پديد آورندگان :
صحرايي مقدم، اميرحسين دانشگاه لرستان خرم آباد , اميدي نسب، فريدون دانشگاه لرستان خرم آباد - دانشكده فني , دالوند، احمد دانشگاه لرستان خرم آباد - دانشكده فني
كليدواژه :
مقاومت ضربه‌اي , دال‌هاي چندلايه , الياف فولادي , الياف پلاستيكي , ضربه پرتابه
چكيده فارسي :
در اين پژوهش مقاومت ضربه‌اي دال هاي چندلايه مسلح شده به الياف فولادي، پلاستيكي و تركيبي از اين دو الياف تحت اثر برخورد پرتابه با سرعت زياد بررسي شد. براي تحقق اين هدف، تعداد 30 عدد دال يك لايه و سه لايه با ابعاد 7/5*40*40 سانتي‌متر مسلح شده به 1 درصد الياف ساخته شد،30 عدد دال ساخته شده از 10 مدل متفاوت مي‌باشند، از هرمدل، 3 نمونه ساخته شد. 1 مدل بدون الياف بعنوان نمونه شاهد و ديگر دال‌ها داراي حجم ثابت 1 درصد الياف مي‌باشند كه تفاوت آن‌ها در نوع و نحوه تركيب الياف ها در لايه‌هاي مختلف مي‌باشد. دال‌هاي ساخته شده با سه اسلحه متفاوت در فاصله 50 متر آزمايش شدند. بر اساس نتايج،الياف فولادي مي‌تواند مقاومت دال‌هاي بتني را در مقابل ضربه پرتابه افزايش و سطح و حجم ناحيه تخريب شده و عمق نفوذ را به ميزان چشم‌گيري كاهش دهد. الياف فولادي مي‌تواند با افزايش انسجام دال از گسترش ترك‌ها جلوگيري نمايد، در صورتي كه الياف‌هاي پلاستيكي تاثير به مراتب كمتري نسبت به الياف‌هاي فولادي دارند. در اين تحقيق تعداد 12 عدد نمونه فشاري مكعبي، 12 عدد نمونه كششي استوانه‌اي و 12 عدد تير خمشي كوچك نيز ساخته و آزمايش شد. و مشاهده شد كه الياف فولادي و پلاستيكي نمي‌توانند تاثير محسوسي بر روي مقاومت فشاري داشته باشند، اما الياف فولادي مي‌تواند مقاومت كششي و خمشي بتن را بصورت قابل توجهي افزايش دهد. اين در صورتي است كه الياف پلاستيكي تاثير قابل توجهي بر روي مقاومت كششي و خمشي نخواهد داشت.
چكيده لاتين :
In this study, the impact strength multi-layer slabs reinforced by steel and nylon fibers, as well as the combination of these two fibers under the influence high velocity projectile, was investigated. To achieve this goal, 30 slabs one layer and three layers with dimensions 40 *40 * 7.5 cm were reinforced by 1% of the fiber, 30 slabs made 10 different models , each with 3 models Sample was made. A non-fiber model, as a control sample, and other slabs all have a constant volume 1 percent fiber, the difference being in the type and composition the fibers in different layers the slabs. The slabs were made with Kalashnikov , PK Kalashnikov and Dragunov guns at a distance 50 meters tested. In the test the projectile's encounter, three parameters penetration depth, area the damaged front and rear area and the volume damaged area in the samples were calculated and compared. Based on the results obtained, steel fibers can increase the resistance concrete slabs against the impact the projectile and reduce the surface area and volume the damaged area and significantly reduce the penetration depth. Steel fibers at best reduced the penetration depth 64 % in the kalashinkov gun and reduced the area and volume the damaged area in the dragunov weapon by 88 % and 98 % respectively. Also, steel fibers can prevent crack expansion by increasing the bond strength, provided that the fibers the nylon have a much lower impact than steel fibers. the nylon fiber could reduce the penetration depth and demolition area the sample in kalashnikov weapon by 37 % and 59 %, respectively, and reduce the volume damaged area in the dragunov weapon by 84 %, respectively. In addition, in this research, 12 samples cubic pressure were placed on the side 10 cm, 12 cylindrical tensile samples 10 × 20 cm and 12 small flexion beams with dimensions 32 *8 *6 cm and tested. It was observed that steel and nylon fibers cannot have a significant effect on the compressive strength, As a result the addition one percent the steel fiber, nylon and a combination these, this increase is 7.7, 2.6 and 6.4 % , which can be neglected. but steel fibers can significantly increase the tensile and flexural strength the concrete. addition one percent the steel fiber could create a 2.5 – fold increase in tensile strengths and increase the resistance 2 - fold in bending specimens. This is the nylon fibers do not have a significant impact on the tensile and flexural strength. Adding one percent the nylon fibers in the tensile and flexural samples could increase the resistance these specimens by 16 % and 24 % respectively. It was observed in the bending test of beams that steel and nylon fibers can be bent by bending in the cracks to increase the shape the weld so that the change in the maximum area the beam with the addition one percent steel fiber from about 4 mm in the control sample increase to about 25 mm.
