نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد مکانیک دانشکده فنی و مهندسی، دانشگاه جامع امام حسین (ع)

2 دانشیار گروه مکانیک، دانشکده فنی و مهندسی، دانشگاه جامع امام حسین(ع)

3 مربی، مهندسی هوافضا، دانشگاه جامع امام حسین (ع

4 دانشجوی کارشناسی ارشد عمران دانشکده فنی و مهندسی، دانشگاه جامع امام حسین (ع)

چکیده

رایزرهای دریایی یکی ازمهم‌ترین اعضای سازه‌ی سکوی شناورهستند. از همین رو، تحلیل ارتعاشات آن‌ها، دارای اهمیت ویژه‌ای می‌باشد. برای رسیدن به یک طراحی مناسب، درک چگونگی ارتعاشات عرضی رایزرها و به دست ‌آوردن پاسخ فرکانسی آن‌ها بسیار مفید است. بنابراین در این مقاله، به تحلیل چگونگی ارتعاشات غیرخطی عرضی یک رایزر، تحت بار محوری متغیر با در نظر گرفتن اثر کشیدگی صفحه میانی، پرداخته شده است. برای انجام این تحقیق، از روش مقیاس‌ زمانی چندگانه استفاده می‌شود. به منظور بررسی میزان دقت روش و صحت‌سنجی نتایج به دست آمده، مقایسه‌ای‌ با روش عددی رانگ-کوتای مرتبه‌ی چهارم انجام شده است. بر اساس نتایج، پاسخ فرکانسی تیر بیان‌گر وجود پدیده‌ی تقسیم شدن به دو شاخه‌ی غیرخطی، در ارتعاشات سه بعدی رایزر می‌باشد.هم‌چنین، کشیدگی صفحه میانی رایزر، باعث ایجاد حالت سخت‌شوندگی در پاسخ فرکانسی می‌شود. مطالعه‌ای پارامتری انجام شده است که در آن، تأثیر پارامترهای مختلف بر نقطه شروع دو شاخگی غیرخطی بررسی شده است.

کلیدواژه‌ها

عنوان مقاله [English]

Analysis of Sub-Harmonic Resonance and Nonlinear Bifurcation Phenomena of Three-Dimensional Beams Under Parametric Excitation

نویسندگان [English]

  • mahmoud pour jamshidian 1
  • saed mahjob moghadas 2
  • amir motalebi 3
  • javad sheykhi 4

چکیده [English]

Risers are one of the main vessel structural members. So, non-linear vibration analysis of risers, is particularly important. To achieve a proper design, understanding how the transverse vibrations of risers and obtain their frequency response is very useful. In this paper, the transverse vibrations analysis of risers under variable axial load are investigated. The effects of mid-plane stretching is also considered. For this study, the method of multiple time scale is used. In order to verify the accuracy of this method, the results are compared with the results of four order Runge-Kutta numerical method, which has a good accuracy. The frequency response of the system is represented Bifurcation phenomenon. Study of frequency response indicating that there is bifurcation  phenomenon in vibrational system, and also the mid-plane stretching of riser will create a hardening  behavior. Parametric study is also performed that the effect of various parameters is review on the starting point of the bifurcation  phenomenon.  

کلیدواژه‌ها [English]

  • Multiple time scales method
  • frequency response
  • bifurcation phenomenon
  • marine riser

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