بررسی مکانیک شکست پانل بتنی لایه‌ای تابعی مقاوم در برابر بارگذاری ضربه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه عمران

2 دانشکده مهندسی عمران، پردیس دانشکده‌های فنی دانشگاه تهران، تهران، ایران

چکیده

در این تحقیق مطالعات عددی مکانیک شکست مربوط به رشد ترک یک ماده بتنی لایه‌ای تابعی مقاوم در برابر بارگذاری ضربه گلوله شامل بتن معمولی،مسلح الیافی و سنگدانه‌های سفت به وسیله مدل‌سازی آزمایش خمش سه نقطه‌ای در حضور ترک اولیه ارائه شده است. از مدل ناحیه چسبنده دو خطی برای بتن معمولی و بتن با سنگدانه‌های سفت و سه خطی برای بتن مسلح الیافی به منظور رفتار شکست در ناحیه فرآیند استفاده شده و روش محاسباتی المان محدودتوسعه یافته ( XFEM )  برای آنالیز عددی به کار گرفته شده است. نتایج حاصل از مدل‌سازی عددی آزمایش خمش سه نقطه‌ای به وسیله منحنی بار-بازشدگی نوک ترک( P-CMOD ) مورد بررسی و مقایسه قرار گرفته است. نمونه لایه‌ای تابعی در مقایسه با نمونه‌های همگن بتن معمولی، مسلح الیافی و سنگدانه‌های سفت موردبررسی قرار گرفته و نتایج نشان دادکه نمونه مسلح الیافی همگن رفتار شکست به مراتب بهتریازنمونه‌های دیگر داردونمونه لایه‌ای تابعی نیزبه دلیل دارا بودن الیه مسلح الیافی در لایه انتهایی در مقایسه با نمونه‌های بتن معمولی و بتن با سنگدانه‌های سفت دچار شکست ناگهانی نمی‌شود.همچنین اثرات هر یک از لایه‌ها و تغییر ضخامت آن‌ها موردارزیابی قرار گرفته و مشاهده گردید که لایه مسلح الیافی با توجه به انرژی شکست زیاد ناشی از پل‌بندی الیاف‌ها نسبت به سایر لایه‌ها، تاثیر مفیدی بر رفتار شکست نمونه داردوبا اتخاذموقعیتو ضخامت مناسب برای این لایه می‌توان ضمن تامین کارایی مناسب دررفتار شکست،هزینه مصالح را نیزبه میزان قابل توجهی کاهش داد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of crack propagation behavior of impact-resistant functionally graded concrete

نویسندگان [English]

  • safa peyman 1
  • pouya heydari digesara 2
1 دانشگاه جامع امام حسین (ع)/ تهران
2 School of Civil Engineering, University of Tehran, Tehran, Iran
چکیده [English]

This paper conducted research on numerical studies of fracture mechanics related to crack propagation of projectile impact-resistant functionally graded concrete consisting of plain, fiber reinforced and tough aggregate concrete layers, which are presented by modeling a three-point bending test in presence of initial notch. To consider fracture behavior in process zone, a bilinear softening model for plain and tough aggregate concrete and a trilinear softening model obtained from traction-separation relationship of cohesive zone model is used. Extended finite element method is utilized for numerical analysis. result of numerical modeling of three-point bending test have been investigated and compared using loading versus crack mouth opening displacement (P-CMOD) curves. Functionally graded model has been studied in comparison with homogeneous plain, fiber reinforced and tough aggregate concrete models, and the results showed that homogeneous fiber reinforced concrete model has a better fracture behavior than others models. The functionally graded model has not been subjected to sudden failure in comparison with plain and tough aggregate concrete models due to the fiber reinforced in end layer. Also, effect of each layer and their thickness change in the functionally graded model are evaluated and it was observed that fiber reinforced layer due to high fracture energy created by fiber bridging has a beneficial effect on the fracture behavior related to other layers. In this way, by considering proper position and thickness for this layer, in addition to providing appropriate performance in the fracture behavior, cost of materials also be significantly reduced.

کلیدواژه‌ها [English]

  • Fracture mechanics
  • Functionally graded concrete
  • Three point bending test model
  • Cohesive zone model
  • P-CMOD curves
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