scholarly journals Basic experiments for identification of the cap model of flexible graphite plasticity

2020 ◽  
pp. 131-142
Author(s):  
Анатолий Арсангалеевич Адамов ◽  
Илья Эрнстович Келлер ◽  
Наталья Сергеевна Подкина
Keyword(s):  
Axial Compression ◽  
Triaxial Compression ◽  
Expanded Graphite ◽  
Plastic Properties ◽  
Material Functions ◽  
The Matrix ◽  
Indentation Tests ◽  
Cap Model ◽  
Cylinder Compression ◽  
Flexible Graphite

Разработка методики экспериментального определения пластических свойств листового материала из терморасширенного графита (гибкого графита) в условиях сжимающих средних напряжений является предметом настоящего исследования. С учетом условий производства и эксплуатации уплотнительных элементов и требований однородности напряженного и деформированного состояний в образце выделен ряд испытаний (всестороннее, трехосное, свободное или стесненное сжатие цилиндра, сжатие цилиндра в упругой трубе и сжатие параллелепипеда в канале), образцы для которых имеют форму сплошного цилиндра либо куба и собираются из дисков или квадратов, вырезанных из листа. Для колец, изготавливаемых навивкой графитовой фольги на цилиндрический сердечник с последующим осевым прессованием в матрице, дополнительно предлагаются испытания всесторонним сжатием, осевым сжатием в зазоре между внешней и внутренней упругими цилиндрическими оболочками, а также растяжением в полудисках. Пластические деформации гибкого графита сопровождаются дилатансией - связанностью сдвиговых и объемных компонент. Обзор подходящих моделей выделил кэп-модель Димаджио и Сэндлера, для материальных функций и констант которой получены выражения через измеряемые и контролируемые в перечисленных испытаниях величины. Избыточное количество данных может служить для проверки адекватности применения кэп-модели для описания пластических свойств гибкого графита. The development of a method for experimental determination of the plastic properties of thermally expanded graphite sheets (flexible graphite) under compressive medium stresses is the subject of this study. This problem is practically not reflected in publications, with the exception of several that offer uniaxial tension and indentation tests for its solution. The conditions of manufacture and operation of sealing elements and uniformity of stress-strain state in the specimen is allowed to allocate a range of suitable tests (all-round and triaxial compression of cylinder, free and constrained compression of cylinder, compression of cylinder in an elastic pipe and compression of parallelepiped in the channel), the samples which have the form of a solid cylinder or cube and is made of discs or squares cut from the sheet. For rings made by winding graphite foil on a cylindrical core with subsequent axial compression in the matrix, tests are additionally offered for all-round compression, axial compression in the gap between the outer and inner elastic cylindrical shells, as well as stretching in half-disks. A feature of the plastic properties of flexible graphite is its dilatancy, that is coupling of shear and volumetric plastic strains. A review of the relevant models was performed, as a result of which DiMaggio and Sandler cap model was selected, its material functions and constants were associated with the values measured and controlled in the above tests. The excessive amount of data allows us to check the adequacy of the application of the cap model to describe the plastic properties of flexible graphite.

ELASTO-PLASTIC PROPERTIES OF Mo-MODIFIED Ti DEDUCED FROM INDENTATION TESTS AND FINITE ELEMENT ANALYSIS

2019 ◽  
Vol 26 (07) ◽  
pp. 1850225
Author(s):  
YONG MA ◽  
ZHAO YANG ◽  
SHENGWANG YU ◽  
BING ZHOU ◽  
HONGJUN HEI ◽  
...  
Keyword(s):  
Finite Element ◽  
Surface Treatment ◽  
Load Capacity ◽  
Indentation Test ◽  
Element Analysis ◽  
Plastic Properties ◽  
Polynomial Expression ◽  
Indentation Tests ◽  
Graded Material ◽  
Micro Indentation

The aim of this paper is to establish an approach to quantitatively determine the elasto-plastic parameters of the Mo-modified Ti obtained by the plasma surface alloying technique. A micro-indentation test is conducted on the surface under 10[Formula: see text]N. Considering size effects, nanoindentation tests are conducted on the cross-section with two loads of 6 and 8[Formula: see text]mN. Assuming nanoindentation testing sublayers are homogeneous, finite element reverse analysis is adopted to determine their plastic parameters. According to the gradient distributions of the elasto-plastic parameters with depth in the Mo-modified Ti, two types of mathematical expressions are proposed. Compared with the polynomial expression, the linear simplified expression does not need the graded material to be sectioned and has practical utility in the surface treatment industry. The validation of the linear simplified expression is verified by the micro-indentation test and corresponding finite element forward analysis. This approach can assist in improving the surface treatment process of the Mo-modified Ti and further enhancing its load capacity and wear resistance.

A Thermomechanical Model of Retention of a Diamond Particle in Matrices Based on Fe

2020 ◽  
Vol 405 ◽  
pp. 48-53
Author(s):  
Joanna Borowiecka-Jamrozek ◽  
Jan Lachowski
Keyword(s):  
Diamond Tool ◽  
Matrix Material ◽  
Diamond Particle ◽  
Metallic Matrix ◽  
Thermomechanical Model ◽  
Plastic Properties ◽  
Diamond Particles ◽  
The Matrix ◽  
Mechanical Bonding ◽  
Abaqus Software

The aim of this paper was to determine the influence of the mechanical and thermal parameters of the matrix materials on their retentive properties. The term ‘matrix retention’ denotes the capacity of a metallic matrix material to retain diamond particles at the surface of a diamond tool during working. The bonding is obtained during cooling after the hot pressing process. Proper mechanical bonding depends on elastic and plastic properties of the matrix. The model of a diamond particle embedded in a metallic matrix was created using Abaqus software. The analysis has indicated the mechanical parameters that are responsible for the retention of diamond particles in a matrix.

scholarly journals Microstructure and mechanical properties of HR6W alloy dedicated for manufacturing of pressure elements in supercritical and ultrasupercritical power units

2019 ◽  
Vol 82 ◽  
pp. 01005 ◽  
Author(s):  
Grzegorz Golański ◽  
Agata Merda ◽  
Adam Zieliński ◽  
Paweł Urbańczyk ◽  
Jacek Słania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Yield Strength ◽  
Base Alloy ◽  
Strength Properties ◽  
Laves Phase ◽  
Plastic Properties ◽  
The Matrix ◽  
Isothermal Ageing ◽  
Nickel Base

The article presents the results of research on the microstructure and selected mechanical properties of HR6W nickel-base alloy. The test alloy was subjected to isothermal ageing at 700°C and for up to 10000h. The tests of the HR6W microstructure were performed using the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The performed microstructural tests of the HR6W alloy showed that in the as-received condition it was characterised by the structure of nickel austenite with numerous primary precipitates of NbC and TiN. Ageing of the investigated alloy contributed to the precipitation of numerous particles of varying morphologies inside the grains and at the grain boundaries, as well as at the boundaries of twins - they were the secondary precipitates of M23C6 and Laves phase. The number of the particles precipitated at the boundaries was so large that they formed the so-called continuous grid of precipitates. Inside the grains, the presence of compound complexes of precipitates was observed. These complexes consisted of the TiN particles, as well as the M23C6 carbides and Laves phase nucleating on them. The tests of the mechanical properties of HR6W alloy showed that in the as-received condition the alloy showed high plastic properties, with relatively low strength properties - in particular, the yield strength. Ageing of the HR6W alloy, as a result of precipitation of numerous particles in the matrix, through the strengthening with the precipitation mechanism, resulted in a considerable growth of the strength properties - inter alia the yield strength by over 60%, with the reduction of the plastic properties - elongation decreased by around 40%. Similar growth in the test alloy was observed for hardness.

scholarly journals Numerical verification for instrumented spherical indentation techniques in determining the plastic properties of materials

2009 ◽  
Vol 24 (12) ◽  
pp. 3653-3663 ◽  
Author(s):  
Taihua Zhang ◽  
Peng Jiang ◽  
Yihui Feng ◽  
Rong Yang
Keyword(s):  
Numerical Experiments ◽  
Spherical Indentation ◽  
Numerical Verification ◽  
Instrumented Indentation ◽  
Plastic Properties ◽  
Wide Range ◽  
Validity Range ◽  
Indentation Tests ◽  
Properties Of Materials ◽  
Indentation Methods

Instrumented indentation tests have been widely adopted for elastic modulus determination. Recently, a number of indentation-based methods for plastic properties characterization have been proposed, and rigorous verification is absolutely necessary for their wide application. In view of the advantages of spherical indentation compared with conical indentation in determining plastic properties, this study mainly concerns verification of spherical indentation methods. Five convenient and simple models were selected for this purpose, and numerical experiments for a wide range of materials are carried out to identify their accuracy and sensitivity characteristics. The verification results show that four of these five methods can give relatively accurate and stable results within a certain material domain, which is defined as their validity range and has been summarized for each method.

scholarly journals Effect of Reactive SPS on the Microstructure and Properties of a Dual-Phase Ni-Al Intermetallic Compound and Ni-Al-TiB2 Composite

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5668
Author(s):  
Paweł Hyjek ◽  
Iwona Sulima ◽  
Piotr Malczewski ◽  
Krzysztof Bryła ◽  
Lucyna Jaworska
Keyword(s):  
Intermetallic Compound ◽  
Tribological Properties ◽  
Matrix Material ◽  
Dual Phase ◽  
Compression Tests ◽  
Two Phase ◽  
Alloy Matrix ◽  
Plastic Properties ◽  
Mechanical And Tribological Properties ◽  
The Matrix

As part of the tests, a two-phase NiAl/Ni3Al alloy and a composite based on this alloy with 4 vol% addition of TiB2 were produced by the reactive FAST/SPS (Field Assisted Sintering Technology/Spark Plasma Sintering) sintering method. The sintering process was carried out at 1273 K for 30 s under an argon atmosphere. The effect of reactive SPS on the density, microstructure, and mechanical and tribological properties of a dual-phase Ni-Al intermetallic compound and Ni-Al-TiB2 composite was investigated. Products obtained were characterized by a high degree of sintering (over 99% of the theoretical density). The microstructure of sinters was characterized by a large diversity, mainly in regard to the structure of the dual-phase alloy (matrix). Compression tests showed satisfactory plastic properties of the manufactured materials, especially at high temperature (1073 K). For both materials at room temperature, the compressive strength was over 3 GPa. The stress–strain curves were observed to assume a different course for the matrix material and composite material, including differences in the maximum plastic flow stress depending on the test temperature. The brittle-to-ductile transition temperature was determined to be above 873 K. The research has revealed differences in the physical, mechanical and tribological properties of the produced sinters. However, the differences favourable for the composite were mostly the result of the addition of TiB2 ceramic particles uniformly distributed on grain boundaries.

Effect of Silane Coupling Agents on Mechanical Properties of Nano-SiO2 Filled High-Density Polyethylene Composites

2007 ◽  
Vol 555 ◽  
pp. 479-484 ◽  
Author(s):  
D. Stojanović ◽  
P. S. Uskoković ◽  
I. Balać ◽  
V.J. Radojević ◽  
R. Aleksić
Keyword(s):  
Mechanical Properties ◽  
High Density Polyethylene ◽  
Particle Surface ◽  
High Density ◽  
Coupling Agents ◽  
Stress Concentrations ◽  
Silane Coupling Agents ◽  
Silane Coupling ◽  
The Matrix ◽  
Indentation Tests

Composites with nano-SiO2 particles and high density polyethylene (HDPE) matrix were produced by hot pressing with various particle contents and particle surface treatment using commercially available silane coupling agents: γ-methacryloxypropyltrimethoxy silane and γ- glycidyloxypropyltrimethoxysilane. The influence of the particle treatment on the mechanical properties of composites was determined by compression and indentation tests. Additionally, numerical analysis was performed in order to calculate Young’s modulus and stress concentrations for various particle contents in order to provide reference data by simulating micro- and macro particle composites with perfect bonding to the matrix.

Local Mechanical Characterization of Metal Foams by Nanoindentation

2015 ◽  
Vol 662 ◽  
pp. 59-62 ◽  
Author(s):  
Jiří Němeček ◽  
Vlastimil Kralik
Keyword(s):  
Cell Walls ◽  
Plastic Material ◽  
Spherical Indentation ◽  
Isotropic Hardening ◽  
Plastic Properties ◽  
Macro Scale ◽  
Static Indentation ◽  
Indentation Tests ◽  
Constitutive Parameters

This paper deals with microstructure and micromechanical properties of two commercially available aluminium foams (Alporas and Aluhab). Since none of the materials is available in a bulk and standard mechanical testing at macro-scale is not possible the materials need to be tested at micro-scale. To obtain both elastic and plastic properties quasi-static indentation was performed with two different indenter geometries (Berkovich and spherical tips). The material phase properties were analyzed with statistical grid indentation method and micromechanical homogenization was applied to obtain effective elastic wall properties. In addition, effective inelastic properties of cell walls were identified with spherical indentation. Constitutive parameters related to elasto-plastic material with linear isotropic hardening (the yield point and tangent modulus) were directly deduced from the load–depth curves of spherical indentation tests using formulations of the representative strain and stress introduced by Tabor.

Estimation of Elastic-Plastic Tensile Properties Using Nano-Indentation Tests and FE Simulations

2006 ◽  
Vol 326-328 ◽  
pp. 361-364
Author(s):  
Yun Jae Kim ◽  
Tae Kwang Song ◽  
Jun Hee Hanh ◽  
Jun Hyub Park
Keyword(s):  
Tensile Properties ◽  
Reference Strain ◽  
Careful Examination ◽  
Plastic Properties ◽  
Nano Indentation ◽  
Elastic Plastic ◽  
Displacement Response ◽  
Fe Simulations ◽  
Indentation Tests ◽  
Depth Curves

This paper discusses possibilities to extract elastic-plastic properties of nano-scale materials using combined nano-indentation tests with FE simulations. One interesting finding is that FE simulations of nano-indentation with a number of different plastic properties give same load-displacement response, which suggests that plastic properties cannot be determined from simulating load-depth curves from nano-indentation tests. However, careful examination of possible plastic properties suggests a concept of the reference strain, which makes it possible to effectively determine plastic properties from nano-indentation tests with FE simulations.

Flame retardancy and toughening properties of epoxy composites containing ammonium polyphosphate microcapsules and expanded graphite

2017 ◽  
Vol 30 (10) ◽  
pp. 1247-1259 ◽  
Author(s):  
Da He ◽  
Chunxia Zhao ◽  
Haolan Gou ◽  
Yuntao Li ◽  
Dong Xiang
Keyword(s):  
Flame Retardancy ◽  
Expanded Graphite ◽  
Ammonium Polyphosphate ◽  
Cone Calorimetry ◽  
Sem Images ◽  
Thermal Degradation Behavior ◽  
The Matrix ◽  
Limited Oxygen

Ammonium polyphosphate microcapsules (BM (polybenzoxazine modified) APP) were prepared through the in situ ring-opening polymerization of allyl group containing benzoxazine monomers on the surfaces of ammonium polyphosphate (APP), and they were significantly hydrophobic than the APP. A flame retardant system of epoxy (EP) resin was prepared with BMAPP and expanded graphite (EG). Flame retardancy, the thermal degradation behavior, a mechanical property of EP and EP/BMAPP/EG composites was investigated through limited oxygen index, vertical burning test, cone calorimetry (CONE), and the thermogravimetric analysis (TGA). The flame retardancy tests indicated that the EG could improve the thermal performance, promote the charring, and enhance the char quality of EP/BMAPP. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were employed to analyze the morphology and composition of the char residue formed during CONE testing, and to understand the mechanism of char formation. The results of TG-FTIR confirmed the possible mechanism of flame retardancy of EP/BMAPP/EG in the gas phase during combustion. The EG content effects on Young’s modulus, the tensile strength, and the fracture toughness ( KIC) of the EP/BMAPP composites were also investigated. The KIC of the composites containing 1% of EG and 10% of BMAPP increased by approximately 76% and 153%, respectively, compared to the neat matrix and EP/BMAPP-10%. The SEM images of the fractured surface indicated that the enhanced toughness of EP/BMAPP/EG composites mainly attributed to the debonding of the BMAPP and the subsequent plastic void growth of the matrix, as well as the crack deflection effect of the BMAPP/EG.

New Solutions to Rigid-Plastic Deformation Problems Using a Matrix Method

1973 ◽  
Vol 95 (3) ◽  
pp. 865-873 ◽  
Author(s):  
C. H. Lee ◽  
S. Kobayashi
Keyword(s):  
Plastic Deformation ◽  
Plane Stress ◽  
Matrix Method ◽  
Stress Distributions ◽  
Planar Anisotropy ◽  
Rigid Plastic ◽  
Relative Slip ◽  
The Matrix ◽  
Simple Compression ◽  
Cylinder Compression

The matrix method for the analysis of rigid-plastic deformation problems was described and applied to simple compression of cylinders and plane-stress bore expanding and flange drawing. In cylinder compression new solutions were obtained with regard to the effect of specimen dimensions on the contact stress distributions, the effect of friction on the relative slip at the tool-workpiece interface, and bulging and “folding”. In plane-stress problems the planar anisotropy was taken into account and the application of the matrix method resulted in new solutions for nonaxisymmetric hole expansion and “earing” in flange drawing.

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