DOCSLIB.ORG

Suspension Stiffness

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Suspension Stiffness 1 of 39 Determination of anti-pitch geometry – acceleration [1/3] • Similar to anti-squat • Opposite direction of D’Alembert’s forces. Front wheel forces and effective pivot locations Figure from Smith,2002 2 of 39 Determination of anti-pitch geometry – acceleration [2/3] It follows that the change in the front spring force is: where kf = front suspension stiffness. Similarly for the rear wheels. 3 of 39 Determination of anti-pitch geometry – acceleration [3/3] Pitch angle • Zero pitch occurs when θ = 0, i.e. when the term in square brackets is zero. • anti-squat and anti-pitch performance depends on the following vehicle properties – – suspension geometry, – suspension stiffnesses (front and rear) and – Tractive force distribution. 4 of 39 Lateral load transfer during cornering Notation and assumptions in the analysis are: • G is the sprung mass centre of gravity; • The transverse acceleration at G due to cornering is ‘a’; • The sprung mass rolls through the angle φ about the roll axis; • The centrifugal (inertia) force on the sprung mass msa acts horizontally through G; • The gravity force on the sprung mass msg acts vertically downwards through G; • The inertia forces mufa and mura act directly on the unsprung masses at the front and rear axles. Each transfers load only between its own pair of wheels. Steady-state cornering analysis Figure from Smith,2002 5 of 39 Load transfer due to the roll moment [1/2] Replace the two forces at G with the same forces at A plus a moment (the roll moment) Ms about the roll axis, i.e Assuming linear relationship between Mφ and φ Mφ = ksφ ks = total roll stiffness 6 of 39 Load transfer due to the roll moment [2/2] ksf + ksr = ks • Load transfer sin two axles are • Tf and Tr are the front and rear track widths of the vehicle 7 of 39 Load transfer due to sprung mass inertia force The sprung mass is distributed to the roll centers at front and rear axles. Centrifugal force distribution is Corresponding load transfers are 8 of 39 Load transfer due to the unsprung mass inertia forces Total load transfer 9 of 39 Suspension components • Need for compliance between unsprung and sprung mass. Requirements: • Good isolation of the body(Good ride) – Soft response – Inconsistent with roll resistance in cornering – Roll stiffening using ant-roll bars – Spring can hit limits – Additional springs as bump stops • Prevent high frequency vibration from being transmitted – Use rubber bush connections • Good road grip (Good handling) – Hard response 10 of 39 Steel springs • Semi-elliptic springs – earliest developments in motor vehicle • Robust and simple – used for heavy applications • Hotchkiss type- to provide both vertical compliance and lateral constraint for the wheel travel • change in length of the spring produced by bump loading is accommodated Leaf spring design by the swinging shackle Figure from Smith,2002 11 of 39 Leaf spring analysis • Wheel load FW , is vertical. • FC is parallel to the shackle • Two load member • The stiffness (rate) of the spring is determined by the number, length, width and thickness of the leaves • Angling of the shackle link used to give a variable rate • When the angle θ < 90° , the spring rate will increase (i.e. rising rate) with bump loading Figure from Smith,2002 12 of 39 Coil springs • Light and compact form of compliance for weight and packaging constraints • Little maintenance and provides • Opportunity for co-axial mounting with a damper • Variable rate springs produced either by varying the coil diameter and/or pitch of the coils along its length Disadvantages: • Low levels of structural damping, there is a possibility of surging (resonance along the length of coils) • Spring as a whole does not provide any lateral support for guiding the wheel motion. 13 of 39 Torsion bars • Very simple form of spring and consequently very cheap • The principle of operation is to convert the applied load FW into a torque FW × R producing twist in the bar • Stiffness related to diameter, length of the torsion bar and the torsion modulus of the material Principle of operation of a torsion bar spring Figure from Smith,2002 14 of 39 Hydro-pneumatic springs • Spring is produced by a constant mass of gas (typically nitrogen) in a variable volume Basic diaphragm accumulator spring enclosure • As the wheel deflects in bump, the piston moves upwards transmitting the motion to the fluid and compressing the gas via the flexible diaphragm • The gas pressure increases as its volume decreases to produce a hardening spring characteristic • Systems are complex (and Principles of a hydro-pneumatic expensive) and maintenance suspension spring Figure from Smith,2002 15 of 39 Anti-roll bars (stabilizer) • Reduce body roll • Ends of the U-shaped bar connected to the wheel supports and • Central length of bar attached to body of the vehicle • Attachment points need to be selected to ensure that bar is subjected to Torsional loading without bending Anti-roll bar layout Figure from Smith,2002 16 of 39 Anti-roll bars (stabilizer) Conditions: Total roll stiffness krs is equal to the sum • One wheels is lifted relative to of the roll-stiffness produced by the the other, half the total anti-roll suspension springs kr,sus and the roll stiffness acts downwards on the stiffness of the anti-roll bars kr,ar, wheel and the reaction on the vehicle body tends to resist body roll. • If both wheels lift by the same amount the bar is not twisted and there is no transfer of load to the vehicle body. • If the displacements of the wheels are mutually opposed (one wheel up and the other down by the same amount), the full effect of the anti-roll stiffness Roll bar contribution to total roll stiffness is produced. Figure from Smith,2002 17 of 39 Dampers – types and characteristics • Frequently called shock absorbers • Main energy dissipators in a vehicle suspension • Two types: dual tube, Mono tube. • In mono tube – Surplus fluid accommodated by gas Damper types, (a) dual tube damper, pressurized free piston (b) free-piston monotube damper Figure from Smith,2002 18 of 39 Dampers – types and characteristics • In dealing with road surface undulations in the bump direction (damper being compressed) relatively low levels of damping are required compared with the rebound motion (damper being extended) • These requirements lead to damper characteristics which are asymmetrical when plotted on force- velocity axes • Ratios of 3:1 Damper characteristics Figure from Smith,2002 19 of 39 Dampers – types and characteristics • Damper designs are achieved by a combination of orifice flow and flows through spring-loaded one-way valves – At low speeds orifices are Shaping of damper characteristics effective – At higher pressure valves open up • lot of scope for shaping and fine tuning of damper characteristics Typical curves for a three position (electronically) adjustable damper Figure from Smith,2002 20 of 39 Road surface roughness and vehicle excitation • Road surfaces have random profiles -> non- deterministic. • Methods based on the Fourier transform • Power spectral density ‘S(n)’ of the height variations as a function of the spatial frequency ‘n’ κ = the roughness coefficient 21 of 39 Road surface roughness and vehicle excitation Substituting The variation of S( f ) for a vehicle traversing a poor minor road at 20 m/s is shown Figure from Smith,2002 22 of 39 Human response to whole body vibration • Human body –complex assemblage of linear and non- linear elements • Range of body resonances - 1 to 900 Hz • For a seated human – 1–2 Hz (head–neck) – 4–8 Hz (thorax–abdomen) • Perception of vibration motions diminishes above 25 Hz and emerges as audible sound. • Dual perception (vibration and sound) up to several hundred Hz is related to the term harshness 23 of 39 Human response to whole body vibration • Motion sickness (kinetosis) – low frequency , normally in ships • ISO 2631 (ISO, 1978) and the equivalent British Standard BS 6841 (BSI, 1987) • whole-body vibration from a supporting surface to either the feet of a standing person or the buttocks of a seated person The criteria are specified in terms of • Direction of vibration input to the human torso • Acceleration magnitude • Frequency of excitation • Exposure duration 24 of 39 Human response to whole body vibration • Most sensitive frequency range for vertical vibration is from 4–8 Hz corresponding to the thorax– abdomen resonance • most sensitive range for transverse vibration is from 1 to 2 Hz corresponding to head– neck resonance • ISO 2631 discomfort boundaries RCB – – 0.1 to 0.63 Hz for motion Reduced sickness. Comfort – most sensitive range is from 0.1 Boundary to 0.315 Hz Whole-body RCB vibration criteria, (a) RCB for vertical (z-axis) vibration (b) RCB for lateral (x Figure from Smith,2002 and y axis vibration) 25 of 39 Analysis of vehicle response to road excitation • Most comprehensive of these has seven degrees of freedom • Three degrees of freedom for the vehicle body (pitch, bounce and roll) • Vertical degree of freedom at each of the four unsprung masses. • This model allows the pitch, bounce and roll • The suspension stiffness and damping rates are derived from the individual spring and damping units Full vehicle model Figure from Smith,2002 26 of 39 Analysis of vehicle response to road excitation • Much useful information can be derived from simpler vehicle models. • The two most often used for passenger cars are the half- vehicle model and the quarter vehicle model. • These have four and two degrees of freedom respectively. • Reduced number of degrees of freedom
Load more

Recommended publications
  • JAN 30 1968 Efgineering Llbf
    \NT O ECJW .' J IS1 1967 4-1P-RA RIE-: OPTIMIZATION OF THE RANDOM VIBRATION CHARACTERISTICS OF VEHICLE SUSPENSIONS by ERICH KENNETH BENDER S.B., Massachusetts Institute of Technology (1962) S.M., Massachusetts Institute of Technology (1963) M.E., Massachusetts Institute of Technology (1966) SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF SCIENCE at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June, 1967 Signature of Author ., Department of Mechanical Engineering, ') /) Wfril 27, 1967 Certified by Thesfs Su4'sor, /K/J Accepted by ....... ...... Chairman, Departktnital'Commit 4 'ee on Graduate Students .\ST. OF TECHN 010 JAN 30 1968 EfGINEERING Llbf. OPTIMIZATION OF THE RANDOM VIBRATION CHARACTERISTICS OF VEHICLE SUSPENSIONS by ERICH KENNETH BENDER Submitted in partial fulfillment of the require- ments for the degree of Doctor of Science at the Massachusetts Institute of Technology, June, 1967. ABSTRACT Some of the fundamental limitations and trade-offs regard- ing the capabilities of vehicle suspensions to control random vi- brations are investigated. The vehicle inputs considered are sta- tistically described roadway elevations and static loading vara- tions on the sprung mass. The vehicle is modeled as a two-degree- of-freedom linear system consisting of a sprung mass, suspension and an unsprung mass which is connected to the roadway by a spring. The criterion used to optimize the suspension characteristics is the weighted sum of rms vehicle acceleration and clearance space required for sprung mass-unsprung mass relative excursions. Two ap- proaches to find the suspension characteristics which optimize the trade-off between vibration and clearance space are considered. The first, based on Wiener filter theory, is used to synthesize the optimum suspension transfer function.
    [Show full text]
  • Vehicle Model for Tyre-Ground Contact Force Evaluation
    Vehicle model for tyre-ground contact force evaluation Lejia Jiao Master Thesis in Vehicle Engineering Department of Aeronautical and Vehicle Engineering KTH Royal Institute of Technology TRITA-AVE 2013:40 ISSN 1651-7660 Postal address Visiting Address Telephone Telefax Internet KTH Teknikringen 8 +46 8 790 6000 +46 8 790 6500 www.kth.se Vehicle Dynamics Stockholm SE-100 44 Stockholm, Sweden Acknowledgment I owe gratitude to many people for supporting me during my thesis work. Especially, I would like to express my deepest appreciation to my supervisor, Associate professor Jenny Jerrelind, for her enthusiasm and infinite passion for this project. Without her patient guidance and persistent help, this thesis would not have been possible. I am particularly indebted to my parents for inspiring me to this work. I would like to thank Associate professor Lars Drugge, who introduced me to vehicle-road interaction and gave me enlightening instruction. In addition, I would like to give my sincere thanks to Nicole Kringos and Parisa Khavassefat, for helping me to understand the pavement and sharing model and data with me; to Ines Lopez Arteaga, for giving me feedbacks from tyre expert’s point of view. The great interdisciplinary cooperation and teamwork helped me to have a good understanding of the whole vehicle-tyre-pavement system, and get rational tyre and pavement parts included in my models. Last but not least, I would like to thank all my friends, for their understanding, encouragement and support. Stockholm June 26, 2013 Lejia Jiao i ii Abstract Economic development and growing integration process of world trade increases the demand for road transport.
    [Show full text]
  • Car Suspension and Handling Fourth Edition
    Car Suspension and Handling Fourth Edition List of Chapters: Preface to the Fourth Edition 3.8 Tire Uniformity 3.9 Aspect Ratios Preface to the First Edition 3.10 Tire Selection and Air Chamber Geometry Notation 3.11 References Chapter 1 Introduction Chapter 4 Steering 1.1 Scope and Layout of the Book 4.1 Dynamic Function of the Steering 1.2 The Function of the Suspension System System 4.2 Steering Angles: Effects of Tire Slip 1.3 Suspension Geometry Angles and Steering and Suspension 1.4 Kinematics and Compliance (K&C) Kinematics 1.5 Vehicle Dynamics 4.3 Relative Positions of Front- and Rear- 1.6 References Wheel Tracks 4.4 Understeer and Oversteer Chapter 2 Disturbances and Sensitivity 4.5 Directional Stability 2.1 Road Irregularities 4.6 Torque in the Steering System 2.2 Influence of Wheel Size 4.7 Steering Torque Effects Due to 2.3 Subjective Assessment of Ride Steering Geometry 2.4 Human Sensitivity to Vibration 4.8 The Steering Column 2.5 Measurement Standards for Vibration 4.9 Steering Gear 2.6 Influence of Noise on Assessment of 4.10 Constant Velocity (CV) Driveshaft Ride Comfort Joints 2.7 Influence of Phase of Differential 4.11 Torque Steer Effects Vibration on Assessment of Ride 4.12 Front-Wheel Steering Oscillations— Comfort Shimmy 2.8 References 4.13 Power Assistance 4.14 Electric Power Steering Chapter 3 The Wheel and Tire 4.15 Rear-Wheel Steering Systems 3.1 Introduction 4.16 References 3.2 The Wheel Rim 3.3 Tire Size Designation Chapter 5 Suspension Systems and 3.4 Tire Construction Types Their Effects 3.5 Tire Properties
    [Show full text]
  • Approach for the Development of Suspensions with Integrated
    Approach for the Development of Suspensions with Integrated Electric Motors Von der Fakultät Konstruktions-, Produktions- und Fahrzeugtechnik der Universität Stuttgart zur Erlangung der Würde eines Doktors der Ingenieurwissenschaften (Dr.-Ing.) genehmigte Abhandlung Vorgelegt von Meng Wang aus Hebei, China Hauptberichter: Prof. Dr. -Ing. Horst E. Friedrich Mitberichter: Prof. Dr. -Ing. Eckhard Kirchner Tag der mündlichen Prüfung: 06. May 2020 Institut für Verbrennungsmotoren und Kraftfahrwesen, Universität Stuttgart Angefertigt am Institut für Fahrzeugkonzepte, Deutsches Zentrum für Luft- und Raumfahrt (DLR) e.V. Stuttgart 2020 D93 (Dissertation Universität Stuttgart) Acknowledgments The author would like to thank his supervisors Prof. Dr. -Ing. Friedrich and Prof. Dr. - Ing. Kirchner for their consistent support and patience to his Ph.D study. The author is sincerely thankful to his advisor Dr. Elmar Beeh for his encouragement and guidance with his professional knowledge. Without their support, this thesis would not be completed. I am grateful to have these colleagues, who provided me honest communication and exchange of learning experience: Dr. Zhou Ping, Dr. Andreas Höfer, Dr. Diego Schierle, Dr. Jens König, Dr. Gerhard Kopp and so on. I wish to thank the support of colleagues in laboratory of DLR FK, who helped me to complete the test and acquired the useful data in this work: Michael Kriescher, Philipp Straßburger, Cedric Rieger and so on. I wish to thank these friendly colleagues: David Krüger, Lucia Areces Fernandez, Marco Münster, Erik Chowson, Thomas Grünheid and so on, who let me enjoy the work in DLR FK. You are already my best friends in Germany. I want to mention Moritz Fisher, Dr.
    [Show full text]
  • Truck Handling Stability Simulation and Comparison of Taper-Leaf and Multi-Leaf Spring Suspensions with the Same Vertical Stiffness
    applied sciences Article Truck Handling Stability Simulation and Comparison of Taper-Leaf and Multi-Leaf Spring Suspensions with the Same Vertical Stiffness Leilei Zhao 1, Yunshan Zhang 2, Yuewei Yu 1,*, Changcheng Zhou 1,*, Xiaohan Li 1 and Hongyan Li 3 1 School of Transportation and Vehicle Engineering, Shandong University of Technology, Zibo 255000, China; [email protected] (L.Z.); [email protected] (X.L.) 2 Shandong Automobile Spring Factory Zibo Co.,Ltd., Zibo 255000, China; [email protected] 3 State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130022, China; [email protected] * Correspondence: [email protected] (Y.Y.); [email protected] (C.Z.); Tel.: +86-135-7338-7800 (C.Z.) Received: 16 December 2019; Accepted: 31 January 2020; Published: 14 February 2020 Abstract: The lightweight design of trucks is of great importance to enhance the load capacity and reduce the production cost. As a result, the taper-leaf spring will gradually replace the multi-leaf spring to become the main elastic element of the suspension for trucks. To reveal the changes of the handling stability after the replacement, the simulations and comparison of the taper-leaf and the multi-leaf spring suspensions with the same vertical stiffness for trucks were conducted. Firstly, to ensure the same comfort of the truck before and after the replacement, an analytical method of replacing the multi-leaf spring with the taper-leaf spring was proposed. Secondly, the effectiveness of the method was verified by the stiffness tests based on a case study. Thirdly, the dynamic models of the taper-leaf spring and the multi-leaf spring with the same vertical stiffness are established and validated, respectively.
    [Show full text]
  • L1262 Rev B 01-20 © 2016 – 2019 Hendrickson USA, L.L.C
    THE EVOLUTION OF TRAILER SUSPENSION DAMPING: A GUIDE TO BEST PRACTICES The noticeable ride benefits of suspension damping devices also bring maintenance challenges for fleets. Educate yourself on the evolution of damping methods to better manage long-term costs. All vehicles, passenger or commercial, are designed with damping in mind when it comes to the suspension. The primary goal of a suspension system is to carry the load from the vehicle while providing compliance between the sprung mass (chassis, trailer body, etc.) and the unsprung mass (the suspension, tires, wheels, brakes, etc). Damping devices, such as shock absorbers, are designed to add comfort and control by resisting the motion of the suspension. Without damping forces, a vehicle would have a tendency to bounce at its natural, or resonant, frequency. But over the service life of the vehicle, most suspension damping devices result in a compromise of either ride quality or added component maintenance. In the commercial trailer industry, managing issues like driver comfort, cargo protection, vehicle safety and government compliance can be a complicated balancing act. Understanding the fundamentals of damping enables fleets to better manage long-term maintenance and operation costs while keeping ride quality and driver satisfaction high. What Is Damping and Why Do I Need It? Damping describes the process of absorbing energy of road inputs that are transmitted through the suspension system. Suspension damping reduces the number and intensity of these inputs to the vehicle thereby helping to prolong the life of the vehicle and its components. In turn, this helps reduce overall operating and maintenance costs.
    [Show full text]
  • Design, Modelling & Analysis of Double Wishbone Suspension
    International Journal on Mechanical Engineering and Robotics (IJMER) _______________________________________________________________________________________________ Design, Modelling & Analysis of Double Wishbone Suspension System 1Nikita Gawai, 2Deepak Yadav, 3Shweta Chavan, 4Apoorva Lele, 5Shreyash Dalvi Thakur College of Engineering & Technology, Kandivali (E), Mumbai-400101. Email: [email protected], [email protected], [email protected], [email protected], [email protected] Fig.1: Double wishbone Suspension system Abstract : The main objective of the project is to analyze the entire Double wishbone suspension system for Green F1 car, It is popular as front suspension mostly used in rear wheel as it allows the engineer to carefully control the motion of drive vehicles. Design of the geometry of double the wheel throughout suspension travel. A 3D CAD model of wishbone suspension system along with design of spring the Double wishbone is prepared by using SolidWorks plays a very important role in maintaining the stability of (CAD Software) for analyzing the system capable of handling Green F1 car while maintaining the ride quality. the vehicle. The topic is focused on designing the above mentioned suspension system considering the dynamics of the vehicle The upper arm is usually shorter to induce negative along with minimizing the unsprung mass. camber as the suspension jounces (rises), and often this arrangement is titled an "SLA” or Short Long Arms Index Terms—Roll center, Stiffness, Spring, Strut, Sprung suspension. When the vehicle is in a turn, body roll results ,Wishbone. in positive camber gain on the lightly loaded inside wheel, while the heavily loaded outer wheel gains negative I. INTRODUCTION camber. Suspension system is the term given to the system of The Four bar link mechanism formed by the unequal arm springs, shock absorbers and linkages that connect a lengths causes a change in the camber of the vehicle as it vehicle to its wheels.
    [Show full text]
  • Active Anti-Roll Bar Control Using Electronic Servo Valve Hydraulic Damper on Single Unit Heavy Vehicle Van Tan Vu, Olivier Sename, Luc Dugard, Peter Gáspár
    Active anti-roll bar control using electronic servo valve hydraulic damper on single unit heavy vehicle van Tan Vu, Olivier Sename, Luc Dugard, Peter Gáspár To cite this version: van Tan Vu, Olivier Sename, Luc Dugard, Peter Gáspár. Active anti-roll bar control using elec- tronic servo valve hydraulic damper on single unit heavy vehicle. AAC 2016 - 8th IFAC Interna- tional Symposium on Advances in Automotive Control, Jun 2016, Norrköping, Sweden. pp.418 - 425, 10.1016/j.ifacol.2016.08.062. hal-01314529 HAL Id: hal-01314529 https://hal.archives-ouvertes.fr/hal-01314529 Submitted on 11 May 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Active anti-roll bar control using electronic servo valve hydraulic damper on single unit heavy vehicle Van Tan Vu ∗ Olivier Sename ∗ Luc Dugard ∗ Peter Gaspar ∗∗ ∗ Univ. Grenoble Alpes, GIPSA-lab, F-38402 Grenoble Cedex, France CNRS, GIPSA-lab, F-38402 Grenoble Cedex, France. E-mail: fVan-Tan.Vu, olivier.sename, [email protected] ∗∗ Systems and Control Laboratory, Institute for Computer Science and Control, Hungarian Academy of Sciences, Kende u. 13-17, H-1111 Budapest, Hungary.
    [Show full text]
  • Comparative Study Between Double Wish-Bone and Macpherson Suspension System
    IOP Conference Series: Materials Science and Engineering PAPER • OPEN ACCESS Related content - Intelligent systems of the vehicles’ Comparative study between double wish-bone and suspension D Yurlin macpherson suspension system - Analysis of a front suspension system for UniART FSAE car using FEA M N A Zaidie, M S M Hashim, M Tasyrif et To cite this article: Shoaib Khan et al 2017 IOP Conf. Ser.: Mater. Sci. Eng. 263 062079 al. - A nonlinear kinematic and dynamic modeling of Macpherson suspension systems with a magneto-rheological damper View the article online for updates and enhancements. Saikat Dutta and Seung-Bok Choi This content was downloaded from IP address 170.106.33.14 on 23/09/2021 at 19:36 14th ICSET-2017 IOP Publishing IOP Conf. Series: Materials Science and Engineering1234567890 263 (2017) 062079 doi:10.1088/1757-899X/263/6/062079 Comparative study between double wish-bone and macpherson suspension system Shoaib Khan, Yagvendra Joshi, Ashutosh Kumar and Ramesh Babu Vemuluri School of Mechanical Engineering, VIT University, Vellore-632014, Tamil Nadu, India. Email id: [email protected] Abstract: The present paper proposes comparative study between Double Wish-Bone and Macpherson Suspension system. The objective is achieved by using ANSYS simulation package. Dynamic and static loads are applied on the suspension systems. Various analysis such as Structural analysis with static as well as dynamic loading, Modal analysis and Transient analysis are carried out in order to study deflection, stress, frequency and strain of both the suspension systems and a thorough comparative study is accomplished. 1. Introduction The two of the most popular suspensions systems for cars are the Double wishbone suspension system and the MacPherson’s strut suspension system.
    [Show full text]
  • Comparison Between Passive and Active Flexible Anti-Roll Bars Modelled by Finite Element Method on Prevention of Vehicle Rollovers
    COMPARISON BETWEEN PASSIVE AND ACTIVE FLEXIBLE ANTI-ROLL BARS MODELLED BY FINITE ELEMENT METHOD ON PREVENTION OF VEHICLE ROLLOVERS Joed Henrique Paes∗, Diego Colon´ ∗ ∗Av. Prof. Luciano Gualberto, travessa 3, n 158, CEP 05508-900 USP / Escola Polit´ecnica - Laborat´orio de Automa¸c~aoe Controle (LAC) S~aoPaulo, S~aoPaulo, Brazil Emails: [email protected], [email protected] Abstract| Anti-roll bars aims to increase the driving comfort by reducing the roll angle during cornering and also assist the self-steering behaviour of the vehicle chassis. This paper presents a comparison between a passive anti-roll bar and an active anti-roll bar. The bars are modelled by FEM (Finite Element Method) and a controller LQG (Linear Quadratic Gaussian) is designed to the active system. In addition, the vehicle lateral dynamic is hybridized to the flexible model in order to obtain an unique mathematical model. It reviews the vehicle roll dynamics and describes the FEM applied to dynamic modelling of flexible structures. The influence of the active anti-roll system is illustrated through numerical simulation, and a comparison among the passive anti-roll system and the system without anti-roll is also presented. To the best of the authors' knowledge, the modelling approach presented in Sections 3.1 and 3.2 have not been reported in the literature. Keywords| Anti-roll system, flexible structures, control, finite element method. Resumo| Barras de anti-rolagem visam aumentar o conforto atrav´esda redu¸c~aodo ^angulo de rolagem em curvas e tamb´em auxiliam na auto-dirigibilidade do chassis do ve´ıculo.
    [Show full text]
  • Analysis of Vehicle Suspension System Subjected to Forced Vibration Using MAT LAB/Simulink
    South Asian Journal of Engineering and Technology Vol.2, No.23 (2016) 171 – 177 Analysis of Vehicle Suspension System Subjected to forced vibration using MAT LAB/Simulink P.Mohana, K.V. Poornachandrana, P.Pravinkumarb, M.Magudeswaranc, M.Mohanrajc a Department of Mechanical Engineering,Tamilnadu College of Engineering, Coimbatore, b Department of Mechanical Engineering, Sasurie College of Engineering, Vijayamangalam c Department of Mechanical Engineering, Nandha College of Technology, Erode, [email protected] Abstract A safe vehicle must be able to stop and maneuver over a wide range of road conditions. Good contact between the tires and the road will able to stop and maneuver quickly and it is achieved by vehicle suspension system. Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Shock absorber is an important part of automotive suspension system which has an effect on ride characteristics. Shock absorbers are also critical for tire to road contact which to reduce the tendency of a tire to lift off the road. This affects braking, steering, cornering and overall stability. The removal of the shock absorber from suspension can cause the vehicle bounce up and down. It is possible for the vehicle to be driven, but if the suspension drops from the driving over a severe bump, the rear spring can fall out. The main role of a suspension engineer is to tune the suspension in such a way as to maximize the road holding performance of the vehicle. One of the more difficult components in achieving this is the selection of the dampers which was done empirically in the past.
    [Show full text]
  • Assessment of Tire Features for Modeling Vehicle Stability in Case of Vertical Road Excitation
    applied sciences Article Assessment of Tire Features for Modeling Vehicle Stability in Case of Vertical Road Excitation Vaidas Lukoševiˇcius*, Rolandas Makaras and Andrius Dargužis Faculty of Mechanical Engineering and Design, Kaunas University of Technology, Studentu˛Str. 56, 44249 Kaunas, Lithuania; [email protected] (R.M.); [email protected] (A.D.) * Correspondence: [email protected] Abstract: Two trends could be observed in the evolution of road transport. First, with the traffic becoming increasingly intensive, the motor road infrastructure is developed; more advanced, greater quality, and more durable materials are used; and pavement laying and repair techniques are im- proved continuously. The continued growth in the number of vehicles on the road is accompanied by the ongoing improvement of the vehicle design with the view towards greater vehicle controllability as the key traffic safety factor. The change has covered a series of vehicle systems. The tire structure and materials used are subject to continuous improvements in order to provide the maximum possi- ble grip with the road pavement. New solutions in the improvement of the suspension and driving systems are explored. Nonetheless, inevitable controversies have been encountered, primarily, in the efforts to combine riding comfort and vehicle controllability. Practice shows that these systems perform to a satisfactory degree only on good quality roads, as they have been designed specifically for the latter. This could be the cause of the more complicated car control and accidents on the lower-quality roads. Road ruts and local unevenness that impair car stability and traffic safety are not Citation: Lukoševiˇcius,V.; Makaras, avoided even on the trunk roads.
    [Show full text]