A New Test Bench for Friction Measurements and the Evolution of the Lugre Model to the Frozen Model

2009 ◽  
Author(s):  
J. L. Dion ◽  
G. Chevallier ◽  
O. Penas ◽  
N. Peyret
Keyword(s):  
Test Bench ◽  
Large Range ◽  
Measurement Techniques ◽  
Excitation Frequency ◽  
Parametric Identification ◽  
Lugre Model ◽  
Friction Forces ◽  
Dynamic Excitation ◽  
Accuracy Of Measurements ◽  
Friction Measurements

After a description of existing experimental methods and models built on the dynamic behavior of friction forces between two solids, this paper presents an original new test bench and specific measurement techniques used to better define the accuracy of measurements. This test bench has been designed for a large range of tests in terms of static strain, dynamic excitation, frequency and kinds of surfaces. The second part describes the choice of the model which is a development of the Lugre model we have called “Frozen” Model. Methods for parametric identification are proposed and comparisons between experiments and simulations are presented. In the third part a critical analysis is carried out on the test bench and its applications. (This paper is a part of a study on the prediction of vibration level of space launchers - Ariane V program). A parametrical analysis was conducted to lead and conclude a study on the robustness of the chosen model.

On the Application of the Lu-Gre Model to Simulate Joint Friction in Multi-Body Systems

2011 ◽  
Author(s):  
Kedar Gajanan Kale ◽  
Rajiv Rampalli
Keyword(s):  
Friction Model ◽  
Lugre Model ◽  
Friction Forces ◽  
Joint Friction ◽  
Modeling Techniques ◽  
Static Regime ◽  
Increasing Demand ◽  
Automotive Suspension ◽  
Multi Body

Advances in the application of multi-body simulation technology to real world problems have led to an ever increasing demand for higher fidelity modeling techniques. Of these, accurate modeling of friction is of strategic interest in applications such as control system design, automotive suspension analysis, robotics etc. Joints (sometimes referred to as constraints) play an important role in defining the dynamics of a multi-body system. Hence, it is imperative to accurately account for friction forces arising at these joints due to the underlying interface dynamics. In this paper, we discuss the application of LuGre, a dynamic friction model to simulate joint friction. We choose the LuGre model due to its ability to capture important effects such as the Stribeck effect and the Dahl effect. The native 1-d LuGre model is extended to formulate friction computations for non-trivial joint geometries and dynamics in 2 and 3 dimensions. It is also extended to work in the quasi-static regime. Specific applications to revolute, cylindrical and spherical joints in multi-body systems are discussed. Finally, an engineering case study on the effects of joint friction in automotive suspension analysis is presented.

scholarly journals Identification of factors influencing insertion characteristics of cochlear implant electrode carriers

2019 ◽  
Vol 5 (1) ◽  
pp. 441-443
Author(s):  
Silke Hügl ◽  
Nina Aldag ◽  
Thomas Lenarz ◽  
Thomas S. Rau ◽  
Alexander Becker ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Test Bench ◽  
Time Interval ◽  
Dynamic Force ◽  
Friction Forces ◽  
Factors Influencing ◽  
Constant Diameter ◽  
Constant Radius ◽  
Force Components ◽  
Insertion Process

AbstractInsertion studies in artificial cochlea models (aCM) are used for the analysis of insertion characteristics of different cochlear implant electrode carrier (EC) designs by measuring insertion forces. These forces are summed forces due to the measuring position which is directly underneath the aCM. The current hypothesis is that they include dynamic friction forces during the insertion process and the forces needed to bend an initially straight EC into the curved form of the aCM. For the purposes of the present study, straight EC substitutes with a constant diameter of 0.7 mm and 20.5 mm intracochlear length were fabricated out of silicone in two versions with different stiffness by varying the number of embedded wires. The EC substitutes were inserted into three different models made of polytetrafluoroethylene (PTFE), each model showing only one constant radius. Three different insertion speeds were used (0.11 / 0.4 / 1.6 mm/s) with an automated insertion test bench. For each parameter combination (curvature, speed, stiffness) twelve insertions were conducted. Measurements included six full insertions and six paused insertions. Paused insertions include a ten second paused time interval without further insertion movement each five millimetres. Measurements showed that dynamic and static components of the measured summed forces can be identified. Dynamic force components increase with increased insertion speeds and also with increased stiffness of the EC substitutes. Both force components decrease with larger radius of the PTFE model. After the insertion, the EC substitutes showed a curved shape, which indicates a plastic deformation of the embedded wires due to the insertion into the curved models. The results can be used for further research on an analytical model to predict the insertions forces of a specific combination of selected parameters as insertion speed and type of EC, combined with given factors such as cochlear geometry.

Optimum Design of Engine Test Bench Based on Finite Element Analysis

2011 ◽  
Vol 338 ◽  
pp. 255-258 ◽  
Author(s):  
Shao Bo Wen
Keyword(s):  
Test Bench ◽  
Excitation Frequency ◽  
Three Dimensional ◽  
Natural Vibration Frequency ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Vehicle Engine ◽  
Stress And Deformation ◽  
The Stability ◽  
Engine Excitation

A test bench of vehicle engine is designed and the three-dimensional solid model is established in UG software. Then the model is imported into ANSYS software to conduct static stress analysis, the stress and deformation distribution of test bench are obtained, referenced the results and the bracket are optimized to improve support ability, the maximum stress and the maximum displacement of test bench decreased 66.9% and 76.9%, respectively. Lastly modal analysis of test bench is performed, the chassis base is strengthen design according to the first-order mode shape, then the first natural vibration frequency is heightened 91.0%, it is far away from the engine excitation frequency range, the stability of test bench is enhanced.

Acoustoelastic-Based Stress Measurement Utilizing Low-Frequency Flexural Waves

2017 ◽  
Author(s):  
Mohammad I. Albakri ◽  
Vijaya V. N. Sriram Malladi ◽  
Pablo A. Tarazaga
Keyword(s):  
Stress Measurement ◽  
Measurement Techniques ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Lower Sensitivity ◽  
Flexural Waves ◽  
Dispersive Waves ◽  
High Frequencies ◽  
Geometric Uncertainties ◽  
The Cost

Current acoustoelastic-based stress measurement techniques operate at the high-frequency, weakly-dispersive portions of the dispersion curves. The weak dispersive effects at such high frequencies allow the utilization of time-of-flight measurements to quantify the effects of stress on wave speed. However, this comes at the cost of lower sensitivity to the state-of-stress of the structure, and hence calibration at a known stress state is required to compensate for material and geometric uncertainties in the structure under test. In this work, the strongly-dispersive, highly stress-sensitive, low-frequency flexural waves are utilized for stress measurement in structural components. A new model-based technique is developed for this purpose, where the acoustoelastic theory is integrated into a numerical optimization algorithm to analyze dispersive waves propagating along the structure under test. The developed technique is found to be robust against material and geometric uncertainties. In the absence of calibration experiments, the robustness of this technique is inversely proportional to the excitation frequency. The capabilities of the developed technique are experimentally demonstrated on a long rectangular beam, where reference-free, un-calibrated stress measurements are successfully conducted.

Dynamics Modeling of Nanoparticle in AFM-Based Manipulation Using Two Nanoscale Friction Models

2009 ◽  
Author(s):  
Hesam Babahosseini ◽  
Seyed Hanif Mahboobi ◽  
Ali Meghdari
Keyword(s):  
Normal Force ◽  
Dynamics Modeling ◽  
Lugre Model ◽  
Stick Slip ◽  
Interaction Forces ◽  
Friction Forces ◽  
Lumped Model ◽  
Atomic Force ◽  
Friction Models ◽  
Afm Probe

Application of atomic force microscope (AFM) as a manipulator for pushing-based positioning of nanoparticles has been of considerable interest during recent years. Nevertheless comprehensive researches has been done on modeling and the dynamics analysis of nanoparticle behavior during the positioning process. The development of dynamics modeling of nanoparticle is crucial to have an accurate manipulation. In this paper, a comprehensive model of pushing based manipulation of a nanoparticle by AFM probe is presented. The proposed nanomanipulation model consists of all effective phenomena in nanoscale. Nanoscale interaction forces, elastic deformation in contact areas and friction forces in tip/particle/substrate system are considered. These effects are utilized to derive governing dynamics of the lumped model of AFM and nanoparticle during the manipulation process. The utilized friction models are a modified Coulomb approach and Lund-Grenoble (LuGre) model. The former is a combination of both normal force and contact surface area. The latter is dependent on the velocity of the nanoparticle and leads to stick-slip behavior of the nanoparticle. Finally, the compatibility and effectiveness of the two proposed models are simulated and compared.

Nonlinear Modeling and Experimental Validation of Uni-Axial Servo-Hydraulic Shaking Table

2016 ◽  
Author(s):  
Paolo Righettini ◽  
Roberto Strada ◽  
Shirin Valilou ◽  
Ehsan Khademolama
Keyword(s):  
High Performance ◽  
Nonlinear Modeling ◽  
Least Square Method ◽  
Hydraulic Cylinder ◽  
Difficult Problem ◽  
Least Square ◽  
Shaking Table ◽  
Lugre Model ◽  
Friction Forces ◽  
Friction Models

An effective way for the testing of a large number of systems is using single and multi-axis shaking tables. Among the possible applications, the civil engineering field stands out for the testing of structures, or part of them, both on a reduced and on a full scale. However, design a high performance controller for a servo-hydraulic shaking table is a difficult problem due to its non-linarites and large friction forces. The goal of this paper is to develop and experimentally validate a robust numerical model that simulates the acceleration behavior of a uni-axial servo-hydraulic shaking table system with considering three friction models, the LuGre model, the modified LuGre model and the new modified LuGre model. First, a full system model of servo-hydraulic system is developed based on fluid mechanical expressions and then the friction force of hydraulic cylinder is modeled and validated on the real shaking table. Data of the experiment are gathered from input command valve, and the output acceleration and position of the table. All models are simulated by using MATLAB and SIMULINK computer program. The parameters of the system and the friction models are estimated by using least square method (LSM). Finally, the comparisons of simulated results with experimental ones show that the model of the system with considering third model of the friction can predict accurately the shaking table’s behaviors.

INVESTIGATION OF THE DYNAMICS OF THE ELASTIC-MASS SYSTEM OF THE MOBILE HEARTH OF AN ELECTRIC KILN FOR FIRING THERMALLY ACTIVATED MATERIALS

2020 ◽  
Author(s):  
Anatoliy Nizhegorodov ◽  
Aleksey Gavrilin ◽  
Boris Moyzes ◽  
Georgiy Odnokopylov ◽  
G. Izmalov
Keyword(s):  
Elastic Element ◽  
Thermal Field ◽  
Bulk Material ◽  
Excitation Frequency ◽  
Heating System ◽  
Strong Nonlinearity ◽  
Mass System ◽  
Friction Forces ◽  
Thermally Activated ◽  
Horizontal Arrangement

In article results of research of properties elastic element platform furnace with a movable hearth, the analytical model of motion, characterized by sloping skeletal curve of its amplitude-frequency characteristics. The study of the dynamics of elastic-mass system of the platform with unilateral elastic element in the form of a flattened elastic ring that provides her a strong nonlinearity, it is confirmed that the system does not symmetrical oscillation with peak acceleration values of 5.17 and 1.17 m/S2, corresponding to the extreme provisions of the different platform and four and a half times. It is shown that the horizontal arrangement of the movable hearth of the furnace significantly reduces the sensitivity of its vibrations to changes in the excitation frequency, spring stiffness, friction forces, and other factors that change due to the influence of high temperature and external environmental factors. The effect of vibration transport of bulk material along the horizontal surface of the mobile hearth of the furnace platform in the thermal field of its heating system is confirmed.

Pavement Friction Modeling using Texture Measurements and Pendulum Skid Tester

2018 ◽  
Vol 2672 (40) ◽  
pp. 440-451 ◽  
Author(s):  
Ahmad Alhasan ◽  
Omar Smadi ◽  
Georges Bou-Saab ◽  
Nacu Hernandez ◽  
Eric Cochran
Keyword(s):  
Surface Texture ◽  
Friction Model ◽  
Operating Conditions ◽  
Friction Modeling ◽  
Friction Forces ◽  
Frictional Behavior ◽  
Kinetic Coefficients ◽  
Friction Measurements ◽  
The Impact ◽  
Pavement Friction

Pavement frictional behavior affects pavement performance in terms of vehicle safety, fuel consumption, and tire wear. Comprehending and interpreting pavement friction measurements is a challenging task, because of friction sensitivity to several uncontrollable factors. These factors include: pavement surface conditions, such as the type and thickness of contaminants and fluids on the surface and their interaction with friction forces; and the device operating conditions, such as sliding speed, material properties and geometry of the rubber slider used, and operating temperature. Despite the efforts to describe and quantify the impact of varying conditions on pavement friction, which ultimately will allow for a better harmonization of friction measurements, there is a need to better understand the link between the surface texture and physical friction measurements. In this paper, Persson’s friction model is used to analyze and understand the impact of surface texture on frictional behavior of dry pavement surfaces. The model was used to analyze 18 test locations, which were compared with the dry kinetic coefficients of friction (COF) estimated using a British pendulum tester (BPT). The results show that Persson’s friction model could predict the COF estimated from the BPT results with relatively high accuracy. In addition, the model could provide a profound explanation of the frictional forces mechanism. Finally, it was found that the mean profile depth (MPD) cannot provide a full picture of the frictional behavior. However, combining MPD with the Hurst exponent, texture measurements can potentially provide a full physical explanation of the frictional behavior for road surfaces.

Dynamic Friction Measurements on a Small Engine Test Bench

2015 ◽  
Author(s):  
Kevin P. Horn ◽  
Alex K. Rowton ◽  
Marc D. Polanka ◽  
Joseph Ausserer ◽  
Paul J. Litke ◽  
...  
Keyword(s):  
Test Bench ◽  
Dynamic Friction ◽  
Engine Test ◽  
Engine Test Bench ◽  
Friction Measurements

Direct Full Surface Skin Friction Measurement Using Nematic Liquid Crystal Techniques

1998 ◽  
Vol 120 (4) ◽  
pp. 847-853 ◽  
Author(s):  
D. R. Buttsworth ◽  
S. J. Elston ◽  
T. V. Jones
Keyword(s):  
Mathematical Model ◽  
Liquid Crystal ◽  
Skin Friction ◽  
Nematic Liquid Crystal ◽  
Measurement Techniques ◽  
Surface Measurement ◽  
Calibration Data ◽  
Surface Shear Stress ◽  
Orientation Technique ◽  
Friction Measurements

New techniques for the direct measurement of skin friction using nematic liquid crystal layers are demonstrated. Skin friction measurements can be made using a molecular rotation time technique or an equilibrium orientation technique. A mathematical model describing the molecular dynamics of the nematic liquid crystal layer has been introduced. Theoretical results from the proposed mathematical model are in excellent agreement with the current experimental measurements. It is thus demonstrated that the present model captures the essential physics of the nematic liquid crystal measurement techniques. Estimates based on the variance of the liquid crystal calibration data indicate that skin friction measurements to within ±4 percent should certainly be possible. The techniques offer the considerable advantage of simplicity, without any compromise on the accuracy, relative to other surface shear stress measurement techniques. The full surface measurement capacity of the equilibrium orientation technique is demonstrated by measuring the skin friction distribution around a cylindrical obstruction in a fully developed laminar flow.

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