Carbon Nanotube Reinforced Composites: The Smaller Diameter, the Higher Fracture Toughness?

2015 ◽  
Vol 82 (8) ◽  
Author(s):  
Yuli Chen ◽  
Zhiyong Wang ◽  
Shengtao Wang ◽  
Zhenggang Zhou ◽  
Jianyu Zhang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Failure Mode ◽  
Failure Modes ◽  
Reinforced Composites ◽  
Failure Mode Transition ◽  
Reinforced Composite ◽  
Mechanical And Physical Properties ◽  
Potential Applications ◽  
Toughness Enhancement

Carbon nanotube (CNT) reinforced composites have been drawing intense attentions of researchers due to their good mechanical and physical properties as well as potential applications. The diameter, as an important geometric parameter of CNTs, significantly affects the performance of CNTs in the reinforced composites, not only in a direct way but also in an indirect way by influencing the effective modulus and strength of reinforcing CNTs. This paper investigates the comprehensive effect of CNT diameter on the fracture toughness of CNT reinforced composites by accounting for both direct and indirect influences of CNT diameter based on the three-level failure analysis. The criteria for failure modes are established analytically, and the types of failure mode transition with the corresponding optimal CNT diameter are obtained. It is found that reducing CNT diameter can cause a sudden drop in fracture toughness of composites due to the transition of dominant failure mode. Therefore, the CNTs with smaller diameter do not definitely confer a better fracture toughness on their reinforced composites, and the optimal CNT diameter may exist in the transition between failure modes, especially from interfacial debonding to CNT break. In addition, according to the results, the failure mode of CNT break is suggested to be avoided in the composite design because of the low fracture toughness enhancement of CNTs in this mode. This study can provide guiding reference for CNT reinforced composite design.

scholarly journals Fracture Toughness of Carbon Nanotube-Reinforced Metal- and Ceramic-Matrix Composites

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Y. L. Chen ◽  
B. Liu ◽  
Y. Huang ◽  
K. C. Hwang
Keyword(s):  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Ceramic Matrix Composites ◽  
Short Fiber ◽  
Matrix Composites ◽  
Reinforced Composites ◽  
Soft Matrix ◽  
Bond Density ◽  
Pull Out ◽  
Toughness Enhancement

Hierarchical analysis of the fracture toughness enhancement of carbon nanotube- (CNT-) reinforced hard matrix composites is carried out on the basis of shear-lag theory and facture mechanics. It is found that stronger CNT/matrix interfaces cannot definitely lead to the better fracture toughness of these composites, and the optimal interfacial chemical bond density is that making the failure mode just in the transition from CNT pull-out to CNT break. For hard matrix composites, the fracture toughness of composites with weak interfaces can be improved effectively by increasing the CNT length. However, for soft matrix composite, the fracture toughness improvement due to the reinforcing CNTs quickly becomes saturated with an increase in CNT length. The proposed theoretical model is also applicable to short fiber-reinforced composites.

Ductile Phase Toughening of MoSi2-Chemical Compatibility and Fracture Toughness

1990 ◽  
Vol 194 ◽  
Author(s):  
L. Xiao ◽  
Y. S. Kim ◽  
Reza Abbaschian
Keyword(s):  
Fracture Toughness ◽  
Reinforced Composites ◽  
Matrix Interface ◽  
Chemical Compatibility ◽  
Interaction Zone ◽  
Ductile Phase ◽  
Reinforced Composite ◽  
The Matrix ◽  
Mullite Coatings ◽  
Bonding Characteristics

AbstractChemical compatibility between oxide coated Nb filament reinforcements and MoSi2 was investigated. It was determined that ZrO2, Al2O3, and mullite coatings were chemically compatible with both Nb and MoSi2. Comparison between coated and uncoated filaments indicated that the coatings reduced the thickness of the interaction zone. The fracture toughness of the Nb filament reinforced composites showed an increase, while W filament reinforced composite showed a decrease, in the toughness compared to that of the matrix. The results are discussed in terms of the mismatches in the coefficients of thermal expansion and the bonding characteristics of the reinforcement/matrix interface.

Effects of the Length of Carbon Nanotube (CNT) in CNT Reinforced Composites

2006 ◽  
Vol 324-325 ◽  
pp. 855-858
Author(s):  
Q. Wang ◽  
X. F. Sun ◽  
Kimihiro Ozaki
Keyword(s):  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Stress Intensity ◽  
Stress Field ◽  
Stress Intensity Factors ◽  
Reinforced Composites ◽  
Intensity Factors ◽  
Singular Stress ◽  
Singular Stress Field

In this paper, the strength of the singular stress field near the ends of the CNTs in composites was analyzed to clarify the effects of the CNT length on stress filed in the CNT reinforced composites when studying the fracture toughness. The singular stress field was separated into two types of singularities, symmetric and skew-symmetric, near the ends of CNTs according to the deformation and loading types. The stress intensity factors of the singular stress field were calculated for these two types of singularities. The effects of the CNT length in CNT reinforced composites on these stress intensity factors were investigated.

Load and Geometry Effect on Failure Mode Initiation of Composite Sandwich Beams

2006 ◽  
Vol 3-4 ◽  
pp. 173-178
Author(s):  
E.E. Gdoutos ◽  
M.S. Konsta-Gdoutos
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Sandwich Beams ◽  
Compressive Failure ◽  
Honeycomb Core ◽  
Composite Sandwich ◽  
Failure Mode Transition ◽  
Aluminum Honeycomb ◽  
Geometrical Dimensions

Facing compressive failure, facing wrinkling and core shear failure are the most commonly encountered failure modes in sandwich beams with facings made of composite materials. The occurrence and sequence of these failure modes depends on the geometrical dimensions, the form of loading and type of support of the beam. In this paper the above three failure modes in sandwich beams with facings made of carbon/epoxy composites and cores made of aluminum honeycomb and two types of foam have been investigated. Two types of beams, the simply supported and the cantilever have been considered. Loading included concentrated and uniform. It was found that in beams with foam core facing wrinkling and core shear failure occur, whereas in beams with honeycomb core facing compressive failure and core shear crimping take place. Results were obtained for the dependence of failure mode on the geometry of the beam and the type of loading. The critical beam spans for failure mode transition from core shear to wrinkling failure were established. It was found that initiation of a particular failure mode depends on the properties of the facing and core materials, the geometrical configuration and loading of composite sandwich beams.

Influence of multi-wall carbon nanotube content on dry and corrosive wear performances of pure magnesium

2018 ◽  
Vol 52 (23) ◽  
pp. 3127-3135 ◽  
Author(s):  
Muhammet E Turan ◽  
Yavuz Sun ◽  
Fatih Aydın ◽  
Yasin Akgul
Keyword(s):  
Carbon Nanotube ◽  
Hardness Test ◽  
Corrosive Wear ◽  
Pure Magnesium ◽  
Reinforced Composites ◽  
Wear Performance ◽  
Reinforced Composite ◽  
The Matrix ◽  
Corrosive Environments ◽  
Multi Wall Carbon Nanotube

The present study aims to investigate the effect of Multi-Wall Carbon Nanotube on dry sliding and corrosive wear performance of pure magnesium. Multi-wall carbon nanotube reinforced composites with different weight fractions (0.25 wt.% and 0.5 wt.%) were fabricated by semi powder metallurgy. Hardness test was performed for all samples. To evaluate wear performance of the samples, three different loads (10 N, 20 N, and 40 N) were applied at the room temperature in both dry and 3.5 wt.% NaCl corrosive environments. Worn surfaces and microstructures of the samples were characterized using Scanning Electron Microscope. Results show that carbon nanotubes embedded in the matrix without any macro-defects. The hardness of pure magnesium was improved with the addition of multi-wall carbon nanotube considerably. 0.5 wt.% multi-wall carbon nanotube reinforced composite exhibited best wear performance both in dry and corrosive conditions.

scholarly journals Comparative Investigation on the Failure Modes of Natural Kenaf/Epoxy Reinforced Composite Hexagonal Tubes

2016 ◽  
Vol 709 ◽  
pp. 7-10 ◽  
Author(s):  
M.F.M. Alkbir ◽  
S.M. Sapuan ◽  
A.A. Nuraini ◽  
Mohamad Ridzwan Ishak
Keyword(s):  
Failure Mode ◽  
Transverse Crack ◽  
Failure Modes ◽  
Epoxy Composite ◽  
Local Buckling ◽  
Comparative Investigation ◽  
Composite Tubes ◽  
Reinforced Composite ◽  
Buckling Failure ◽  
Mode Response

This study aims to investigate failure mode response of woven natural kenaf/epoxy composite hexagonal tubes subjected to an axial and lateral quasi-static crushing test. The hexagonal composite tubes were prepared by the hand lay-up technique using a variety of hexagonal angles 40ο, 50 ο, and 60 ο. The result showed that hexagonal composite tubes under an axial compression test exhibited few failure modes such as, the transverse crack failure mode . Splaying failure mode and local buckling failure mode respectively, whereas the tubes under lateral test only exhibited longitudinal fracture.

Compressive fracture of brittle materials

1984 ◽  
Vol 396 (1811) ◽  
pp. 297-314 ◽  
Keyword(s):  
Crack Length ◽  
Failure Mode ◽  
Failure Modes ◽  
Plastic Instability ◽  
Elastic Model ◽  
Failure Mode Transition ◽  
Splitting Failure ◽  
Flat Steel ◽  
Axial Splitting ◽  
Brittle Polymers

Pre-cracked rectangular blocks of two different glassy brittle polymers were compressed under a flat steel platen until failure occurred. Three distinct failure modes, gross yielding under platen, axial splitting and plastic instability (buckling) were observed, depending on the pre-crack length and platen width. The axial splitting failure mode is explained by invoking the energy balance concept of fracture with a two-strut elastic model. In this mode, the elastic fracture surface energy or, equivalently, the stress intensity factor and not the compressive strength, is found to be the fundamental material property dictating compression failure. The role played by the pre-crack length and platen width in controlling the failure mode transition from gross yielding to compression splitting and to buckling is highlighted. Finite element and boundary element calculations support the proposed two-strut model for compression splitting.

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