Characterization and Modeling of Large Displacement Micro-/Nano-Indentation of Polymeric Solids

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Y. C. Lu ◽  
D. M. Shinozaki
Keyword(s):  
Large Strain ◽  
Large Displacement ◽  
Plastic State ◽  
Large Strains ◽  
Displacement Curve ◽  
Plastic Properties ◽  
Indentation Tests ◽  
The Mean ◽  
Strain Hardening Behavior ◽  
Micro Indentation

Large displacement micro-indentation tests have been performed on various polymeric solids to measure the plastic properties. Cylindrical flat-ended indenters with diameter in the range of 10–90 μm are mostly used. The mechanism of large-strain indentation has been examined with optical microscopy and finite element simulations. Results show that under a flat-tipped indenter, the material can quickly reach a fully plastic state. The size (diameter) of the plastic zone is constant in large-strain regions and unaffected by the exact tip profile (flat, spherical, and conical). The indentation stress-displacement curve at large strains is linear as a result of the steady-state plastic flow, from which the mean indentation pressure, a measure of yield strength, can be readily extrapolated. The indentation stress-displacement response is independent of the indenter diameters but strongly dependent on the strain-hardening behavior of the material and the friction between a material and an indenter. Compared with other shaped indenters, the flat-ended indenter requires the least penetration depth in order to probe the plastic properties of a material or structure.

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.

Elastic-plastic properties evaluation of copper by micro-indentation tests

2000 ◽  
Vol 2000 (0) ◽  
pp. 593-594
Author(s):  
Chikao KURAMOCHI ◽  
Norimasa CHIBA ◽  
Nagahisa OGASAWARA
Keyword(s):  
Plastic Properties ◽  
Elastic Plastic ◽  
Indentation Tests ◽  
Micro Indentation

scholarly journals Study of mechanical performance of polymer nanocomposites reinforced with exfoliated graphite of different mesh sizes using micro-indentation

2021 ◽  
pp. 002199832199321
Author(s):  
S Khammassi ◽  
M Tarfaoui ◽  
K Lafdi
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Exfoliated Graphite ◽  
Displacement Curve ◽  
Particle Sizes ◽  
Reinforced Polymers ◽  
Indentation Tests ◽  
Nano Additives ◽  
The Right ◽  
Micro Indentation

The first phase of this work aims to use the right additive nano-fillers choices, such as exfoliated Graphite (ExG), increasing the mechanical, electrical, and thermal performances. In this work, we are interested in quantifying the effect particles' size on a polymer matrix's performance. For this, three sets of exfoliated polymers filled with Graphite, characterized by three particle sizes, called meshes 50, 100, and 150, were investigated. In this analysis, exfoliated Graphite reinforced polymers were subjected to indentation tests to define local mechanical properties. The sample is an epoxy 862 matrix reinforced with exfoliated graphite additives. For each specific size, the additives are mixed in percentages of 0% in the act of control, 0.5%, 4%, 8%, and 16% by weight. Matching pure polymers, polymers reinforced by exfoliated Graphite have proven to have significant improvements in local elastic properties (such as modulus, hardness, stiffness, etc.). Results showed that the reinforced epoxy's local mechanical properties are affected by the size and the percentage of nano-additives. Through the inspection of the load-displacement curve, it can be concluded that the nano-additive has a significant influence on the plastic mechanical properties of the sample. Therefore, the size of nanoparticles has significantly improved in material properties.

Large Strain, High Strain Rate Testing of Copper

1980 ◽  
Vol 102 (4) ◽  
pp. 376-381 ◽  
Author(s):  
U. S. Lindholm ◽  
A. Nagy ◽  
G. R. Johnson ◽  
J. M. Hoegfeldt
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Large Strain ◽  
Shear Banding ◽  
Testing Machine ◽  
Shear Instability ◽  
Large Strains ◽  
Rate Dependent ◽  
Torsional Testing ◽  
Strain Hardening Behavior

This paper describes the development of a high-speed torsional testing machine and results obtained on the strain-rate dependent strength of copper at large shear strains. Test techniques and data obtained are intended to be useful in applications such as ballistics and machining. For copper, the results indicate positive strain hardening behavior to very large strains under low rate, isothermal conditions and the transition to adiabatic thermal softening, shear instability and localization (shear banding) at high rates.

Experimental and Finite Element Analysis of Large-Strain Indentation of Polymeric Solids

2007 ◽  
Author(s):  
Y. C. Lu ◽  
D. M. Shinozaki
Keyword(s):  
Finite Element ◽  
Experimental Testing ◽  
Large Strain ◽  
Indentation Test ◽  
Optical Microscope ◽  
Displacement Curve ◽  
Element Analysis ◽  
Element Simulation ◽  
The Mean ◽  
Engineering Polymers

The large-strain indentation test has been examined using experimental testing and finite element simulation on various engineering polymers. Cylindrical, flat-ended tips with diameter range from 10μm–100μm are used. In the large-strain region, the indentation stress-displacement curve shows linear response from which the mean indentation stress is extrapolated. The mechanism of large-strain indentation has been investigated through optical microscope and finite element simulations. Once a critical indentation depth is reached, the plastic zone surrounding the indenter remains constant.

Prediction of the Bilinear Stress-Strain Curve of Engineering Material by Nanoindentation Test

2010 ◽  
Vol 437 ◽  
pp. 589-593
Author(s):  
Tung Sheng Yang ◽  
Te Hua Fang ◽  
C.T. Kawn ◽  
G.L. Ke ◽  
S.Y. Chang
Keyword(s):  
Plastic Material ◽  
Bulk Material ◽  
Strain Curve ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Film Material ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Plastic Properties ◽  
Indentation Tests

Instrumented indentation is widely used to probe the elastic and plastic properties of engineering materials. Finite Element Method (FEM) has been widely used for numerical simulation of indentation tests on bulk and film material in order to analyze its deformation response. This study proposed an improved technique to determine the stress-strain curve of bulk material. FEM in conjunction with an abductive network is used to predict the stress-strain relationship of bilinear elastic-plastic material from the nanoindentation test’s force-displacement curve.

Uniqueness of reverse analysis from conical indentation tests

2004 ◽  
Vol 19 (8) ◽  
pp. 2498-2502 ◽  
Author(s):  
K.K. Tho ◽  
S. Swaddiwudhipong ◽  
Z.S. Liu ◽  
K. Zeng ◽  
J. Hua
Keyword(s):  
Material Properties ◽  
Plastic Material ◽  
Large Strain ◽  
Indentation Load ◽  
Initial Slope ◽  
Displacement Curve ◽  
Maximum Indentation Depth ◽  
Indentation Tests ◽  
Reverse Analysis ◽  
Load Displacement

The curvature of the loading curve, the initial slope of the unloading curve, and the ratio of the residual depth to maximum indentation depth are three main quantitiesthat can be established from an indentation load-displacement curve. A relationship among these three quantities was analytically derived. This relationship is valid for elasto-plastic material with power law strain hardening and indented by conical indenters of any geometry. The validity of this relationship is numerically verified through large strain, large deformation finite element analyses. The existence of an intrinsic relationship among the three quantities implies that only two independent quantities can be obtained from the load-displacement curve of a single conical indenter. The reverse analysis of a single load-displacement curve will yield non-unique combinations of elasto-plastic material properties due to the availability of only two independent quantities to solve for the three unknown material properties.

scholarly journals Dynamics of the Ice-Crushing Process

1988 ◽  
Vol 34 (118) ◽  
pp. 318-326 ◽  
Author(s):  
Ian J. Jordaan ◽  
Garry W. Timco
Keyword(s):  
Ice Sheet ◽  
Load Cycle ◽  
Stored Energy ◽  
Indentation Process ◽  
Ice Particles ◽  
Mode Of Failure ◽  
Indentation Tests ◽  
Energy Exchanges ◽  
The Mean ◽  
Crushed Ice

Abstract During fast indentation tests on ice sheets at constant rates, crushing is commonly observed at appropriate combinations of speed and aspect ratio. An analysis is made of this mode of failure, using as a basis a recently conducted test on an ice sheet under controlled conditions. The variation of load with time is given special attention, and cyclic variation of load is associated with periodic crushing (pulverization) events, followed by clearing of the crushed ice particles. An analysis of the clearing process is summarized in the paper, treating the crushed ice as a viscous material. A detailed analysis of the energy exchanges during the indentation process is given. Elastic variations of stored energy in the indenter and in the ice sheet are calculated; these are relatively minor. The dissipation of energy during a typical load cycle (3 mm movement during 0.05 s) is about 8 J. The energy required to create surfaces of the crushed ice particles is small (0.006 J), as is the work of crushing based on mechanical testing (0.09 J). It is concluded that the process of viscous extrusion of crushed ice is the main seat of energy dissipation, basically as a frictional process. A relationship for the mean thickness of the crushed ice layer is developed, based on energy-balance considerations.

Analytical Solutions for Circular Bars Subjected to Large Strain Plastic Torsion

1990 ◽  
Vol 57 (2) ◽  
pp. 298-306 ◽  
Author(s):  
K. W. Neale ◽  
S. C. Shrivastava
Keyword(s):  
Closed Form ◽  
Analytical Solutions ◽  
Large Strain ◽  
Kinematic Hardening ◽  
Flow Theory ◽  
Constitutive Laws ◽  
Isotropic Hardening ◽  
Large Strains ◽  
Inelastic Behavior ◽  
Rate Dependent

The inelastic behavior of solid circular bars twisted to arbitrarily large strains is considered. Various phenomenological constitutive laws currently employed to model finite strain inelastic behavior are shown to lead to closed-form analytical solutions for torsion. These include rate-independent elastic-plastic isotropic hardening J2 flow theory of plasticity, various kinematic hardening models of flow theory, and both hypoelastic and hyperelastic formulations of J2 deformation theory. Certain rate-dependent inelastic laws, including creep and strain-rate sensitivity models, also permit the development of closed-form solutions. The derivation of these solutions is presented as well as numerous applications to a wide variety of time-independent and rate-dependent plastic constitutive laws.

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