scholarly journals Mechanical Characterization of Nanocrystalline Materials via a Finite Element Nanoindentation Model

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1827
Author(s):  
Konstantinos Tserpes ◽  
Panagiotis Bazios ◽  
Spiros G. Pantelakis ◽  
Maria Pappa ◽  
Nikolaos Michailidis
Keyword(s):  
Material Properties ◽  
Nanocrystalline Materials ◽  
Mechanical Characterization ◽  
Numerical Technique ◽  
Nanoindentation Test ◽  
Inverse Algorithm ◽  
Average Grain Size ◽  
Alternative Means ◽  
Porosity Effect

The difficulty of producing sufficient quantities of nanocrystalline materials for test specimens has led to an effort to explore alternative means for the mechanical characterization of small material volumes. In the present work, a numerical model simulating a nanoindentation test was developed using Abaqus software. In order to implement the model, the principal material properties were used. The numerical nanoindentation results were converted to stress–strain curves through an inverse algorithm in order to obtain the macroscopic mechanical properties. For the validation of the developed model, nanoindentation tests were carried out in accordance with the ISO 14577. The composition of 75% wt. tungsten and 25% wt. copper was investigated by producing two batches of specimens with a coarse-grain microstructure with an average grain size of 150 nm and a nanocrystalline microstructure with a grain diameter of 100 nm, respectively. The porosity of both batches was derived to range between 9% and 10% based on X-ray diffraction analyses. The experimental nanoidentation results in terms of load–displacement curves show a good agreement with the numerical nanoindentation results. The proposed numerical technique combined with the inverse algorithm predicts the material properties of a fully dense, nanocrystalline material with very good accuracy, but it shows an appreciable deviation with the corresponding compression results, leading to the finding that the porosity effect is a crucial parameter which needs to be taken into account in the multiscale numerical methodology.

Stress and Material Property Estimation in the Intervertebral Disc From MRI-Based Finite Strains

2013 ◽  
Author(s):  
Kent D. Butz ◽  
Deva D. Chan ◽  
Corey P. Neu ◽  
Eric A. Nauman
Keyword(s):  
Intervertebral Disc ◽  
Computational Modeling ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Intervention Strategies ◽  
Non Invasive ◽  
Property Estimation ◽  
Level Of Understanding ◽  
Material Property Estimation

The ability to estimate stresses and material properties within the intervertebral disc (IVD) has potential to provide a greater level of understanding and insight in the study of disc degeneration as well as the development of effective intervention strategies. By integrating non-invasive MRI-based imaging methods with computational modeling, a more complete mechanical characterization of the IVD may be achieved, thereby eliminating the need to disturb the tissue or potentially alter the structure destructively.

scholarly journals Position-dependent mechanical characterization of the PBF-EB-manufactured Ti6Al4V alloy

2021 ◽  
Author(s):  
Daniel Kotzem ◽  
Alexandra Höffgen ◽  
Rajevan Raveendran ◽  
Felix Stern ◽  
Kerstin Möhring ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Ti6al4v Alloy ◽  
Effective Diameter ◽  
Powder Bed Fusion ◽  
Powder Bed

AbstractBy means of additive manufacturing, the production of components with nearly unlimited geometrical design complexity is feasible. Especially, powder bed fusion techniques such as electron beam powder bed fusion (PBF-EB) are currently focused. However, equal material properties are mandatory to be able to transfer this technique to a wide scope of industrial applications. Within the scope of this work, the mechanical properties of the PBF-EB-manufactured Ti6Al4V alloy are investigated as a function of the position on the building platform. It can be stated that as-built surface roughness changes within building platform whereby highest surface roughness detected by computed tomography (Ra = 46.0 ± 5.3 µm) was found for specimens located in the front of the building platform. In contrast, no significant differences in relative density could be determined and specimens can be assumed as nearly fully dense (> 99.9%). Furthermore, all specimens are affected by an undersized effective diameter compared to the CAD data. Fatigue tests revealed that specimens in the front of the building platform show slightly lower performance at higher stress amplitudes as compared to specimens in the back of the building platform. However, process-induced notch-like defects based on the surface roughness were found to be the preferred location for early crack initiation.

Metallographic, Structural and Mechanical Characterization of a Low Density Fe-Mn-Al-C Steel Microalloyed with Ti/B in As-Cast and Homogenized Conditions

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3971-3978 ◽  
Author(s):  
O.E. Villanueva-Perez ◽  
I. Mejía ◽  
V. García-García ◽  
A. Bedolla-Jacuinde
Keyword(s):  
Grain Size ◽  
Mechanical Characterization ◽  
The Other ◽  
Low Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Other Hand ◽  
Average Grain Size ◽  
Cast Condition

ABSTRACTLow density (LD) steels have shown particular characteristics in terms of mechanical properties and microstructure, since they have high strength, high ductility and density reduction up to 18%. On the other hand, the addition of microalloying elements such as Ti and B generate hardening by solid solution and precipitation, as well as grain refinement effect. LD steels generate nano-sized kappa phase precipitated from the austenite matrix, and these advanced steels can reach strength and elongation up to 780 MPa and 60%, respectively. The main objective of this research work is the metallographic, structural and mechanical characterization of a LD steel microalloyed with Ti/B in as-cast and -homogenized conditions. For this purpose a Fe-27Mn-7Al-1.2C (%wt) LD steel microalloyed with Ti/B was melted in a vacuum-induction furnace and cast in metallic mold. LD-Ti/B steel samples were homogenized at 1100 °C during 20, 50, 100, 150 and 200 minutes followed by water quenching. Metallographic, structural and mechanical characterization was carried out by optical (LOM) and scanning electron (SEM) microscopy, X-ray diffraction (XRD) and microhardness Vickers testing (HV10), respectively. In general, results showed a typical dendritic microstructure with average grain size of 1256 μm in the as-cast condition. On the other hand, the as-homogenized condition showed an austenitic equiaxial microstructure with average grain size from 164 to 940 μm. Austenite, ferrite and kappa phases were detected by X-ray diffraction (XRD). Also, second-phase particles such as AlN, TiC and MnS were detected by LOM and SEM-EDS analysis. LD steel microalloyed with Ti/B exhibited the highest microhardness Vickers value (235 HV10) in the as-cast condition, whilst in the as-homogenized condition microhardness gradually decreases from 223 to 198 HV10 as holding time increases.

Microstructural and Mechanical Characterization of ARB AZ31

2013 ◽  
Vol 765 ◽  
pp. 403-407 ◽  
Author(s):  
Friederike Schwarz ◽  
Katja Lange ◽  
Lutz Krüger ◽  
Rudolf Kawalla ◽  
Stephan Reichelt
Keyword(s):  
Grain Size ◽  
Mechanical Characteristics ◽  
Mechanical Characterization ◽  
Basal Texture ◽  
Electron Backscattered Diffraction ◽  
Roll Bonding ◽  
Average Grain Size ◽  
Twin Roll Cast ◽  
Twin Roll

In this work the influence of accumulative roll bonding (ARB) process on the microstructure and the mechanical characteristic is investigated. Therefore, AZ31 magnesium sheets were successfully deformed through ARB for a maximum of three passes. Twin roll cast sheets and twin roll cast sheets with subsequent heat treatment (480 °C, 1 h) were used as initial materials. After one ARB pass, the highest microstructure changes were measured. Electron backscattered diffraction (EBSD) reveals a bimodal microstructure with an average grain size of ~1µm. In comparison to the initial material a strong basal texture was measured. The significant refinement of grain size after severe plastic deformation cause an increase of tensile and compressive strength, e.g. rising yield stress and ultimate tensile strength of 42% and 15%, respectively. However, the maximum formability remains nearly at the same level. Further ARB passes do not improve the mechanical characteristics further.

Research Survey of Electroformed Nickel Material Properties Used in MEMS

2015 ◽  
Vol 645-646 ◽  
pp. 259-264 ◽  
Author(s):  
Guo Zhong Li ◽  
Geng Chen Shi ◽  
Li Sui ◽  
Fu Ting Yi ◽  
Bo Wang
Keyword(s):  
Material Properties ◽  
Mechanical Characterization ◽  
External Environment ◽  
Structural Materials ◽  
Research Status ◽  
Research Survey ◽  
Electroforming Process ◽  
Electroformed Nickel ◽  
Materials Used

As one of the significant structural materials used in safe and arming system of MEMS fuze, the research on micro-electroforming process technologies and micro-electroforming nickel’s properties have been a popular field for MEMS area. This paper surveys present domestic and overseas research status of mechanical characterization of electroformed nickel, summarizes and analyzes that changes of the microstructure led by parameters of micro-electroforming process and the external environment make great effects.

Microtensile Methodology for Mechanical Characterization of Thin Films

2001 ◽  
Author(s):  
Betty H. Yeung ◽  
Bill Lytle ◽  
Vijay Sarihan ◽  
David T. Read ◽  
Yifan Guo
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Technology Development ◽  
Metal Films ◽  
Metallic Films ◽  
Information Base ◽  
Constitutive Properties

Abstract A microtensile methodology developed at the National Institute of Standards and Technology (NIST) has been adopted and applied at Motorola to evaluate material properties of thin films. This methodology is a significant part of the materials technology development at Motorola. Special specimens of thin metal films are designed and produced based on common microlithographic techniques and silicon processing methods. The experimentation is performed using the microtensile tester, which was developed for the accurate measurement of constitutive properties of thin metallic films. Through the application of the techniques presented here, valuable information and results have been achieved, which provide an extended information base for thin-film materials. Ultimately, such data are applied to processing and reliability predictions and the optimization of thin-film processes and materials.

Sign in / Sign up

Export Citation Format

Share Document