کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6479374 1428536 2017 14 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
An upper bound theory to approximate the natural frequencies and parameters identification of composite beams
ترجمه فارسی عنوان
تئوری محدودیت بالا برای تقریب فرکانس های طبیعی و تعیین پارامترهای پارامترهای کامپوزیت
کلمات کلیدی
پرتو کامپوزیت / غیر یکنواخت، فرکانس طبیعی، ریکی فاکتور، روش توابع مرزی، نظریه مرزی بالایی مشکلات معکوس،
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی عمران و سازه
چکیده انگلیسی

For the free vibration of composite beams and non-uniform beams we propose a new upper bound theory to approximate the first few natural frequencies. The Rayleigh quotient is expressed in terms of boundary functions, instead of that in terms of eigenfunctions. The boundary function satisfies all boundary conditions of the given beam, and is at least the fourth-order polynomial with leading coefficient to be one. We prove that the maximality of the Rayleigh quotient in the space of the kth order boundary functions is equivalent to the orthogonality of the kth order boundary function to lower order optimal boundary functions. Hence, we can easily find the kth order natural frequency through an orthogonalization technique provided. When the first three natural frequencies are compared with the exact or numerically found ones, good results are obtained, which confirm the applicability of the present upper bound theory. We address the inverse problems of composite beam equations, where we use the orthogonal system of boundary functions as bases to expand the unknown functions and derive linear algebraic equations to determine the expansion coefficients. As a consequence, we can fast and accurately estimate the unknown rigidity function and planar inertial function with the help of the first three natural frequencies, and the supplemented measured data of recovered function on two boundaries. The robustness of the present inversion methods is demonstrated by numerical examples.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Composite Structures - Volume 171, 1 July 2017, Pages 131-144
نویسندگان
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