An AFM Dynamic Contact Model with Finite Thickness Correction to Study Micro-Rheology of Biological Cells

2018 ◽  
Vol 42 (5) ◽  
pp. 551-561
Author(s):  
V. Managuli ◽  
S. Roy
Keyword(s):  
Finite Thickness ◽  
Dynamic Contact ◽  
Contact Model ◽  
Biological Cells ◽  
Thickness Correction

scholarly journals Axisymmetric Contact Problem for a Flattened Cell: Contributions of Substrate Effect and Cell Thickness to the Determination of Viscoelastic Properties by Using AFM Indentation

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Xinyao Zhu ◽  
Lanjiao Liu ◽  
Zuobin Wang ◽  
X. Liu
Keyword(s):  
Mechanical Properties ◽  
Linear Elasticity ◽  
Viscoelastic Properties ◽  
Present Model ◽  
Finite Thickness ◽  
Contact Model ◽  
Substrate Effect ◽  
Biological Cells ◽  
Hertz Contact ◽  
Hertz Contact Model

Nanoindentation technology has proven to be an effective method to investigate the viscoelastic properties of biological cells. The experimental data obtained by nanoindentation are frequently interpreted by Hertz contact model. However, in order to validate Hertz contact model, some studies assume that cells have infinite thickness which does not necessarily represent the real situation. In this study, a rigorous contact model based upon linear elasticity is developed for the interpretation of indentation tests of flattened cells. The cell, normally bonded to the Petri dish, is initially treated as an elastic layer of finite thickness perfectly fixed to a rigid substrate. The theory of linear elasticity is utilized to solve this contact issue and then the solutions are extended to viscoelastic situation which is regarded as a good indicator for mechanical properties of biological cells. To test the present model, AFM-based creep test has been conducted on living human hepatocellular carcinoma cell (SMMC-7721 cell) and its fullerenol-treated counterpart. The results indicate that the present model could not only describe very well the creep behavior of SMMC-7721 cells, but also curb overestimation of the mechanical properties due to substrate effect.

Dynamic contact model of shell for multibody system applications

2018 ◽  
Vol 44 (4) ◽  
pp. 335-366 ◽  
Author(s):  
Jiabei Shi ◽  
Zhuyong Liu ◽  
Jiazhen Hong
Keyword(s):  
Multibody System ◽  
Dynamic Contact ◽  
Contact Model

A Dynamic Contact Model of Rough Surfaces Based on the Microscopic Contact Analysis of Asperities

2013 ◽  
Vol 785-786 ◽  
pp. 1208-1211
Author(s):  
Yan Qing Tan ◽  
Lian Hong Zhang ◽  
Ya Hui Hu
Keyword(s):  
Surface Topography ◽  
Rough Surfaces ◽  
Dynamic Contact ◽  
Contact Model ◽  
Fatigue Wear ◽  
Contact Parameter ◽  
Wear Process ◽  
Static Contact ◽  
Contact Models ◽  
Set Up

Dynamic contact model of rough surfaces can provide the theoretical basis for analyzing the microscopic damage of surfaces in wear process and constructing the analytical wear model to predict wear. A dynamic contact model of sliding rough surfaces is innovatively constructed based on the characterization of the contact asperities on rough surfaces in this paper. Firstly, an asperity model of rough surface is set up according to the surface topography parameters and the static contact parameters is evaluated in the light of statistics contact theory; Then the contact characteristic of surface topography in sliding is analyzed and a series of equivalent contact models are proposed; Finally, the dynamic contact model of rough surfaces is established and from which the dynamic contact parameter of rough surfaces is formulated. The dynamic contact model can be further improved to analyze the friction fatigue wear of sliding pairs and provide reference for tribology design of mechanical surfaces.

Micropitting Fatigue Wear Simulation in Conformal-Contact Under Mixed Elastohydrodynamic Lubrication

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Hang Jia ◽  
Junyang Li ◽  
Jiaxu Wang ◽  
Guo Xiang ◽  
Ke Xiao ◽  
...  
Keyword(s):  
Prediction Model ◽  
Theoretical Calculations ◽  
Normal Load ◽  
Elastohydrodynamic Lubrication ◽  
Dynamic Contact ◽  
Contact Model ◽  
Fatigue Wear ◽  
Cycle Number ◽  
Average Maximum ◽  
Stress Prediction

In this study, a physics-based fatigue wear model is proposed to evaluate the reliability and to predict the life of cumulative micropitting wear for lubricated conformal contacts on rough surfaces. The surface normal load, mean film thickness, and frictional shear traction are simulated by a mixed elastohydrodynamic lubrication (EHL) model for a stress prediction model to calculate the average maximum Hertzian pressure of contact asperities and unit with the statistical contact model and dynamic contact model to obtain the asperity stress cycle number. The wear formula is established through combining a micropitting life prediction model of surface asperities and a mean micropitting damage constant of asperities. The four dominant aspects affecting wear behaviors of the surface contact pairs, working conditions, structure and surface topographies, material properties and lubrication conditions are all taken into account in the model. It is a high-fidelity and comprehensive model that can be used to analyze and optimize the tribological design of rolling–sliding pairs in machinery. The micropitting fatigue wear modeling scheme is validated by comparison of theoretical calculations and available experimental wear data.

A Note in Non-Intermittent Contact Problems of a Special Class of Ultrasonic Motors

1999 ◽  
Author(s):  
Thomas Sattel ◽  
Peter Hagedorn
Keyword(s):  
Numerical Simulations ◽  
Detailed Analysis ◽  
Special Class ◽  
Experimental Studies ◽  
Contact Problems ◽  
Dynamic Contact ◽  
Contact Model ◽  
Ultrasonic Motors ◽  
Intermittent Contact ◽  
Simple Contact

Abstract Contact problems play a key-role in ultrasonic motors. Our aim is the formulation of a contact model for stationary and non-stationary stator-rotor contact problems for a special class of non-intermittent ultrasonic motors. With the models proposed up to now, a detailed analysis of dynamic contact problems is only possible in a very limited manner. The simple contact model presented here can be used for numerical simulations and parameter studies and is verified by experimental studies carried out in our lab. First simulations show that, depending on the friction law, momentary perturbations can lead to self-excited vibrations in the rotor.

DYNAMIC SIMULATION OF BIPED WALKING ON LOOSE SOIL

2012 ◽  
Vol 09 (04) ◽  
pp. 1250032 ◽  
Author(s):  
SHUNSUKE KOMIZUNAI ◽  
ATSUSHI KONNO ◽  
SATOKO ABIKO ◽  
XIN JIANG ◽  
MASARU UCHIYAMA
Keyword(s):  
Dynamic Simulation ◽  
Humanoid Robot ◽  
Dynamic Contact ◽  
Biped Robot ◽  
Contact Model ◽  
Reactive Force ◽  
Biped Walking ◽  
Uneven Terrain ◽  
Loose Soil ◽  
Slip Phenomenon

Most of the studies on biped walking on even or uneven terrain have assumed stiff ground. This paper proposes a dynamic contact model between foot and loose soil. The proposed contact model provides sinkage of the foot, slip of the sole and reactive force acting on the foot on loose soil. Sinkage of the foot and slip of the sole are calculated utilizing terramechanics model, which are important characteristics for biped robot to walk on loose soil. Reactive force acting on the foot on loose soil is calculated using spring-damper model between the foot and the deformed ground. By applying the proposed contact model to a usual dynamics simulator, dynamic sinkage and slip phenomenon during biped walking on loose soil are simulated. Additionally, in order to verify the simulation result, experiments were carried out using a humanoid robot.

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