پاسخ ديناميكي تير ساندويچي خميده داراي هسته انعطاف‌پذير تحت ضربه شعاعي با سرعت پايين

Dynamic Response of Curved Sandwich Beam with a Soft Flexible Core Subjected to Radial Low Velocity Impact

در مقاله حاضر، پاسخ ديناميكي تير خميده با هسته انعطاف پذير تحت يك ضربه عرضي شعاعي با سرعت پايين در وسط رويه بالا، مطالعه شده است. اين پاسخ شامل، جابه‎جايي شعاعي و محيطي رويه‌ها و هسته و تنشهاي برشي و شعاعي در هسته است. ابتدا از تيوري برشي مرتبه بالا براي ميدان جابه‎جايي استفاده شد. نيروي ضربه نيز با مدل جرم و فنر دو درجه آزادي، براي محدوده بارگذاري الاستيك معادل سازي گرديد و از اصل هميلتون براي استخراج معادلات حاكم بر حركت تير استفاده شد. نتايج به‎دست آمده، با نتايج حاصل از نرم افزار المان محدود آباكوس و آخرين تحقيقات انجام شده مقايسه شدند. آنگاه نحوه تاثير خصوصيات اجزاي سازه‌ ساندويچي نظير، مدول الاستيسيته هسته و ضخامت هسته بر جابه‎جايي شعاعي و تنش برشي تير و نيز تاثير سرعت ضربه‎زننده و ضخامت هسته بر مقدار نيروي ضربه، مورد بررسي قرار گرفت. مشخص گرديد كه با دو برابر شدن نسبت مدول الاستيسيته هسته به رويه بالايي (از 05/0 تا 1/0)، جابه‎جايي هسته تنها 1/0 درصد كاهش مي‌يابد؛ در حالي كه با افزايش نسبت ضخامت هسته به تير (از 1/0 تا 9/0)،جابه‎جايي هسته تا 6 برابر كاهش خواهد يافت.

In this paper, the dynamic response of a curved sandwich beam with soft flexible core, subjected to a radially low velocity foreign impact on the middle of top face sheet is studied. The dynamic responses which are composed of circumferential and radial displacement of the core, top and bottom face sheets, as well as the radial and shear stresses in the core layer are identified. The higher order shear deformation theory was used in the structural formulation. The two degrees of freedom mass-spring model with linearized stiffness was used for modeling of impact phenomena. In order to derive the governing equations of beam structure, the Hamilton principle was used. The results were validated and compared with the results obtained from finite element ABAQUS software and the latest available literature. The effects of some structural properties like the module of elasticity and the thickness of core layer on the displacement, shear stresses and strains were studied. Also, the effects of radius and initial velocity of the impactor on contact force history were investigated. It was seen that by multiplying by 2 of the elasticity modulus of core to upper layer ratio(from 0.05 to 0.1), the core deflection only reduces about 0.1 percent. One sees that by multiplying by 9 the core to beam thickness ratio(from 0.1 to 0.9), the core deflection reduces about 6 times.