This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Magic Numbers in Design of Suspensions for Passenger Cars
Annotation ability available
Sector:
Language:
English
Abstract
Design specifications for suspensions of passenger cars for ride and handling in the past half century were amazingly associated with some “Magic Numbers.” These parameter values are needed for mathematical models which describe the dynamic motions of a vehicle on the road, help researchers to validate the overall performance of their simulations. Moreover, these numbers should be viewed as a guide for evaluation of vehicle design practice for moderate payload and driving conditions. Number 1, for instance, is the magic number associated with bounce resonant frequency of the sprung mass, but also related to the desired value for the dynamic index for ride quality and directional control. Number 10, on the other hand, is the magic number associated with wheel hop resonant frequency and the desired total mass/-unsprung masses ratio. This paper demonstrates through some illustrative, examples, computer simulation, laboratory and road test results, that since the introduction of the Independent Front Suspension (IFS) in the automobile industry more than 50 years ago, a series of specific numbers govern vehicle design for ride and handling. Moreover, these numbers will continue to control our design philosophy in the next decade regardless of high technology concepts such as active suspension and four-wheel steer. These magic numbers are timeless. They are the product of the so-called “Past Experience” and/or “The Slide-Rule Generation” in the automobile industry. In this respect, despite innovations in suspension design the reality is that there is no chanse in these design specifications.
Recommended Content
Authors
Citation
Barak, P., "Magic Numbers in Design of Suspensions for Passenger Cars," SAE Technical Paper 911921, 1991, https://doi.org/10.4271/911921.Also In
References
- Shoenberger, R. W. “Human Response to Whole-Body Vibration,” Perceptual and Motor Skills 34 127 160 1972
- Varterasian, J.H. Thompson, R.R. “The Dynamic Characteristics of Automobile Seats with Human Occupants,” SAE Transactions 86 Paper No. 770249 1173 1182 1977
- VanDeusen, B.D. “Human Response to Vehicle Vibration,” SAE Transactions 77 Paper No. 680090 328 345 1968
- Olley, M. “Independent Wheel Suspension -- Its Whys and Wherefores,” SAE Journal March 1934
- Janeway, R.N. “Passenger Vibration Limits,” SAE Journal August 1948 48 49
- Pradko, F. Lee, R.A. “Vibration Comfort Criteria,” SAE-Paper 660139 1966
- Jones, A.J. Saunders, D.J. “Equal Comfort Contours for Whole-Body Vertical Pulses Sinusoidal Vibration,” Journal of Sound and vibration 23 1 1 14 1972
- Miwa, T. “Evaluation Methods for Vibration Effect - Part 2, Measurement of Equal Sensation Level for Whole Body Between Vertical and Horizontal Sinusoidal Vibrations,” Industrial Health Japan 5 206 212 1967
- “Ride and Vibration Data Manual - SAE J6a,” Society of Automotive Engineers SAE Information Report December 1965
- “Guide for the Evaluation of Human Exposure to Whole-Body Vibration,” Draft International Standard ISO/DIS 2631 1973
- Smith, C.C. McGehee, D.Y. Healey, A.J. “The Prediction of Passenger Riding Comfort from Acceleration Data,” Journal of Dvnamic Svstem, Measurement, and Control Trans. ASME 100 1 34 41 1978
- Kamal, M.M. et al “Modern Automotive Structural Analysis,” Van Nostrand Reinhold Company 1982
- Carstens, J. P. et al. “Literature Survey of Passenger Comfort Limitations of High-Speed Ground Transports,” United States Department of Commerce Report PB168-71 July 26 1965
- Sinha, B.P. “Influence of Road Unevenness on Road Holding and Ride Comfort,” Report No. 28 National Swedish Road and Traffic Research Institute Stockholm 1973
- Barak, P. Sachs, H. “On the Optimal Ride Control of a Dynamic Model for an Automotive Vehicle System,” the Dynamics of Vehicles on Roads and Tracks Proceedings 9th IAVSD-Symposium Linkoping Sweden June 24-28 1985
- Wong, J.Y. “Theory of Ground Vehicles,” John Wiley & Sons 1978
- Olley, M. “Notes on Suspension,” August 1961
- Deutsh, C. 1971
- Evans, R. D. “Properties of Tires Affecting Riding, Steering, and Handling,” SAE Transactions February 1935
- Olley, M. “National Influences on American Passenger Car Design,” Proc. Inst. Automobile Ens. 32 1937-38
- Bull, A.W. “Tire Behavior in Steering,” SAE Transactions August 1939
- Stonex, K. A. “Car Control.Factors and the Measurement,” SAE Journal (Transactions) March 1941
- Olley, M. “Road Manners of the Modern Car,” Proc. Inst. Automobile Ena. 51 1946
- schilling, R. “Directional Control of Automobiles,” Industrial Mathematics Soc. Paper 1953
- Segel, L. Theoretical Prediction and Experimental Substantiation of the Response of the Automobile to Steering Control Proceedinus of the Institution of Mechanical Engineers Automobile Division 1956-1957
- Milliken, W.F. et al “Research in Automobile Stability and Control,” (5 papers) Inst. of Mechanical Engineers London, England 1956
- Nordeen, D. L. “Vehicle Handling: Its Dependence Upon Vehicle Parameters,” SAE Paper 640031 1964
- Bergmann, W. “The Basic Nature of Understeer-Oversteer,” SAE Paper Detroit, Michigan January 1965
- Bundorf, R.T. “The Influence of Vehicle Design Parameters on Characteristic Speed and Understeer,” SAE Preprint 670078 January 1967
- Ellis, J.R. “Vehicle Dynamics,” Business Books London, England 1969
- Bundorf, R. T. Leffert, R. L. “The Cornering Compliance Concept for Description of Directional Control (Handling) Properties General Motors Report January 1969
- “Vehicle Dynamics Terminology,” SAJ670e June 1978
- van Eldik Thieme H.C.A. Pacejka, H.B. The Tire as a Vehicle Component Clark S.K. “Mechanics of Pneumatic Tires,” Monograph 122 National Bureau of Standards Washington, DC 1971
- Riede, P.M. et al “Typical Vehicle Parameters for Dynamics Studies Revised for the 1980's,” SAE Paper No. 84051 February 1984