نوع مقاله : مقاله پژوهشی
نویسنده
دانشکده مهندسی مکانیک، دانشگاه گیلان، رشت، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسنده [English]
The viscoelastic material was presented using Boltzman viscoelastic model and Shapery constitutive equation for orthotropic material with a multidimensional integral. Employing Prony series, solution of the time integral was obtained in the form of a recursive-iterative approach that estimate the current time parameters based on parameters of the preceding time. After finding the lamina properties, overall properties of laminate are obtained with 3D lamination theory of Pagano. These properties are assigned to every integration point of the finite elements. Since this material is not available in standard finite element codes, viscoelastic laminated composite system was developed for commercial codes. The formulation was implemented into ANSYS USERMAT subroutine which is applicable for 3D structures with only one element through the thickness. For instance, buckling problem of a plate with a circular cutout was considered. Force-deflection curves of elastic material were obtained with ANSYS and subroutine material and compared well. For viscoelastic response, creep buckling of viscoelastic plate was obtained for various applied loads and imperfection. Long-term deflections and end-shortenings versus time were illustrated for two different fiber orientations. The results show that for creep bulking, imperfections do not have significant effect on end-shortening.
کلیدواژهها [English]
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