پديد آورنده :
صادق زاده حسن آبادي، علي
عنوان :
تحليل ارتعاشات آزاد، خطي و غيرخطي استوانه هاي چين دار با استفاده از معادل سازي با پوسته ارتوتروپ بدون چين
مقطع تحصيلي :
كارشناسي ارشد
گرايش تحصيلي :
طراحي كاربردي
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مكانيك
صفحه شمار :
سيزده، 100ص.: مصور
استاد راهنما :
مصطفي غيور، حسن نحوي
استاد مشاور :
عليرضا شهيدي
توصيفگر ها :
روش مقياس هاي زماني چندگانه
استاد داور :
سعيد ضيايي راد، رضا تكيني
تاريخ ورود اطلاعات :
1395/01/17
چكيده فارسي :
1 چكيده در اين پاياننامه تحليل ارتعاشات آزاد بدون استهالك خطي و غيرخطي پوستههاي استوانهاي چيندار با چينهاي سينوسي انجام شده است استوانهي چيندار با يك استوانه ارتوتروپ بدونچين معادل شدهاست با استفاده از تئوري پوستههاي كمضخامت دانل استوانه ارتوتروپ بدونچين مورد مطالعه قرارگرفته و فركانسهاي طبيعي ارتعاش خطي آنها استخراج شده است استوانه چيندار در نرمافزار آباكوس مدلسازي شده و فركانسهاي طبيعي ارتعاش خطي آن استخراج شدهاند با مقايسه نتايج بدست آمده از تئوري دانل با نتايج حاصل از حل اجزا محدود در نرمافزار آباكوس ميزان خطاي روش معادلسازي استوانه چيندار با استوانه ارتوتروپ بدونچين مشخص شده است تاثير عواملي چون هندسه و مشخصات چينها عمق و دوره چين در فركانسهاي طبيعي روي نمودار آورده شده است در ادامه ارتعاشات آزاد غيرخطي استوانههاي چيندار مورد مطالعه قرارگرفته است معادالت غيرخطي مربوطه با استفاده از روش گالركين بدست آمدند و با استفاده از روش مقياسهاي زماني چندگانه حلشدند با مقايسه نتايج حاصل از حلهاي عددي و حل بدست آمده از روش مقياسهاي زماني چندگانه اعتبار روش مقياس هاي زماني براي مطالعه دسته مسائل مورد نظر تاييد شده است فركانسهاي نوسانات دامنههاي مودال بدست آمده و حالت تشديد داخلي نيز مورد بررسي قرارگرفته است در انتها نيز نتايج بدستآمده مرور شده و پيشنهاداتي براي ادامه كار مطرح گرديده است كلمات كليدي استوانههاي چيندار ارتعاشات غيرخطي روش مقياسهاي زماني چندگانه
چكيده انگليسي :
Linear and Nonlinear Free Vibration Analysis of Corrugated Cylindrical Shells Using Equivalent Uncorrugated Orthotropic Shell Ali Sadeghzade Hassanabadi a sadeghzade@me iut ac ir date of submissiom 8 2 2016 Department of Mechanical Engineering Isfahan University of technology Isfahan 84156 83111 IranDegree M Se Language FarsiSupervisors Mostafa Ghayour Hassan NahviAbstract As we know when systems with mass and elasticity are exposed to an oscillating force with a frequencyclose to its natural frequency will experience large amplitude vibration which can cause static failures oraccelerating fatigue phenomenon Therefore the natural frequencies of such structures and factors affectingthem and the force acting these structures and their origin and their frequency must be determined and structuraldesign done in such a way that the natural frequencies of these structural are enough away from frequence offorces applied to them to avoid resonance or large amplitude vibration it will be more important if we are facedwith a long and thin structures on of the structures that are subject to resonance or large amplitude vibration arecorrugated circular cylindrical tubes with a diameter greater than 36 inches these structures are widely used inwater transfer and wastewater collection and transfer system from the cities and the transfer rainwater from thewide roads culverts The origin of loads acting on these structures can be due to the Car crossing the road machinery working at ground level earth tremor and fluid flow passing through them If the frequency of theforces acting on these structures are close to the natural frequency of the structure they will experience largeamplitude vibration and resonance which will cause static failures or accelerating fatigue phenomenon Therefore the natural frequencies of the structure and the factors effective them should be identified andconsidered in their design In this thesis linear and nonlinear free vibration analysis of corrugated circular cylindrical shells withsinusoidal corrugation have been performed The corrugated circular cylindrical shell is made equivalent with anuncorrugated orthotropic circular cylindrical shell The undamped linear free vibration analysis has beenstudied using Donnell s shallow shell theory and natural frequencies were obtained More over naturalfrequencies were obtained using Abaqus software The accuracy of the proposed method was determined bycomparing the results of this study with the results obtained from Abaqus software The effect of the geometricshell characteristics i e radius length and thickness of shell and depth and period of the corrugation on thenatural frequencies are investigated Non linear free vibration analysys of corrugated circular cylindrical shells are examined Non linearities dueto large amplitude shell motion are considered by using the non linear Donnell s shallow shell theory A modalexpansion is used for the normal displacement that satisfies the boundary conditions for the normaldisplacement exactly but the boundary conditions for the in plane displacements are approximately satisfied byan averaging technique The system is discretizd by Galerkin s method and is investigated by using a modelinvolving three degrees of freedom Galerkin technique is used to reduce the problem to a system of threecoupled non linear ordinary differential equations for the modal amplitudes These non linear differentialequations are solved for arbitrary initial conditions by using the multiple time scale technique Comparison ofresults with numerical solution showed the accuracy of multiple time scale results natural frequencies of themodal amplitudes are obtained and internal resonance is investigated Keywords Corrugated shell Nonlinear vibration Multiple time scale technique Perturbation method
استاد راهنما :
مصطفي غيور، حسن نحوي
استاد مشاور :
عليرضا شهيدي
استاد داور :
سعيد ضيايي راد، رضا تكيني
