scholarly journals Exploitation of static and dynamic methods for the analysis of the mechanical nanoproperties of polymethylmetacrylate by indentation

2021 ◽  
Vol 15 (56) ◽  
pp. 46-55
Author(s):  
Soufiane Benaissa ◽  
Samir Habibi ◽  
Djameleddine Semsoum ◽  
Hassen Merzouk ◽  
Abdelnou Mezough ◽  
...  
Keyword(s):  
Indentation Size Effect ◽  
Surface Hardness ◽  
Material Surface ◽  
Indentation Size ◽  
Nanomechanical Properties ◽  
Indentation Force ◽  
Dynamic Methods ◽  
Increasing Trend ◽  
Non Destructive ◽  
Hardness Gradient

The development of instrumented nanoindentation consists of non-destructive tests applied to miniature volumes of material (PMMA). The present research focuses on the factors explaining the variation in the trends of the mechanical properties studied. The evolution of Young's modulus (E) and contact hardness (H) with depth (h) and indentation force (P) shows the existence of an inflection point (2.77 nm) at low penetrations which separates two zones with the first increasing trend and the second decreasing. Explained respectively by the surface hardening induced by the preparation of the material surface and the existence of a surface hardness gradient denoted by the indentation size effect (ISE) observed at very low depths. In addition, on detection of a critical penetration depth below which the effect of the surface on the nanohardness dominates, the variation in the penetration charge is of the order of 9.71 nm. The differences in results of E and H between the dynamic and static modes are of the order of 8.46% and 6.44% inducing an overestimation of 35 MPa in value of E and an underestimation of 1.23 MPa in value of H. They tend to affect the expected nanoscale precision of the indentation to determine the nanomechanical properties of PMMA.

The Identation Size Effect and Hall-Petch Behaviour of Annealed Polycrystalline Copper

2006 ◽  
Vol 976 ◽  
Author(s):  
XiaoDong Hou ◽  
T.T. Zhu ◽  
N. M. Jennett ◽  
A. J. Bushby
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Size Effects ◽  
Indentation Size Effect ◽  
Indentation Test ◽  
Small Radius ◽  
Contact Radius ◽  
Length Scale ◽  
Indentation Size ◽  
Non Destructive

AbstractMethods to obtain tensile stress-strain properties of materials from a practically non-destructive indentation test are of great industrial interest. However, to do this successfully, indentation size effects must be accounted for. Many indentation size effects, such as strain gradient plasticity and micro-pillar experiments [1], show a size dependence proportional to the inverse square root of a length scale, in common with Hall-Petch behavior. Recently, however, the indentation size effect from small radius spherical indenters has been shown, for a range of fcc metals, not to follow a Hall-Petch-like relationship but to be proportional to the inverse cube root of indenter radius [2]. Here, we investigate these differences further and present results for the indentation size effect with spherical indenters on Cu samples that have been engineered to have different grain sizes. The important experimental control parameter of the relative size of the indentation compared to the grain size is also explored since the cross over from grains significantly smaller than the contact radius to grains significantly larger than the contact radius occurs at different length scales in each sample. A thorough understanding of the various length-scale effects in the different test methods (e.g. the indentation size effect and grain size effect in indentation), is essential if a relationship, robust enough for industrial application, is to be defined to obtain tensile properties from an essentially non-destructive indentation test.

scholarly journals Control of Local Hardness Gradient of Metal Surface by Inclined Surface Treatment Using Ultrasonic Nanocrystal Surface Modification

2021 ◽  
Vol 8 (2) ◽  
pp. 533-546
Author(s):  
Yeong-Kwan Jo ◽  
Yeong-Wook Gil ◽  
Do-Sik Shim ◽  
Young-Sik Pyun ◽  
Sang-Hu Park
Keyword(s):  
Surface Modification ◽  
Surface Treatment ◽  
Metal Surface ◽  
Incident Angle ◽  
Surface Hardness ◽  
Parameter Study ◽  
Local Hardness ◽  
Practical Usefulness ◽  
Inclined Surface ◽  
Hardness Gradient

AbstractWe propose an effective method to control the local hardness and morphology of a metal surface by tilting the incident angle of a horn during ultrasonic nanocrystal surface modification (UNSM). In this study, surface treatment using UNSM was performed on an S45C specimen and a parameter study was conducted for optimization. The process parameters were the feeding rate, static load, striking force, and processing angle (Ф). In particular, the Ф was analyzed by tilting the horn by 0°, 10°, 20°, 30°, 40°, and 45° to understand its effect on surface hardness and changes in the morphology. From fundamental experiments, some important phenomena were observed, such as grain-microstructure changes along the processing and thickness directions. Furthermore, to verify the practical usefulness of this study, a flat and a hemispherical specimen of S45C material were treated using UNSM with various values of Ф. A significant change in hardness (an increase from 2–45%) and a gradual hardness gradient on the tested specimens could be easily realized by the proposed method. Therefore, we believe that the method is effective for controlling the mechanical hardness of a metal surface.

scholarly journals Investigation of the mechanism of the indentation size effect for titanium

2019 ◽  
Vol 6 (2) ◽  
pp. 18-00545-18-00545
Author(s):  
Shota HASUNUMA ◽  
Hirohisa MIYAZAKI ◽  
Takeshi OGAWA
Keyword(s):  
Size Effect ◽  
Indentation Size Effect ◽  
Indentation Size

scholarly journals Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

2019 ◽  
Vol 9 (23) ◽  
pp. 5109 ◽  
Author(s):  
Miguel C. S. Nepomuceno ◽  
Luís F. A. Bernardo
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Surface Hardness ◽  
Pulse Velocity ◽  
Concrete Compressive Strength ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Pull Out ◽  
Concrete Maturity ◽  
Non Destructive

Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.

Indentation size effect of cortical bones submitted to different soft tissue removals

2013 ◽  
Vol 20 ◽  
pp. 338-346 ◽  
Author(s):  
A. Bandini ◽  
D. Chicot ◽  
P. Berry ◽  
X. Decoopman ◽  
A. Pertuz ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Size Effect ◽  
Indentation Size Effect ◽  
Indentation Size

The Effect of Airflow Speed as Cooling Media in the Hardening Process to the Hardness, Corrosion Rate and Fatigue Life of Medium Carbon Steel

2021 ◽  
Vol 1045 ◽  
pp. 40-49
Author(s):  
Sunardi Sunardi ◽  
Rina Lusiani ◽  
Erny Listijorini ◽  
Ruddy Santoso ◽  
Iman Saefuloh
Keyword(s):  
Fatigue Life ◽  
Barium Carbonate ◽  
Surface Hardness ◽  
Medium Carbon Steel ◽  
Holding Time ◽  
Material Surface ◽  
Airflow Rate ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
1045 Steel

Carburizing is a method for obtaining a sturdy material surface. This hard surface is used for machine elements that intersect with other materials, so failure due to wear can be avoided. However, this increase in hardness has always been followed by decreased ductility. This condition certainly lowers the fatigue life of the material. For that, it is necessary to compromise between surface hardness and ductility. This study used AISI 1045 steel, which has a surface roughness of 0.4 and 4.7 μm with carburation media used, is a mixture of 80% coconut shell charcoal and 20% Barium carbonate. The sample was given the pack carburization treatment at 850°C and holding time for 3 hours, and then cooled in the open air. The samples were reheated at 850°C, holding time for 17 minutes, and then cooled with airflow at speeds of 10.34, 15.51, and 20.06 m/s for 30 minutes. This research shows that the surface of steel with a roughness of 0.4 μm has excellent performance with the hardness and corrosion level respectively 228.6 HV and 2.3586 mpy at cooling airflow rate of 20.06 m/s while the fatigue life of material occurs at the speed of airflow cooling 10.43 m/s.

scholarly journals Structure and Deformation Behavior of Ti-SiC Composites Made by Mechanical Alloying and Spark Plasma Sintering

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1276 ◽  
Author(s):  
Dariusz Garbiec ◽  
Volf Leshchynsky ◽  
Alberto Colella ◽  
Paolo Matteazzi ◽  
Piotr Siwak
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Indentation Size Effect ◽  
Sintering Temperature ◽  
High Energy ◽  
Indentation Size ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball

Combining high energy ball milling and spark plasma sintering is one of the most promising technologies in materials science. The mechanical alloying process enables the production of nanostructured composite powders that can be successfully spark plasma sintered in a very short time, while preserving the nanostructure and enhancing the mechanical properties of the composite. Composites with MAX phases are among the most promising materials. In this study, Ti/SiC composite powder was produced by high energy ball milling and then consolidated by spark plasma sintering. During both processes, Ti3SiC2, TiC and Ti5Si3 phases were formed. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction study showed that the phase composition of the spark plasma sintered composites consists mainly of Ti3SiC2 and a mixture of TiC and Ti5Si3 phases which have a different indentation size effect. The influence of the sintering temperature on the Ti-SiC composite structure and properties is defined. The effect of the Ti3SiC2 MAX phase grain growth was found at a sintering temperature of 1400–1450 °C. The indentation size effect at the nanoscale for Ti3SiC2, TiC+Ti5Si3 and SiC-Ti phases is analyzed on the basis of the strain gradient plasticity theory and the equation constants were defined.

Sign in / Sign up

Export Citation Format

Share Document