Investigations Into Asperity Persistence in Heavily Loaded Contacts

1999 ◽  
Vol 121 (3) ◽  
pp. 441-448 ◽  
Author(s):  
I. Lee-Prudhoe ◽  
R. S. Sayles ◽  
A. Kaderic
Keyword(s):  
Rough Surface ◽  
Simulation Models ◽  
Simulation Method ◽  
Asperity Contact ◽  
Local Contact ◽  
Before And After ◽  
Indentation Tests ◽  
Mechanisms Of Persistence ◽  
Contact Pressures ◽  
Smooth Roller

Experimental results are presented along the lines of the early work of Moore (1948) where a hard smooth roller is pressed into a softer rough surface to study the resulting real to apparent areas of contact and their associated local contact pressures. Results are presented for a hard steel roller deforming mild-steel and aluminum-alloy rough surface specimens. An analysis of the local contact mechanics is performed before and after indentation using a recently developed numerical elastic contact simulation method which allows local asperity contact pressures and areas to be studied in detail. The method is shown to reveal the level and distribution of pressures and asperity contact areas prevalent during the indentation process, and therefore allows the contribution of elastic and plastic load support to be quantified. The persistence of asperities during such indentation tests is discussed in terms of the pressures the asperities can support in relation to reported mechanisms of persistence. Results of subsequent sub-surface stresses are also presented and discussed in terms of how the method might be used to create an elastic-plasticdeformation model that can account for asperity persistence in future numerical contact simulation models.

Contact Analysis of a Smooth Ball on an Anisotropic Rough Surface

1994 ◽  
Vol 116 (4) ◽  
pp. 850-859 ◽  
Author(s):  
C. Y. Poon ◽  
R. S. Sayles
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Stochastic Approach ◽  
Contact Analysis ◽  
Asperity Contact ◽  
Correlation Lengths ◽  
Real Contact ◽  
Rough Surface Contact ◽  
Contact Pressures ◽  
Contact Spots

The effects of surface roughness and waviness upon the real contact areas, gaps between contact spots, and asperity contact pressures were studied. The distribution of real areas, gaps, and contact pressures are presented for different surface roughness, σ and correlation lengths, β*. The load-area relationship is compared to Bush’s model of strongly anisotropic rough surface contact using a stochastic approach.

A Simulation Method for Non-Gaussian Rough Surfaces Using Fast Fourier Transform and Translation Process Theory

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Yuechang Wang ◽  
Ying Liu ◽  
Gaolong Zhang ◽  
Yuming Wang
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Rough Surface ◽  
Tribological Behavior ◽  
Rough Surfaces ◽  
Simulation Method ◽  
Process Theory ◽  
Asperity Contact ◽  
Translation Process ◽  
Non Gaussian

The simulated rough surface with desired parameters is widely used as an input for the numerical simulation of tribological behavior such as the asperity contact, lubrication, and wear. In this study, a simulation method for generating non-Gaussian rough surfaces with desired autocorrelation function (ACF) and spatial statistical parameters, including skewness (Ssk) and kurtosis (Sku), was developed by combining the fast Fourier transform (FFT), translation process theory, and Johnson translator system. The proposed method was verified by several numerical examples and proved to be faster and more accurate than the previous methods used for the simulation of non-Gaussian rough surfaces. It is convenient to simulate the non-Gaussian rough surfaces with various types of ACFs and large autocorrelation lengths. The significance of this study is to provide an efficient and accurate method of non-Gaussian rough surfaces generation to numerically simulate the tribological behavior with desired rough surface parameters.

RANCANG BANGUN SIMULATOR SISTEM TREATMENT BAHAN BAKAR BIODISEL B20 PADA TANKI INDUK BAHAN BAKAR KRI YOS SUDARSO

ROTOR ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 55
Author(s):  
Hadi Prasutiyon ◽  
Arif Winarno ◽  
Edlyn Criptosan
Keyword(s):  
Diesel Fuel ◽  
Simulation Models ◽  
Simulation Method ◽  
Fuel Tank ◽  
Ansys Software ◽  
Software Simulation ◽  
Circulation Pump ◽  
Before And After ◽  
Main Engine

Biodiesel B20 is a mixture of 80% fossil diesel fuel and 20% biofuel. When using B20, the fuel has problems in the form of jelly or mud deposition, so it needs to be overcome by treatment. The treatment that is used today uses a circulation pump but has shortcomings and is not efficient so it needs to be modified using a stirrer. In this research, an analysis of the stirrer treatment using ANSYS software simulation method was carried out to determine the change of sediment before and after stirring, with stirring speed 150 rpm. The use of a stirrer simulation is to make 2 simulation models in the main tank as the largest volume and the daily tank as the smallest volume aims to determine the differences in the results of stirring in the largest and smallest tank.. At the time of stirring, the result is a decrease in sediment from 0 minutes to 4 minutes, then 4 minutes to 8 minutes, then 8 minutes to 12 minutes, then 12 minutes to 16 minutes, then 16 minutes to 20 minutes the fuel has decreased very much and the sediment is almost gone. When stirring is carried out for 20 minutes, the sediment in the fuel tank has not reached 0% so it needs to be stirred continuously until the deposit is 0%. After the fuel has not settled, the fuel is transferred to the main engine using a transfer pump. 

scholarly journals Factors Affecting the Compression and Energy Absorption Properties of Small-Sized Thin-Walled Metal Tubes

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoqin Hao ◽  
Jia Yu ◽  
Weidong He ◽  
Yi Jiang
Keyword(s):  
Energy Absorption ◽  
Simulation Models ◽  
Simulation Method ◽  
Engineering Practice ◽  
Small Ring ◽  
Metal Tube ◽  
Absorption Properties ◽  
Factors Affecting ◽  
Thin Walled ◽  
Hollow Metal

To solve the problem of the effective cushioning of fast-moving mechanical components in small ring-shaped spaces, the factors affecting the compression and energy absorption properties of small-sized hollow metal tubes were studied. Simulation models were constructed to analyse the influences of tube diameter, wall thickness, relative position, and number of stacked components on the compression and energy absorption properties. The correctness of the simulation method and its output were verified by experiments, which proved the effectiveness of compression and energy absorption properties of small-sized thin-walled metal tubes. The research provides support for the application of metal tube buffers in armament launch technology and engineering practice.

scholarly journals Lingual–Alveolar Contact Pressure During Speech in Amyotrophic Lateral Sclerosis: Preliminary Findings

2017 ◽  
Vol 60 (4) ◽  
pp. 810-825 ◽  
Author(s):  
Jeff Searl ◽  
Stephanie Knollhoff ◽  
Richard J. Barohn
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Healthy Volunteers ◽  
Contact Pressure ◽  
Statistical Difference ◽  
Healthy Controls ◽  
Perceptual Judgments ◽  
Before And After ◽  
Preliminary Study ◽  
Contact Pressures ◽  
Lateral Sclerosis

Purpose This preliminary study on lingual–alveolar contact pressures (LACP) in people with amyotrophic lateral sclerosis (ALS) had several aims: (a) to evaluate whether the protocol induced fatigue, (b) to compare LACP during speech (LACP-Sp) and during maximum isometric pressing (LACP-Max) in people with ALS (PALS) versus healthy controls, (c) to compare the percentage of LACP-Max utilized during speech (%Max) for PALS versus controls, and (d) to evaluate relationships between LACP-Sp and LACP-Max with word intelligibility. Method Thirteen PALS and 12 healthy volunteers produced /t, d, s, z, l, n/ sounds while LACP-Sp was recorded. LACP-Max was obtained before and after the speech protocol. Word intelligibility was obtained from auditory–perceptual judgments. Results LACP-Max values measured before and after completion of the speech protocol did not differ. LACP-Sp and LACP-Max were statistically lower in the ALS bulbar group compared with controls and PALS with only spinal symptoms. There was no statistical difference between groups for %Max. LACP-Sp and LACP-Max were correlated with word intelligibility. Conclusions It was feasible to obtain LACP-Sp measures without inducing fatigue. Reductions in LACP-Sp and LACP-Max for bulbar speakers might reflect tongue weakness. Although confirmation of results is needed, the data indicate that individuals with high word intelligibility maintained LACP-Sp at or above 2 kPa and LACP-Max at or above 50 kPa.

Numerical Modeling of Mixed Lubrication and Flash Temperature in EHL Elliptical Contacts

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Neelesh Deolalikar ◽  
Farshid Sadeghi ◽  
Sean Marble
Keyword(s):  
Surface Deformation ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Lubrication Regime ◽  
Predicting Performance ◽  
Pure Rolling ◽  
Rolling Element ◽  
Contact Pressures ◽  
Film Lubrication

Highly loaded ball and rolling element bearings are often required to operate in the mixed elastohydrodynamic lubrication regime in which surface asperity contact occurs simultaneously during the lubrication process. Predicting performance (i.e., pressure, temperature) of components operating in this regime is important as the high asperity contact pressures can significantly reduce the fatigue life of the interacting components. In this study, a deterministic mixed lubrication model was developed to determine the pressure and temperature of mixed lubricated circular and elliptic contacts for measured and simulated surfaces operating under pure rolling and rolling/sliding condition. In this model, we simultaneously solve for lubricant and asperity contact pressures. The model allows investigation of the condition and transition from boundary to full-film lubrication. The variation of contact area and load ratios is examined for various velocities and slide-to-roll ratios. The mixed lubricated model is also used to predict the transient flash temperatures occurring in contacts due to asperity contact interactions and friction. In order to significantly reduce the computational efforts associated with surface deformation and temperature calculation, the fast Fourier transform algorithm is implemented.

Comparative Contact Analysis Study of Finite Element Method Based Deterministic, Simplified Multi-Asperity and Modified Statistical Contact Models

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
A. Megalingam ◽  
M. M. Mayuram
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Rough Surface ◽  
Contact Area ◽  
Model Analysis ◽  
Contact Model ◽  
Contact Load ◽  
Asperity Contact ◽  
Single Asperity ◽  
Contact Models

The study of the contact stresses generated when two surfaces are in contact plays a significant role in understanding the tribology of contact pairs. Most of the present contact models are based on the statistical treatment of the single asperity contact model. For a clear understanding about the elastic-plastic behavior of two rough surfaces in contact, comparative study involving the deterministic contact model, simplified multi-asperity contact model, and modified statistical model are undertaken. In deterministic contact model analysis, a three dimensional deformable rough surface pressed against a rigid flat surface is carried out using the finite element method in steps. A simplified multi-asperity contact model is developed using actual summit radii deduced from the rough surface, applying single asperity contact model results. The resultant contact parameters like contact load, contact area, and contact pressure are compared. The asperity interaction noticed in the deterministic contact model analysis leads to wide disparity in the results. Observing the elastic-plastic transition of the summits and the sharing of contact load and contact area among the summits, modifications are employed in single asperity statistical contact model approaches in the form of a correction factor arising from asperity interaction to reduce the variations. Consequently, the modified statistical contact model and simplified multi-asperity contact model based on actual summit radius results show improved agreement with the deterministic contact model results.

Prediction Reliability of Container Terminal Simulation Models

2010 ◽  
pp. 315-335
Author(s):  
Armando Cartenì
Keyword(s):  
Decision Support ◽  
Decision Support System ◽  
Support System ◽  
Optimization Problem ◽  
Container Terminal ◽  
Simulation Models ◽  
Large Set ◽  
Model Application ◽  
Before And After ◽  
Prediction Reliability

In this chapter attention is focused on the container terminal optimization problem, given that today most international cargo is transported through seaports and on containerized vessels. In this context, in order to manage a container terminal it is sometimes necessary to develop a Decision Support System (DSS). This chapter investigated the prediction reliability of container terminal simulation models (DSS), through a before and after analysis, taking advantage of some significant investment made by the Salerno Container Terminal (Italy) between 2003 and 2008. In particular, disaggregate and an aggregate simulation models implemented in 2003 were validated with a large set of data acquired in 2008 after some structural and functional terminal modifications. Through this analysis it was possible to study both the mathematical details required for model application and the field of application (prediction reliability) of the different simulation approaches implemented.

A complete elastic-plastic spherical asperity contact model with the effect of isotropic strain hardening

2020 ◽  
pp. 135065012092989 ◽  
Author(s):  
A Megalingam ◽  
KS Hanumanth Ramji
Keyword(s):  
Strain Hardening ◽  
Rough Surface ◽  
Contact Area ◽  
Poisson’S Ratio ◽  
Combined Effect ◽  
Contact Model ◽  
Poisson's Ratio ◽  
Contact Load ◽  
Asperity Contact ◽  
Strain Hardening Rate

Understanding the deformation behavior of rough surface contacts is essential to minimise the tribological consequences of contacts. Mostly, statistical, deterministic and fractal approaches are adopted to explore the contact of rough surfaces. In statistical approach, a single asperity contact model is developed and extended to the whole surface. In the present work, a deformable spherical asperity contact with a rigid flat is modeled and analysed by accounting the combined effect of Young’s modulus, Poisson’s ratio, yield strength and isotropic strain hardening rate using finite element method. The results reveal that the elastic, elastoplastic and plastic contact states are highly influenced by E/Y ratio and strain hardening rate followed by Poisson’s ratio. The dimensionless contact radius is an inadequate parameter to explore the combined effect of material properties. For all E/Y ratio and Poisson’s ratio, as the strain hardening rate increases, the dimensionless contact area decreases for the same dimensionless contact load at elastoplastic and fully plastic contact states. As the strain hardening rate increases, the fully plastic contact state is reached at low dimensionless interference compared to elastic perfectly plastic materials for all E/Y ratio and Poisson’s ratio. For a common elastic-plastic material, empirical relations are developed to calculate the contact load and contact area appropriately with E/Y ratio, Poisson’s ratio and interference ratio as input variables. It can be utilised to study the interaction of rough surface contacts for most of the practical materials.

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