Effect of Carbon Nanotube (CNT) Loading on the Thermomechanical Properties and the Machinability of CNT-Reinforced Polymer Composites

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
J. Samuel ◽  
A. Dikshit ◽  
R. E. DeVor ◽  
S. G. Kapoor ◽  
K. J. Hsia
Keyword(s):  
Carbon Nanotube ◽  
Polymer Composites ◽  
Shear Bands ◽  
Chip Thickness ◽  
Chip Morphology ◽  
Thermomechanical Properties ◽  
Reinforced Polymer ◽  
Ductile To Brittle Transition ◽  
Burr Width ◽  
Interface Effects

The machinability of carbon nanotube (CNT)-reinforced polymer composites is studied as a function of CNT loading, in light of the trends seen in their material properties. To this end, the thermomechanical properties of the CNT composites with different loadings of CNTs are characterized. Micro-endmilling experiments are also conducted on all the materials under investigation. Chip morphology, burr width, surface roughness, and cutting forces are used as the machinability measures to compare the composites. For composites with lower loadings of CNTs (1.75% by weight), the visco-elastic/plastic deformation of the polymer-phase plays a significant role during machining, whereas, at loadings ≥5% by weight, the CNT distribution and interface effects dictate the machining response of the composite. The ductile-to-brittle transition that occurs with an increase in CNT loading results in reduced minimum chip thickness values and burr dimensions in the CNT composite. The increase in thermal conductivity with the increase in CNT loading results in reduced number of adiabatic shear bands being observed on the chips and reduced thermal softening effects at high cutting velocities. Thus, overall, an increase in CNT loading appears to improve the machinability of the composite.

Effect of Carbon Nanotube (CNT) Loading on the Thermo-Mechanical Properties and the Machinability of CNT-Reinforced Polymer Composites

2008 ◽  
Author(s):  
Johnson Samuel ◽  
Ashutosh Dikshit ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor ◽  
K. Jimmy Hsia
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Polymer Composites ◽  
Cutting Forces ◽  
Shear Bands ◽  
Chip Thickness ◽  
Chip Morphology ◽  
Reinforced Polymer ◽  
Ductile To Brittle Transition ◽  
Burr Width

The machinability of carbon nanotube (CNT)-reinforced polymer composites is studied as a function of CNT loading, in light of the trends seen in their material properties. To this end, the thermo-mechanical properties of CNT composites with different loadings of CNTs are characterized. Micro endmilling experiments are also conducted on all the materials under investigation. Chip morphology, burr width, surface roughness and cutting forces are used as the machinability measures to compare the composites. For composites with lower loadings of CNTs (1.75% by weight), the visco-elastic/plastic deformation of the polymer phase plays a significant role during machining, whereas, at loadings ≥ 5% by weight, the CNT distribution and interface effects dictate the machining response of the composite. The ductile-to-brittle transition and reduction in fracture strength that occurs with an increase in CNT loading, results in reduced minimum chip thickness values, burr dimensions and cutting forces in the CNT composite. The increase in thermal conductivity with the increase in CNT loading, results in reduced number of adiabatic shear bands being observed on the chips and reduced thermal softening effects at high cutting velocities. Thus, overall the increase in CNT loading improves the machinability of the composite.

Microstructure-Level Machining Simulation of Carbon Nanotube Reinforced Polymer Composites—Part I: Model Development and Validation

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
A. Dikshit ◽  
J. Samuel ◽  
R. E. DeVor ◽  
S. G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Polymer Composites ◽  
Model Development ◽  
Shear Bands ◽  
Chip Morphology ◽  
Material Model ◽  
Failure Model ◽  
Orthogonal Machining ◽  
Modes Of Failure ◽  
Reinforced Polymer

A microstructure-level finite element machining model has been developed to simulate the machining of carbon nanotube (CNT) reinforced polymer composites. The model integrates a failure model with a previously developed microstructure-based material model. The competition between ductile and brittle modes of failure in the polymer phase (polycarbonate) is captured by implementing the Gearing and Anand failure model calibrated at different temperatures. The CNT phase is given a simple strain-to-failure criterion. The proposed machining model has been validated at different orthogonal machining conditions for the plain polycarbonate and for composites with two different percentage loadings of CNTs. On an average, the model is seen to successfully predict the cutting forces with an accuracy of 8% and the thrust forces with an accuracy of 13.4% for all the materials. The machining model also predicts the continuous chip morphology and formation of adiabatic shear bands in plain polycarbonate and for composites with lower loadings of CNTs. On an average, the chip thicknesses are predicted within an accuracy of 14% for plain polycarbonate and 10% for the CNT composites.

Electrothermomechanical Modeling and Analyses of Carbon Nanotube Polymer Composites

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
S. Xu ◽  
O. Rezvanian ◽  
M. A. Zikry
Keyword(s):  
Finite Element ◽  
Carbon Nanotube ◽  
Polymer Composites ◽  
Volume Fraction ◽  
Electron Tunneling ◽  
Three Dimensional ◽  
Fe Modeling ◽  
Aspect Ratios ◽  
Reinforced Polymer ◽  
Polymer Dispersions

A new finite element (FE) modeling method has been developed to investigate how the electrical-mechanical-thermal behavior of carbon nanotube (CNT)–reinforced polymer composites is affected by electron tunneling distances, volume fraction, and physically realistic tube aspect ratios. A representative CNT polymer composite conductive path was chosen from a percolation analysis to establish the three-dimensional (3D) computational finite-element (FE) approach. A specialized Maxwell FE formulation with a Fermi-based tunneling resistance was then used to obtain current density evolution for different CNT/polymer dispersions and tunneling distances. Analyses based on thermoelectrical and electrothermomechanical FE approaches were used to understand how CNT-epoxy composites behave under electrothermomechanical loading conditions.

Utilizing interfaces in carbon nanotube reinforced polymer composites for structural damping

2006 ◽  
Vol 41 (23) ◽  
pp. 7824-7829 ◽  
Author(s):  
Pulickel M. Ajayan ◽  
Jonghwan Suhr ◽  
Nikhil Koratkar
Keyword(s):  
Carbon Nanotube ◽  
Polymer Composites ◽  
Structural Damping ◽  
Reinforced Polymer
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