نوع مقاله : مقاله پژوهشی

نویسندگان

1 محقق پسادکترا، دانشکده مهندسی و علم مواد دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران.

2 استاد، دانشکده مهندسی و علم مواد دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران.

10.22068/jstc.2020.129066.1663

چکیده

فوم های پلی یورتان کم چگالی به عنوان موادی ارزان‌قیمت و در عین ‌حال سبک، در ساخت بخش هایی از سازه شناورهای دریایی استفاده می شوند. با این وجود، این فوم ها دارای خواص مکانیکی پایین بوده و در برابر نفوذ آب و رطوبت حساس هستند. وجود عیوب اولیه یا آسیب‌های ناشی از ضربه در سطح خارجی شناورهای دریایی می تواند به نفوذ آب به داخل هسته فومی منجر شود که عموماً به فساد هسته و متعاقب آن تورق در ناحیه اتصال هسته/پوسته خواهد انجامید. بر این اساس، هدف اصلی این پژوهش کاهش نقاط ضعف ساختارهای مبتنی بر فوم های پلی یورتان کم چگالی از طریق معرفی یک ماده جدید در این حوزه است. بدین منظور، یک پانل ساندویچی با هسته هیبریدی متشکل از کورک آگلومره و فوم پلی یورتان کم چگالی، تقویت شده با ساختار مشبک کامپوزیت اپوکسی/الیاف شیشه، طراحی، ساخته و مورد آزمون قرار گرفت. نتایج آزمون پیرسازی 100 روزه در آب نشان داد که جذب آب نمونه های جدید کمتر از نصف نمونه های ساندویچی متداول مبتنی بر فوم پلی‌یورتان است. همچنین جایگزین نمودن هسته هیبریدی فوم پلی‌یورتان/کورک تقویت‌شده به‌جای هسته فوم پلی‌یورتان منجر به افزایش 506، 814 و 144.94 درصد به ترتیب در بیشینه بار خمشی، سفتی خمشی اولیه و چقرمگی خمشی پانل شد. در ادامه با استفاده از شبیه سازی عددی آزمون خمش، رفتار سازه‌ای دو نوع ساختار جدید و متداول مورد بررسی قرار گرفت. نتایج تحلیل عددی نشان داد که سفتی خمشی پانل جدید نسبت به ساختار متداول حدود 884% ارتقاء یافته است.

کلیدواژه‌ها

عنوان مقاله [English]

Introducing novel sandwich panels based on of cork/polyurethane foam hybrid core and composite grid structure for marine applications

نویسندگان [English]

  • Moslem Najafi 1
  • Reza Eslami-Farsani 2

1 Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.

2 Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.

چکیده [English]

Low-density polyurethane foams as the low-cost and lightweight materials are used to produce some structural parts of marine vessels. However, these foams have low mechanical properties and they are susceptible to water and moisture penetration. The presence of initial defects or impact-induced damages on the external surface of the marine vessels can lead to the water penetration into the foam core, which generally results in core decay and, subsequently, delamination in core/skin interfacial bonding. Thus, the main objective of this research is to reduce the weaknesses of low-density polyurethane foam-based structures by introducing a novel material in this field. For this purpose, a sandwich panel with a hybrid core consisting of agglomerated cork and low-density polyurethane foam reinforced by a composite grid from epoxy/glass fibers structure is successfully designed, fabricated, and tested. Results of 100-days aging indicated that the water absorption of novel specimens was less than half of the conventional polyurethane-based specimens. In addition, replacing the stiffened cork/polyurethane hybrid core instead of the polyurethane core resulted in 506, 814 and 144.94 % increase in maximum flexural load, initial flexural stiffness and flexural toughness, respectively. In the following, the structural behavior of both the novel and conventional structures was investigated by numerical simulation of bending test. The results of numerical analysis showed that the flexural stiffness of novel panel was enhanced about 884%, comparing to the conventional structure.

کلیدواژه‌ها [English]

  • Sandwich Panels
  • Hybrid core
  • Cork
  • Polyurethane foam
  • Composite grid structure

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