۱۷۸۸۲پ
per
استفاده از حساب تغییرات و روش‌صهای طیفی برای تحلیل کمانشی اعضاء با ضخامت متغیر ساخته شده از مواد هدفمند
/عباس حیدری
: فنی مهندسی عمران
، ۱۳۹۶
، راشدی
چاپی
دکتری
مهندسی عمران گرایش سازه
۱۳۹۶/۰۲/۱۴
تبریز
If there is the economic justification then the functionally graded material (FGM) is the best choice to improve the mechanical and thero-mechanical properties of structural members. The mechanical properties of FGM at a point in the material domain are functions of the position of that point. The classical rule of mixture including power law distribution of the constituents volume fraction was used to describe the through-thickness variation of material properties. In bidirectional functionally graded materials, the variation of the properties are occurred in both the transverse and longitudinal directions. In the present work for the first time, the buckling analysis of bidirectional functionally graded (BFG) Euler beam having arbitrary thickness variation rested on Hetenyi elastic medium was presented. In addition, a new scheme based on calculus of variations and collocation method for converting the buckling problem to an algebraic system of equations was proposed. The mentioned scheme leads to obtain the buckling characteristic equation of beam and therefore the first buckling loads were obtained. Various conditions including variation of mechanical properties across the thickness and through the axis, arbitrary thickness variation, Hetenyi elastic foundation, special boundary conditions like the shear hinge and classical boundary conditions such as clamped, simply supported, clamped-simply supported and cantilever beams were considered to show the compatibility of proposed scheme with the various circumstances. The fast convergence and compatibility with the various circumstances are the advantages of the proposed method. Due to the lack of similar studies in the literature, the same exercises were conducted by using the Spectral Ritz method to pursue the validity of the proposed scheme. The same basis was used for Spectral Ritz and proposed methods. Excellent agreement was found between the results of well-known Spectral Ritz method and the results of the proposed scheme, which validated the outcome of the proposed method. Moreover, a numerical scheme for the buckling analysis of functionally graded circular plate (FGCP) subjected to uniform radial compression including shear deformation rested on Pasternak elastic foundation was presented. The linear and quadratic thickness variation patterns with various boundary conditions were considered. A modified EulerLagrange equation was achieved and then solved by converting differential equation to a nonlinear algebraic system of equations. Also, based on tractionfree surface without using shear correction factor, a new approach by considering shear deformation for buckling analysis of FGCP rested on elastic foundation was carried out. The stability equation based on shear stress-free surface was solved by the spectral Ritz method. The spectral Ritz method has good flexibility in the sense of satisfying the boundary conditions. The effects of both linear and quadratic thick- ness variations and Poissons ratio were investigated. By taking small numbers of the basis, the outcomes in literature were improved
حیدری، عباس
جلالی، عبدالرحیم، استاد راهنما
سیاه و سفید
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