روشهای عددی در مهندسی

روشهای عددی در مهندسی

تحلیل کمانش نانوصفحه‌های تابعی مدرج تقویت‌شده با نانوگرافن بر بستر کشسان با استفاده از روش بدون شبکه بر اساس نظریه گرادیان کرنش غیر محلی

نوع مقاله : مقاله پژوهشی

نویسندگان
1 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه فردوسی مشهد
2 گروه مهندسی عمران، دانشکده علوم مهندسی، دانشگاه صنعتی قوچان
چکیده
در این پژوهش، یک روش نوین بدون شبکه وابسته به اندازه در چارچوب نظریه گرادیان کرنش غیرمحلی برای ارزیابی رفتار کمانش نانوصفحه‌های فلزنیمه‌هادی تابعی مدرج تقویت‌شده با نانو صفحه‌های گرافن بر روی بستر کشسان وینکلر-پاسترناک و دارای مهار مرزی کشسان پیشنهاد شده است. این رویکرد به‌طور همزمان اثر سختی غیرمحلی و گرادیان کرنش را در نظر می‌گیرد و سازوکارهای نرم‌شدن و سخت‌شدن ذاتی در مقیاس نانو را پوشش می‌دهد. معادله‌های حاکم با استفاده از اصل حداقل انرژی پتانسیل کل استخراج شده و با استفاده از روش بدون شبکه کریجینگ متحرک گسسته‌سازی می‌شوند. این روش به‌طور مؤثر مشتق‌های مرتبه بالای موجود در نظریه گرادیان کرنش غیرمحلی را حل می‌کند. ویژگی‌های مکانیکی مربوط به هر لایه از صفحه در راستای ضخامت، که با استفاده از نانوگرافن‌ها تقویت شده است، از طریق مدل میکرومکانیکی اصلاح‌شده هالپینتسای همراه با قانون مخلوط، تعیین شده است. مقایسه نتیجه‌های حاصل از تحلیل با روش‌های تحلیلی و عددی موجود، صحت و کارآیی محاسباتی روش پیشنهادی را تأیید می‌کند. در این پژوهش، تأثیر گرادیان ماده، سهم وزنی گرافن، متغیرهای غیرمحلی و گرادیان کرنش، ابعاد بازشوی دایره‌ای، سختی بستر کشسان و اثر سختی مهار کشسان تکیه‌گاهی بر پاسخ‌های کمانشی نانوصفحه‌های تابعی مدرج تقویت‌شده با گرافن مورد تحلیل و بررسی قرار گرفته است.
کلیدواژه‌ها
موضوعات

عنوان مقاله English

Buckling Analysis of Graphene Platelet-Reinforced Functionally Graded Nanoplates Resting on Elastic Foundation Using a Meshfree Formulation Based on Nonlocal Strain-Gradient Theory

نویسندگان English

Sajjad Tohidi 1
Farzad Shahabian 1
Mohammad Hossein Ghadiri Rad 2
1 Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
2 Department of Civil Engineering, Faculty of Engineering of Science, Quchan University of Technology, Quchan, Iran
چکیده English

In this research, a novel size-dependent meshfree method is proposed within the framework of the nonlocal strain-gradient theory in order to evaluate the buckling behavior of functionally graded metal–semiconductor nanoplates reinforced with graphene nanoplatelets. The nanoplates with elastically restrained edges are rested on a Winkler–Pasternak elastic foundation. The presented model simultaneously accounts for the effects of nonlocal stiffness and strain gradient, thereby covering the intrinsic softening and stiffening mechanisms at the nanoscale. The governing equations are derived using the principle of minimum total potential energy, and are discretized using the moving Kriging meshfree method. This method effectively resolves the higher-order derivatives appearing in the nonlocal strain-gradient theory. The mechanical properties corresponding to each layer of the plate through the thickness, reinforced by graphene nanoplatelets, are determined using the modified Halpin–Tsai micromechanical model together with the rule of mixtures. Comparison of the results obtained from the proposed method with available analytical and numerical approaches confirms the accuracy and computational efficiency of the proposed method. Furthermore, a parameter-based investigation is carried out to clarify the effects of material gradation, graphene weight fraction, nonlocal and strain-gradient parameters, circular cutout size, the stiffness of the elastic foundation and stiffnesses of the elastically restrained edges on the buckling responses of the functionally graded graphene-reinforced nanoplates.

کلیدواژه‌ها English

Moving Kriging meshfree method, Nonlocal strain-gradient theory, Functionally graded metal&ndash
semiconductor nanoplates reinforced with graphene nanoplatelets, Buckling analysis
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