This paper experimentally and numerically investigated the impact of a blunt projectile to perforated steel targets. In this study, projectiles were made of AISI 52100 and perforated plates were made of AISI 1045. In order to investigate the effect of the hole diameter on the projectile, three different diameters of the hole were considered, along with the effect of the projectile overlap with the hole. After examining different hitting states, the projectile was deviated from its movement direction after hitting the hole and changed from vertical hit to skew. The deviation of the projectile increased when the diameter of the hole increased or the amount of projectile overlap with the hole increased. Then, numerical modeling of impacting the projectile was performed by ABAQUS software and the results were compared with experimental results and the accuracy of the model was confirmed. And this model was used to investigate the effect of initial projectile speed on deviation of the projectile, accordingly, an increase in the initial velocity of the impact led to an increase in the deviation of the projectile. Manuscript profile

در این مقاله به بررسی مدل‌های تحلیلی ارائه شده در زمینه نفوذ پرتابه در صفحات فلزی (نازک، ضخیم و نیمه بی‌نهایت) پرداخته شده است، تلاش بر این بوده‌است که مدل‌های مرجع در این زمینه ارائه گردد و در ادامه به کارهای تحلیلی ارائه شده توسط محققین داخلی و خارجی پرداخته شود. ‎ ‎این مقاله می‌تواند مرجعی جهت خوانندگان علاقه‌مند به بررسی تحلیلی در زمینه نفوذ در اهداف فلزی باشد. و با تئوری‌های مختلف ارائه شده توسط محققین آشنا گردند . Manuscript profile

در این مقاله ‌ به بررسی تجربی، عددی و تحلیلی برخورد پرتابه سرتخت تغییرشکل ناپذیر به اهدف فولادی پرداخته شده‌است. بدین منظور در بخش اول به تست‌های تجربی جهت یافتن عمق نفوذ پرتابه پرداخته شده‌است، پرتابه‌ها در این آزمایش به‌صورت استوانه‌ای با قطر 10 و طول20 میلی‌متر از جنس فولاد AISI 52100‎ و صفحات فولادی با ابعاد 10×100×120 از جنس AISI 1045‎ انتخاب شده‌اند. در بخش دوم به شبیه‌سازی عددی مدل برخورد در نرم- افزار آباکوس پرداخته و با توجه به میزان خطای 8 درصدی نتایج حاصل از حل عددی با نتایج تجربی ، صحت مدل عددی به اثبات رسیده‌است. در بخش سوم به ارائه مدل تحلیلی برگرفته از مدل تحلیلی چن پرداخته و عمق‌نفوذ پرتابه را به‌دست آورده و در انتها مقایسه‌ای بین نتایج تجربی، عددی و تحلیلی انجام گرفته‌است، نتایج به‌دست‌آمده در سه حالت حل (تجربی، عددی و تحلیلی) دارای تطابق قابل قبولی می‌باشند. Manuscript profile

In this paper, modeling of high speed projectiles with different nose shapes, penetrating into steel fiber reinforced concrete is investigated. This is a novel study because it considers the length to diameter ratio of steel fiber as well as projectile length to diameter ratio and volume fraction of fiber used in concrete matrix on the impact resistance of steel fiber reinforced concrete fibers at high speeds. Numerical simulation is used using LS-DYNA explicit code. The projectiles have an approximate mass of 45 (gr) and their velocities are about 2500 (m/s) penetrating into steel fiber reinforced concrete panel with volume fraction of 1.0%, 1.5% and 2.0%. In this article the exact behavior of steel fiber reinforced concrete confronting metallic projectiles at high speed is predicted. The results of the simulations are compared with experimental work of other investigators and, the results show that ogive nose projectiles are more efficient than other projectiles. In other words, by increasing the projectile length to diameter ratio from 0.5 to 0.9, for flat, hemispherical and ogive projectiles their residual velocities are increased. Also, it is shown that by increasing the volume fraction of steel fibers in concrete matrix, damage of top surface damage is reduced dramatically. The analytical model presented in this paper considers the speed variations of the projectile during the penetration process into steel fiber reinforced concrete is an important achievements this respect. Manuscript profile

Comeld” is a novel technology which can be applied in connecting composites and metals by manufacture of an array of metal pins on the metal part and layup the composite layers on the pins to make an adhesive and mechanical Joint at the same time. The aim of this paper is an experimental, numerical and analytical investigation on strength of comeld joint system and also to calculate the stiffness properties of composite after comeld process. Experimental test were carried out with fabrication of 21 specimens of comeld and uncomeld joints with different geometry and arrays of pins. Samples were tested under pure tensile loading. For the numerical simulation and investigation, the commerical software ABAQUS has been used and the tensile test were carried out to model a 3D Simulation of the joints considering adhesive behaviour. The analytical investigation were focused on the calculation of laminate stiffness properties after comeld process and the results were calculated using MATLAB capabilities. The results of experimental tests showed a good agreement with those of numerical results. The results show that the comeld joint system has a high potential for effective joining of metal and composite. Manuscript profile