Abstract
The article presents a study of the influence of vehicle’s conditions of use, such as road class, vehicle speed or its load, on its vertical dynamic responses. In the article only the kinematic excitations were analysed, as these are more common than the dynamic ones. The road profiles were artificially generated according to the ISO 8608 standard, which classifies roads based on power spectral density of excitations which they generate. Ride safety, ride comfort and fatigue strength indicators were computed. Ride safety was defined by the DLC – Dynamic Load Coefficient. Ride comfort was judged taking into consideration the recommendations from the ISO 2631 standard (which contains the information on vibration frequencies and their effect on human body, as well as the allowed exposure times to given vibrations) by calculating root mean square values of sprung mass accelerations for bandwidths defined in the standard. Load spectrums for the fatigue analysis were created using forces generated in a simulation as a basis and further research venues were proposed. Lastly conclusions were drawn from the results, that imply that linear models are sufficient for many standard applications on roads of acceptable quality, however the use of non-linear models is recommended in fatigue strength analysis regardless of conditions of use.
Highlights
The most commonly considered ones are the safety and ride comfort requirements, both really important for the user of the vehicle. Both for manufacturer and its user, is fatigue strength of the suspension elements. This one is related to geometrical dimensions of elements, which are limited in terms of space and mass used in a vehicle
The question arises how should this design or research process look like? In a modern age, most of the work is at first done using Computer Aided Engineering software, which is understandable considering the high costs of prototype manufacturing
The vehicle model was tested with excitations from four different road irregularity profiles, belonging to classes A to D defined in ISO 8608 standard
Summary
Suspension systems in automobiles must fulfil many, often conflicting, requirements. The most commonly considered ones are the safety and ride comfort requirements, both really important for the user of the vehicle. At first researchers analysed mainly simple linear quarter-car models, which can be found in [13], [19], [25] These models are still used in newer publications, for example in [4] or [5]. Work [26] describes all three kinds of vehicle models, with the addition of non-linear variants for quarter- and half-car models. When it comes to road models and their generation, most publications began by analysing periodical excitations consisting of one or more sine waves [19], [25], followed by the gradual shift towards random profiles described by statistical values [3], [6], [11]. Kinematic excitations were modelle2d.1uVsienhgiclperomcoeddeulsres based on [21], which discusses the generation of road profiles according to classes defined in ISO 8608 standard. They interact with each other via spring with stiffness kM and damper with damping coefficient cM, which depending on the model are either simple coefficients or (in the non-linear models) are modelled in the
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