scholarly journals Analysis of Viscoelastic Behavior of Polypropylene/Carbon Nanotube Nanocomposites by Instrumented Indentation

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2535
Author(s):  
Felicia Stan ◽  
Adriana-Madalina Turcanu (Constantinescu) ◽  
Catalin Fetecau
Keyword(s):  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Viscoelastic Behavior ◽  
Creep Function ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Shear Creep ◽  
Kelvin Model ◽  
Indentation Tests ◽  
Mwcnt Loading

In this work, the viscoelastic behavior of polypropylene (PP)/multi-walled carbon nanotube (MWCNT) nanocomposites was investigated by indentation testing and phenomenological modeling. Firstly, indentation tests including two-cycle indentation were carried out on PP/MWCNT nanocomposite with three MWCNT loadings (1, 3 and 5 wt %). Next, the Maxwell–Voigt–Kelvin model coupled with two-cycle indentation tests was used to predict the shear creep compliance function and the equivalent indentation modulus. The indentation hardness and elastic modulus of the PP/MWCNT nanocomposites extracted based on the Oliver and Pharr method were compared with the equivalent indentation modulus predicted based on the Maxwell–Voigt–Kelvin mode. The experimental results indicated that the addition of nanotubes into the polypropylene has a positive effect on the micro-mechanical properties of PP/MWCNT nanocomposites. Indentation hardness and elastic modulus increased significantly with increasing MWCNT loading. The creep resistance at the micro-scale of the PP/MWCNT nanocomposites improved with the addition of MWCNTs, with creep displacement reduced by up to 20% by increasing the carbon nanotube loading from 1 to 5 wt %. The Maxwell–Voigt–Kelvin model with three and five Voigt–Kelvin units accurately predicted the shear creep function and its change with increasing MWCNT loading. However, the equivalent indentation modulus was found to be sensitive to the number of Voigt–Kelvin units: the more Voigt–Kelvin units, the better the model predicts the equivalent indentation modulus.

scholarly journals Study on the Influence of the Grind Percentage Over the Surface Hardness and Modulus of Elasticity of Parts Made of ABS, P6.6 and POM through Nanoindentation

2019 ◽  
Vol 56 (1) ◽  
pp. 65-70
Author(s):  
Gheorghe Radu Emil Maries ◽  
Constantin Bungau ◽  
Dan Chira ◽  
Traian Costea ◽  
Danut-Eugeniu Mosteanu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Surface Hardness ◽  
Acrylonitrile Butadiene Styrene ◽  
The Other ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Maximum Hardness ◽  
New Material ◽  
Butadiene Styrene

This paper analyzes the indentation hardness and the indentation elastic modulus variation depending on the variation of the grind percentage of polymer, when the other factors that can influence the injection molding remain unchanged. The analyzed polymers were: acrylonitrile butadiene styrene ABS MAGNUM 3453, polyamide PA 6.6 TECHNYL AR218V30 Blak and polyoxymethylene POM EUROTAL C9 NAT. The samples that were studied had different compositions in new and grinding material. The G-Series Basic Hardness Modulus at a Depth method was used. The increase of the grind percentage of ABS (from 0 to 100 %) leads to insignificant changes in the indentation hardness, indentation modulus, and maximum force applied to samples of tested material. The maximum hardness (0.137 GPa) of PA 6.6 is recorded in the case of the sample with 80% grind content, and the maximum hardness of POM is recorded as well in the case of the sample with 80% grind content, as being 0.215 GPa. The variation of the grind content in the analyzed samples determines changes in the evaluated parameters, depending on the type of polymer. Combining the new material with grind in proportions experimentally established for each techno polymer leads to changes in their mechanical properties.

scholarly journals Analysis of depth-sensing indentation tests with a Knoop indenter

2001 ◽  
Vol 16 (6) ◽  
pp. 1660-1667 ◽  
Author(s):  
L. Riester ◽  
T. J. Bell ◽  
A. C. Fischer-Cripps
Keyword(s):  
Elastic Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Short Axis ◽  
Depth Sensing ◽  
Specimen Material ◽  
Indentation Tests ◽  
Conventional Methods ◽  
Knoop Indenter

The present work shows how data obtained in a depth-sensing indentation test using a Knoop indenter may be analyzed to provide elastic modulus and hardness of the specimen material. The method takes into account the elastic recovery along the direction of the short axis of the residual impression as the indenter is removed. If elastic recovery is not accounted for, the elastic modulus and hardness are overestimated by an amount that depends on the ratio of E/H of the specimen material. The new method of analysis expresses the elastic recovery of the short diagonal of the residual impression into an equivalent face angle for one side of the Knoop indenter. Conventional methods of analysis using this corrected angle provide results for modulus and hardness that are consistent with those obtained with other types of indenters.

EXPERIMENTAL RESEARCH ON VISCOELASTICITY PROPERTY OF DIFFERENT LAYERS PERIODONTAL LIGAMENT UNDER COMPRESSION

2021 ◽  
pp. 2150050
Author(s):  
JINLAI ZHOU ◽  
YANG SONG ◽  
CHENGUANG XU ◽  
CHUNQIU ZHANG ◽  
XUE SHI
Keyword(s):  
Elastic Modulus ◽  
Periodontal Ligament ◽  
Creep Compliance ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
Kelvin Model ◽  
Generalized Maxwell Model ◽  
Relaxation Stress ◽  
Generalized Kelvin Model ◽  
Fitting Accuracy

The periodontal ligament (PDL) exhibits different material mechanical properties along the long axis of the teeth. To explore the creep and the relaxation effects of dissimilar layers of PDL, this paper took the central incisors of porcine mandibular as experimental subjects and divided them perpendicular to the teeth axis into five layers. Creep experiments and relaxation experiments on five layers were conducted to obtain the creep compliance and relaxation modulus at different layers. Linear elastic model, generalized Kelvin model, and generalized Maxwell model were used to describe the major characteristics of the PDL: Instantaneous elasticity, creep and relaxation. Fitting accuracy of three-parameter, five-parameter, and seven-parameter of the model was compared, and the constitutive equations of different layers were established by the least square method. The results presented that the creep strain and the relaxation stress of PDL were exponentially correlated with time under different loading conditions. Different layers showed a significant effect on the creep strain and relaxation stress of PDL. Along the long axis of the teeth, the changing rule of the creep compliance and relaxation modulus of each layer showed quite the contrary, and the instantaneous elastic modulus first decreased to the minimum, then increased to the maximum. Higher instantaneous elastic modulus led to lower creep compliance and higher relaxation modulus. The generalized Kelvin model and the generalized Maxwell model well characterized the creep and relaxation properties of PDL. Fitting accuracy increased with the number of model parameters. The relaxation time of PDL was about one order of magnitude shorter than the creep retardation time, which indicated that the relaxation effect lasted shorter than the creep effect.

Further analysis of the size effect in indentation hardness tests of some metals

1995 ◽  
Vol 10 (11) ◽  
pp. 2908-2915 ◽  
Author(s):  
M. Atkinson
Keyword(s):  
Size Effect ◽  
Strain Hardening ◽  
Indentation Size Effect ◽  
Plastic Hinge ◽  
Small Scale ◽  
Indentation Hardness ◽  
Vickers Indentation ◽  
Indentation Size ◽  
Hardness Tests ◽  
Indentation Tests

The variation of apparent hardness observed in previously reported Vickers indentation tests of metals is reexamined. Common deseriptions of the effect are shown to be inaccurate: the variation of apparent hardness is monotonic but not simple. The effect is consistent with varying size of a previously postulated “plastic hinge” at the perimeter of the indent. This complexity confers uncertainty on the estimation of characteristic macrohardness from small scale tests. Association of the indentation size effect with friction and with strain hardening is confirmed.

Fabrication of Carbon Nanotube Reinforced Boron Carbide Composite by Hot-Pressing Following Extrusion Molding

2014 ◽  
Vol 616 ◽  
pp. 27-31 ◽  
Author(s):  
Tomohiro Kobayashi ◽  
Katsumi Yoshida ◽  
Toyohiko Yano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Boron Carbide ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Bending Strength ◽  
Extrusion Direction ◽  
Sem Observation

The CNT/B4C composite with Al2O3 additive was fabricated by hot-pressing following extrusion molding of a CNT/B4C paste, and mechanical properties of the obtained composite were investigated. Many CNTs in the composite aligned along the extrusion direction from SEM observation. 3-points bending strength of the composite was slightly lower than that of the monolithic B4C. Elastic modulus and Vickers hardness of the composite drastically decreased with CNT addition. Fracture toughness of the composite was higher than that of the monolithic B4C.

The influence of functionalization time of carbon nanotube on the mechanical properties of the epoxy composites

2017 ◽  
Vol 51 (12) ◽  
pp. 1693-1701 ◽  
Author(s):  
EA Zakharychev ◽  
EN Razov ◽  
Yu D Semchikov ◽  
NS Zakharycheva ◽  
MA Kabina
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Composite Materials ◽  
Polymer Composites ◽  
Epoxy Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

This paper investigates the structure, length, and percentage of functional groups of multi-walled carbon nanotubes (CNT) depending on the time taken for functionalization in HNO3 and H2SO4 mixture. The carbon nanotube content and influence of functionalization time on mechanical properties of polymer composite materials based on epoxy matrix are studied. The extreme dependencies of mechanical properties of carbon nanotube functionalization time of polymer composites were established. The rise in tensile strength of obtained composites reaches 102% and elastic modulus reaches 227% as compared to that of unfilled polymer. The composites exhibited best mechanical properties by including carbon nanotube with 0.5 h functionalization time.

Effect of Different Factors on Measured Values of Indentation Hardness of Interstitial Free Steel by Depth Sensing Indentation

2018 ◽  
Vol 784 ◽  
pp. 49-54
Author(s):  
Peter Burik ◽  
Ladislav Pešek ◽  
Zuzana Andršová ◽  
Pavel Kejzlar
Keyword(s):  
Mechanical Properties ◽  
Sample Surface ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Interstitial Free ◽  
Depth Sensing ◽  
Multiphase Materials ◽  
Material Characteristics ◽  
Straightforward Solution ◽  
Characterization Of Materials

Nanomechanical testing using depth sensing indentation (DSI) provides a straightforward solution for quantitatively characterizing each of phases in microstructure because it is very powerful technique for characterization of materials in small volumes. Measuring the local properties (indentation hardness HIT, indentation modulus EIT, indentation energy: total Wtotal, elastic Welast, plastic Wplast) of each microstructure component separately in multiphase materials gives information that is valuable for the development of new materials and for modelling. The mechanical properties of materials measured by DSI are affected by the experimental procedure, by the measurement conditions and factors which result from the material characteristics and device construction. We have to determine the effect of individual factors on the measurement in order to reach the repeatability and to allow the comparing the mechanical properties of the material. The aim of this investigation is to determine the measurement factors that affect indentation hardness of individual microstructural components and global mechanical properties of thin steel sheets. We investigated the factors which result from the material characteristics (crystallographic orientation of grain, grain boundary and anisotropy), preparation of the sample surface (roughness of sample surface) and method of measurement (pile-up, ISE).

scholarly journals Manufacturing Aluminum/Multiwalled Carbon Nanotube Composites via Laser Powder Bed Fusion

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3927
Author(s):  
Eo Ryeong Lee ◽  
Se Eun Shin ◽  
Naoki Takata ◽  
Makoto Kobashi ◽  
Masaki Kato
Keyword(s):  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Energy Density ◽  
Laser Power ◽  
Multiwalled Carbon Nanotube ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Multiwalled Carbon ◽  
Powder Bed ◽  
Scan Speed

This study provides a novel approach to fabricating Al/C composites using laser powder bed fusion (LPBF) for a wide range of structural applications utilizing Al-matrix composites in additive manufacturing. We investigated the effects of LPBF on the fabrication of aluminum/multiwalled carbon nanotube (Al/MWCNT) composites under 25 different conditions, using varying laser power levels and scan speeds. The microstructures and mechanical properties of the specimens, such as elastic modulus and nanohardness, were analyzed, and trends were identified. We observed favorable sintering behavior under laser conditions with low energy density, which verified the suitability of Al/MWCNT composites for a fabrication process using LPBF. The size and number of pores increased in specimens produced under high energy density conditions, suggesting that they are more influenced by laser power than scan speed. Similarly, the elastic modulus of a specimen was also more affected by laser power than scan speed. In contrast, scan speed had a greater influence on the final nanohardness. Depending on the laser power used, we observed a difference in the crystallographic orientation of the specimens by a laser power during LPBF. When energy density is high, texture development of all samples tended to be more pronounced.

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