تشخیص ترک در تیرها به کمک تبدیل هیلبرت-هوانگ

نوع مقاله: کاربردی

نویسندگان

دانشگاه شهید جمران اهواز

چکیده

در این پژوهش یک روش یک روش غیرمخرب به‏ منظور تشخیص ترک در تیرها ارائه شده است. در این روش از تبدیل هیلبرت-هوانگ به ‏عنوان یک روش پردازش سیگنال استفاده می‏شود. ترک که به‏ صورت باز در نظر شده است، توسط فنر چرخشی مد‎لسازی می‏گردد. به ‏منظور محاسبه فرکانس‏های طبیعی تیر ترکدار، تئوری تیموشنکو بکار گرفته شده است. سپس با استفاده از سیگنال‏های ارتعاشی تیر ترکدار، فرکانس‏های طبیعی تجربی به ‏کمک تبدیل فوریه سریع و تبدیل هیلبرت-هوانگ محاسبه شده‏اند. سرانجام با کمینه ‏نمودن یک تابع هدف به‏ کمک الگوریتم‏ کلونی زنبور عسل مصنوعی، محل و عمق ترک‏ها تعیین می‏گردند. تابع هدف به ‏صورت مجموع وزنی مربعات خطای بین مقادیر عددی و تجربی فرکانس‏های طبیعی تیر ترکدار است. به ‏منظور بررسی صحت روش ارائه شده، ترک‏هایی در محل‏ها و عمق‏های گوناگون در تیرهای فولادی ایجاد و پارامترهای ترک با دقت مناسب تشخیص داده شده‏اند. نتایج نشان می‏دهد که با استفاده از فرکانس‏های تجربی حاصل از تبدیل هیلبرت-هوانگ می‏توان ترک (خصوصاً ترک در عمق‏ کم) را با دقت بهتری نسبت به تبدیل فوریه سریع شناسایی نمود.

کلیدواژه‌ها


عنوان مقاله [English]

Crack detection in beams using Hilbert-Huang transform

نویسندگان [English]

  • Mohammad Reza Galeban
  • Shapour Moradi
چکیده [English]

This study presents a non-destructive method for detecting location and depth of crack in beams. The method utilizes Hilbert-Huang Transform (HHT) as a time-series analysis technique. Crack is considered to be open and has been modeled by rotational spring. First, the natural frequencies of the cracked beam are calculated using Timoshenko’s beam theory. Then by using the vibration signals corresponding to the beam, experimental natural frequencies are calculated by Fast Fourier Transform (FFT) and HHT. Finally, with the help of Artificial Bee Colony, the location and depth of the crack are predicted by minimization of an objective function. The objective function is constructed by the weighted sum of the squared errors between the theoretical and experimental natural frequencies of the cracked beams. To investigate the feasibility of proposed method, cracks in different locations and depths are introduced in steel beams and crack parameters are predicted. The results show that both the location and depth of the crack can be predicted well through the proposed method. Moreover, by using the experimental natural frequencies obtained by HHT method, cracks (especially small depth) can be detected with a better precision than FFT method.

کلیدواژه‌ها [English]

  • Crack Detection
  • Hilbert-Huang Transform
  • Fast Fourier Transform
  • Timoshenko’s beam theory
  • Artificial Bee Colony
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