A study of indentation work in homogeneous materials

2006 ◽  
Vol 21 (6) ◽  
pp. 1363-1374 ◽  
Author(s):  
Mengxi Tan
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Elastic Energy ◽  
Size Effects ◽  
Unit Volume ◽  
Plastic Work ◽  
Total Work ◽  
Indentation Size ◽  
Scaling Relationships ◽  
Homogeneous Materials

The work of indentation is investigated experimentally in this article. A method of using the elastic energy to extract the elastic modulus is proposed and verified. Two types of hardness related to the work of indentation are defined and examined: Hwtis defined as the total work required creating a unit volume of contact deformationand Hwp is defined as the plastic work required creating a unit volume of plastic deformation; experiments show that both hardness definitions are good choices for characterizing hardness. Several features that may provide significant insights in understanding indentation measurements are studied. These features mainly concern some scaling relationships in indentation measurements and the indentation size effects.

Indentation Size Effects in Ductile and Brittle Materials

2013 ◽  
Vol 586 ◽  
pp. 51-54
Author(s):  
Jaroslav Menčík ◽  
Martin Elstner
Keyword(s):  
Size Effect ◽  
Size Effects ◽  
Indentation Size Effect ◽  
Brittle Materials ◽  
Indentation Hardness ◽  
Indentation Size ◽  
Homogeneous Materials

Indentation hardness of homogeneous materials should be constant. However, at very small depths, the apparent hardness often increases with decreasing imprint size. The paper discusses various cases of this indentation size effect in metals and ceramics and explains the extrinsic and intrinsic reasons.

Plastic and Elastic Behavior of Sputtered Bilayered Films by Nanoindedtation

1999 ◽  
Vol 594 ◽  
Author(s):  
N. Kikuchi ◽  
E. Kusano ◽  
Y. Sawahira ◽  
A. Kinbara
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Sapphire Substrate ◽  
Elastic Energy ◽  
Deformation Behavior ◽  
Elastic Behavior ◽  
Dissipated Energy ◽  
Displacement Curve ◽  
Plastic Energy

AbstractDeformation behavior of sputtered Al/TiN and Cu/TiN bilayered films was examined by using dissipated and elastic energies estimated from the area enclosed by the load-displacement curve of nanoindentation. These films studied consisted of TiN top-layer of 500 nm and Al or Cu underlayer of 0 - 500 nm on glass or sapphire substrate. The dissipated energy for plastic deformation increased with increasing thickness of metal underlayer, while the elastic energy remained constant. A decrease in plastic energy was observed by changing the underlayer material from Al to Cu. Further, a reduction in elastic energy was observed when a sapphire was used as a substrate. Experimental results show that the plastic deformation mainly occurred in metal underlayer and the elastic deformation did in TiN layer and in the substrate. It was concluded that the yield stress and elastic modulus of layers and substrate strongly affect the deformation behavior of the films.

scholarly journals Round Robin into Best Practices for the Determination of Indentation Size Effects

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 130 ◽  
Author(s):  
Ana Ruiz-Moreno ◽  
Peter Hähner ◽  
Lukasz Kurpaska ◽  
Jacek Jagielski ◽  
Philippe Spätig ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Size Effects ◽  
Nuclear Fission ◽  
Round Robin ◽  
Indentation Hardness ◽  
Martensitic Steels ◽  
Indentation Size ◽  
Single Cycle ◽  
Fusion Applications ◽  
Methodological Bias

The paper presents a statistical study of nanoindentation results obtained in seven European laboratories that have joined a round robin exercise to assess methods for the evaluation of indentation size effects. The study focuses on the characterization of ferritic/martensitic steels T91 and Eurofer97, envisaged as structural materials for nuclear fission and fusion applications, respectively. Depth-controlled single cycle measurements at various final indentation depths, force-controlled single cycle and force-controlled progressive multi-cycle measurements using Berkovich indenters at room temperature have been combined to calculate the indentation hardness and the elastic modulus as a function of depth applying the Oliver and Pharr method. Intra- and inter-laboratory variabilities have been evaluated. Elastic modulus corrections have been applied to the hardness data to compensate for materials related systematic errors, like pile-up behaviour, which is not accounted for by the Oliver and Pharr theory, and other sources of instrumental or methodological bias. The correction modifies the statistical hardness profiles and allows determining more reliable indentation size effects.

scholarly journals Investigation on the Influences of Hygrothermal Aging on the Indentation Size Effects and Micro-Indentation Measurements of PMMA. Part I: Experimental Results

2020 ◽  
Vol 10 (16) ◽  
pp. 5454 ◽  
Author(s):  
Hui Lin ◽  
Lin Lv ◽  
Tao Jin
Keyword(s):  
Elastic Modulus ◽  
Aging Time ◽  
Size Effects ◽  
Companion Paper ◽  
Strain Rates ◽  
Indentation Size ◽  
Hygrothermal Aging ◽  
Shear Transformation ◽  
Micro Indentation ◽  
Indentation Strain

The polymethyl methacrylate (PMMA) subjected to hygrothermal aging was applied to nanoindentation tests under different indentation strain rates. The influences of hygrothermal aging on the indentation behaviors of PMMA are discussed. Results show that the indentation elastic modulus and hardness decrease with increasing aging time. Furthermore, the indentation size effects (ISE) can be observed in aged PMMA specimens as they are sensitive to aging time as well as to the indentation strain rate. The quantitative analysis of ISE is proposed on the basis of shear transformation-mediated plasticity and was presented in our companion paper.

Plasticity size effects in nanoindentation

2004 ◽  
Vol 19 (1) ◽  
pp. 137-142 ◽  
Author(s):  
A.J. Bushby ◽  
D.J. Dunstan
Keyword(s):  
Phase Transition ◽  
Plastic Deformation ◽  
Size Effect ◽  
Finite Volume ◽  
Continuum Mechanics ◽  
Size Effects ◽  
Fused Silica ◽  
Length Scale ◽  
Indentation Size ◽  
Yield Behavior

In conventional continuum mechanics, the yield behavior of a material is size independent. However, in nanoindentation, plasticity size effects have been observed for many years, where a higher hardness is measured for smaller indentation size. In this paper we show that there was a size effect in the initiation of plasticity, by using spherical indenters with different radii, and that the length scale at which the size effect became significant depended on the mechanism of plastic deformation. For yield by densification (fused silica), there was no size effect in the nanoindentation regime. For phase transition (silicon), the length scale was of the order tens of nanometers. For materials that deform by dislocations (InGaAs/InP), the length scale was of the order a micrometer, to provide the space required for a dislocation to operate. We show that these size effects are the result of yield initiating over a finite volume and predict the length scale over which each mechanism should become significant.

On the origin of indentation size effects and depth dependent mechanical properties of elastic polymers

2016 ◽  
Vol 36 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Chung-Souk Han ◽  
Seyed H.R. Sanei ◽  
Farid Alisafaei
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Size Effects ◽  
Indentation Depth ◽  
Second Order ◽  
Indentation Size

Abstract Indentation size effects have been observed in both polymers and metals but, unlike in metals, the origin of size effects in polymers is not well understood. To clarify the role of second order gradients of displacements, a model polymer is examined with spherical and Berkovich tips at probing depths between 5 and 25 μm. Applying different theories to determine the elastic modulus, it is found that with a pyramidal tip, the elastic modulus increases with decreasing indentation depth, while tests with the spherical tip yielded essentially constant values for the elastic modulus independent of indentation depth. The differences between these tips are attributed to second order displacement gradients, as they remain essentially constant with a spherical tip while they increase in magnitude with decreasing indentation depth applying a Berkovich tip.

Virtual Material Model of Joint Interfaces Considering Elastic-Plastic Deformation of Asperities

2013 ◽  
Vol 457-458 ◽  
pp. 257-261
Author(s):  
Li Gang Cai ◽  
Teng Yun Xu ◽  
Yong Sheng Zhao
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Fractal Theory ◽  
Material Model ◽  
Contact Theory ◽  
Hertz Contact ◽  
Calculation Methods ◽  
Elastic Plastic ◽  
Element Simulation ◽  
Simulation Results

A virtual material model of joint interfaces was established based on the Hertz contact theory and fractal theory, this model was improved by considering the influence of the elastic-plastic deformation of asperities and ameliorating the calculation methods of the elastic modulus. The simulation results of elastic-plastic considered and elastic-plastic unconsidered were compared, moreover, the finite element simulation results and experimental results were compared to fully explain the necessity of considering the influence of the elastic-plastic deformation and the the correctness of the method to calculate the elastic modulus. The research suggested that under a same load the elastic modulus of the model considering the influence of the elastic-plastic deformation was slightly larger than the un considering one, which means it could describe the characteristics of joint interfaces more accurately.

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