scholarly journals Multi-scale Modeling of Polymeric Composites Including Nanoporous Fillers of Milled Anodic Alumina

2021 ◽  
Author(s):  
Roham Rafiee ◽  
Amirali Eskandariyun ◽  
Claudio Larosa ◽  
Marco Salerno
Keyword(s):  
Elastic Response ◽  
Chemical Agent ◽  
Multi Scale ◽  
Scale Modeling ◽  
Three Phase ◽  
Macro Scale ◽  
The Matrix ◽  
First Time ◽  
Shed Light ◽  
Standard Concept

AbstractA polymer composite based on an innovative filler consisting of microscale powder of nanoporous alumina is modeled. The passing-through nanoscale pores in this system—roughly columnar cylindrical, with diameter of the order of 100 nm—are fully penetrated by the resin, which is not bonded to the inner pore walls by any chemical agent. This system, previously assessed by laboratory experiments, is modeled here for the first time, based on a computational multi-scale hierarchical approach. First, microscale representative volume element (RVE) is modeled in two steps using finite element modeling. Then, the macro-scale RVE is characterized, using a combination of micromechanical rules. The elastic response of the composite is simulated to predict its Young’s modulus. This simulation confirms the former experimental results and helps to shed light on the response of the investigated material, which may represent a novel system for use in disparate composite applications. In particular, the nanoporous microfillers composite is compared with a composite material containing the fillers of the same material yet nonporous, bonded to the matrix. It appears that, with respect to this standard concept of three-phase composites, the presence of the nanopores can compensate for the absence of the bonding agent.

scholarly journals Energy Dissipation During Prey Capture Process in Spider Orb Webs

2020 ◽  
Vol 87 (9) ◽  
Author(s):  
Yanhui Jiang ◽  
Hamid Nayeb-Hashemi
Keyword(s):  
Energy Dissipation ◽  
Significant Role ◽  
Prey Capture ◽  
Aerodynamic Drag ◽  
Material Damping ◽  
Capture Process ◽  
Spider Dragline Silk ◽  
Multi Scale ◽  
Scale Modeling ◽  
Macro Scale

Abstract Capture of a prey by spider orb webs is a dynamic process with energy dissipation. The dynamic response of spider orb webs under prey impact requires a multi-scale modeling by considering the material microstructures and the assembly of spider silks in the macro-scale. To better understand the prey capture process, this paper addresses a multi-scale approach to uncover the underlying energy dissipation mechanisms. Simulation results show that the microstructures of spider dragline silk play a significant role on energy absorption during prey capture. The alteration of the microstructures, material internal friction, and plastic deformation lead to energy dissipation, which is called material damping. In addition to the material damping in the micro-scale modeling, the energy dissipation due to drag force on the prey is also taken into consideration in the macro-scale modeling. The results indicate that aerodynamic drag, i.e., aero-damping, plays a significant role when the prey size is larger than a critical size.

Advanced three-dimensional electromagnetic modeling using a nested integral equation approach

2021 ◽  
Author(s):  
Chaojian Chen ◽  
Mikhail Kruglyakov ◽  
Alexey Kuvshinov
Keyword(s):  
Integral Equation ◽  
Three Dimensional ◽  
Region Of Interest ◽  
Electromagnetic Modeling ◽  
Multi Scale ◽  
Scale Modeling ◽  
Uniform Grids ◽  
The Matrix ◽  
Integral Equation Approach ◽  
Matrix Vector

Summary Most of the existing three-dimensional (3-D) electromagnetic (EM) modeling solvers based on the integral equation (IE) method exploit fast Fourier transform (FFT) to accelerate the matrix-vector multiplications. This in turn requires a laterally-uniform discretization of the modeling domain. However, there is often a need for multi-scale modeling and inversion, for instance, to properly account for the effects of non-uniform distant structures, and at the same time, to accurately model the effects from local anomalies. In such scenarios, the usage of laterally-uniform grids leads to excessive computational loads, both in terms of memory and time. To alleviate this problem, we developed an efficient 3-D EM modeling tool based on a multi-nested IE approach. Within this approach, the IE modeling is first performed at a large domain and on a (laterally-uniform) coarse grid, and then the results are refined in the region of interest by performing modeling at a smaller domain and on a (laterally-uniform) denser grid. At the latter stage, the modeling results obtained at the previous stage are exploited. The lateral uniformity of the grids at each stage allows us to keep using the FFT for the matrix-vector multiplications. An important novelty of the paper is a development of a “rim domain” concept which further improves the performance of the multi-nested IE approach. We verify the developed tool on both idealized and realistic 3-D conductivity models, and demonstrate its efficiency and accuracy.

New Approach of Multi Scale Modeling Based on the Hygro-Cosserat Theory for Self Desiccation Deformation of Cement Mortars at Early Age

2010 ◽  
Vol 123-125 ◽  
pp. 563-566 ◽  
Author(s):  
J. Jeong ◽  
P. Mounanga ◽  
Hamidreza Ramezani ◽  
Marwen Bouasker ◽  
D. Bassir
Keyword(s):  
Autogenous Shrinkage ◽  
Early Age ◽  
Cosserat Theory ◽  
Sem Images ◽  
Element Analysis ◽  
New Approach ◽  
Multi Scale ◽  
Scale Modeling ◽  
Cement Mortars ◽  
Macro Scale

In the present paper, we concentrate on the heterogeneous cement mortars and we treat them as Cosserat-based media. The autogenous shrinkage phenomenon at early age (from 1 up to 3 days after mixing) has been analyzed by means of Cosserat theory. The characteristic length scale parameter Lc in this theory helps us to change the size specimen from macro-scale to micro-scale using the theoretical size effect aspects. This methodology is also capable of treating cracks initiation and their appearance in the cementitious matrix surrounding the sand-inclusions, which should occurred inside of the Representative Volume Elementary (RVE) of mortar subjected to self-desiccation shrinkage during hydration at early age. By taking advantage of the Nonlinear Finite Element Analysis (NFEA), the numerical experiments have been performed. The numerical outcomes are well agreed with the experimental observations coming from Scanning Electronic Microscopy (SEM) images. It concludes that the inclusions create not only a hygro stress concentration around the grains but also the number of inclusions should influence the network in cementitous matrix.

Degradation Modeling Research of Biodegradable Tissue Engineering Scaffold

2013 ◽  
Vol 873 ◽  
pp. 642-651
Author(s):  
Tao Hong Zhang ◽  
Shou Gang Xu ◽  
De Zheng Zhang ◽  
Aziguli Wulamu
Keyword(s):  
Tissue Engineering ◽  
Initial Step ◽  
Tissue Engineering Scaffold ◽  
Multi Scale ◽  
Modeling Methods ◽  
Degradation Modeling ◽  
Scale Modeling ◽  
Single Scale ◽  
Macro Scale ◽  
Scale Models

Although the degradation modeling of tissue engineering scaffold is in its initial step, it can direct the design, optimization of scaffold and help the application in medical case of illness. This paper analyzes the modeling methods and gives the speciality of every model which is put forward by researchers in China and abroad about the degradation of tissue engineering scaffold. These models are divided into micro scale, macro scale and two scale models based on the modeling scales. The recent research is belonging to single scale modeling. Some researchers abroad probed to two scale modeling. The future model is prospected in multi scale coupling macro, micro, and meta-macro model.

Integrating an Analytical Uncertainty Quantification Approach to Multi-Scale Modeling of Nanocomposites

2019 ◽  
pp. 1-22
Author(s):  
Pinar Acar
Keyword(s):  
Uncertainty Quantification ◽  
Uncertainty Propagation ◽  
Epoxy Nanocomposites ◽  
Linear Solution ◽  
Analytical Uncertainty ◽  
Multi Scale ◽  
Scale Modeling ◽  
Macro Scale ◽  
Multi Scale Modeling ◽  
Scale Properties

Abstract The present study addresses the integration of an analytical uncertainty quantification approach to multi-scale modeling of single-walled carbon nanotube (SWNT)-epoxy nanocomposites. The main highlight is the investigation of the stochasticity of nanotube orientations, and its effects on the homogenized properties. Even though the properties of SWNT-epoxy nanocomposites are well-studied in the literature, the natural stochasticity that arises from the nanotube orientations has not been observed. To understand the effects of the variability in SWNT orientations to material properties of interest, an analytical uncertainty quantification algorithm is utilized. The analytical scheme computes the propagation of the orientational uncertainty to the volume-averaged properties with a linear solution and uses the transformation of random variables principle to obtain the variations in non-linear properties. The results indicate that the uncertainty propagation affects the macro-scale properties, including stiffness, thermal expansion, thermal conductivity, and natural frequencies.

scholarly journals Continuum Approach to Computational Multi-Scale Modeling of Fracture

2014 ◽  
Vol 627 ◽  
pp. 349-352 ◽  
Author(s):  
Javier Oliver ◽  
M. Caicedo ◽  
E. Roubin ◽  
A.E. Huespe
Keyword(s):  
Mesh Size ◽  
Cementitious Materials ◽  
Strong Discontinuity ◽  
Structural Failure ◽  
Multi Scale ◽  
Scale Modeling ◽  
Macro Scale ◽  
Numerical Tools ◽  
Continuum Strong Discontinuity Approach ◽  
The Continuum

This paper presents a FE2 multi-scale framework for numerical modeling of the structural failure of heterogeneous quasi-brittle materials. The model is assessed by application to cementitious materials. Using the Continuum Strong Discontinuity Approach (CSD), innovative numerical tools, such as strain injection and crack path field techniques, provide a robust, and mesh-size, mesh-bias and RVE-size objective, procedure to model crack onset and propagation at the macro-scale.

Influence of microstructure morphology on multi-scale modeling of low-alloyed TRIP-steels

2018 ◽  
Vol 35 (2) ◽  
pp. 499-528 ◽  
Author(s):  
Stefan Prüger ◽  
Ashutosh Gandhi ◽  
Daniel Balzani
Keyword(s):  
Volume Fraction ◽  
Measurement Techniques ◽  
Content Type ◽  
Systematic Assessment ◽  
Microstructural Parameters ◽  
Multi Scale ◽  
Scale Modeling ◽  
Macro Scale ◽  
Microstructure Morphology ◽  
The Impact

Purpose The purpose of this study is to quantify the impact of the variation of microstructural features on macroscopic and microscopic fields. The application of multi-scale methods in the context of constitutive modeling of microheterogeneous materials requires the choice of a representative volume element (RVE) of the considered microstructure, which may be based on some idealized assumptions and/or on experimental observations. In any case, a realistic microstructure within the RVE is either computationally too expensive or not fully accessible by experimental measurement techniques, which introduces some uncertainty regarding the microstructural features. Design/methodology/approach In this paper, a systematical variation of microstructural parameters controlling the morphology of an RVE with an idealized microstructure is conducted and the impact on macroscopic quantities of interest as well as microstructural fields and their statistics is investigated. The study is carried out under macroscopically homogeneous deformation states using the direct micro-macro scale transition approach. Findings The variation of microstructural parameters, such as inclusion volume fraction, aspect ratio and orientation of the inclusion with respect to the overall loading, influences the macroscopic behavior, especially the micromechanical fields significantly. Originality/value The systematic assessment of the impact of microstructural parameters on both macroscopic quantities and statistics of the micromechanical fields allows for a quantitative comparison of different microstructure morphologies and a reliable identification of microstructural parameters that promote failure initialization in microheterogeneous materials.

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