Self-Excited Full-Vehicle Oscillations Caused by Tire–Road Interaction: Virtual and Real-World Experimental Investigation

2021 ◽  
Author(s):  
Dirk Engel
Keyword(s):  
Experimental Investigation ◽  
Real World ◽  
Tire Model ◽  
Multibody Simulation ◽  
Test Rig ◽  
Vehicle Modeling ◽  
Full Vehicle ◽  
Simulation Based ◽  
Tangential Forces ◽  
Footprint Area

ABSTRACT In this article, self-excited full-vehicle oscillations (power-hops) are introduced. Initially, results of full-vehicle measurements are shown followed by the presentation of a specially build test rig (longitudinal dynamics test rig). Subsequently, these oscillations are investigated by using simulation-based tools within multibody simulation–related full-vehicle modeling. Tire–road interaction is evaluated in this process either by characteristic curves or by a proprietary quasistatic tire model that returns overall tangential forces by evaluating the state of every discretized element within the footprint area.

Decoupling control of active suspension and four-wheel steering based on Backstepping-ADRC with mechanical elastic wheel

2021 ◽  
pp. 095440702110561
Author(s):  
Han Xu ◽  
Youqun Zhao ◽  
Qiuwei Wang ◽  
Fen Lin ◽  
Wei Pi
Keyword(s):  
Ride Comfort ◽  
Active Suspension ◽  
Extended State Observer ◽  
Decoupling Control ◽  
Tire Model ◽  
Extended State ◽  
Full Vehicle ◽  
Elastic Wheel ◽  
Yaw Stability ◽  
Mechanical Elastic Wheel

Mechanical elastic wheel (MEW) has the advantages of explosion-proof and prick-proof, which is conducive to the safety and maneuverability of the vehicle. However, the research on the performance of the full vehicle equipped with MEW is rare. Considering the particular properties of the radial and cornering stiffness of MEW, this paper aims to take into account both ride comfort and yaw stability of the vehicle equipped with the MEW through a nonlinear control method. Firstly, a 9-DOF nonlinear full vehicle model with the MEW tire model is constructed. The tire model is fitted based on experimental data, which corrects the impacts of vertical load on the cornering characteristic of the MEW. Then the full vehicle system is decoupled into four subsystems with a single input and a single output each according to active disturbance rejection control (ADRC) technology. In this process, the coupling relationship between different motions of the original system is regarded as the disturbance. Afterward, a novel nonlinear extended state observer is proposed, which has a similar structure of traditional linear extended state observer but smaller estimation error. Next, the control law of Backstepping-ADRC for different subsystems are derived respectively based on the Lyapunov theory. For the first time, the Backstepping-ADRC method is applied to the decoupling control of four-wheel steering and active suspension systems. Furthermore, the parameters of the controllers are adjusted through a multi-objective optimization scheme. Finally, simulation results validate the effectiveness and robustness of the proposed controller, especially when encountering some disturbances. The indices of vehicle body attitude and ride comfort are improved significantly, and also the yaw stability is guaranteed simultaneously.

Boosting branch-and-bound MaxSAT solvers with clause learning

2021 ◽  
pp. 1-21
Author(s):  
Chu-Min Li ◽  
Zhenxing Xu ◽  
Jordi Coll ◽  
Felip Manyà ◽  
Djamal Habet ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Combinatorial Optimization ◽  
Problem Solving ◽  
Branch And Bound ◽  
Real World ◽  
Optimization Problems ◽  
Satisfiability Problem ◽  
Maximum Satisfiability ◽  
Combinatorial Optimization Problems ◽  
Clause Learning

The Maximum Satisfiability Problem, or MaxSAT, offers a suitable problem solving formalism for combinatorial optimization problems. Nevertheless, MaxSAT solvers implementing the Branch-and-Bound (BnB) scheme have not succeeded in solving challenging real-world optimization problems. It is widely believed that BnB MaxSAT solvers are only superior on random and some specific crafted instances. At the same time, SAT-based MaxSAT solvers perform particularly well on real-world instances. To overcome this shortcoming of BnB MaxSAT solvers, this paper proposes a new BnB MaxSAT solver called MaxCDCL. The main feature of MaxCDCL is the combination of clause learning of soft conflicts and an efficient bounding procedure. Moreover, the paper reports on an experimental investigation showing that MaxCDCL is competitive when compared with the best performing solvers of the 2020 MaxSAT Evaluation. MaxCDCL performs very well on real-world instances, and solves a number of instances that other solvers cannot solve. Furthermore, MaxCDCL, when combined with the best performing MaxSAT solvers, solves the highest number of instances of a collection from all the MaxSAT evaluations held so far.

Surface Topography and Noise Emission in Gearboxes

1997 ◽  
Author(s):  
Naser Amini ◽  
B. G. Rosén
Keyword(s):  
Experimental Investigation ◽  
Total Energy ◽  
Surface Topography ◽  
Noise Generation ◽  
Test Rig ◽  
Noise Emission ◽  
Applied Torque ◽  
Surface Topographies ◽  
Before And After ◽  
Noise Assessment

Abstract This paper, by the experimental investigation, deals with the effect of different surface topographies on noise generation in gears. Results from the noise assessment of one gear before and after honing are discussed. The honing operation was applied to the gear after the grinding. The gear was tested in an actual gearbox, operated in a test rig. Running conditions were systematically changed during the test; however, the same conditions were utilized for the gear before and after honing. The aim of the study was to identify the mechanism of the expected noise reduction, with surfaces being evaluated in 3D. The following results have been obtained: The total energy in the noise decreases significantly. The magnitude of the tooth-mesh frequency dose not change, but the level of its higher harmonics decreases significantly. These reductions are especially significant, when running at higher rotational speeds or when the applied torque is increased.

Learning Scrum

2021 ◽  
pp. 169-189
Author(s):  
Simon Bourdeau ◽  
Alejandro Romero-Torres ◽  
Marie-Claude Petit
Keyword(s):  
Data Collection ◽  
Software Development ◽  
Real World ◽  
Learning Experience ◽  
Project Managers ◽  
Development Projects ◽  
Simulation Based ◽  
Realistic Representation ◽  
Learn By Doing ◽  
Agile Approach

The LEGO®-Scrum simulation-based training (SBT) described here shows how LEGO® bricks can help professionals learn first-hand about Scrum methodology, an Agile approach to software development projects. The chapter's objectives are 1) to present the modalities of the LEGO®-Scrum SBT, 2) to demonstrate how LEGO® bricks can help professionals learn, first-hand, about Scrum, and 3) to illustrate how this learning can be relevant and impactful for participants. Based on observations, interviews, and a data collection by questionnaire carried out with 198 participants, the proposed SBT appears to provide a significant, relevant, and valuable learning experience. In addition, four experienced Scrum masters and IT project managers, who played key roles in the SBT, argued that the LEGO®-Scrum SBT provides a realistic representation of real-world Scrum projects; that it is dynamic, complex, challenging, and motivating; and that participants' learning is evocative and relevant, since they learn by doing.

scholarly journals Tire Model with Temperature Effects for Formula SAE Vehicle

2019 ◽  
Vol 9 (24) ◽  
pp. 5328 ◽  
Author(s):  
Diwakar Harsh ◽  
Barys Shyrokau
Keyword(s):  
Steady State ◽  
Measurement Data ◽  
Transient Behavior ◽  
Lateral Acceleration ◽  
Tire Model ◽  
Magic Formula ◽  
Vehicle Simulation ◽  
Formula Sae ◽  
Full Vehicle ◽  
Design Competition

Formula Society of Automotive Engineers (SAE) (FSAE) is a student design competition organized by SAE International (previously known as the Society of Automotive Engineers, SAE). Commonly, the student team performs a lap simulation as a point mass, bicycle or planar model of vehicle dynamics allow for the design of a top-level concept of the FSAE vehicle. However, to design different FSAE components, a full vehicle simulation is required including a comprehensive tire model. In the proposed study, the different tires of a FSAE vehicle were tested at a track to parametrize the tire based on the empirical approach commonly known as the magic formula. A thermal tire model was proposed to describe the tread, carcass, and inflation gas temperatures. The magic formula was modified to incorporate the temperature effect on the force capability of a FSAE tire to achieve higher accuracy in the simulation environment. Considering the model validation, the several maneuvers, typical for FSAE competitions, were performed. A skidpad and full lap maneuvers were chosen to simulate steady-state and transient behavior of the FSAE vehicle. The full vehicle simulation results demonstrated a high correlation to the measurement data for steady-state maneuvers and limited accuracy in highly dynamic driving. In addition, the results show that neglecting temperature in the tire model results in higher root mean square error (RMSE) of lateral acceleration and yaw rate.

A disc to air heat flux error and uncertainty analysis applied to a turbomachinery test rig design

2008 ◽  
Vol 223 (3) ◽  
pp. 659-674 ◽  
Author(s):  
A Cooke ◽  
P Childs ◽  
N Sayma ◽  
C A Long
Keyword(s):  
Heat Flux ◽  
Uncertainty Analysis ◽  
Inverse Analysis ◽  
Heat Fluxes ◽  
Bias Error ◽  
Test Rig ◽  
Care Needs ◽  
Disc Surface ◽  
Simulation Based ◽  
Study Heat Transfer

This article describes a Monte Carlo simulation-based error and an uncertainty analysis for values of disc to air heat fluxes as part of the design of an experimental axial turbine test rig. This work is of interest for those who study heat transfer and measurement or the design and use of experimental test rigs. An inverse analysis of theoretical disc surface temperatures was performed for different thermocouple configurations to compare the errors and uncertainties resulting from each to establish whether there was any configuration that would return the lowest magnitudes of error and uncertainty and hence influence the location of the proposed instrumentation. It is shown that great care needs to be taken when using an analysis of this kind together with temperature measurements having realistic and typical uncertainty values. This is because such an analysis is purely analytical, and any small fluctuations in the inputs, such as typical thermocouple uncertainties and noise, result in the process of an inverse analysis becoming unstable. This instability has two effects: (a) the returned values of heat flux have an inbuilt bias error and (b) the magnitudes of uncertainty can exceed>100 per cent.

Experimental Investigation on Marine Main Shaft Bearings With Reduced Length to Diameter Ratio

2010 ◽  
Author(s):  
Wojciech Litwin
Keyword(s):  
Experimental Investigation ◽  
Working Conditions ◽  
Hydrodynamic Pressure ◽  
Diameter Ratio ◽  
Main Shaft ◽  
Test Rig ◽  
The Past ◽  
Flexible Support ◽  
Shaft Misalignment ◽  
Significant Bearing

Water lubricated bearings are often installed on new and modernized ships. The main reasons are: unit simplicity, no danger of pollution and low price. One of the main problems connected with this the bearings of this kind is defining maximum hydrodynamic film capacity. Due to very thin hydrodynamic film and significant bearing bush deformation, the EHL model should be used for calculations. Experimental research conducted in the past was carried out on a single bearing test rig [1, 2, 3]. Unfortunately that test rig has some disadvantages. Its flexible support gives possibility of shaft misalignment for instance in case of asymmetric hydrodynamic pressure film in the bearing. The new test rig, presented in this paper gives wide research possibilities and working conditions are very similar to those on a real ship.

Experimental Investigation of the Flow-Induced Vibrations of a Rod Cluster Control Assembly Inside Guides With Enlarged Gaps

2019 ◽  
Author(s):  
Pierre Moussou ◽  
Vincent Fichet ◽  
Luc Pastur ◽  
Constance Duhamel ◽  
Yannick Tampango
Keyword(s):  
Experimental Investigation ◽  
Flow Velocity ◽  
Nuclear Power ◽  
Axial Flow ◽  
Fretting Wear ◽  
Pressurized Water Reactor ◽  
Test Rig ◽  
Pressurized Water ◽  
Control Assembly ◽  
Control Rods

Abstract In order to better understand the mechanisms of fretting wear damage of guide cards in some Pressurized Water Reactor (PWR) Nuclear Power Plant (NPP), an experimental investigation is undertaken at the Magaly facility in Le Creusot. The test rig consists of a complete Rod Cluster with eleven Guide Cards, submitted to axial flow inside a water tunnel. In order to mimic the effect of fretting wear, the four lower guide cards have enlarged gaps, so that the Control Rods are free to oscillate. The test rig is operated at ambient temperature and pressure, and Plexiglas walls can be arranged along its upper part, and a series of camera records the vibrations of the control rods above and below the guide cards. The vertical flow velocity is in the range of a few m/s. Beam-like pinned-pinned modes at about 5 Hz are observed, and oscillations of several mm of the central rods are measured, which come along with impacts at the higher flow velocities. A simple non-linear calculation reveals that the main effect of the impacts between Control Rods and Guide Cards is an increase of the natural frequency of the rods by about 10%. Furthermore, as the vibration spectra collapse remarkably well with the flow velocity, the experiments prove that turbulent forcing is responsible for the large oscillations of the control rods, no other mechanism being involved.

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