پديد آورنده :
باقري نوري، محمد
عنوان :
ارائه يك ساختار نامتجانس جديد كريستال فونونيك جهت هدايت امواج زاويه دلخواه و بررسي اثرات نقص ساختاري
گرايش تحصيلي :
طراحي كاربردي
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك
صفحه شمار :
ده،121ص.: مصور،جدول،نمودار
استاد راهنما :
مهران مرادي
استاد مشاور :
حميدرضا ميردامادي
توصيفگر ها :
توسعه شكاف نواري , روش تفاضل محدود در حوزه زمان , فرمول بندي - جابجايي مبنا , هدايت كننده با زاويه دلخواه , نقص ساختاري , هدايت كننده هاي به هم متصل
استاد داور :
سعيد ضيايي راد، معدي سلماني تهراني، پرويز پروين، احمد امجدي
تاريخ ورود اطلاعات :
1395/08/01
كد ايرانداك :
ID921 دكتري
چكيده انگليسي :
Presentation of a new phononic crystal heterostructure to guide elasticwaves in arbitrary angles and investigation of effects of structural defects Mohammad bagheri nouri m bagherinouri@me iut ac ir Date of submission 2016 08 24 Department of mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree PHD Language Farsi Supervisor Mehran Moradi moradi@cc iut ac ir Abstract Subject of this dissertation is presentation of a new phononic crystal structure to guideelastic waves in arbitrary angles and investigation of effects of structural defects A newalgorithm for studying of elastic wave propagation in the phononic crystals has beenpresented at first In contrast with conventional finite difference time domain method byusing constitutive equations and strain displacement relations elastic wave equations havebeen derived based on displacement Then these displacement based equations have beendiscretized using finite difference method By this technique components of stress tensorcan be removed from the updating equations The new algorithm is called displacementbased finite difference time domain method DBFDTD Since the proposed method needsless elementary arithmetical operations its computational cost is less than that of theconventional FDTD method Several numerical examples were computed with this methodand the results were compared with experimental measurements and conventional FDTDmethod The computational cost of the new approach was compared with conventionalFDTD method as well The comparison showed that the calculation time of the DBFDTDmethod is 37 5 percents less than that of the FDTD method Afterward a new heterostructure phononic crystal has been introduced The newheterostructure is composed of square and rhombus phononic crystals Presentedheterostructure analyzing showed that the band gap can be extended by using the newstructure Effect of rhombus angular constant on the band gap of the heterostructure wasstudied too This investigation showed that the band gap of the heterostructure phononiccrystal would be wider than those of other heterostructures studied if the angular constantof the rhombus lattice is 80 degree In addition the ability of the presented structure in the arbitrary angle guiding of elasticwaves was investigated This study showed that by creating line defects in the compositionof the square and triangular lattices 30 degree bend waveguide can be realized This bendguides elastic waves in the frequency range of 94 129 kHz Also the study showed that bycreating line defects in the composition of the square and rhombus lattices 40 20 degreebend waveguide could be obtained if the angular constant of the rhombus lattice is 80 40
استاد راهنما :
مهران مرادي
استاد مشاور :
حميدرضا ميردامادي
استاد داور :
سعيد ضيايي راد، معدي سلماني تهراني، پرويز پروين، احمد امجدي
