مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

تحلیل المان محدود خمش میکرو ورق مربعی با سوراخ دایروی بر اساس تئوری الاستیسیته سه‌بعدی گرایان کرنش

نویسندگان
1 دانشکده مهندسی مکانیک، دانشگاه گیلان، رشت، ایران
2 دانشیار دانشگاه گیلان
چکیده
مشاهدات تجربی نشان داده‌اند که رفتار مکانیکی مواد در مقیاس میکرو و نانو به واسطه تاثیر مشخصه‌های ابعادی، وابسته به اندازه می‌باشد. از آنجا که تئوری‌های کلاسیک مکانیک محیط پیوسته امکان در نظر گرفتن اثرات وابسته به اندازه را ندارند، استفاده از تئوری‌های غیر کلاسیک به منظور تحلیل رفتارهای مکانیکی میکرو و نانو سازه‌ها مورد توجه بسیاری از محققان قرار گرفته است. در تحقیق حاضر، فرمول‌بندی المان محدود به منظور بررسی خمش میکرو ورق‌های مربعی با سوراخ‌ دایروی تحت بار گسترده یکنواخت بر اساس تئوری الاستیسیته سه‌بعدی گرادیان کرنش ارائه می‌شود. بدین منظور المان شش وجهی هشت گرهی پیوسته مرتبه یک معرفی می‌شود که در آن علاوه بر مقادیر مولفه‌های میدان جابجایی، مشتقات مراتب بالاتر آنها نیز به عنوان مقادیر گره‌ای در نظر گرفته شده‌اند. در ابتدا روابط حاکم بر اساس تئوری گرادیان کرنش و مدل الاستیسیته سه‌بعدی ارائه شده و سپس با توجه به المان معرفی شده، فرمول‌بندی المان محدود بیان می‌گردد. لازم به ذکر است با در نظر گرفتن مقدیر خاص برای ضرایب تئوری گرادیان کرنش، می‌توان نتایج مربوط به تئوری‌های گرادیان کرنش اصلاح شده و تنش کوپل اصلاح شده را به دست آورد. به منظور نشان دادن کارایی المان معرفی شده، در ابتدا همگرایی و دقت نتایج مورد بررسی قرار گرفته و سپس تاثیر پارامترهای هندسی بر تحلیل خمش میکرو ورق سوراخ‌دار مورد ارزیابی قرار می-گیرد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Finite element bending analysis of square microplates with circular hole based on the three-dimensional strain gradient elasticity theory

نویسندگان English

Jalal Torabi 1
Reza Ansari 2
1 Faculty of mechanical engineering, University of Guilan, Rasht, Iran
چکیده English

ٍExperimental studies indicates that the mechanical behavior of materials at micro and nano scales are size-dependent. Since the classical continuum mechanics theories cannot capture the size effect, employment of different non-classical theories has received a considerable attention among researchers. In this study, the finite element formulation is presented to investigate the bending of square microplates with circular hole subjected to uniform pressure based on the three-dimensional strain gradient elasticity theory. For this account, the 8-node C^1 continuous hexahedral element is introduced in which, in addition to the values of displacement components, some related higher-order mix derivatives are further considered as nodal values. The governing equations are derived based on the strain gradient theory and three-dimensional elasticity model and the finite element formulation is presented using the introduced element. Note that by considering some specified values for coefficients of strain gradient theory, the numerical results can be obtained for modified strain gradient theory and modified couple stress theory. To demonstrate the efficiency of the proposed finite element, the convergence and accuracy of the results are firstly checked and then the impacts of geometrical parameters on the bending of microplates with circular hole are studied.

کلیدواژه‌ها English

Finite element
Bending
Microplate with circular hole
Strain gradient
Three-dimensional elasticity
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