Nanomechanics Modeling of Interface Interactions in Asphalt Concrete: Traction and Shearing Failure Study

2019 ◽  
Vol 10 (01) ◽  
pp. 1841004 ◽  
Author(s):  
Yang Lu ◽  
Linbing Wang
Keyword(s):  
Asphalt Concrete ◽  
Load Transfer ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Molecular Structures ◽  
Atomic Scale ◽  
Model Parameters ◽  
Zone Model ◽  
Loading Modes ◽  
Interface Bonding Strength

The interface bonding strength is critical for asphalt concrete performance under external load applications. A thorough understanding of the load transfer mechanism bridging the nanoscale interfacial details and the macroscale properties is required to accurately predict the performance of asphalt concrete. This research presents a multiscale analysis procedure for the modeling of interface behaviors, in which material properties are evaluated by atomic scale interactions, emphasizing the complex shearing and separation mechanisms under various loading modes. The representative model system was established based on multiscale experimental characterization of the tight-bonding interface between asphalt and aggregate. Interfacial load transfer and failure studies were conducted for investigating the effect of tension and compression on shearing mode separation. The cohesive zone model parameters, such as peak traction and energy of separation were evaluated for each loading mode. Different boundary conditions were applied to obtain the representative volume element (RVE) and connection to continuum level properties. Results indicated that depending on the various loading modes, the failure of the nanoscale interface system may occur within the asphalt phase or at the interface. These results set the basis for continuum length-scale micromechanical models which may be used to determine the bulk material response, incorporating interfacial phenomena. The findings presented in this paper are consistent with observations reported in previous studies and expand on the understanding of the relationship between molecular structures and combined shearing separation failure properties of asphalt concrete interfaces.

Effects of asphalt concrete characteristics on cohesive zone model parameters of hot mix asphalt mixtures

2016 ◽  
Vol 43 (3) ◽  
pp. 226-232 ◽  
Author(s):  
S. Pirmohammad ◽  
H. Khoramishad ◽  
M.R. Ayatollahi
Keyword(s):  
Asphalt Concrete ◽  
Cohesive Energy ◽  
Cohesive Zone ◽  
Hot Mix Asphalt ◽  
Cohesive Zone Model ◽  
Experimental Tests ◽  
Model Parameters ◽  
Zone Model ◽  
Binder Type ◽  
Air Void

In this paper, the effects of the main asphalt concrete characteristics including the binder type and the air void percentage on the cohesive zone model (CZM) parameters were studied. Experimental tests were conducted on semi-circular bend (SCB) specimens made of asphalt concrete and the fracture behavior was simulated using a proper CZM. The CZM parameters of various hot mix asphalt (HMA) mixtures were determined using the SCB experimental results. Five types of HMA mixtures were tested and modeled to consider the effects of binder type and air void percentage on the CZM parameters. The results showed that as the binder in HMA mixture softened, the cohesive energy strength increased, whereas enhancing the air void percentage led to reduction of the cohesive energy and strength values. Among the studied HMA mixtures, the highest values of CZM parameters were found for the HMA mixture containing a copolymer called styrene-butadiene-styrene.

Effects of adhesive thickness on the mode I cohesive zone model parameters of a high toughness structural adhesive

2018 ◽  
Author(s):  
M. H. R. de Oliveira ◽  
A. F. Ávila ◽  
R. R. Chaves ◽  
H. Nascimento Júnior ◽  
F. D. Passos
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Model Parameters ◽  
Mode I ◽  
Zone Model ◽  
High Toughness ◽  
Adhesive Thickness ◽  
Structural Adhesive

Multiscale Model to Study the Effect of Interfaces in Carbon Nanotube-Based Composites

2005 ◽  
Vol 127 (2) ◽  
pp. 222-232 ◽  
Author(s):  
S. Namilae ◽  
N. Chandra
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Region ◽  
Model Parameters ◽  
Zone Model ◽  
Pullout Tests ◽  
Nanoscale Interfaces

In order to fully harness the outstanding mechanical properties of carbon nanotubes (CNT) as fiber reinforcements, it is essential to understand the nature of load transfer in the fiber matrix interfacial region of CNT-based composites. With controlled experimentation on nanoscale interfaces far off, molecular dynamics (MD) is evolving as the primary method to model these systems and processes. While MD is capable of simulating atomistic behavior in a deterministic manner, the extremely small length and time scales modeled by MD necessitate multiscale approaches. To study the atomic scale interface effects on composite behavior, we herein develop a hierarchical multiscale methodology linking molecular dynamics and the finite element method through atomically informed cohesive zone model parameters to represent interfaces. Motivated by the successful application of pullout tests in conventional composites, we simulate fiber pullout tests of carbon nanotubes in a given matrix using MD. The results of the pullout simulations are then used to evaluate cohesive zone model parameters. These cohesive zone models (CZM) are then used in a finite element setting to study the macroscopic mechanical response of the composites. Thus, the method suggested explicitly accounts for the behavior of nanoscale interfaces existing between the matrix and CNT. The developed methodology is used to study the effect of interface strength on stiffness of the CNT-based composite.

scholarly journals Application of a Cohesive Zone Model for Simulating Fatigue Crack Growth from Moderate to High ΔK Levels of Inconel 718

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Huan Li ◽  
Jinshan Li ◽  
Huang Yuan
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Small Scale ◽  
Model Parameters ◽  
Zone Model ◽  
Crack Growth Rates

A cyclic cohesive zone model is applied to characterize the fatigue crack growth behavior of a IN718 superalloy which is frequently used in aerospace components. In order to improve the limitation of fracture mechanics-based models, besides the predictions of the moderate fatigue crack growth rates at the Paris’ regime and the high fatigue crack growth rates at the high stress intensity factor ΔK levels, the present work is also aimed at simulating the material damage uniformly and examining the influence of the cohesive model parameters on fatigue crack growth systematically. The gradual loss of the stress-bearing ability of the material is considered through the degradation of a novel cohesive envelope. The experimental data of cracked specimens are used to validate the simulation result. Based on the reasonable estimation for the model parameters, the fatigue crack growth from moderate to high ΔK levels can be reproduced under the small-scale yielding condition, which is in fair agreement with the experimental results.

Multiscale cohesive zone modeling and simulation of high-speed impact, penetration, and fragmentation

2018 ◽  
Vol 03 (01n02) ◽  
pp. 1850003
Author(s):  
Chao Wang ◽  
Dandan Lyu
Keyword(s):  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Spall Fracture ◽  
Weak Formulation ◽  
High Speed Impact ◽  
Different Characteristics

In this work, a multiscale cohesive zone model (MCZM) is developed to simulate the high-speed penetration induced dynamic fracture process such as fragmentation in crystalline solids. This model describes bulk material as a local quasi-continuum medium which follows the Cauchy–Born rule while cohesive zone element is governed by an interface depletion potential, such that the cohesive zone constitutive descriptions are genetically consistent with that of bulk element. This multiscale method proved to be effective in describing material inhomogeneities and it is constructed and implemented in a cohesive finite element Galerkin weak formulation. Numerical simulations of high-speed penetration with different shape of penetrators, i.e., square, circle and parabola nose penetrators are performed. Results show that the proposed MCZM can successfully capture spall fracture, the penetration process and different characteristics of fragmentation under different shape of penetrators.

Rate-dependent fracture modeling of asphalt concrete using the discrete element method

2009 ◽  
Vol 36 (2) ◽  
pp. 320-330 ◽  
Author(s):  
Hyunwook Kim ◽  
Michael P. Wagoner ◽  
William G. Buttlar
Keyword(s):  
Discrete Element Method ◽  
Asphalt Concrete ◽  
Cohesive Zone Model ◽  
Discrete Element ◽  
Fracture Mechanisms ◽  
Zone Model ◽  
Rate Dependency ◽  
Heterogeneous Model ◽  
Rate Dependent ◽  
Element Method

The discrete element method (DEM) represents a convenient and powerful tool for studying effects of material microstructure on fracture mechanisms in asphalt concrete. In this paper, the rate-dependency of asphalt concrete is investigated using a cohesive zone model with bulk viscoelastic properties combined with bilinear post-peak softening. Details of the constitutive models implemented in the DEM, with particular emphasis on the verification of viscoelastic models, are presented. Experimental test results based on a disk-shaped compact tension test are obtained under different loading rates and those are compared to numerical simulations with the help of the rate-dependent model. Homogeneous and heterogeneous model results are compared, where heterogeneous models are constructed to consider aggregate morphology for particles larger than 1.18 mm. The relative importance of time-dependence and the consideration of material heterogeneity in the simulation of monotonic Mode I fracture tests are demonstrated.

Estimating the Cohesive Zone Model Parameters of Carbon Nanotube–Polymer Interface for Machining Simulations

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Lingyun Jiang ◽  
Chandra Nath ◽  
Johnson Samuel ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Weight Fraction ◽  
Model Parameters ◽  
Zone Model ◽  
Fe Model ◽  
Polymer Interface ◽  
Two Parameters

The failure mechanisms encountered during the machining of carbon nanotube (CNT) polymer composites are primarily governed by the strength of the CNT–polymer interface. Therefore, the interface should be explicitly modeled in microstructure-level machining simulations for these composites. One way of effectively capturing the behavior of this interface is by the use of a cohesive zone model (CZM) that is characterized by two parameters, viz., interfacial strength and interfacial fracture energy. The objective of this study is to estimate these two CZM parameters of the interface using an inverse iterative finite element (FE) approach. A microstructure-level 3D FE model for nanoindentation simulation has been developed where the composite microstructure is modeled using three distinct phases, viz., the CNT, the polymer, and the interface. The unknown CZM parameters of the interface are then determined by minimizing the root mean square (RMS) error between the simulated and the experimental nanoindentation load–displacement curves for a 2 wt. % CNT–polyvinyl alcohol (PVA) composite sample at room temperature and quasi-static strain state of up to 0.04 s−1, and then validated using the 1 wt. % and 4 wt. % CNT–PVA composites. The results indicate that for well-dispersed and aligned CNT–PVA composites, the CZM parameters of the interface are independent of the CNT loading in the weight fraction range of 1–4%.

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