلدهنده صكحتسكنجي شكده و پس از آن نمودارهايي براي بار بحراني كمانش برحسكب نسبت ضخامت رسم شده است كه اثر تغييرات پارامترهاي مختلف دخيل در مسأله را نشان ميدهند اين پارامترها عبارتند از شرايط تكيهگاهي نسبت ابعادي نماي مربوط به مادهي هدفمند و نسبت بارگذاري نتايج گوياي اين هستند كه مهمترين پارامتر اثرگذار در اين مورد خاص نسبت بارگذاري است كلمات كليدي كمانش االستيك پالستيك مواد هدفمند صفحهي ضخيم نظريهي نموي نظريهي تغييرشكل
چكيده انگليسي :
72 Elastic Plastic Buckling Analysis of a FG Thick Rectangular Plate under Biaxial Loading Hossein Alinaghian Jouzdani h alinaghian@me iut ac ir Date of Submission 2016 06 22 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mehdi Salmani Tehrani tehrani@cc iut ac irAbstractFunctionally Graded Materials FGMs are special class of composite materials that are composed of twodifferent materials In these materials mechanical and thermal properties vary smoothly through the thicknessor other directions In this thesis elastic plastic buckling of a FG thick rectangular plate under biaxial loadingis studied The analysis is based on the both common plasticity theories Incremental Theory IT andDeformation Theory DT After presenting elastic plastic buckling relations for a homogenous plate theformulation is redeveloped for a FG plate Using the derived governing equations elastic plastic bucklinganalysis is conducted for the FG material case study A metal metal type Aluminum Steel was selected asthe FG case study The mechanical properties such as elastic modules density and Romberg Osgoodparameters is assumed to vary as a power function through the thickness of the plate The Mindlin plate theoryor First Order Shear Deformation Theory FSDT has been utilized to consider shear deformation As it isknown in FSD plate theory the shear strain is assumed to be constant through the thickness and then acorrection factor is applied to modify the non zero shear strain on the top and bottom surfaces of the plate Theminimum total potential energy functional uniqueness criterion is used to determine the critical bucklingstress Based on Rayleigh Ritz method the displacement fields are approximated using complete polynomialfunctions which involve unknown coefficients The geometric boundary conditions are satisfied usingappropriate base functions multiplied into the approximation polynomials The dimensionless form ofparameters is introduced to rederive dimensionless form of the equations This enables the analysis to representmore comprehensive results of the buckling study By substituting the approximate functions of displacementfield into the integral uniqueness criterion the integral is calculated as a function of the unknown coefficientsof the displacement polynomials The integral result should then be minimized with respect to these unknowncoefficients to determine the critical buckling stress This minimization procedure results in a homogeneoussystem of equations with respect to unknown coefficients For nontrivial solution zero value for all unknowncoefficients the determinant of the coefficient matrix of the equations system should be equal to zero Anonlinear algebraic equation is then obtained in which the boundary traction loading is unknown The smallestroot of this equation is the critical buckling stress In this thesis a computer code has been developed inMATHEMATICA software to implement the solution approach and calculate the critical buckling stress Tovalidate the analysis the convergence of results with respect to the polynomial order is first investigated Afifth order polynomial was found to be adequate to obtain sufficiently accurate results Then the buckling stressfor a homogeneous thick plate has been calculated and compared with previously published results A veryclose agreement was observed After the validation was carried out the effect of important factors on thebuckling of FG thick plate is investigated These factors involves thickness ratio aspect ratio of the rectangularplate boundary conditions the loading ratio and the exponent parameter in FG model The effect of FGexponent parameter was found to be insignificant This is due to relatively close values of the mechanicalparameters for the two materials which constitute the FG plate On the other hand the loading ratio was foundto be the most important factor which may affect the critical buckling str
استاد راهنما :
مهدي سلماني تهراني
استاد مشاور :
عليرضا شهيدي
استاد داور :
محمدرضا فروزان، مهران مرادي
