This paper presents the buckling and out-of-plane free vibration response of a sandwich panel with flexible core for the different boundary condition. In the desired configuration of the sandwich panel, the top and bottom plates are made of magneto-electro-elastic (MEE) plates. Moreover, the in-plane electric and magnetic potential fields are neglected for the derivation of the required relations. The sandwich structure is subjected to axial force in both longitudinal and transverse directions; in addition, and the top and bottom plates are exposed to electric and magnetic fields. The governing equations of motion for MEE sandwich panel with a flexible core are derived based on the first-order shear deformation theory by neglecting the displacement of the mid-plate and using the Hamilton’s principle. Furthermore, the derived partial differential equations (PDEs) are solved. According to the obtained numerical results, the core thickness, variation of electric field, variation of magnetic field and plate length are introduced as the most influential parameters on the free vibration response of the panel as well as the critical force of buckling. As one of the results, the electric potential is inversely related to the natural frequency and buckling load, so that with increasing the electric potential, the natural frequency and critical load of the structure is also increased.Moreover, the magnetic potential is directly related to the natural frequency and buckling load of the system, and increasing trends of natural frequency and critical load are observed by increasing the magnetic potential. Manuscript profile

در این مقاله، رفتار ارتعاشی غیرخطی یک نانو ورق با هندسه دایره با فرض شرایط مرزی گیردار مورد بررسی قرار گرفته است. برای این منظور، ترکیبی از شکل دیفرانسیلی نظریه الاستیسیته غیرمحلی، مدل گرادیان کرنش و اصل همیلتون، به همراه روابط کرنش-جابجایی غیرخطی فون کارمان و روش باقیمانده وزنی گالرکین برای گسسته سازی معادلات حاکم استفاده شده است. در ادامه تأثیر اثرات اندازه (اثر غیرمحلی و اثر مادی مدل گرادیان کرنش) و شرایط اولیه بر رفتار ارتعاشی سازه مدنظر بررسی شده است. نتایج نشان می دهند که این پارامترهای غیرمحلی و مادی به ترتیب منجر به کاهش و افزایش رفتار فرکانس های غیرخطی شده اند. در نهایت، افزایش مقدار اولیه جابجابی یک روند افزایشی برای نسبت فرکانسی به ازای هر پارامتر غیرمحلی و پارامتر مادی ایجاد می‌کند. همچنین، برای تمام پارامترهای غیرمحلی و پارامتر ماده، تفاوت بین نسبت فرکانس با افزایش شرایط اولیه کاهش یافته است. Manuscript profile

In this paper, failure modes of sandwich panels are investigated numerically using finite element method. For this purpose, four sandwich beams of GFRP laminateskins and Nomex honeycomb core are considered. The models have been chosen so that they could cover all failure modes according to available experimental failure mode maps. Models are created and analyzed based on standard 3-points bending test, using ASTM standard C393-62. In order to investigate the effect of loading and sandwich panelparameters on failure behavior, finite element analysis has been utilized. The results are verified by comparing experimental and theoretical results. The constructed failure mode map shows dependence of failure mode on the ratio of skin thickness to span length, and honeycomb relative density. To Then, effect of temperature on the failure modes ofsandwich panels, has been investigated. Results show that failure modes haven’t depended on environment temperature and failure load decreases by increasing environmentaltemperature. The slope of reduction is a function of beam geometrical parameters.Depending on the parameters, the failure loads decrease between 10% to 40% byincreasing environmental temperature. Manuscript profile