scholarly journals Study on Friction in Automotive Shock Absorbers Part 2: Validation of Friction Simulations via Novel Single Friction Point Test Rigs

Vehicles ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 197-211
Author(s):  
Ludwig Herzog ◽  
Klaus Augsburg
Keyword(s):  
Ride Comfort ◽  
Viscous Friction ◽  
Friction Model ◽  
Operating Conditions ◽  
Model Parameters ◽  
Friction Modeling ◽  
Friction Behavior ◽  
General Applicability ◽  
Reliable Determination ◽  
Shock Absorbers

The most important change in the transition from partial to high automation is that the vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorbers with two friction types. The intended viscous friction dissipates the chassis’ vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In the current article, the simulation approach introduced in part 1 of this study is validated against a single friction point and full damper friction measurements. To achieve that, a friction measurement method with novel test rigs has been developed, which allows for reliable determination of the friction behavior of each single friction point, while appropriately resembling the operating conditions of the real damper. The subsequent presentation of a friction simulation using friction model parameters from different geometry shows the general applicability of the overall friction investigation methodology. Accordingly, the presented simulation and measurement approaches enable the investigation of dynamic friction in automotive shock absorbers with significantly increased development efficiency.

scholarly journals Study on Friction in Automotive Shock Absorbers Part 1: Friction Simulation Using a Dynamic Friction Model in the Contact Zone of an FEM Model

Vehicles ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 212-232
Author(s):  
Ludwig Herzog ◽  
Klaus Augsburg
Keyword(s):  
Ride Comfort ◽  
Viscous Friction ◽  
Simulation Method ◽  
Friction Model ◽  
Model Parameters ◽  
Dynamic Friction ◽  
Friction Modeling ◽  
Shock Absorbers ◽  
Operation Conditions ◽  
Wide Range

The important change in the transition from partial to high automation is that a vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorber with two friction types: The intended viscous friction dissipates the chassis vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In this article, a simulation approach is introduced to model damper friction based on the most friction-relevant parameters. Since damper friction is highly dependent on geometry, which can vary widely, three-dimensional (3D) structural FEM is used to determine the deformations of the damper parts resulting from mounting and varying operation conditions. In the respective contact zones, a dynamic friction model is applied and parameterized based on the single friction point measurements. Subsequent to the parameterization of the overall friction model with geometry data, operation conditions, material properties and friction model parameters, single friction point simulations are performed, analyzed and validated against single friction point measurements. It is shown that this simulation method allows for friction prediction with high accuracy. Consequently, its application enables a wide range of parameters relevant to damper friction to be investigated with significantly increased development efficiency.

Parameter Identification of LuGre Friction Model: Experimental Set-up Design and Measurement

2015 ◽  
Author(s):  
Yun-Hsiang Sun ◽  
Tao Chen ◽  
Cyrus Shafai
Keyword(s):  
High Performance ◽  
Controller Design ◽  
Measurement Procedure ◽  
Friction Model ◽  
Operating Conditions ◽  
Dynamic Friction ◽  
Friction Modeling ◽  
Friction Behavior ◽  
Wide Range ◽  
Set Up

This work proposes a simple but general experimental approach including the rig design and measurement procedure to carry out a wide range of experiments required for identifying parameters for LuGre dynamic friction model. The design choice is based on accuracy of the estimated friction and flexibility in terms of changing contact conditions. The experimental results allow a complete LuGre model, which facilitates, but not limited to, other advanced friction modeling and high performance controller design if needed. In addition, several well-known dynamic friction features (varying break-away force, friction lag and presliding) are successfully demonstrated by our rig, which indicates the adequacy of our approach for capturing highly sophisticated and dynamic friction behavior over a wide range of operating conditions. The proposed set-up and the produced experimental data are believed to greatly facilitate the development of advanced friction compensation and modeling in friction affected mechanisms.

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.

Nonlinear Normal Modes and the LuGre Friction Model Parameter Identification

2014 ◽  
Author(s):  
Abdallah Hadji ◽  
Njuki Mureithi
Keyword(s):  
Contact Region ◽  
Signal Reconstruction ◽  
Superposition Principle ◽  
Harmonic Balance Method ◽  
Friction Model ◽  
Contact Forces ◽  
Fourier Series Expansion ◽  
Model Parameters ◽  
Harmonic Forms ◽  
Friction Behavior

A Hybrid friction model has recently been developed by Azizian and Mureithi [1] to simulate the general friction behavior between surfaces in contact. However, identification of the model parameters remains an unresolved problem. To identify the parameters of the friction model, the following quantities are required: contact forces (friction and impact forces), the slip velocity and displacement in the contact region. Direct measurement of these quantities is difficult. In the present work, a beam clamped at one end and simply supported with the consideration of friction effect at the other is used as a mechanical amplifier of the friction effects at the microscopic level. Using this simplified approach, the contact forces, the sliding velocity and the displacement can be indirectly obtained by measuring the beam vibration response. A new method based on nonlinear modal analysis to calculate the contact forces is developed in the present work. The method is based on the modal superposition principle and Fourier series expansion. For the harmonic balance method, two approaches were tested. The approach based on sub-harmonic forms gave the best results. Signal reconstruction made it possible to accurately identify the parameters of the hybrid friction model with a multiple step approach.

Independent Identification of Friction Characteristics for Parallel Manipulators

2006 ◽  
Vol 129 (3) ◽  
pp. 294-302 ◽  
Author(s):  
Houssem Abdellatif ◽  
Martin Grotjahn ◽  
Bodo Heimann
Keyword(s):  
Steady State ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Friction Model ◽  
Rigid Body Dynamics ◽  
Model Parameters ◽  
Friction Modeling ◽  
Friction Characteristics ◽  
Experimental Identification ◽  
Kinematic Coupling

The compensation for friction or joint losses in robotic manipulators contributes to an important improvement of the control quality. Besides appropriate friction modeling, experimental identification of the model parameters is fundamental toward better control performance. Conventionally steady-state friction characteristics are investigated for mechanical systems in the first step. However, and due to the high kinematic coupling, such procedure is already complicated for complex multiple closed-loop mechanisms, like parallel manipulators. Actuation friction of such mechanisms becomes configuration dependent. This paper presents a methodology that deals with such challenge. The kinematic coupling is regarded in the friction model and therefore in the design of the experimental identification. With the proposed strategy, it is possible to identify the steady-state friction parameters independently from any knowledge about inertial or rigid-body dynamics. Friction models for sensorless passive joints can also be provided. Besides, the method is kept very practical, since there is no need for any additional hardware devices or interfaces than a standard industrial control. The suitability for the industrial field is proven by experimental application to PaLiDA that is a six degrees of freedom parallel manipulator equipped with linear directly driven actuators.

scholarly journals Nonlinear Frictional Dynamics on Rolling Contact

2020 ◽  
Author(s):  
Yasunori Sakai
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Friction Model ◽  
Rolling Contact ◽  
Nonlinear Friction ◽  
Friction Modeling ◽  
Friction Behavior ◽  
Machine Element ◽  
Linear Friction ◽  
Rolling Elements

The rolling machine element is indispensable for realizing high-precision and high-speed relative motion. In addition, its positioning accuracy is approaching the nanometer order, and its importance is expected to increase in the future. However, since the rolling elements and the raceways are mechanically in contact, various nonlinear phenomena occur. This complicated phenomenon must be clear by theoretically and experimentally. This chapter describes the nonlinear friction behavior occurred with rolling contact condition and its effect on the dynamics of bearings. First, the characteristics of the non-linear friction caused by rolling machine elements and the nonlinear friction modeling method using the Masing rule are described. From the numerical analysis using the friction model, it is clarified that the motion accuracy decreases due to sudden velocity variation caused by nonlinear friction. Also, the author show that the resonance phenomenon and force dependency of the dynamic characteristics of rolling machine element due to the nonlinear friction. Finally, the author indicates nonlinear friction influences on the dynamic characteristics in the directions other than the feed direction.

Friction Modeling of a Free-Spinning Bicycle Wheel

2003 ◽  
Author(s):  
Shuguang Huang ◽  
Mark Nagurka
Keyword(s):  
Dry Friction ◽  
Time History ◽  
Viscous Friction ◽  
Angular Speed ◽  
Friction Model ◽  
Wheel Speed ◽  
Friction Modeling ◽  
Free Standing ◽  
Two Phases ◽  
Bicycle Wheel

An experiment is conducted in which a free-standing bicycle wheel is given an initial angular speed and then allowed to slow down to rest. Measurements of the wheel speed, using a magnetic sensor, during the decay are compared to predictions from a model accounting for a combination of viscous and dry friction at the wheel bearing. The time history data indicate two dynamic regimes: (i) a higher speed phase corresponding to the first part of the motion for which a simple viscous friction model applies, and (ii) a slower speed phase corresponding to low speed to stop behavior for which a model involving both viscous and dry friction is proposed. A method is presented for finding the viscous and dry friction coefficients of the two phases.

Feasibility Study for the Identification of FTire Model Parameters Using FE Simulations

2017 ◽  
Vol 45 (3) ◽  
pp. 200-226 ◽  
Author(s):  
Zheng Zhou ◽  
Wang Guolin ◽  
Liang Chen ◽  
Yang Jian ◽  
Li Kaiqiang
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Friction Model ◽  
Operating Conditions ◽  
Model Parameters ◽  
Fe Model ◽  
Vertical Stiffness ◽  
User Subroutine ◽  
Fe Simulations ◽  
Geometry Measurement

ABSTRACT Normally, FTire model parameters are determined by experimental tests. However, because of the high cost of experiment equipment and limitations in rig design and operating conditions, it is hard to obtain all the required data by experimental tests, especially for some large tires, such as the running wheel tires of straddle-type monorail vehicles. To solve this problem, a method based on finite element (FE) simulations is put forward. To achieve the goal, a three-dimensional FE model of a 345/85R16 radial tire is developed using ABAQUS software. In addition, a modified exponential decay friction model, derived from tire tread rubber friction tests, is put forward and applied in the following FE simulations using the ABAQUS user subroutine FRIC. To verify the accuracy of the present model, tire vertical stiffness test, lateral stiffness test, and tire contour geometry measurement are designed. Through the comparison of measurements and FE simulations, it turns out that the model is capable of predicting tire properties accurately. Tire static, steady-state, modal, and dynamic cleat tests are modeled. Finally, data such as vertical stiffness, cornering stiffness, and natural frequencies are derived from FE simulations. Based on the data derived from FE simulations, the FTire model parameters are identified and then validated by comparing the force responses of the FTire simulation in the ADAMS/Tire test rig and FE simulations. The results show that there is an acceptable agreement between them, reflecting that the method is feasible.

scholarly journals Experimental investigation of friction behavior in pre-sliding regime for pneumatic cylinder

2014 ◽  
Vol 36 (4) ◽  
pp. 283-290
Author(s):  
Tran Xuan Bo ◽  
Pham Tat Thang ◽  
Do Thanh Cong ◽  
Ngo Sy Loc
Keyword(s):  
Friction Force ◽  
Friction Model ◽  
Operating Conditions ◽  
Experimental Results ◽  
Hysteretic Behavior ◽  
Pneumatic Cylinder ◽  
Experimental Investigations ◽  
Friction Behavior ◽  
Piston Displacement ◽  
Pneumatic Cylinders

Friction always presents in pneumatic cylinders and causes difficulties in controlling position and velocity of pneumatic systems. In order to improve the control performance of the pneumatic systems, it is necessary to fully understand behavior of friction in the pneumatic cylinders. So far, dynamic friction behavior of pneumatic cylinders has been investigated but mainly focused on the friction behavior in sliding regime. In pre-sliding regime, friction behavior has not been investigated. In this paper, experimental investigations of friction behavior of a pneumatic cylinder in pre-sliding regime are made. The friction force is calculated from the equation of motion of the piston using the measured values of pressures in the two cylinder chambers and the piston displacement. The pressures are controlled by using two proportional pressure control valve. The friction force versus piston displacement characteristics are measured and analysed under various operating conditions of the applied force and the pressures. Experimental results show that: i) the piston motion in pre-sliding regime exhibits a nonlinear spring behavior; ii) hysteretic behavior with nonlocal memory is verified; iii) the pressures have influence only on the size of the hysteretic loop. These experimental results can be applied to develop a friction model for pneumatic cylinders.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

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