بررسی تجربی و تئوری بار بحرانی در نمونه‌های چندلایة کامپوزیتی حاوی شیار یو-شکل، تحت بارگذاری برش درون صفحه‌ای

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه آموزشی هوافضا، دانشکده علوم و فنون نوین دانشگاه تهران

چکیده

مدل‌های خرابی متعددی مبتنی بر پیش‌بینی میزان ظرفیت باربری چندلایه‌های کامپوزیتی حاوی ترک و شیار، مورد توجه محققین بسیاری در حوزة مکانیک شکست قرار گرفته است. دلیل اهمیت این امر، استفادة بسیار زیاد قطعات کامپوزیتی شیاردار در صنایع هوایی و فضایی در چند دهة اخیر می‌باشد. در این پژوهش سعی شده است تا با به‌کارگیری روشی بدیع و درعین حال ساده، که اخیراً توسط نویسندگان این مقاله پیشنهاد شده است، میزان ظرفیت باربری (ظرفیت باربری آخرین لایه) چندلایه‌های کامپوزیتی حاوی شیار یو-شکل، با لایه‌چینی‌های متفاوت، تحت بارگذاری برش داخل صفحه‌ای (مود دوخالص) بررسی گردد. معیارهای ترکیبی جدید ارائه‌شده برای اولین بار در حوزة مکانیک شکست مواد ارتوتروپ ارائه شده است. به همین منظور، با استفاده از مفهوم جدیدی به نام مفهوم مادة ایزوتروپ مجازی و ترکیب آن با دو معیار شناخته شده و پرکاربرد در حوزة مکانیک شکست الاستیک خطی به نامهای معیار حداکثر تنش محیطی و تنش متوسط، نتایج حاصل از آزمایش نمونه‌های چندلایة کامپوزیتی نیم‌دیسک خمشی حاوی شیار یو-شکل تحت بارگذاری برش داخل صفحه‌ای، با پیش‌بینی‌های تئوری انجام‌شده مقایسه می‌گردند. نتایج بدست‌آمده حاکی از تطابق بسیار خوب تمامی نتایج آزمایشگاهی با نتایج حاصل از تئوری‌های شکست جدید ترکیبی پیشنهاد شده می‌باشند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental and theoretical investigation of the critical load of U-notched laminated composite specimens under in-plane shear loading

نویسندگان [English]

  • Ali Reza Torabi
  • Ebrahim Pirhadi
Faculty of New Science and Technologies, University of Tehran
چکیده [English]

Numerous failure models for prediction of the load-carrying capacity of cracked and notched laminated composites have been of interest to researchers in the field of fracture mechanics. The cause of the importance of this subject was the extensive use of notched composite laminates in aerospace industries in the last decades. In this investigation, it was tried to predict the load-carrying capacity (critical failure load) of U-notched laminated composite specimens with various layup configurations under pure mode II loading (in-plane shear loading) conditions, by utilizing a simple and novel concept proposed recently by the authors. The new composed criteria have been proposed in the field of orthotropic fracture mechanics for the first time. For this aim, by using a newly proposed concept, namely the virtual isotropic material concept, and combining it with two well-known brittle fracture criteria in the field of linear elastic fracture mechanics, namely the maximum tangential stress and the mean stress criteria, the experimental results of the failure of the U-notched laminated semi-circular bend composite specimens under pure mode II loading condition, were theoretically predicted by using new last-ply-failure load curves. It was revealed that the experimental results are in good agreement with the theoretical predictions.

کلیدواژه‌ها [English]

  • Laminated composites
  • U-notch
  • Critical load
  • Semi-circular bend
  • Translaminar fracture toughness
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