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چكيده انگليسي :

Elastic and Inelastic Buckling of Thick Laminated Plates Using Finite Layer Method Arezu Samady Dinany arezu samady@gmail com Date of Submission 12 02 2012 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Dr Mojtaba Azhari mojtaba@cc iut ac irAbstract Composite materials have been obtained by combining two or more material on the microscopic scale Laminated plates are made of several individual layers In which the fibers are oriented in a specified direction toefficiently provide required strength and stiffness parameters Rectangular plates made of laminated composite material have been used extensively in various branches ofengineering and industrial products such as building structures aerospace aircraft marine and etc due to highstrength and stiffness low weight excellent resistance to corrosive substances and satisfactory durability underfatigue loading To use laminated composite plates effectively and rightly a perfect understanding of theirmechanical behavior under various loading with different boundary conditions is needed These plates are often employed in situation where they are subjected to in plane compressive loading sobuckling is very probable for them Buckling of composite laminated plates usually generates large deformation inlow stress Thus it can be dangerous and solving the buckling problems accurately is very important The buckling problem of laminated composite plates has been investigated by many researchers with differentmethods In the present study the elastic stability of both isotropic and composite laminated plates with different endconditions and also the inelastic buckling of thick plates are studied by the finite layer method The plate can besubjected to uniaxial or biaxial compression loading The finite layer method is an extension of the well knownfinite element method This method efficiently transformed three dimensional problem into one dimensionalbecause of the trigonometric properties By using the finite layer method the transverse shear stiffness is calculatedso the results can be more accurate for buckling of thick plates In the finite layer method each lamina in thecomposite plate is divided by one or more finite layers For the in plane interpolations of displacementstrigonometric functions are used that are dependent on boundary condition while polynomials are employed in thethickness direction By assuming the displacement functions u v and w and using energy approach for each layerthe stiffness and stability matrices are obtained Then for all the layers forming the plate stiffness and stabilitymatrices by using connectivity matrix is assembled to give an eigenvalue matrix which can be solved for the criticalbuckling load of the plate Deformation theory is used for solving the inelastic buckling of the plates Deformation theory gives moreaccurate results than flow theory for inelastic buckling For the plates with high width to thickness ratio elasticbuckling and for the plates with low width to thickness ratio inelastic buckling is happened For solving the inelasticbuckling of thick plates by using the finite layer method three dimensional formulations is needed This method enables a full three dimensional analysis it is economical and simple to program saves time andcomputing effort and also reduces storage requirement Numerical results for elastic and inelastic buckling of platesare presented to demonstrate the accuracy and efficiency of this method The effects of thickness loading aspectratios different boundary conditions and number of layers on buckling of plates are studied Keywords Finite Layer Method Laminated Composite plate Local buckling Inelastic buckling

صمدي ديناني، آرزو

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