Analytical model for predicting the interfacial stresses of carbon nanotubes-reinforced nanocomposites

2014 ◽  
Vol 31 (2) ◽  
pp. 353-364 ◽  
Author(s):  
Shiuh-Chuan Her ◽  
Shou-Jan Liu
Keyword(s):  
Volume Fraction ◽  
Stress Transfer ◽  
Matrix Interface ◽  
Interfacial Stresses ◽  
Content Type ◽  
Large Volume Fraction ◽  
Proposed Model ◽  
The Matrix ◽  
Small Matrix ◽  
Matrix Modulus

Purpose – Carbon nanotubes (CNTs) with exceptional mechanical, thermal and electrical properties are considered to be ideal for reinforcing high-performance structures. The interfacial stresses between the CNTs and surrounding matrix are important phenomena which critically govern the mechanical properties of CNTs-reinforced nanocomposites. A number of methods have been proposed to investigate the stress transfer across the CNT/matrix interface, such as experimental measurement and molecular dynamics (MDs). Experimental tests are difficulty and expensive. MDs simulations, on the other hand, are computationally inefficient. The purpose of this paper is to present a reasonably simplified model. Incorporating the simplified model, the analytical expressions of the interface stresses including the shear stress and longitudinal normal stress are obtained. Design/methodology/approach – The analytical model consists of two concentric cylinders, namely a single-walled carbon nanotube (SWCNT) cylinder and a matrix cylinder, as the representative volume element (RVE). The interfacial stress analysis is performed using the shear lag model for the axisymmetric RVE. Analytical solutions for the normal stresses in the SWCNT and matrix, and the interfacial shear stress across the SWCNT/matrix interface are obtained. The proposed model has a great ability to theoretical prediction of the stress transfer between the matrix and CNTs. Findings – In order to demonstrate the simulation capabilities of the proposed model, parametric studies are conducted to investigate the effects of the volume fraction of SWCNT and matrix modulus on the stress transfer. The axial stress in the matrix is decreasing with the increase of the volume fraction and decrease of the matrix modulus. As a result of more loads can be transferred to the SWCNT for a large volume fraction and small matrix modulus. These results show that using a large volume fraction and a small matrix modulus improves the efficiency of the stress transfer from the matrix to the CNTs. Originality/value – A simple but accurate model using a simplified 2D RVE for characterizing the stress transfer in CNT-reinforced nanocomposites is presented. The predictions from the current method compare favourably with those by existing experimental, analytical and computational studies. The simple and explicit expressions of the interfacial stresses provide valuable analysis tools accessible to practical users.

Stress Analysis of Carbon Nanotubes Reinforced Nanocomposites

2013 ◽  
Vol 284-287 ◽  
pp. 357-361
Author(s):  
Shiuh Chuan Her ◽  
Shou Jan Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Stress Analysis ◽  
Volume Fraction ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Large Volume Fraction ◽  
Concentric Cylinders ◽  
The Matrix ◽  
Lag Model

Stress transfer in the carbon nanotube reinforced nanocomposites is investigated in this work. The model consists of two concentric cylinders, namely, a single-walled carbon nanotube cylinder (SWCNT) and a matrix cylinder, as the representative volume element (RVE). The stress analysis is performed using the shear lag model for the axisymmetric RVE. Analytical solutions for the axial normal stresses in the SWCNT and matrix, and the interfacial shear stress across the SWCNT/matrix interface are obtained. Numerical results show that using a large volume fraction improves the efficiency of the stress transfer from the matrix to the carbon nanotubes.

scholarly journals Stress Transfer from Axially Loaded Fiber to Matrix in a Microcomposite

1994 ◽  
Vol 365 ◽  
Author(s):  
Chun-Hway Hsueh
Keyword(s):  
Analytical Solutions ◽  
Volume Fraction ◽  
Axial Stress ◽  
Stress Transfer ◽  
Radial Dependence ◽  
Shear Lag ◽  
Shear Lag Model ◽  
The Matrix ◽  
Lag Model ◽  
Loaded Fiber

ABSTRACTThe shear lag model has been used extensively to analyze the stress transfer in a singe fiberreinforced composite (i.e., a microcomposite). To achieve analytical solutions, various simplifications have been adopted in the stress analysis. Questions regarding the adequacy of those simplifications are discussed in the present study for the following two cases: bonded interfaces and frictional interfaces. Specifically, simplifications regarding (1) Poisson's effect, and (2) the radial dependences of axial stresses in the fiber and the matrix are addressed. For bonded interfaces, the former can be ignored, and the latter can generally be ignored. However, when the volume fraction of the fiber is high, the radial dependence of the axial stress in the fiber should be considered. For frictional interfaces, the latter can be ignored, but the former should be considered; however, it can be considered in an average sense to simplify the analysis. Comparisons among results obtained from analyses with various simplifications are made.

scholarly journals Effects of Annealing on Microstructure and Mechanical Properties of Metastable Powder Metallurgy CoCrFeNiMo0.2 High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (5) ◽  
pp. 448 ◽  
Author(s):  
Cui Zhang ◽  
Bin Liu ◽  
Yong Liu ◽  
Qihong Fang ◽  
Wenmin Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Volume Fraction ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Large Volume Fraction ◽  
The Matrix ◽  
Coarse Precipitation ◽  
Precipitation Enhancement ◽  
Precipitation Phase

A CoCrFeNiMo0.2 high entropy alloy (HEA) was prepared through powder metallurgy (P/M) process. The effects of annealing on microstructural evolution and mechanical properties of P/M HEAs were investigated. The results show that the P/M HEA exhibit a metastable FCC single-phase structure. Subsequently, annealing causes precipitation in the grains and at the grain boundaries simultaneously. As the temperature increases, the size of the precipitates grows, while the content of the precipitates tends to increase gradually first, and then decrease as the annealing temperature goes up to 1000 °C. As the annealing time is prolonged, the size and content of the precipitates gradually increases, eventually reaching a saturated stable value. The mechanical properties of the annealed alloys have a significant correspondence with the precipitation behavior. The larger the volume fraction and the size of the precipitates, the higher the strength and the lower the plasticity of the HEA. The CoCrFeNiMo0.2 high entropy alloy, which annealed at 800 °C for 72 h, exhibited the most excellent mechanical properties with the ultimate tensile strength of about 850 MPa and an elongation of about 30%. Nearly all of the annealed HEAs exhibit good strength–ductility combinations due to the significant precipitation enhancement and nanotwinning. The separation of the coarse precipitation phase and the matrix during the deformation process is the main reason for the formation of micropores. Formation of large volume fraction of micropores results in a decrease in the plasticity of the alloy.

Interfacial stresses analysis of damaged structures strengthened with bonded prestressed FRP plate having variable fiber spacing

2015 ◽  
Vol 6 (2) ◽  
pp. 159-175 ◽  
Author(s):  
Ismail Bensaid ◽  
Bachir Kerboua ◽  
Cheikh Abdelmajid
Keyword(s):  
Volume Fraction ◽  
Mechanical Load ◽  
Interfacial Stress ◽  
Fiber Volume ◽  
Interfacial Stresses ◽  
Content Type ◽  
Prestressing Force ◽  
Fiber Spacing ◽  
Present Solution ◽  
Analytical Approaches

Purpose – The purpose of this paper is to develop a new improved solution and a new model to predict both shear and normal interfacial stress in simply supported beams strengthened with bonded prestressed FRP laminates by taking into account the fiber volume fraction spacing that play an important role on the interfacial stresses concentration. Design/methodology/approach – The study has been conducted by using analytical approaches for interfacial stresses in plated beams. The analysis is based on the deformation compatibility approach where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. In addition, an unrealistic restriction of the same curvatures in the RC beam and FRP panel commonly used in most of the existing studies is released in the present theoretical formulation. Findings – To verify the analytical model, the present predictions are compared first with those of (Malek et al., 1998; Smith and Teng, 2001) in the case of the absence of the prestressing force; for the second time, the present method is compared with that developed by (Al-Emrani and Kliger, 2006; Benachour et al., 2008) in the case where only the prestressing force is applied. From the presented results, it can be seen that the present solution agree closely with the other methods in the literature. Originality/value – The paper puts in evidence a new originality approach theory, taking into account the mechanical load, and the prestressed FRP plate model having variable fiber spacing which considers a strength rigidity and resistance of the damaged structures, which is one aspect that has not been taken into account by the previous studies.

The strengthening of metals by dispersed particles

1964 ◽  
Vol 282 (1388) ◽  
pp. 63-79 ◽  
Keyword(s):  
Metal Matrix ◽  
Volume Fraction ◽  
Dislocation Motion ◽  
Model Systems ◽  
Dispersed Phase ◽  
Strong Phase ◽  
Large Volume Fraction ◽  
Density Of Dislocations ◽  
Dispersed Particles ◽  
The Matrix

A review is made of the yield strength attainable by dispersing particles in a metal matrix in order to hinder dislocation motion. The advantages and drawbacks of the various methods used to introduce the particles are considered. The greatest strengths are found in materials containing a large volume fraction of dispersed phase coupled with a high density of dislocations in the matrix. The greatest strengths should be achieved if the dispersed particles are very strong and are loaded to fracture. To load the particles they must be needle-shaped. Experiments on model systems of a metal containing wires to simulate the strong phase are described. These indicate some of the conditions necessary to obtain maximum strength and suggest how extreme brittleness can be avoided.

scholarly journals Toughening Behavior and Interfacial Properties of Fiber-Reinforced Ceramic Composites

1991 ◽  
Vol 113 (3) ◽  
pp. 197-203
Author(s):  
C. H. Hsueh
Keyword(s):  
Critical Role ◽  
Stress Transfer ◽  
Interfacial Properties ◽  
Ceramic Composites ◽  
Matrix Interface ◽  
Fiber Bridging ◽  
The Matrix ◽  
Fiber Matrix Interface ◽  
New Generation

Toughening of ceramics by incorporating strong fibers has become an established technology, resulting in the creation of a new generation of tough ceramic composites. This toughening effect is primarily due to bridging of the crack surfaces by intact fibers when the composite is subjected to tension. The fiber bridging mechanisms, which are contingent upon the stress transfer phenomena between the fiber and the matrix, are reviewed in this paper. The critical role of the properties at the fiber/matrix interface in controlling the stress transfer phenomena is examined. Finally, evaluations of the interfacial properties of the composite by the indentation technique and the corresponding analysis are presented.

Fabrication and tensile testing of 3D printed continuous wire polymer composites

2018 ◽  
Vol 24 (7) ◽  
pp. 1131-1141 ◽  
Author(s):  
Yehia Ibrahim ◽  
Garrett W. Melenka ◽  
Roger Kempers
Keyword(s):  
Tensile Properties ◽  
Polymer Composites ◽  
Volume Fraction ◽  
Tensile Modulus ◽  
Analytical Prediction ◽  
Content Type ◽  
Continuous Wire ◽  
The Matrix ◽  
3D Printed ◽  
American Society

Purpose This paper aims to evaluate and predict the tensile properties of additively manufactured continuous wire polymer composites (CWPCs). Design/methodology/approach An open-source 3D printer was modified to print CWPCs where metal wires act as a reinforcement within a polymer matrix. The influence of different wire materials and diameters on the tensile modulus and ultimate tensile strength was studied. Different polymer matrixes were used to investigate the effect of the matrix on CWPCs’ tensile properties. The behaviour of samples was predicted analytically using the rule of mixture micromechanical approach and investigated experimentally using an American society for testing and materials standard tensile test. Findings Experimental results showed improvement in the elastic modulus and ultimate strength of CWPCs compared with non-reinforced specimens. Deviation between the experimental data and the analytical prediction was found to be dependent on the matrix type, wire volume fraction and wire material. Originality/value This paper introduces novel continuous metal wire-reinforced 3D printed composites. The continuous wire inside the print can be used as a strain gauge which can give an early alert for material failure. Applications for CWPCs include 3D-printed pressure and temperature sensors which measure the change in the wire’s electrical resistance and 3D-printed heaters which would work by supplying current through continuous wires.

Finite element prediction of stress transfer in h-BN sheet nanocomposites

2018 ◽  
Vol 9 (1) ◽  
pp. 2-16
Author(s):  
Konstantinos Spanos ◽  
Androniki Tsiamaki ◽  
Nicolaos Anifantis
Keyword(s):  
Finite Element ◽  
Hexagonal Boron Nitride ◽  
Matrix Material ◽  
Three Dimensional ◽  
Stress Transfer ◽  
Content Type ◽  
The Matrix ◽  
Element Approach ◽  
Solid Finite Elements ◽  
Heterogeneous Region

Purpose The purpose of this paper is to implement a micromechanical hybrid finite element approach in order to investigate the stress transfer behavior of composites reinforced with hexagonal boron nitride (h-BN) nanosheets. Design/methodology/approach For the analysis of the problem, a three-dimensional representative volume element, consisting of three phases, has been used. The reinforcement is modeled discretely using spring elements of specific stiffness while the matrix material is modeled as a continuum medium using solid finite elements. The third phase, the intermediate one, known as the interface, has been simulated by appropriate stiffness variations which define a heterogeneous region affecting the stress transfer characteristics of the nanocomposite. Findings The results show a good agreement with corresponding ones from the literature and also the effect of a number of factors is indicated in stress transfer efficiency. Originality/value This is the first time that such a modeling is employed in the stress transfer examination of h-BN nanocomposites.

scholarly journals Analysis of Weight Change in Fly Ash – Epoxy Particulate Composites Immersed under Hot Water

2001 ◽  
Vol 10 (5) ◽  
pp. 096369350101000 ◽  
Author(s):  
S.M. Kulkarni ◽  
Kishore
Keyword(s):  
Fly Ash ◽  
Volume Fraction ◽  
Low Cost ◽  
Percolation Model ◽  
Hot Water ◽  
Particulate Composites ◽  
Matrix Interface ◽  
Weight Changes ◽  
Absorption Data ◽  
The Matrix

Weight changes in epoxy filled with low-cost abundantly available filler, fly ash subjected to immersion in water maintained at an elevated temperature are studied. The effect of volume fraction of the filler on the water absorption characteristics is analysed. The extent and possible modes of water transport in the matrix and in the filler or filler-matrix interface are inferred through the study of absorption data. An attempt to explain this movement through the percolation model is made and support for the inferences arrived at is sought from microscopic observation using Scanning Electron Microscope.

Prediction of Effective Permittivity of Foam-Polymer Materials

2021 ◽  
Vol 26 (2) ◽  
pp. 115-122
Author(s):  
I.V. Lavrov ◽  
◽  
V.V. Bardushkin ◽  
V.B. Yakovlev ◽  
A.V. Bardushkin ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Effective Permittivity ◽  
Polymer Materials ◽  
Model Calculations ◽  
Large Volume Fraction ◽  
The Matrix ◽  
Consistent Method ◽  
Isotropic Foam ◽  
Dielectric And Mechanical Properties ◽  
Good Heat

Porous plastics are used in various fields of industry, including radio- and electrotechnical fields. They are characterized by good heat- and sound isolating, dielectric and mechanical properties as well as by resistance to effect of various external factors during operation. The problem of estimation of effective permittivity of foam-polymer materials with a large volume fraction of pores, in particular, polyepoxide foam materials, has been considered. Two methods for solving it, both based on the matrix have been proposed. In the first method the matrix is considered as a polyepoxide binder, and the cavities filled with gas are taken as inclusions. In the second method the polyepoxide walls, separating cavities, are taken as inclusions, and gas filling cavities is considered as a matrix. To obtain the formulas for calculation, both methods use a generalized singular approximation of the theory of random fields. Based on the obtained expressions, the model calculations of the effective permittivity of a macroscopically isotropic foam material with a polymer binder based on E-20 and the cavities filled with freon, depending on the apparent density of the material, have been made. The calculations in the generalized singular approximations have been carried out for two of its variants: when the matrix was considered as a comparison medium; and, also by the self-consistent method. In the calculations using the second method two variants of the shape of the cells of the material have been considered: a weakly leaked or heavily leaked polyhedron. The calculated dependences obtained by all me-thods have shown the qualitative compliance with the experimental data.

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