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چكيده انگليسي :

104 Local Buckling Analysis of Various Shapes of Plates with Intermediate Point Supports by the Use of Hp Cloud Method and Lagrange Multiplier Sajad Jamshidy s jamshidy@cv iut ac ir Date of Submission 2012 01 7 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mojtaba Azhari Mojtaba@cc iut ac ir AbstractThe orthotropic plate with intermediate point supports has extensive applications in construction of deck ofbridges wings of airplanes body of ships and rockets Plates with point supports are not readily amenable tosolution because the concentrated shear force at the point supports locations makes discontinuous force field onthe plate For this reason making the equilibrium conditions on the point supports in the ordinary continuum plateanalysis couldn t be straightforward In this study elastic buckling of orthotropic plates with various geometries and intermediate point supports isinvestigated Hp Cloud shape functions are used to approximate the displacement Some of the great advantagesof Hp cloud approach include possibility to make approximation functions with desirable continuity by means ofmaking the appropriate weighting functions and selection of proper enrichment functions possibility to improveapproximation procedure by reducing the influence radius h refinement and increasing the monomials orchanging the type of enrichment function p refinement accessing to shape functions of the nodes without anyinverting operation due to selecting Shepard functions as the partition of unity and local approximation norm ofthe Hp cloud shape functions that reduce density of elastic and geometry stiffness matrix In this study byselecting the special pattern for influence radius of nodes and polynomial type of enrichment function Hp cloudshape functions with kronecker delta property are constructed Therefore it is feasible to satisfy zero displacementcondition in point supports location that is placed on the field nodes It must be noted that there are somegeometric constraints in constructing Hp cloud shape functions with kronecker delta property So in general moreconsiderations for satisfying essential boundary condition are needed In this case the Lagrange multiplier methodhas been used Classical small deflection theory of thin plates has been employed in order to derive the relationsof orthotropic thin plate and the computations were carried out by the Ritz method For calculating the elastic and geometry stiffness matrix elements one must integrate on the subscription surfaceof two corresponding clouds In this study refined cell structure method is introduced for numerical integration In the refined cell structure method first the subscription surface of two clouds is divided in number of segments Again every segment that is in conjunction with the boundary of plates is divided in order to access more exactconsideration of real surface of integration Proper results are achieved by the use of refined cell structure forsolving the plate with complex geometry just like regular geometric one Equivalent distribution of one and two row point supports on the plate edges for modeling the ordinary simplysupported and clamped supported boundary condition is indicated by comparing buckling coefficients of twomanners Tendency of boundary conditions of plate edges with periodic distribution of point supports towardsimply supported condition is studied for various shapes of trilateral and quadrilateral plates Buckling modes andbehavior of plates are also examined under in plane forces such as uniaxial pressure biaxial pressure shear bending and interaction of these forces Furthermore interaction curves of in plane forces are plotted for cornersupported plates with different geometry Keywords Elastic buckling plates with various shapes intermediate point supports Hp cloud shape functions Ritz method

جمشيدي، سجاد

كمانش موضعي ورق ها با اشكال مختلف با تكيه گاه هاي نقطه اي با استفاده از روش Hp-Cloud همراه با ضرايب لاگرانژ

كمانش الاستيك , روش تغييراتي رتيز