The determination of film hardness from the composite response of film and substrate to nanometer scale indentations

1992 ◽  
Vol 7 (11) ◽  
pp. 3056-3064 ◽  
Author(s):  
B.D. Fabes ◽  
W.C. Oliver ◽  
R.A. McKee ◽  
F.J. Walker
Keyword(s):  
Finite Element ◽  
Film Thickness ◽  
Weighted Average ◽  
Element Model ◽  
Basic Structure ◽  
Depth Sensing ◽  
Area Function ◽  
Volume Fractions ◽  
Film Hardness ◽  
Titanium Coatings

Two equations for determining the hardness of thin films from depth-sensing indentation data are examined. The first equation is based on an empirical fit of hardness versus indenter displacement data obtained from finite element calculations on a variety of hypothetical films. The second equation is based on a model which assumes that measured hardness is determined by the weighted average of the volume of plastically deformed material in the coating and that in the substrate. The equations are evaluated by fitting the predicted hardness versus contact depth to data obtained from titanium coatings on a sapphire substrate. Only the volume fractions model allows the data to be fitted with a single adjustable parameter, the film hardness; the finite element equation requires two thickness-dependent parameters to obtain acceptable fits. It is argued that the difficulty in applying the finite element model lies in the use of an unrealistic area function for the indenter. For real indenters, which have finite radii, the area function must appear explicitly in the final equation. This is difficult to do with the finite element approach, but is naturally incorporated into the volume fractions equation. Finally, using the volume fractions approach the hardnesses of the titanium films are found to be relatively insensitive to film thickness. Thus, the apparent increase in hardness with decreasing film thickness for the titanium films is most likely due to increased interactions between the film and substrate for the thinner films rather than to a change in the basic structure of the titanium films.

A pragmatic approach for the evaluation of depth-sensing indentation in the self-similar regime

2021 ◽  
pp. 1-24
Author(s):  
Hamidreza Mahdavi ◽  
Konstantinos Poulios ◽  
Christian F. Niordson
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Depth Sensing ◽  
Finite Element Software ◽  
Element Simulation ◽  
Unique Material ◽  
Reverse Analysis ◽  
Supplementary Material ◽  
Two Parameters ◽  
Force Displacement

Abstract This work evaluates and revisits elements from the depth-sensing indentation literature by means of carefully chosen practical indentation cases, simulated numerically and compared to experiments. The aim is to close a series of debated subjects, which constitute major sources of inaccuracies in the evaluation of depth-sensing indentation data in practice. Firstly, own examples and references from the literature are presented in order to demonstrate how crucial self-similarity detection and blunting distance compensation are, for establishing a rigorous link between experiments and simple sharp-indenter models. Moreover, it is demonstrated, once again, in terms of clear and practical examples, that no more than two parameters are necessary to achieve an excellent match between a sharp indenter finite element simulation and experimental force-displacement data. The clear conclusion is that reverse analysis methods promising to deliver a set of three unique material parameters from depth-sensing indentation cannot be reliable. Lastly, in light of the broad availability of modern finite element software, we also suggest to avoid the rigid indenter approximation, as it is shown to lead to unnecessary inaccuracies. All conclusions from the critical literature review performed lead to a new semi-analytical reverse analysis method, based on available dimensionless functions from the literature and a calibration against case specific finite element simulations. Implementations of the finite element model employed are released as supplementary material, for two major finite element software packages.

Analysis on sealing performance of VL seals based on mixed lubrication theory

2019 ◽  
Vol 71 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Shixian Xu ◽  
Zhengtao Su ◽  
Jian Wu
Keyword(s):  
Finite Element ◽  
Film Thickness ◽  
Finite Element Model ◽  
Friction Factor ◽  
Contact Pressure ◽  
Element Model ◽  
Mixed Lubrication ◽  
Content Type ◽  
Deformation Mechanics ◽  
The Finite Element Model

Purpose This paper aims to research the influence of pressure, friction factors, roughness and actuating speed to the mixed lubrication models of outstroke and instroke. Design/methodology/approach Mixed lubrication model is solved by finite volume method, which consists of coupled fluid mechanics, deformation mechanics and contact mechanics analyses. The influence of friction factor on the finite element model is also considered. Then, contact pressure, film thickness, friction and leakage have been studied. Findings It was found that the amount of leakage is sensitive to the film thickness. The larger the film thickness is, the greater the influence received from the friction factor, however, the effect of oil film on the friction is negligible. The friction is determined mainly by the contact pressure. The trend of friction and leakage influenced by actuating velocity and roughness is also obtained. Originality/value The influence of friction factor on the finite element model is considered. This can make the calculation more accurate.

Bearing Loads Study for High-Speed Motorized Spindle

2011 ◽  
Vol 480-481 ◽  
pp. 1511-1515
Author(s):  
Dong Man Yu ◽  
Chang Pei Shang ◽  
Di Wang ◽  
Zhi Hua Gao
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Basic Structure ◽  
Maximum Temperature ◽  
Motorized Spindle ◽  
Finite Element Software ◽  
Bearing Loads ◽  
Precision Machine Tools

Due to high rotation accuracy, high dynamic stiffness, high vibration damping and long life, high-speed spindles supported by hydrodynamic and hydrostatic hybrid bearings are widely applied in the field of high-speed precision machine tools. The basic structure and working principal was detailed introduced, and then demonstrated a series of models and specifications of motorized spindle manufactured by FISCHER company in Switzerland. The finite element model of high-speed motorized spindle was built up and carried out thermal analysis to study the heat generation and heat transfer. With the help of ANSYS finite element software, the temperature field distribution and the temperature rise condition for motorized spindle were analyzed. The result indicates that the front bearing has a higher temperature than that of back bearing. The maximum temperature of inner ring is bigger than that of outer ring.

Finite Element Analysis of Elastoplastic Indentation: Part II—Application to Hard Coatings

1993 ◽  
Vol 115 (1) ◽  
pp. 15-19 ◽  
Author(s):  
P. Montmitonnet ◽  
M. L. Edlinger ◽  
E. Felder
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Film Thickness ◽  
Finite Element Model ◽  
Element Model ◽  
Hard Coatings ◽  
Chromium Layer ◽  
Element Analysis ◽  
Surface And Interface ◽  
State Of Stress

A finite element model previously described is used to analyze indentation of hard-face materials. The materials (substrate and coating) are supposed elastoplastic, the spherical indenter is elastic. The state of stress during indentation (including unloading) of hard-face materials (chromium layer on steel) is investigated in details. The tensile stresses which might lead to failure are especially discussed, and related with experiments showing fracture or delamination of the coating. The model also shows the influence of film thickness on surface and interface stresses.

Design Optimization of a Laser Cutting Machine by Elastodynamic Modeling

2008 ◽  
Author(s):  
Marco Troncossi ◽  
Enrico Troiani ◽  
Alessandro Rivola
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Design Optimization ◽  
Conceptual Design ◽  
Laser Cutting ◽  
Element Model ◽  
Basic Structure ◽  
Dynamic Simulations ◽  
Cutting Machine ◽  
Elastodynamic Modeling

This study deals with the elastodynamic modeling of a laser cutting machine and illustrates the guidelines followed for the design optimization of the machine’s basic structure from the dynamic behavior point of view. A finite element model was set up along with the conceptual design of the new machine, with the aim of performing dynamic simulations. The main purpose is to predict the vibrations arising in the structure that could significantly deteriorate the product quality in order to evaluate different design solutions. The vibrations can be excited by variable forces acting on the moving masses and by the oscillations affecting the machine basement due to external causes. The original modeling of the excitations is presented herein. Modal analysis and forced simulations were performed on the finite element model of the first conceptual design of the machine structure. The analysis of the results indicated some critical parts of the system to be stiffened in order to mitigate the vibrations, that is to improve the cutting quality. Structural modifications to the first conceptual design were therefore suggested and a new model of the machine was developed and simulated. The results of the simulations before and after the design modifications are reported and discussed.

Thermal Analysis Based on Finite Element Analysis for Motorized Spindle

2014 ◽  
Vol 556-562 ◽  
pp. 1170-1173 ◽  
Author(s):  
Dong Man Yu ◽  
Yan Hui Hu ◽  
Di Wang ◽  
Xiao Jing Li
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Basic Structure ◽  
Numerical Control ◽  
Maximum Temperature ◽  
Motorized Spindle ◽  
Element Analysis ◽  
Finite Element Software

High-speed motorized spindle is a key device of modern industry and has been widely used in numerical control machine. Temperature distribution, speed control loading characteristics, precision maintenance, liberation intensity and circumgyration error are not only the key demand of motorized spindle's capability but also an important index to evaluate it's performance. Therefore, this study has detailed described the main structure of motorized spindle. The basic structure and working principal was introduced, and then demonstrated a series of models and specifications of motorized spindle. The finite element model of high-speed motorized spindle was built up and carried out thermal analysis to study the heat generation and heat transfer. With the help of ANSYS finite element software, the temperature field distribution and the temperature rise condition for motorized spindle were analyzed. The result shows that the front bearing has a higher temperature than that of back bearing. The maximum temperature of inner ring is bigger than that of outer ring. The results contribute to selection of appropriate bearing for motorized spindle system.

Numerical Simulation of Cold-Formed Steel Stiffened Lipped Channel Columns with and without Perforations

2011 ◽  
Vol 243-249 ◽  
pp. 761-764
Author(s):  
Zhen Yu Wu ◽  
Yong Hong Yao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Weighted Average ◽  
Element Model ◽  
Short Columns ◽  
Geometrical Imperfections ◽  
Cold Formed Steel ◽  
The Mean ◽  
Nonlinear Finite Element Model ◽  
The Finite Element Model

A nonlinear finite element model of fixed ended cold-formed steel stiffened lipped channel short columns with and without perforations was developed and verified against experiment results. Material and geometrical non-linearities were included in the finite element model. It was proved by comparison analysis that using weighted average tensile yield stresses of the flat and corner areas and the mean geometrical imperfections along the length of the specimens was suitable for predicting the failure mode, ultimate load and load versus displacement curves of the channel short column. The results got by FEA coincided with the experimental results.

Strength Analysis and Calculation of JJ225/42-KC Type Oil Rig Derrick

2012 ◽  
Vol 190-191 ◽  
pp. 551-554
Author(s):  
Xian Zhong Yi ◽  
Sheng Zong Jiang ◽  
Yuan Qiang Ji ◽  
Ding Feng ◽  
De Li Gao
Keyword(s):  
Finite Element ◽  
Working Condition ◽  
Element Model ◽  
Basic Structure ◽  
Wind Load ◽  
Strength Analysis ◽  
Force Characteristic ◽  
Finite Element Software ◽  
Metal Frame ◽  
Oil Rig

Abstract. Oil rig derrick is a large and complex metal frame with lots of bars and complex force. Moreover, the use of working condition is complex and harsh, so it is quite necessary to analyze strength and calculate oil rig derrick. In this paper, with the basic structure and force characteristic of JJ225/42-KC type oil derrick, the ANSYS finite element software is used to establish JJ225/42-KC type oil derrick structure finite element model. The strength and stability analysis of the maximum hook load working condition, the working wind load working condition and the maximum wind load working condition of three combined working conditions indicates that the overall structural design of JJ225/42-KC type oil derrick is reasonable with good both dynamic and static characteristics and the derrick meets the requirements of the strength. What is more, the derrick has a excellent overall stability. In the end, the strength of the lifting devices and the derrick leg pin of JJ225/42-KC type oil derrick are calculated and checked, showing that all meet the requirements of the strength.

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