Nano-Indentation for Characterizing Mechanical Properties of Soft Materials

2013 ◽  
Author(s):  
A. Hossain ◽  
A. Mian
Keyword(s):  
Mechanical Properties ◽  
Indentation Depth ◽  
Contact Stiffness ◽  
Indentation Test ◽  
Soft Materials ◽  
Element Analysis ◽  
Fea Model ◽  
Computer Based ◽  
Loading And Unloading ◽  
Small Indentation

We have attempted to apply the computer-based finite element analysis (FEA) method to accurately measure the mechanical properties (e.g., hardness and elasticity) of a soft material by an indentation test. First, an axisymmetric model has been developed using commercially available FEA code ANSYS. The FEA model consisted of a thin Al-film resting on Si-substrate. A spherical indenter has been used to indent the Al-film, which traveled a predefined depth during the loading and unloading cycles. First, numerical simulations were conducted to get the force vs. displacement plot, which was later used to determine the modulus of elasticity and hardness of Al-film. The effects of substrate modulus and indentation depth were thoroughly investigated to determine the modulus and hardness of Al-film. The effect of friction, considered at the interface of indenter and Al-film, was found to offer minimum impact for relatively small indentation depth. The induced force on the Al-film by the indenter has been found to be higher with increasing indentation depth when friction was considered. However the contact stiffness, represented by the slope of the unloading curve, has been found almost the same with and without considering friction. The variation of substrate modulus has been found to be ineffective to capture the Al-film modulus for relatively small indentation depth. However for higher indentation depth, the substrate modulus has been found to offer profound effect to capture the film modulus. The hardness of the Al-film has also been found to be relatively unaffected with variation of substrate modulus. However, the hardness of the Al-film has been found to be higher with friction for relatively high indentation depth. Results obtained from this preliminary research are important to continue further investigation and to characterize the mechanical properties of other soft-materials, e.g., biofilms to minimize its detrimental effects and utilize its favorable aspects in industrial and biomedical applications.

Finite Element Modeling of Pad Deformation due to Diamond Disc Conditioning in Chemical Mechanical Polishing (CMP)

2012 ◽  
Author(s):  
Emmanuel A. Baisie ◽  
Z. C. Li ◽  
X. H. Zhang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Material Removal ◽  
High Performance ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Element Analysis ◽  
Fea Model ◽  
Pad Wear ◽  
Diamond Disc

Chemical mechanical planarization (CMP) is widely used to planarize and smooth the surface of semiconductor wafers. In CMP, diamond disc conditioning is traditionally employed to restore pad planarity and surface asperity. Pad deformation which occurs during conditioning affects the material removal mechanism of CMP since pad shape, stress and strain are related to cut rate during conditioning, pad wear rate and wafer material removal rate (MRR) during polishing. Available reports concerning the effect of diamond disc conditioning on pad deformation are based on simplified models of the pad and do not consider its microstructure. In this study, a two-dimensional (2-D) finite element analysis (FEA) model is proposed to analyze the interaction between the diamond disc conditioner and the polishing pad. To enhance modeling fidelity, image processing is utilized to characterize the morphological and mechanical properties of the pad. An FEA model of the characterized pad is developed and utilized to study the effects of process parameters (conditioning pressure and pad stiffness) on pad deformation. The study reveals that understanding the morphological and mechanical properties of CMP pads is important to the design of high performance pads.

scholarly journals Effects of Different Interface Forms on Mechanical Properties of Steel Self-Compacting Concrete Composite Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Chengzhi Wang ◽  
Xin Liu ◽  
Wei Liu ◽  
Zhiming Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Bearing Capacity ◽  
Composite Structure ◽  
Mechanical Performance ◽  
Complex Structure ◽  
Self Compacting Concrete ◽  
Element Analysis ◽  
Shear Connectors ◽  
Fea Model

In the water resources allocation project in Pearl River Delta, in order to optimize the structural design, the deep buried tunnel adopts the composite lining structure. However, the weakest link in a complex structure is the connection between two different interfaces. This paper reports the findings of an experimental study that was undertaken to investigate the interface mechanical performance of steel self-compacting concrete composite structure subjected to cyclic loads. In this study, different shear connectors are considered, and six different specimens were designed and tested, respectively. The test is used to research the effect of the different shear connectors on the bearing capacity and interface mechanical properties of composite structure in an experimental study. According to these test results, a detailed analysis was carried out on the relationships, such as the stress-strain and load-displacement relationships for the specimen. These tests show that the shear connectors will significantly enhance the bearing capacity and interface mechanical properties of the composite structure. Among them, the comprehensive performance of the specimens using the stud-longitudinal ribs shear connectors is the best. Additionally, a finite element analysis (FEA) model was developed. The comparison of the simulation results with the experimental results shows that this FEA is applicable for this type of experiment.

Determining Stress-Strain Behavior of Zr60Cu10Al15Ni15 Bulk Metallic Glass Using Object Oriented Finite Element Analysis

2017 ◽  
Vol 29 ◽  
pp. 1-8 ◽  
Author(s):  
Ketul Arvindbhai Patel ◽  
Ganesh R. Karthikeyan ◽  
S. Vincent
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Metallic Glass ◽  
Strain Analysis ◽  
Indentation Test ◽  
Object Oriented ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Determining mechanical properties of Bulk Metallic Glasses (BMGs) requires synthesizing of the alloys in bulk form. However obtaining metallic glass in bulk form is quite challenging due to its tendency towards crystallization. In such circumstances it is beneficial to determine the mechanical properties of materials using finite elemental analysis of microstructures. Thus, in the present investigation, using Object Oriented Finite Element Analysis (OOF2) software package, Stress-Strain analysis has been carried out on Zr60Cu10Al15Ni15 BMG to determine such mechanical properties. Specimen of Zr60Cu10Al15Ni15 BMG exhibiting three microstructurally distinct regions amorphous, partial crystalline and crystalline regions was used for this analysis. The Stress-Strain relationship have been estimated for each of the three distinct phases and the results are validated by determining the Modulus of Elasticity for all the phases and comparing it with the available experimental results from Nano-indentation test.

Nanoindentation of In Situ Polymers in Hydroxyapatite/Poly-L-Lactide Biocomposites

2006 ◽  
Vol 518 ◽  
pp. 501-506 ◽  
Author(s):  
I. Balać ◽  
Chak Yin Tang ◽  
Chi Pong Tsui ◽  
Da Zhu Chen ◽  
P.S. Uskoković ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Indentation Test ◽  
Polymer Processing ◽  
Elastic Behavior ◽  
Element Analysis ◽  
High Resolution Measurement ◽  
Resolution Measurement ◽  
The Matrix ◽  
Indentation Experiment

In order to obtain more accurate properties after compaction of hydroxyapatite (HAp)/poly-L-lactide (PLLA) composite, high-resolution measurement of mechanical properties method is proposed to determine the properties of each phase separately, leading to information that are valuable for the development of new materials as well as for predictive modeling purposes. The PLLA polymer processing conditions used in hot pressing of the composite strongly influence final mechanical properties of the material in the solid state. Since the aim was to measure PLLA material properties, acceptable findings could only be made using unconstrained, cured in situ nanoindentation tests. A finite element analysis of the in situ indentation experiment was performed to determine required size of plain polymer area, needed for indentation test, which would minimize the particle influence on the matrix elastic behavior.

Factors Affecting Spherical Nano-Indentation of Thin Film/Substrate Systems

2014 ◽  
Author(s):  
A. Hossain ◽  
A. Mian
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Mechanical Response ◽  
Indentation Test ◽  
Element Analysis ◽  
Factors Affecting ◽  
Nano Indentation ◽  
Fea Modeling ◽  
Soft Biological Materials ◽  
Film Substrate

Great interests have been made over the last few years in the development of techniques to measure the mechanical properties of many engineering materials at the nano scale. In nano-indentation, a hard tip with known mechanical properties is pressed into a sample whose properties are unknown. The load, indentation depth and deformed area resulting from this test are then used to determine the desired mechanical properties, such as hardness and modulus. In this study, the computer-based finite element analysis (FEA) method is used to investigate factors effecting nano-indentation to ensure reliable measurement of thin film properties. First, the FEA method is used to predict the mechanical response of bulk aluminum (Al) using a spherical indenter. The numerical prediction is then compared with existing published results to validate the FEA modeling scheme. Once the model is validated, additional numerical analyses are conducted to investigate the response of Al-film deposited on different substrate materials. New mathematical formulations are proposed to determine the film modulus from nano-indentation test. The film modulus obtained from the new and existing mathematical formulations are also compared. Results obtained from this research can be used to characterize the mechanical properties of soft biological materials such as biofilm or tissue scaffolds.

Critical Penetration Depth for Nano/Micro Indentation Test to Determine Elastic-Plastic Film Properties Deposited on Hard Substrates

2006 ◽  
Author(s):  
Norimasa Chiba ◽  
Nagahisa Ogasawara ◽  
Constantin Razvan Anghel ◽  
Xi Chen
Keyword(s):  
Penetration Depth ◽  
Indentation Depth ◽  
Indentation Test ◽  
Apex Angle ◽  
Film Material ◽  
Element Analysis ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Film Substrate ◽  
Hard Substrates

The critical indentation depth to obtain proper elastic-plastic properties of thin film when the indentation tests are done on film/substrate system with sharp indenters is investigated. We focus on the characterization problem of soft film material, whose material properties are unknown, deposited on hard substrates. The critical depth is analyzed based on the finite element analysis (FEA) results. In order to extract the mechanical properties of the film from those of the film/substrate compound, we have to restrict the maximum penetration depth within a certain value. In this paper the relation between the load, P, and the depth, h, is analyzed in a power law relation, P = Chm, where the exponent m is a function of h. From extensive FEA results, we found that this exponent m starts to depart from 2 faster with increasing indenter apex angle and increasing hardening exponent of the film material. This means that the critical indentation depth decreases with increasing indenter apex angle and increasing hardening exponent. Based on this analysis, we propose a simple formula to evaluate the critical penetration depth h0, as a function of apex angle, θ, of the indenter: h0/d = 0.243cot θ, where d is the film thickness.

Material Property Identification and Sensitivity Analysis Using Indentation and FEM

2006 ◽  
Author(s):  
Long Ge ◽  
Nam Ho Kim ◽  
Gerald R. Bourne ◽  
W. Gregory Sawyer
Keyword(s):  
Mechanical Properties ◽  
Numerical Technique ◽  
Response Surfaces ◽  
Small Scale ◽  
Test Statistics ◽  
Element Analysis ◽  
Property Identification ◽  
Indentation Experiment ◽  
Loading And Unloading ◽  
The Difference

Mechanical properties of materials in small-scale applications, such as thin coatings, are often different from those of bulk materials due to the difference in the manufacturing process. Indentation has been a convenient tool to study the mechanical properties in such applications. In this paper, a numerical technique is proposed that can identify the mechanical properties by minimizing the difference between the results from indentation experiments and those from finite element analysis. First, two response surfaces are constructed for loading and unloading curves from the indentation experiment of a gold film on the silicon substrate. Unessential coefficients of the response surface are then removed based on the test statistics. Different from the traditional methods of identification, the tip geometry of the indenter is included because its uncertainty significantly affects the results. In order to validate the accuracy and stability of the method, the sensitivity of the identified material properties with respect to each coefficient is analyzed.

EFFECT OF MECHANICAL PROPERTIES OF THE SUBSTRATE TISSUES ON THE DETERMINATION OF ELASTIC MODULUS OF THE SCLERA USING INDENTATION TEST

2016 ◽  
Vol 16 (07) ◽  
pp. 1650085
Author(s):  
XIUQING QIAN ◽  
KUNYA ZHANG ◽  
ZHICHENG LIU
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Elastic Moduli ◽  
Indentation Depth ◽  
Vitreous Body ◽  
Indentation Test ◽  
Posterior Pole

The sclera is an important connective tissue that protects the sensitive layers within the eyeball. Identifying the mechanical properties of the sclera near the posterior pole is necessary to analyze the deformation of the sclera and stresses changing in the optic nerve head tissues. We propose a method to determine the mechanical properties of the sclera using dimensional analysis, finite element method and the indentation test. The elastic moduli of the sclera for different indentation depths and positions were identified. We found that the elastic moduli of the sclera varied with indentation depth. This was due to the effect of the mechanical properties of the substrate tissues inside the sclera. The elastic modulus of the choroid had the biggest effect on the determination of elastic modulus of the sclera, whereas that of the vitreous body could be ignored when the ratio of the indentation depth to the thickness of the sclera was less than 0.5. The effects of mechanical properties of the substrate tissues become more pronounced at greater indentation depths.

Atomic-scale analysis of nanoindentation behavior of high-entropy alloy

2016 ◽  
Vol 01 (01) ◽  
pp. 1650001 ◽  
Author(s):  
Jia Li ◽  
QiHong Fang ◽  
Bin Liu ◽  
YouWen Liu ◽  
Yong Liu
Keyword(s):  
Mechanical Properties ◽  
Indentation Depth ◽  
Plastic Region ◽  
Indentation Test ◽  
Atomic Scale ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Indentation Force ◽  
Elastic And Plastic Deformations ◽  
Dynamics Simulations

Using molecular dynamics simulations, we study the elastic and plastic deformations of indentation in FeCrCuAlNi high-entropy alloy (HEA). The indentation tests are carried out using spherical rigid indenter to investigate the effects of high-entropy and severe lattice distortion in terms of shear strain, indentation force, surface morphology, defect structure, dislocation evolution and radial distribution function on the deformation processes. It can be found that when the indentation depth increases, the shear stress requires for the occurrence of the contact area between the indenter and the substrate increased, which is attributable to a higher probability to observe the dislocation evolution under a large indentation depth. The indentation test also shows that the equal element addition can significantly improve the mechanical properties of HEA compared with the conventional alloy. Based on the Hertzian fitting, the FeCrCuAlNi HEA has the Young’s modulus of 161[Formula: see text]GPa and hardness of 15.4[Formula: see text]GPa, respectively. These values are higher than that of traditional metal materials, due to the low stacking fault energy and the dense atomic arrangement in the slip plane of HEA. In the plastic region, the Fe element causes the more stable crystal structure, much stronger than the Cu element, presumably resulted from a variety of crystal structures for Fe in the multicomponent FeCrCuAlNi alloy. Further, this effective strategy is used to accelerate the discovery of excellent mechanical properties of HEAs.

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