scholarly journals Energy Dissipation and the High-Strain Rate Dynamic Response of Vertically Aligned Carbon Nanotube Ensembles Grown on Silicon Wafer Substrate

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
P. Raju Mantena ◽  
Tezeswi Tadepalli ◽  
Brahmananda Pramanik ◽  
Veera M. Boddu ◽  
Matthew W. Brenner ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
High Strain Rate ◽  
Strain Rate ◽  
Silicon Wafer ◽  
High Strain ◽  
Flexural Rigidity ◽  
Functionally Graded ◽  
Dynamic Mechanical ◽  
Wafer Substrate ◽  
Vertically Aligned

The dynamic mechanical behavior and high-strain rate response characteristics of a functionally graded material (FGM) system consisting of vertically aligned carbon nanotube ensembles grown on silicon wafer substrate (VACNT-Si) are presented. Flexural rigidity (storage modulus) and loss factor (damping) were measured with a dynamic mechanical analyzer in an oscillatory three-point bending mode. It was found that the functionally graded VACNT-Si exhibited significantly higher damping without sacrificing flexural rigidity. A Split-Hopkinson pressure bar (SHPB) was used for determining the system response under high-strain rate compressive loading. Combination of a soft and flexible VACNT forest layer over the hard silicon substrate presented novel challenges for SHPB testing. It was observed that VACNT-Si specimens showed a large increase in the specific energy absorption over a pure Si wafer.

Study on Dynamic Mechanical Response of TC21 Alloy

2011 ◽  
Vol 88-89 ◽  
pp. 674-678
Author(s):  
Shuang Zan Zhao ◽  
Xing Wang Cheng ◽  
Fu Chi Wang
Keyword(s):  
Flow Stress ◽  
High Strain Rate ◽  
Strain Rate ◽  
Strain Hardening ◽  
High Strain ◽  
Dynamic Flow ◽  
Dynamic Mechanical ◽  
Hardening Effect ◽  
High Strain Rate Deformation ◽  
Binary Morphology

Some results of an experimental study on high strain rate deformation of TC21 alloy are discussed in this paper. Cylindrical specimens of the TC21 alloys both in binary morphology and solution and aging morphology were subjected to high strain rate deformation by direct impact using a Split Hopkinson Pressure Bar. The deformation process is dominated by both thermal softening effect and strain hardening effect under high strain rate loading. Thus the flow stress doesn’t increase with strain rate at the strain hardening stage, while the increase is obvious under qusi-static compression. Under high strain rate, the dynamic flow stress is higher than that under quasi-static and dynamic flow stress increase with the increase of the strain rate, which indicates the strain rate hardening effect is great in TC21 alloy. The microstructure affects the dynamic mechanical properties of TC21 titanium alloy obviously. Under high strain rate, the solution and aging morphology has higher dynamic flow stress while the binary morphology has better plasticity and less prone to be instability under high strain rate condition. Shear bands were found both in the solution and aging morphology and the binary morphology.

scholarly journals Dynamic Mechanical Properties and Microstructure of an (Al0.5CoCrFeNi)0.95Mo0.025C0.025 High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1154
Author(s):  
Bingfeng Wang ◽  
Chu Wang ◽  
Bin Liu ◽  
Xiaoyong Zhang
Keyword(s):  
Mechanical Properties ◽  
Shear Band ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Dynamic Mechanical Properties ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Dynamic Mechanical

The dynamic mechanical properties and microstructure of the (Al0.5CoCrFeNi)0.95Mo0.025C0.025 high entropy alloy (HEA) prepared by powder extrusion were investigated by a split Hopkinson pressure bar and electron probe microanalyzer and scanning electron microscope. The (Al0.5CoCrFeNi)0.95Mo0.025C0.025 HEA has a uniform face-centered cubic plus body-centered cubic solid solution structure and a fine grain-sized microstructure with a size of about 2 microns. The HEA possesses an excellent strain hardening rate and high strain rate sensitivity at a high strain rate. The Johnson–Cook plastic model was used to describe the dynamic flow behavior. Hat-shaped specimens with different nominal strain levels were used to investigate forced shear localization. After dynamic deformation, a thin and short shear band was generated in the designed shear zone and then the specimen quickly fractured along the shear band.

scholarly journals Carbon Nanotube Peapods Under High-Strain Rate Conditions: A Molecular Dynamics Investigation

MRS Advances ◽  
2020 ◽  
Vol 5 (33-34) ◽  
pp. 1723-1730
Author(s):  
J. M. De Sousa ◽  
C. F. Woellner ◽  
L. D. Machado ◽  
P. A. S. Autreto ◽  
D. S. Galvao
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Optical Modulation ◽  
Carbon Structures ◽  
Dynamics Simulations ◽  
Forms Of Carbon ◽  
The Impact

ABSTRACTNew forms of carbon-based materials have received great attention, and the developed materials have found many applications in nanotechnology. Interesting novel carbon structures include the carbon peapods, which are comprised of fullerenes encapsulated within carbon nanotubes. Peapod-like nanostructures have been successfully synthesized, and have been used in optical modulation devices, transistors, solar cells, and in other devices. However, the mechanical properties of these structures are not completely elucidated. In this work, we investigated, using fully atomistic molecular dynamics simulations, the deformation of carbon peapods under high-strain rate conditions, which are achieved by shooting the peapods at ultrasonic velocities against a rigid substrate. Our results show that carbon peapods experience large deformation at impact, and undergo multiple fracture pathways, depending primarily on the relative orientation between the peapod and the substrate, and the impact velocity. Observed outcomes include fullerene ejection, carbon nanotube fracture, fullerene, and nanotube coalescence, as well as the formation of amorphous carbon structures.

High Strain Rate Behavior of Graphene Reinforced Polyurethane Composites

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Sanjeev K. Khanna ◽  
Ha T. T. Phan
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Peak Load ◽  
Peak Stress ◽  
Strain Rates ◽  
Peak Strain ◽  
Plateau Stress ◽  
Dynamic Mechanical ◽  
Stress Peak

A compressive split Hopkinson pressure bar (SHPB) was used to investigate the dynamic mechanical behavior of graphene (GR) reinforced polyurethane (PU) composites (GR/PU) at high strain rates ranging from approximately 1500 s−1 to 5000 s−1. Four types of GR/PU composites with different GR contents: 0.25% GR, 0.5% GR, 0.75% GR, and 1% GR were prepared by the solution mixing method and divided into two groups of unheated and postheated specimens. Experimental results show that the GR/PU composite is a strong strain rate dependent material, especially in the high strain rate regime of 3000 s−1–5000 s−1. The dynamic mechanical properties of GR/PU composite in terms of plateau stress, peak stress, and peak load carrying capacity are better than that of pristine PU at most of the applied strain rates. Among the four different GR concentrations used, the 0.5 wt.%-GR specimen shows the highest peak stress, and the 1 wt.% GR specimen has the highest plateau stress; while no significant change in peak strain with changing GR weight fraction was observed. Compared to unheated specimens, the plateau stress, peak stress, and peak strain of postheated specimens are significantly higher.

High-strain rate compressive behavior of multi-walled carbon nanotube dispersed thermoset epoxy resin

2014 ◽  
Vol 49 (8) ◽  
pp. 903-910 ◽  
Author(s):  
Niranjan K Naik ◽  
Kedar S Pandya ◽  
Venkateswara R Kavala ◽  
Wei Zhang ◽  
Nikhil A Koratkar
Keyword(s):  
Carbon Nanotube ◽  
High Strain Rate ◽  
Strain Rate ◽  
Epoxy Resin ◽  
High Strain ◽  
Compressive Behavior ◽  
Multi Walled Carbon Nanotube ◽  
Thermoset Epoxy
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