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

Author(s):  
A. Hossain ◽  
A. Mian

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.

2008 ◽  
Vol 33-37 ◽  
pp. 969-974 ◽  
Author(s):  
Bong Bu Jung ◽  
Seong Hyun Ko ◽  
Hun Kee Lee ◽  
Hyun Chul Park

This paper will discuss two different techniques to measure mechanical properties of thin film, bulge test and nano-indentation test. In the bulge test, uniform pressure applies to one side of thin film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as the elastic modulus and the residual stress. Nano-indentation measurements are accomplished by pushing the indenter tip into a sample and then withdrawing it, recording the force required as a function of position. . In this study, modified King’s model can be used to estimate the mechanical properties of the thin film in order to avoid the effect of substrates. Both techniques can be used to determine Young’s modulus or Poisson’s ratio, but in both cases knowledge of the other variables is needed. However, the mathematical relationship between the modulus and Poisson's ratio is different for the two experimental techniques. Hence, achieving agreement between the techniques means that the modulus and Poisson’s ratio and Young’s modulus of thin films can be determined with no a priori knowledge of either.


2006 ◽  
Vol 306-308 ◽  
pp. 601-606
Author(s):  
Seung Baek ◽  
Jae Mean Koo ◽  
Chang Sung Seok

Nano-indentation test is used widely to determine the fracture toughness of brittle materials and to provide information on important material properties such as the Young’s modulus and hardness. In this study, using nano-indentation testing, atomic force microscope (AFM), and finite element method (FEM), we performed the indentation fracture toughness and fracture strength measurement for a (100) single crystalline silicon at different load states. In addition, the loads of the phase transformation events during unloading were estimated by the load-depth curves. The phase transformation load and micro-crack propagation events at pop-out during the unloading process depended on the maximum applied indentation load.


2004 ◽  
Vol 261-263 ◽  
pp. 417-422 ◽  
Author(s):  
Dong Cheon Baek ◽  
Tae Sang Park ◽  
Soon Bok Lee

Electroplated nickel manufactured via the LIGA process, offers the possibility of stronger structure and connectors in a micro electro mechanical systems (MEMS). In this study, the mechanical properties of electroplated Nickel thin film were characterized using two methods; tension test and nano-indentation test. In tension test, a linear guided motor was used as actuator and the applied force was measured using a load cell. Strain was measured with a dual microscope that obtains the displacement of two separated zone by the tracking process of the image captured with CCD camera. In indentation test, elastic modulus was measured using a CSM(continuous stiffness measurement) module. Two types of specimen were prepared in the same wafer and tested after four months of aging, which reduces the variation of properties caused by fabrication condition and aging effect. The tension specimen is 15 µm thick and 300 µm wide. The indentation specimen is also 15 µm thick. Young's modulus were measured by two different testing methods and compared quantitatively.


2010 ◽  
Vol 2010.7 (0) ◽  
pp. 229-230
Author(s):  
Hideaki ITO ◽  
Kazuhisa SATO ◽  
Atsushi UNEMOTO ◽  
Koji AMEZAWA ◽  
Tatsuya KAWADA

Author(s):  
A. Vidal-Lesso ◽  
E. Ledesma-Orozco ◽  
R. Lesso-Arroyo ◽  
L. Daza-Benitez

Biomechanical properties and dynamic response of soft tissues as articular cartilage remains issues for attention. Currently, linear isotropic models are still used for cartilage analysis in spite of its viscoelastic nature. Therefore, the aim of this study was to propose a nonlinear viscoelastic model for cartilage indentation that combines the geometrical parameters and velocity of the indentation test with the thickness of the sample as well as the mechanical properties of the tissue changing over time due to its viscoelastic behavior. Parameters of the indentation test and mechanical properties as a function of time were performed in Laplace space where the constitutive equation for viscoelasticity and the convolution theorem was applied in addition with the Maxwell model and Hayes et al. model for instantaneous elastic modulus. Results of the models were compared with experimental data of indentation tests on osteoarthritic cartilage of a unicompartmental osteoarthritis cases. The models showed a strong fit for the axial indentation nonlinear force in the loading curve (R2 = 0.992) and a good fit for unloading (R2 = 0.987), while an acceptable fit was observed in the relaxation curve (R2 = 0.967). These models may be used to study the mechanical response of osteoarthritic cartilage to several dynamical and geometrical test conditions.


2018 ◽  
Vol 8 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Simon S. Wang ◽  
Zhanwei Liu ◽  
Christopher M. Harvey

2013 ◽  
Vol 05 (02) ◽  
pp. 1350012 ◽  
Author(s):  
HONG-PING ZHAO ◽  
YECHENG WANG ◽  
BING-WEI LI ◽  
XI-QIAO FENG

The peeling behavior of a thin film bonded to a substrate is investigated by using the cohesive interface model. We compare the peeling processes of film/substrate interfaces with three different geometric shapes, including a flat interface, a curved interface of sinusoidal shape, and a wavy interface with two-level sinusoidal hierarchy. The effect of the peeling angle on the maximal peeling strength is also examined. It is demonstrated that the peeling strength can be significantly improved by introducing a hierarchical wavy morphology at the film/substrate interface. This study may be helpful for the design of film/substrate systems with enhanced mechanical properties.


2002 ◽  
Vol 731 ◽  
Author(s):  
Y. Wei ◽  
M. Zhao ◽  
X. Wang ◽  
S. Tang

AbstractMicro-indentation test at scales on the order of sub-micron has shown that the measured hardness increases strongly with decreasing indent depth or indent size, which is frequently referred to as the size effect. Simultaneously, at micron or sub-micron scale, the material microstructure size also has an important influence on the measured hardness. This kind of effect, such as the crystal grain size effect, thin film thickness effect, etc., is called the geometrical effect. In the present research, in order to investigate the size effect and the geometrical effect, the micro-indentation experiments are carried out respectively for single crystal copper and aluminum, for polycrystal aluminum, as well as for a thin film/substrate system, Ti/Si3N4. The size effect and geometrical effect are displayed experimentally. Moreover, using strain gradient plasticity theory, the size effect and the geometrical effect are simulated. Through comparing experimental results with simulation results, the length-scale parameter appearing in the strain gradient theory for different cases is predicted. Furthermore, the size effect and the geometrical effect are interpreted using the geometrically necessary dislocation concept and the discrete dislocation theory.


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