18353

۱۸۳۵۳

بررسي اثر انحناي نانو لوله هاي كربني بر مقدار نرخ رهايي انرژي كرنشي در مود اول شكست در نانو كلمپوزيت ها

كارشناسي ارشد

طراحي كاربردي

تيرماه ۱۳۹۶

دكتر محمود مهرداد شكريه

مكانيك

1396/10/27

1/17/2018 12:00:00 AM

Abstract: The purpose of this study is to estimate the strain energy release rate in mode I fracture toughness of nano composites, filled by carbon nanotubes (CNT), analytically and experimentally. Adding CNTs as filler to resins causes extreme enhancement in the fracture toughness. Several damaging mechanisms taking place at the nanoscale to enhance the fracture toughness of nanocomposites. In the present thesis, two mechanisms of debonding CNTs from resin and plastic growth of nano-voids have been studied analytically. The present model is a multi-scale model based on the relationship between stress fields in three scales, macro, micro and nano. In this model, CNTs are assumed to be solid with a cosinosoidal curvature. Also, the represented volume element considered is including three phases of matrix, interphase and the CNT, to consider the effect of interphase material on the results. The tensile behavior and fracture toughness of nanocomposites filled made of different weight fraction of CNT studied experimentally and the magnitudes of the fracture toughness and the Young’s modulus were characterized.The results showed that the fracture toughness is entirely a function of CNT diameter and properties of the interphase. A comparison of experimental and analytical results showed that the two studied mechanisms absorbed 25 percent of strain the energy release rate of all toughening mechanisms. Keywords: Facture toughness, CNT, analytical model.