Ph.D. Tezi Görüntüleme | |||||||||||||||||||||
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| Summary: SUMMARY In the finite element method, although many formulations on shell elements are proposed there is no such a unique shell element formulation that provides all the shortages come from both theory and practice. Recently, the shell elements obtained by using the refined element method have been successfully used in many problems. In this study flat shell element formulations are driven to associate the membrane element with drilling degrees of freedom and the plate element obtained from the refined element formulation. 4-node 4-sided (quadrilateral) (SKQ, SRMQ), 5-node 4/5 sided (pentagonal) (SKP, SRMP) and 7-node 4/6 sided (hexagonal) (SKS, SRMS) flat shell elements have been developed with 6-DOF at each node by using the refined element method. In these elements which are free from the shear and membrane locking phenomena Kirchhoff plate theory has been used for thin plates while Reissner/Mindlin plate theory has been used for thick/thin plates. The new element formulations developed in this study by using the refined element method have then been adapted to FEAP finite element program to create the mentioned flat shell elements and the numerical results have been obtained. The elements developed have been applied first to the patch tests, second to the standard test problems given in the literature, and then to some static and dynamic problems selected on purpose. The results obtained using these flat shell elements have been then compared with the theoretical solutions and with those of element given in the literature and in ANSYS commercial program, and their performances have been determined. It has been seen from the results obtained for 4-node quadrilateral element (SRMQ) that it had a high accuracy for both Kirchhoff and Reissner/Mindlin plate theories. SRMP and SRMS elements were provided the closed values to those of SRMQ element. SRMP element along with SRMQ element has been successfully used as a transition element where mesh refinement is necessary. When 7-node hexagonal SRMS flat shell element was used to discrete the domain, it was determined that it had to be used along with 5-node 4/5 sided SRMP flat shell element.
Key words: Membrane element, Kirchhoff Plate, Reissner/Mindlin Plate Refined Element Method, 4 Node Quadrilateral Flat Shell Element5 Node Pentagonal Flat Shell Element, 7 Node Hexagonal Flat Shell Element
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