نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری، هوافضا، پژوهشگاه هوافضا، تهران ، ایران

2 استادیار، مهندسی مکانیک، دانشگاه امام علی، تهران ، ایران

3 استاد، مهندسی مکانیک، دانشگاه مالک اشتر،مجتمع هوافضا، تهران ، ایران

4 استادیار، مهندسی مکانیک، پژوهشگاه فضایی، تهران، ایران

10.22068/jstc.2018.80212.1415

چکیده

یک سازه در عمر کاری خود به ندرت تنها تحت اثر بار استاتیکی قرار می‌گیرد و معمولاً ماهیت بارگذاری بر روی سازه‌ها دینامیکی است. پوسته‌های کامپوزیتی تحت بارهای دینامیکی دچار تغییر شکل‌های بزرگ می‌گردند که این امر منجر به کاهش محسوس استحکام این پوسته‌ها می‌گردد. یکی از راه‌های غلبه بر این ضعف پوسته‌های کامپوزیتی استفاده از پوسته‌های کامپوزیتی فلز و الیاف می‌باشد که به اختصار به آنها FML گفته می‌شود. همچنین بارهای دینامیکی منجر به ایجاد ارتعاشات در سازه‌ها می‌گردند. لذا تعیین خصوصیّات ارتعاشی پوسته‌های FML ، به منظور فهم کاربردهای صنعتی آنها بسیار مهم است. در این مقاله ابتدا به نحوه ساخت پوسته‌های FML تقویت شده اشاره می‌شود سپس سه نمونه پوسته ساخته شده تحت شرایط مرزی گیردار-آزاد و به روش تجربی مورد تحلیل ارتعاشی قرار گرفته و فرکانس‌های آنها استخراج می‌گردند. در نهایت نتایج حاصل از تحلیل‌های تجربی با نتایج عددی حاصل از نرم‌افزار المان محدودی آباکوس مقایسه گردیده تا میزان همپوشانی نتایج عددی و تجربی تعیین گردند. همچنین به منظور تحلیل شرایط مختلف، رفتار ارتعاشی یک پوسته FML با یک پوسته تمام کامپوزیتی از جنس شیشه /اپوکسی مقایسه گردیده است. علاوه بر این تاثیر وجود و عدم وجود تقویت‌کننده‌ها بر پاسخ ارتعاشی پوسته‌های FML نیز مورد بررسی قرار گرفته است. وجود تحلیل‌های تجربی برای ارتعاشات پوسته‌های FML تقویت شده که برای اولین بار در این پژوهش ارائه گردیده است یکی از مهمترین نوآوری‌های مقاله حاضر می‌باشد که می‌توان از این نتایج تجربی به عنوان معیاری مناسب جهت تعیین دقت روش‌های عددی و تحلیلی استفاده نمود.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental and numerical analysis of vibration of FML- stiffened circular cylindrical shell under clamp-free boundary condition

نویسندگان [English]

  • ali nazari 1
  • Ali Asghar Naderi 2
  • Keramat Malekzade‌fard 3
  • ahmad hatami 4

1 Department of Aerospace Engineering, Aerospace Research Institute, Tehran, Iran

2 Department of Mechanical Engineering, University of emamali, Tehran, Iran

3 Department of Aerospace Engineering, University of malekashtar, Tehran, Iran

4 Department of Aerospace Engineering, Aerospace Research Institute, Tehran, Iran

چکیده [English]

Most of composite cylindrical shells always are used under dynamic loads not static loads in working cycle of themes and Application of dynamic loads cause to large deformation and strength reduction. One way to reduce this negative characteristic is to make the fiber metal laminated shells that named FML in abbreviation. Also dynamic loads cause to vibration in structure. In the present study, firstly the fabrication of stiffened-FML cylindrical shell is explained. Then the vibration behavior and natural frequencies of three samples of FML-stiffened cylindrical shells are derived under clamp-free boundary condition. Moreover the vibration behaviors of these shells are investigated using abaqus finite element software and the FEM results are compared with experimental results in order to shows in agreement with each other. Also the effects of various parameters are studied in this article. For this purpose the frequency response of stiffened and unstiffened FML shells are compared with together and the vibration behavior of FML-shell are compared with glass/epoxy composite shell. One of the most innovations of this study is the experimental results that can be used as a benchmark for further study.

کلیدواژه‌ها [English]

  • Vibration
  • Fiber metal laminate
  • experimental analysis
  • natural frequency
  • stiffened shell
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