نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکترا، مهندسی مکانیک، دانشگاه تربیت مدرس، تهرا ن

2 استاد، مهندسی مکانیک، دانشگاه تربیت مدرس ، تهران

3 مهندسی مکانیک، دانشگاه آزاد اسلامی، تاکستان

10.22068/jstc.2020.120400.1629

چکیده

در این تحقیق، یک مدل تحلیلی به منظور بررسی ارتعاشات آزاد پانل-های ساندویچی مخروطی با هسته مشبک ارائه می شود. از یک روش تحلیلی- تقریبی معادل‌سازی جدید برای محاسبه پارامترهای سفتی معادل تقویت‌کننده‌ها استفاده می-گردد. در این روش، هسته مشبک با یک پوسته مخروطی کامپوزیتی معادل‌سازی می‌شود. تقویت‌کننده‌ها (هسته) به صورت تیر در نظر گرفته می‌شوند که قابلیت تحمل ممان‌های خمشی علاوه بر بار محوری را دارا می‌باشند. برای این منظور، در ابتدا با استفاده از آنالیز نیرو و ممان بر روی یک سلول واحد، پارامترهای سفتی معادل تقویت‌کننده‌ها تعیین می‌شوند و سپس به منظور دستیابی به سفتی کل سازه، با سفتی‌های پوسته‌ها جمع می‌شوند. با استفاده از روش گالرکین و تئوری کلاسیک دانل، معادلات حاکم بر پوسته ساندویچی استخراج و فرکانس‌های طبیعی ارتعاش به دست می‌آیند. به منظور اعتبار سنجی نتایج، یک مدل اجزای محدود سه بعدی نیز در نرم افزار آباکوس ساخته می‌شود. مقایسه نتایج توافق خوبی را نشان داد و اثبات کرد که مدل تحلیلی، از دقت کافی برای بررسی ارتعاشات سازه‌های ساندویچی مخروطی با هسته مشبک را داراست. نتایج حاضر جدید بوده و می‌تواند به عنوان مبنایی برای مطالعات آتی مورد استفاده قرار گیرد.

کلیدواژه‌ها

عنوان مقاله [English]

A novel smeared method for investigating the free vibrations of sandwich conical shells with lattice cores

نویسندگان [English]

  • Mehdi Zarei 1
  • Gholamhossein Rahimi 2
  • Milad Hemmatnezhad 3

1 Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran

2 Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran.

3 Faculty of Mechanical Engineering, Takestan Branch, Islamic Azad University, Takestan, Iran

چکیده [English]

In this study, an analytical model was presented for investigating the free vibrations of sandwich conical shells with lattice cores. A novel smeared method was employed to determine the stiffness contribution of the stiffeners. In this approach, the lattice core was approximated with an equivalent composite conical shell. The stiffeners were considered as a beam which support the shear loads and bending moments in addition to the axial loads. For this purpose, the stiffness contribution due to the stiffeners was firstly determined through the forces and moments analysis of a unit cell and then superimposed with those of the inner and outer skins in order to obtain the stiffness parameters of the whole structure. The governing equations were deduced using the classical shell theory of Donnell type and Galerkin method. In order to validate the analytical results, a 3-D finite element model was also created using ABAQUS software. Comparison of the results, revealed good agreements between the two approaches and demonstrated that the proposed analytical model is qualified enough to investigate the free vibrational behavior of sandwich conical shells with lattice cores. Results given are novel and can be used as a benchmark for future studies.

کلیدواژه‌ها [English]

  • Free vibrations
  • Sandwich conical shell
  • Smeared method
  • Galerkin method
  • FEM
[1]  Kidane,  S. Li, G. Helms, J. Pang, S.S. and Woldesenbet, E., “Buckling load analysis of grid stiffened composite cylinders”, Composites part B, Vol. 34, pp. 1-9, 2003.
[2]  Yazdani, M. Rahimi, G.H. Afaghi Khatibi, A. and Hamzeh, S., “An experimental investigation into the buckling of GFRP stiffened shells under axial loading”, Scientific Research and Essays, Vol. 4, No. 9, pp. 914-920, 2009.
[3] Yazdani, M. and Rahimi, G.H., “The effects of helical ribs’ number and grid types on thebuckling of thin-walled GFRP-stiffened shells under axial loading”, Journal of Reinforced Plastics and Composites, Vol. 29, No. 17, pp. 2568-2575, 2010.
[4]  Yazdani, M. and Rahimi, G.H., “The behavior of GFRP-stiffened and -unstiffened shells under cyclic axial loading and unloading”, Journal of Reinforced Plastics and Composites, Vol. 30, No. 5, pp. 440-445, 2011.
[5] Rahimi, G.H. Zandi, M. and Rasouli, S.F., “Analysis of the effect of stiffener profile on  the buckling strength in composite isogrid stiffened shell under axial loading”, Aerospace Science and Technology, Vol. 24, pp. 198-203, 2013.
[6]  Rahimi, G.H. Hemmatnezhad, M. and Ansari, R., “Prediction of Vibrational Behavior of Grid-Stiffened Cylindrical Shells”, Advances in Acoustics and Vibration, Vol. 2014, Article ID 242573, 10 pages.
[7]  Hemmatnezhad, M. Rahimi, G.H. and Ansari, R., “On the free vibrations of grid-stiffened compositecylindrical shells”, Acta Mechanca, Vol. 225, pp. 609-623, 2014.
[8]  Hemmatnezhad, M. Rahimi, G.H. Tajik, M. and Pellicano, F., “Experimental, numerical and analytical investigation of free vibrational behavior of GFRP-stiffened composite cylindrical shells”, Composite Structures, Vol. 120, pp. 509-518, 2015.
[9]  Ghasemi, M.A. Yazdani, M. and Hoseini, S.M., “Analysis of effective parametres on the buckling of grid stiffened composite shells based on first order shear deformation theory”, In Persian, Modares Mechnical Enginerring, Vol. 13, No. 10, pp. 51-61, 2013.
[10] Zarei, M. and Rahimi, G.H., “Free vibration analysis of rotating grid stiffened composite cylindrical shells”, In Persian, Modares Mechanical Engineering, Vol. 16, No. 9, pp. 175-185, 2016.
 [11] Talebitooti, M. Ghayour, M. Ziaei-Rad, S. and Talebitooti, R., “Free vibrations of rotating composite conical shells with stringer and ring stiffeners”, Archive of Applied Mechanics, Vol. 80, pp. 201-215, 2010.
[12] Talebitooti, M. Daneshjou, K. and Talebitooti, R., “Vibration and Critical Speed of Orthogonally Stiffened Rotating FG Cylindrical Shell Under Thermo-Mechanical Loads Using Differential Quadrature Method”, Journal of Thermal Stresses, Vol. 36, pp. 160-188, 2013.
[13] Daneshjou, K. Talebitooti, M. Talebitooti, R. and Saeidi Googarchin, H., “Dynamic analysis and critical speed of rotating laminated conical shells with orthogonal stiffeners using generalized differential quadrature method”, Latin American Journal of Solids and Structure, Vol. 10, pp. 349-390, 2013.
[14] Naderi, A.A. Rahimi, G.H. and Arefi, M., “Influence of fiber paths on buckling load of tailored conical shells”, Steel and Composite Structures, Vol. 16, No. 4, pp. 375-387, 2014.
[15] Zarei, M. and Rahimi, G.H., “Free Vibration Analysis of Grid Stiffened Composite Conical Shells”, In Persian, Journal of Science and Technology of Composites, Vol. 4, No. 1, pp. 1-8, 2017.
[16] Zhang, H. Sun, F. Fan, H. Chen, H. Chen, L. and Fang, D., “Free vibration behaviors of carbon fiber reinforced lattice-core sandwich cylinder”, Composites science and technology, Vol. 100, pp. 26-33, 2014.
[17] Sun, F. Fan, H. Zhou, C. and Fang, D., “Equivalent analysis and failure prediction of quasi-isotropic composite sandwich cylinder with lattice core under uniaxial compression”, Composite Structures, Vol. 101, pp. 180-190, 2013.