نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار، دانشکده مهندسی مکانیک، دانشگاه سمنان، سمنان، ایران

2 دانشجوی کارشناسی ارشد، دانشکده مهندسی مکانیک، دانشگاه سمنان، سمنان، ایران

3 استادیار، دانشکده مهندسی مکانیک و انرژی، دانشگاه شهید بهشتی، تهران، ایران

چکیده

استفاده از کامپوزیت‌های کربن/اپوکسی در اکثر سازه‌ها به دلیل نسبت استحکام به وزن قابل توجه، روشی متداول است. در این رابطه بررسی و دسته بندی انواع خرابی‌ها در سازه‌های کامپوزیتی برای جلوگیری از هرگونه اتفاقات احتمالی و افزایش قابلیت اطمینان آن‏ها، امری ضروری است. در یک دسته بندی کلی، خرابی‌های سازه‏های کامپوزیتی را می‌‌توان به چهار نوع تقسیم نمود: ترک ماتریسی، شکست الیاف، جدایش الیاف از ماتریس و جدایش لایه‌ای. یکی از روش‌های جدید تشخیص عیوب در کامپوزیت‌ها، استفاده از روش انتشار صوت است. بر این اساس، هدف از این مقاله بررسی و دسته بندی انواع مختلف ساز و کار‌های خرابی در نمونه‌های کامپوزیتی چندلایه سوراخدار، تحت بار کششی با استفاده از روش انتشار صوت است. نخست یک قطعة کامپوزیتی سوراخدار بر اساس استاندارد ASME تحت بارگذاری کششی قرار گرفت. موج‌های الاستیک انتشاریافته حاصل از شکست قطعه توسط دو حسگر انتشار صوت از نوع نوار پهن ثبت شدند. برای تشخیص مقدار درصد خرابی از دو روش تبدیل موجک بسته‌ای و خوشه‌بندی فازی استفاده شد. نتایج این دو روش با تحلیل تصاویر حاصل از میکروسکوپ الکترونی روبشی مقایسه گردیدند. نتایج نشان داد که حدود 50% خرابی‌ها مربوط به جدایش الیاف از ماتریس بوده، حدود 30% از ترک ماتریسی ناشی شده و حدود 20% در ارتباط با شکست الیاف می باشد. همچنین بیشترین اختلاف در این دو روش در تشخیص خرابی‌ها 7% می‌باشد. نتایج بدست آمده از این پژوهش نشان دهنده بازدهی مطلوب روش انتشار صوت در تعیین نوع خرابی‌ها و مقدار درصد هریک از آن‌ها در کامپوزیت‌های چندلایه است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Failure mechanisms in open-hole laminated composites under tensile loading using acoustic emission

نویسندگان [English]

  • Ahmad Ghasemi-Ghalebahman 1
  • Hassan Sayyar 2
  • Mohammad Azadi 1
  • Seyed Mohammad Jafari 3

1 Faculty of Mechanical Engineering, Semnan University, Semnan, Iran

2 - Faculty of Mechanical Engineering, Semnan University, Semnan, Iran

3 - Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, A.C., Tehran, Iran.

چکیده [English]

Carbon/epoxy composites have been used frequently in several structures due to their incredible ratio of strengths to weights. In this regard, investigation and classification of damages in composite structures are essential to prevent any probable happenings and to enhance the reliability. Such failures can be generally categorized into 4 groups, including matrix cracking, fiber breakage, debonding of fibers from the matrix, and the delamination. One of the new methods for detection of defects in composites is to utilize the acoustic emission approach. Accordingly, the aim of this article is to investigate and classify the different types of failure mechanisms in open-hole laminate composite specimens under tensile loading using acoustic emission. First, an open-hole specimen was examined under tensile loading based on ASME standards. Then, elastic waves due to failures in the specimen were recorded by wide-band acoustic emission sensors. Two methods have been utilized to detect the failure percent, including Pocket wavelet transform and Fuzzy clustering approaches. Results from these methods were compared to micro-structure images by the scanning electron microscopy. Results showed that about 50% of damages corresponds to debonding, about 30% comes from matrix cracking, and 20% is relevant to fiber breakage. In addition, the difference between two considered methods was 7%. Obtained results in this research indicated the appropriate efficiency of the acoustic emission approach to detect the type of failures and their percent in laminate composites.

کلیدواژه‌ها [English]

  • Composite
  • Acoustic emission
  • Fuzzy clustering
  • Pocket wavelet transform
  • Scanning electron microscopy
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