The description of road surface roughness
TL;DR: It is shown that typical road surfaces may be considered as realizations of homogeneous and isotropic two-dimensional Gaussian random processes, and a single direct spectral density function provides a road surface description which is sufficient for multi-track vehicle response analysis.
About: This article is published in Journal of Sound and Vibration.The article was published on 1973-01-01. It has received 586 citations till now. The article focuses on the topics: Surface roughness & Autocorrelation.
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TL;DR: In this article, the central limit theorem is invoked to show that the variance of the height distribution of a structure is linearly related to the length of sample involved, and this relationship is shown to agree well with measurements taken over many scales of size, and from throughout the physical universe.
Abstract: TOPOGRAPHY is often considered as a narrow bandwidth of features covering the form or shape of the surface. After detailed study of many measurements we consider that as well as the possibility of a dominant range of features there is always an underlying random structure where undulations in surface height continue over as broad a bandwidth as the surface size will allow. We consider this a result of many physical effects each confined to a specific waveband but no band being dominant. We invoke the central limit theorem and show through Gaussian statistics that the variance of the height distribution of such a structure is linearly related to the length of sample involved. In another form, the power spectral density, this relationship is shown to agree well with measurements of structures taken over many scales of size, and from throughout the physical universe.
634 citations
TL;DR: In this paper, a review of the literature relating to the design of automobile suspension systems for ride comfort and control of wheel load variations for frequencies below body structure resonances is reviewed.
Abstract: SUMMARY Based mainly on English language literature, information relating to the design of automobile suspension systems for ride comfort and control of wheel load variations for frequencies below body structure resonances is reviewed. The information is interpreted in the context of vehicles which travel through a wide speed range on roads of markedly differing quality, which do so carrying different loads and which are required to possess good handling qualities. Sections are devoted to describing road surfaces, modelling vehicles and setting up performance criteria, and to passive, active, semi-active and slow-active system types. Methods for deriving active system control laws are outlined. Strengths and weaknesses of the various systems are identified and their relative performance capabilities and equipment requirements are discussed. Attention is given to adaptation of the suspension or control system parameters to changing conditions. Remaining research needs are considered.
344 citations
TL;DR: In this article, the authors compared numerical results and some analytical prediction formulae available for fatigue damage evaluation; amongst all expressions, a new proposed original approach was shown to give sound theoretical framework and improved results.
295 citations
TL;DR: In this article, a methodology is presented for optimizing the suspension damping and stiffness parameters of nonlinear quarter-car models subjected to random road excitation, and a critical comparison is performed between the results obtained for vehicles with passive linear or bilinear suspension dampers and those obtained for cars with semi-active shock absorbers.
Abstract: A methodology is presented for optimizing the suspension damping and stiffness parameters of nonlinear quarter-car models subjected to random road excitation. The investigation starts with car models involving passive damping with constant or dual-rate characteristics. Then, we also examine car models where the damping coefficient of the suspension is selected so that the resulting system approximates the performance of an active suspension system with sky-hook damping. For the models with semi-active or passive dual-rate dampers, the value of the equivalent suspension damping coefficient is a function of the relative velocity of the sprung mass with respect to the wheel subsystem. As a consequence, the resulting equations of motion are strongly nonlinear. For these models, appropriate methodologies are first employed for obtaining the second moment characteristics of motions resulting from roads with a random profile. This information is next utilized in the definition of a vehicle performance index, which is optimized to yield representative numerical results for the most important suspension parameters. Special attention is paid to investigating the effect of road quality as well as on examining effects related to wheel hop. Finally, a critical comparison is performed between the results obtained for vehicles with passive linear or bilinear suspension dampers and those obtained for cars with semi-active shock absorbers.
228 citations
Cites background or result from "The description of road surface rou..."
...Moreover, the road irregularities are assumed to be of random nature and they are described by frequency spectra, which are considered as typical in automotive engineering (Dodds and Robson, 1973 Gillespie, 1992)....
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...Here, this profile is represented by a random process with a statistical distribution, which is consistent with measurements of typical road profiles (Dodds and Robson, 1973)....
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...According to many previous investigations on the subject (e.g. Dodds and Robson, 1973), the geometrical profile of typical roads fits sufficiently accurately the following simple analytical form Sg Ag n (5) which is represented by a line in a log–log scale....
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TL;DR: In this paper, the authors carried out a statistically meaningful study on self-affine rough surfaces in elastic frictionless non-adhesive contact and studied the evolution of the true contact area under increasing squeezing pressure from zero up to full contact.
208 citations
References
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01 Jan 1969
TL;DR: In this article, the authors describe the design and development of a device which records the profiles of roads in a form suitable for statistical analysis, installed in a normal saloon car, is capable of recording road surface profile data over the entire range of wavelengths of likely interest to automobile engineers at such a speed as not to disrupt normal traffic flow.
Abstract: This report describes the design and development of a device which records the profiles of roads in a form suitable for statistical analysis. The device, installed in a normal saloon car, is capable of recording road surface profile data over the entire range of wavelengths of likely interest to automobile engineers at such a speed as not to disrupt normal traffic flow. The device has been used to conduct a survey of roads in Britain, France, Belgium and West Germany. The data obtained are presented in the report and have led to the development of a system of classification of road surfaces and enabled an insight to be gained into the effects of methods of construction and the usage of roads. The data are also being used for the prediction of the response of vehicles using these roads (A).
65 citations
Dissertation•
01 Jan 1972
33 citations
01 Feb 1969
6 citations