Modeliranje prijelaza s atomističkog modela na makro razini u mehanici čvrstih tijela

Marenić, Eduard (2013) Modeliranje prijelaza s atomističkog modela na makro razini u mehanici čvrstih tijela. = Atomistic-to-continuum modelling in solid mechanics. Doctoral thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Sorić, Jurica.

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Abstract (Croatian)

U radu je obrađena nova vrsta dvodimenzijskih materijala poznatih pod imenom "grafen". Eksperimentalno određivanje mehaničkih svojstava grafena vrlo je komplicirano te se danas uglavnom provode numeričke simulacije. Korištena je molekularna mehanika, pri čemu se razmatra atom kao čestica, a elektronska struktura zanemaruje. Zbog ograničene računalne snage molekularna simulacija uređaja temeljenih na grafenu nije uvijek moguća. Stoga je u radu razvijen zamjenski, kontinuumski model neoštećenog grafena pod pretpostavkom malih i velikih deformacija. Osim toga, korišten je i višerazinski pristup temeljen na dekompozicijskoj shemi s djelomičnim preklopom, pri čemu je molekularni model ograničen na područje oko oštećenja, dok je okolo računalno jeftiniji kontinuumski model. Znanstveni doprinosi su sljedeći: određeni su osnovni čimbenici koji rezultiraju rasipanjem rezultata za elastična svojstva, predložene nove granice krutosti za ekvivalentni kontinuumski model grafena, razvijen je hiperelastični konstitutivni model u ovisnosti o glavnim izduženjima namijenjen za velike deformacije grafena te je predložena jedinstvena formulacija spoja atomističkog i kontinuumskog modela.

Abstract

We focus primarily on the conceptually new class of materials that are only one atom thick, called by common name “graphene”. The experimental measurement of the mechanical properties of graphene is still considered a difficult task, thus quantifying the mechanical properties by the numerical simulations is of great importance.rnWe use molecular mechanics and assume that atoms are the smallest unit needed to be modelled. Due to the lack of computational power, performing a fully atomistic simulation of practical carbon nanosystems is not always possible. Thus, we seek to find more effective modelling strategy which considers the development of the substitute, continuum model of pristine graphene in the small and large strain regime. Next, we turn to concurrent multiscale methodology which limits atomic model to a small cluster of atoms near the defect in graphene lattice based on the overlapping domain decomposition scheme and coupling of discreet and continuum models. The latter enables to have efficient continuum model, preserving at the same time the accuracy of atomistic model.rnContributions : main mechanisms resulting in a large dispersion of elastic properties are identified, the novel elastic stiffness bounds in the equivalent continuum modeling of graphene are developed , novel hyperelastic constitutive model in terms of principal stretches for large elastic strain regime is developed, a unified coupling formulation of the atomistic-to-continuum coupling is proposed.

Item Type: Thesis (Doctoral thesis)
Uncontrolled Keywords: grafen; molekularna mehanika; višerazinska metoda; metoda premošćivanja; Arlequin metoda; kvazi-kontinuum metoda
Keywords (Croatian): graphene; molecular mechanics; multiscale; bridging domain; Arlequin; quasicontinuum
Subjects: TECHNICAL SCIENCE > Mechanical Engineering
Date Deposited: 22 Sep 2014 18:00
Last Modified: 30 Apr 2020 17:34
URI: http://repozitorij.fsb.hr/id/eprint/2747

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