Experimental observation and characterization of chaos in the unstable plastic flow domain during tensile testing

1996 ◽  
Vol 15 (7) ◽  
pp. 597-599 ◽  
Author(s):  
S. Rajasekar ◽  
S. Venkadesan ◽  
K. P. N. Murthy
Keyword(s):  
Experimental Observation ◽  
Plastic Flow ◽  
Tensile Testing ◽  
Flow Domain

scholarly journals Structural Factors Inducing Cracking of Brass Fittings

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3255
Author(s):  
Lenka Kunčická ◽  
Michal Jambor ◽  
Adam Weiser ◽  
Jiří Dvořák
Keyword(s):  
Chemical Composition ◽  
Plastic Flow ◽  
Beta Phase ◽  
Alpha Phase ◽  
Structural Factors ◽  
Transmission Electron ◽  
Medical Gas ◽  
Hot Die Forging ◽  
Multiple Step

Cu–Zn–Pb brasses are popular materials, from which numerous industrially and commercially used components are fabricated. These alloys are typically subjected to multiple-step processing—involving casting, extrusion, hot forming, and machining—which can introduce various defects to the final product. The present study focuses on the detailed characterization of the structure of a brass fitting—i.e., a pre-shaped medical gas valve, produced by hot die forging—and attempts to assess the factors beyond local cracking occurring during processing. The analyses involved characterization of plastic flow via optical microscopy, and investigations of the phenomena in the vicinity of the crack, for which we used scanning and transmission electron microscopy. Numerical simulation was implemented not only to characterize the plastic flow more in detail, but primarily to investigate the probability of the occurrence of cracking based on the presence of stress. Last, but not least, microhardness in specific locations of the fitting were examined. The results reveal that the cracking occurring in the location with the highest probability of the occurrence of defects was most likely induced by differences in the chemical composition; the location the crack in which developed exhibited local changes not only in chemical composition—which manifested as the presence of brittle precipitates—but also in beta phase depletion. Moreover, as a result of the presence of oxidic precipitates and the hard and brittle alpha phase, the vicinity of the crack exhibited an increase in microhardness, which contributed to local brittleness.

PREPARATION, MORPHOLOGY AND MECHANICAL PROPERTIES OF EPOXY NANOCOMPOSITES WITH ALUMINA FILLERS

2010 ◽  
Vol 24 (01n02) ◽  
pp. 136-147 ◽  
Author(s):  
SHEAU HOOI LIM ◽  
KAIYANG ZENG ◽  
CHAOBIN HE
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Thermomechanical Properties ◽  
Nano Particles ◽  
Testing Methods ◽  
Transmission Electron ◽  
Alumina Particles ◽  
Thermomechanical Testing ◽  
Platelet Shape

This paper presents recent studies on the processing and characterization of epoxy-alumina nanocomposites. Nano-sized alumina particles are incorporated into epoxy resin via solvent-assisted method, so that the particles are dispersed homogeneously in the epoxy matrix. The morphologies, mechanical and thermomechanical properties of the resulting nanocomposites are studied using transmission electron microscope (TEM), conventional tensile testing and thermomechanical testing methods. TEM results show that the alumina nano-particles with a higher specific surface area tend to agglomerate. Furthermore platelet shape particles shows a better dispersion homogeneity as well as better improvement in the mechanical properties of the composites compared to the rod shape particles.

scholarly journals Influence of the Casting Concentration on the Mechanical and Optical Properties of FA/CaCl2-Derived Silk Fibroin Membranes

2020 ◽  
Vol 21 (18) ◽  
pp. 6704
Author(s):  
Alexander Kopp ◽  
Laura Schunck ◽  
Martin Gosau ◽  
Ralf Smeets ◽  
Simon Burg ◽  
...  
Keyword(s):  
Silk Fibroin ◽  
Tensile Testing ◽  
Biomedical Applications ◽  
Toxic Chemicals ◽  
Membrane Properties ◽  
Limited Extent ◽  
Dissolution Method ◽  
Process Output ◽  
Silkworm Bombyx Mori

In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live–dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.

Characterization of 2017A Anodized Aluminum Alloy by Infrared Thermographic Techniques and SEM Observations During Tensile Testing

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
C. Fares ◽  
M. A. Belouchrani ◽  
M. Hadj Meliani ◽  
A. Alhussein ◽  
N. Merah ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Tensile Testing ◽  
Anodized Aluminum

Mechanical Characterization of Polymer Nanowires Using MEMS

2006 ◽  
Author(s):  
B. A. Samuel ◽  
Bo Yi ◽  
R. Rajagopalan ◽  
H. C. Foley ◽  
M. A. Haque
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Furfuryl Alcohol ◽  
Mechanical Characterization ◽  
Uniaxial Tensile ◽  
Testing Device ◽  
Uniaxial Tensile Testing ◽  
Polymer Nanowires

We present results on the mechanical properties of single freestanding poly-furfuryl alcohol (PFA) nanowires (aspect ratio > 50, diameters 100–300 nm) from experiments conducted using a MEMS-based uniaxial tensile testing device in-situ inside the SEM. The specimens tested were pyrolyzed PFA nanowires (pyrolyzed at 800° C).

Preparation and Characterization of Cellulose Films with Curcumin

2013 ◽  
Vol 834-836 ◽  
pp. 555-558
Author(s):  
Jaranya Suksulap ◽  
Potjanart Suwanruji ◽  
Jantip Setthayanond
Keyword(s):  
Tensile Testing ◽  
Color Change ◽  
Sodium Hydroxide Solution ◽  
Cellulose Fiber ◽  
Regenerated Cellulose ◽  
Color Strength ◽  
X Ray ◽  
Cellulose Films ◽  
Regenerated Cellulose Fiber

The cellulose film was prepared from regenerated cellulose fiber residue by dissolving the cellulose in sodium hydroxide solution at low temperature (-15 °C). The properties of the prepared film were investigated by tensile testing, Scanning Electron Microscope (SEM), X-ray Diffractometer (XRD) and also swelling ratio. Curcumin was added into the film with three different concentrations. The color strength of the curcumin-added film was evaluated and the color change of this film in different pH was also reported.

Formation of Twinned WC Grains during Carbonization of Eta Phase (W3Co3C)

2007 ◽  
Vol 534-536 ◽  
pp. 1189-1192 ◽  
Author(s):  
Jong Dae Kim ◽  
Kern Woo Lee ◽  
Joo Wan Lee ◽  
Moshe Sharon ◽  
Suk Joong L. Kang
Keyword(s):  
Experimental Observation ◽  
Driving Force ◽  
Carbon Activity ◽  
Low Carbon ◽  
High Carbon ◽  
Sem And Tem ◽  
High Supersaturation ◽  
Co Alloys

Twinned WC grains are sometimes observed in WC powder and sintered WC-Co alloys. The present investigation has studied the formation of twinned WC grains during carburization of an Eta phase. Eta grains were carburized at 700-1450°C for 1 min to 9 h. Twinned WC grains formed during the carburization. Crystallographic characterization of the formed twins were made using SEM and TEM. The formation of twins was found to be affected by the carbon activity during carburization. The twins formed under high carbon activities while no twins formed under low carbon activities. Two kinds of twins with different orientations were observed. The present experimental observation suggests that the twins formed via 2-dimensional nucleation and layer-bylayer growth on small WC clusters under high supersaturation and high driving force for the growth of WC grains.

Nanoscale Structural and Mechanical Characterization of Nanowire-Reinforced Polymer Composites

2011 ◽  
Author(s):  
Wyatt Leininger ◽  
Xinnan Wang ◽  
X. W. Tangpong ◽  
Marshall McNea
Keyword(s):  
Elastic Modulus ◽  
Tensile Testing ◽  
Mechanical Characterization ◽  
Tensile Load ◽  
Small Strain ◽  
Epoxy Composites ◽  
Atomic Force ◽  
Reinforced Polymer ◽  
Multi Walled Carbon Nanotube

In this study, the mechanical properties of multi-walled carbon nanotube (MWCNT) reinforced epoxy composites were characterized using an in-house designed micro/nano tensile load stage in conjunction with an atomic force microscope (AFM). The surface of the nanocomposite was scanned by the AFM during intermittent tensile testing. Micro/nano deformation was observed, and the reinforcing mechanisms were discussed in conjunction with architecture and elastic modulus. Results show that the MWCNT reinforced nanocomposite has an increased elastic modulus. The Halpin-Tsai and Hui-Shia models were compared to the experimental results, and the Halpin-Tsai was found to correlate when only the load bearing outer layer of the MWCNTs were considered. Additionally, it is concluded that the combination of the load stage and AFM is capable of capturing insitu deformation progress for small strain increments.

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