کارآیی روش بدون المان توسعه یافته جهت تحلیل پس کمانش میکرولوله¬های هدفمند حاوی سیال تحت میدان¬های دما و سرعت
محورهای موضوعی : یافته های نوین کاربردی و محاسباتی در سیستم های مکانیکی
بهروز آرین نژاد
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امیرحشمت خدمتی بازکیائی
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1 - گروه مهندسی مکانیک، دانشکده فنی مهندسی، دانشگاه آزاد اسلامی، واحد اهواز، اهواز،ایران
2 - گروه مهندسی مکانیک، واحد سوسنگرد، دانشگاه آزاد اسلامی، سوسنگرد، ایران
کلید واژه: کمانش, میکرو لوله, مواد هدفمند, میدان¬های دما و سرعت سیال, روش بدون المان نقطه¬ای ,
چکیده مقاله :
میکرو/ نانولوله ها هدفمند به دلیل هندسه و رفتار مکانیکی خاص کاربرد زیادی درسیستم های الکترومکانیکی دارند. در این تحقیق جهت یافتن معادلات حاکم بر تحلیل از تئوری غیرکلاسیک گرادیان کرنش مبتنی برمدل کلاسیک تیر اویلر برنولی با هندسه غیرخطی وون-کارمن استفاده می شود. در این تحلیل نحوه تاثیر تغییرات دما، قطر خارجی، سرعت بی بعد شده و قانون توانی بر رفتار غیرخطی میکرو لوله نیز مورد مطالعه قرار گرفته است. با حل ضعیف معادلات دیفرانسیلی حاکم به روش درون یابی نقطه ای توسعه یافته، میدان جابجایی ناشی از کمانش میکرو لوله هدفمند تحت میدان های سرعت و دما محاسبه گردیدند. یافته های تحقیق ضمن کارآیی استفاده از روش عددی یاد شده، بیان می دارند که کاهش قطر میکرولوله با فرکانس طبیعی و سرعت بحرانی نسبت عکس دارد. با تاثیر همزمان میدان های سرعت و تغییرات دما، محدوده قطر بحرانی خارجی بین 12 تا 15 میکرو متر و قطر خارجی بحرانی 13 میکرو متر با دامنه بیشینه نوسان 01/0 تعیین گردید. این در حالی است که با این قطر بحرانی و افزایش دما، جابجایی عرضی میکرو لوله هدفمند افزایش، سفتی آن کاهش یافته است. با افزایش اندیس توانی به ویژه در13 n>، مشاهده گردید که رفتار میکرو لوله از جنس مواد خالص به میکرو لوله ای از جنس مواد هدفمند نزدیکتر می شود.
Long tubes with diameters in the micro and nano dimensions, while having a relatively complex manufacturing technology, have a wide range of applications For example, they are used in the fields of: electromechanics, biosensors, atomic microscopes, actuators, fluid transport in drug delivery, medical engineering and surgery, etc. The reason for the widespread use of microtubes is their special geometry and mechanical properties.The use of Functionally Graded Material as heterogeneous and isotropic materials has received much attention.Because these materials, with gradual and continuous changes in structural properties from surface to surface, do not have the problem of sudden changes in material behavior at the interface of composite materials. In this research, the buckling analysis of FGM-microtubes has been studied using a numerical point interpolation meshless method with base functions developed to weakly solve the differential equations governing the analysis based on the classical Euler-Bernoulli beam model and the non-classical strain gradient theory with three length parameters. The research findings, in addition to the effectiveness of using the aforementioned numerical method, indicate that the reduction in microtube diameter has an inverse relationship between the natural frequency and the critical velocity. With the simultaneous effect of velocity fields and temperature changes on the critical diameter, the transverse displacement of the FGM-microtube increases, and its stiffness decreases However, increasing the power index increases the transverse displacement after buckling and causes the microtubule behavior to become closer and closer to that of the FGM material from that of the pure material.
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