Numerical Simulation of Impact of Low Velocity Projectiles With Water Surface

محورهای موضوعی : فصلنامه شبیه سازی و تحلیل تکنولوژی های نوین در مهندسی مکانیک

نجمه خضرائیان ¹ , ناصر دشتیان گرامی ²

1 - استادیار، گروه مهندسی مکانیک، دانشگاه آزاد اسلامی واحد اسلامشهر، تهران، ایران.
2 - دانشجوی دکتری، دانشکده مکانیک، دانشگاه تربیت مدرس، تهران، ایران

تاریخ دریافت : 1394/10/09 تاریخ پذیرش : 1394/10/09 تاریخ انتشار : 1394/02/11

کلید واژه: Fluid-Structure Interaction Water Impact ALE Formulation Finite Element Method,

چکیده مقاله :

In this article, Finite Element Method (FEM) and Eulerian-Lagrangies Algorithm (ELA) formulation were used to numerically simulate the impact of several low-velocity projectiles with water surface. Material models which were used to express behavior of air and water included Null material model. For the projectiles, rigid material model were applied. Results were validated by analyzing the impact of metallic cylinder with a water surface and then the impact of a wedge, sphere and special projectile at low-velocities were simulated. Major outputs were force and pressure applied to the projectile, variations of velocity and acceleration when entering to the water, stress-strain variations and variations of water surface in various steps of the analysis. Results showed that the impact of the structure with fluid can be modeled using finite element model with high accuracy in terms of quality and quantity.Numerical results obtained for cylinder well agrees with the available experimental data. Also the results for other projectiles show a logical trend

چکیده انگلیسی:

 در این مقاله با استفاده از روش المان محدود و فرمول­بندی اولری-لاگرانژی برخورد سازه هایی با سطح آب مورد شبیه­سازی عددی قرار گرفته است. برای بیان رفتار آب و هوا از مدل مادی نول و برای سازه های برخورد کننده از مدل­ مادی صلب استفاده شده است. معادله حالت مای گرونایزن نیز به آب و هوا نسبت داده شده است. در این مقاله، در ابتدا با استفاده از تحلیل برخورد استوانه فلزی با سطح آب، نتایج مورد اعتبار سنجی قرار گرفت و سپس برخورد یک گوه، کره و یک پرتابه خاص شبیه سازی شد. از خروجی­های مهم این نحلیل استخراج نیرو و فشار وارد بر پرتابه، تغییرات سرعت و شتاب در حین ورود به آب، تغییرات تنش-کرنش و نیز تغییرات سطح آب در مراحل مختلف تحلیل هستند. نتایج حاصل از شبیه سازی برای استوانه با نتایج آزمایشگاهی موجود تطابق خوبی نشان می­­ دهد و نتایج حاصله برای دیگر پرتابه­ها دارای روند منطقی هستند

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