نوع مقاله : مقاله پژوهشی
نویسندگان
دانشکده مهندسی عمران، دانشگاه صنعتی اصفهان، اصفهان، ایران
چکیده
ورقهای ساندویچی به عنوان اعضای سازهای، به علت وزن مخصوص پایین، مقاومت در برابر خستگی و نیز مقاومت خمشی بالا در سازههای صنعتی و پروژههای بزرگ عمرانی مورد توجه بسیار قرار گرفتهاند. از آنجا که سازههای صنعتی معمولاً تحت بارهای دینامیکی قرار میگیرند، لرزش صفحات میتواند منجر به آسیب سازهها شود به ویژه وقتی فرکانس تحریک نزدیک به فرکانس طبیعی سازه باشد. بنابراین تحلیل ارتعاش غیرخطی ورقهای ساندویچی یکی از موضوعات پر کاربرد در دینامیک سازهها به شمار میرود. در این مقاله ارتعاش آزاد غیرخطی ورقهای ساندویچی با هسته ویسکوالاستیک بر اساس فرضیات ون کارمن و با استفاده از تئوری برشی مرتبه اول مورد مطالعه قرار میگیرد. خواص ویسکوالاستیک هستهی ورق از قانون انتگرال بولتزمن پیروی میکند. همچنین از تبدیل لاپلاس برای تبدیل معادلات از حوزه زمان به دامنه لاپلاس استفاده میشود. برای گسستهسازی معادلات از روش عددی نوار محدود استفاده میشود. در نهایت با حل عددی مسئلهای مقدار ویژه در حوزه لاپلاس کارسون فرکانسهای غیرخطی ورقهای ساندویچی با هسته ویسکوالاستیک با دامنههای ارتعاش متفاوت محاسبه میشوند. نتایج نشان میدهد که با افزایش دامته ارتعاش و ضرایب تابع آسودگی هسته ویسکوالاستیک نسبت فرکانسهای غیرخطی در این گونه از ورقها کاهش مییابد.
کلیدواژهها
- ورقهای ساندویچی
- هسته ویسکوالاستیک
- روش نوار محدود
- ارتعاش آزاد غیرخطی
- انتگرال بولتزمن
- فرضیات ون کارمن
- تئوری برشی مرتبه اول
موضوعات
عنوان مقاله [English]
Nonlinear free vibration analysis of moderately thick sandwich plates with viscoelastic core using finite strip method
نویسندگان [English]
- Arezoo Hajrahimi
- Nasrin Jafari
- Saeed Sarrami
Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran
چکیده [English]
Sandwich plates as structural members, have received a lot of attention in industrial structures and large construction projects due to their low specific weight, resistance to fatigue and high bending strength. Since Industrial structures are commonly reposed to dynamic loads, plate vibration can result in injury to structures, especially when the excitation frequency is close to the natural frequency of the structure. Therefore, nonlinear vibration analysis of plates is one of the most attended topics in the dynamics of structures. In this article, the nonlinear free vibration of sandwich plates with a viscoelastic core is studied based on von Karman's assumptions and using the First-order shear deformation theory. The viscoelastic properties of the plate core follow Boltzmann's integral law. Also, the Laplace transform is used to convert equations from the time domain to the Laplace domain. For the discretization of the equations, the finite strip numerical method is used. Finally, by numerically solving an eigenvalue problem in the Laplace-Carson domain, the nonlinear frequencies of sandwich plates with a viscoelastic core with different vibration amplitudes are calculated. The results show that, with the increase of the vibration amplitude and the coefficients of the relaxation function of the viscoelastic core, the ratio of the nonlinear frequencies decreases in this type of plates.
کلیدواژهها [English]
- Sandwich plates
- Viscoelastic core
- Finite strip method
- Nonlinear free vibration
- Boltzmann's integral
- Von Karman's assumptions
- First-order shear deformation theory
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