”Tire blow-out” is a fast loss of air pressure that fills a vehicle tire, effecting from a puncture or a fatigue of tire structure. Statistical data, published in the United States, showed that “tire blow-out” caused more than 300,000 road accidents in the period of 1992–96 [1, 3]. Over 2000 people died in those accidents and many more were injured [1, 3]. The data and successful attempts of simulation presented in the work [1], prompted the author to try modeling and simulating this case of vehicle motion. The main emphasis in the hereto presented tests was put on qualitative assessment of vehicle behavior after a “tire blow-out”. The results presented in the work [1] show that the smallest motion disturbance of a vehicle takes place when the driver does not react (by turning the steering wheel or pressing the brake pedal). So, an assumption was made that the driver keeps a zero value of the steering wheel turning angle and pressure on the brake pedal. A description of changes in elastic force of a tire along with declining internal pressure, as assumed by authors of this work [1], were assessed for correctness and then modified by using own tests of radial stiffness of tired wheels. Ability of the vehicle to balance the effects of an emergency situation described after a “blow-out” of either a front or a rear wheel tire was tested on dry and wet surface for longitudinal rectilinear motion. The impact of tire pressure reduction time on the course and effects of the analyzed cases of motion was assessed. Simulation tests were also conducted for more complex maneuvers, with a disturbance effecting from a damaged tire: for circular steady state motion and ramp angular input on the steering wheel.

The study is dedicated to the problem of uncertainty in the analysis of accident situations in road traffic. The term “uncertainty” is generally known when used with reference to measurement techniques, but its application to the analyses of accident situations in road traffic, including accident reconstruction, is a relatively new field of knowledge. The objectives of this work include the presentation and examination of selected aspects related to the taking of uncertainty into account when analysing the course of an accident and making the necessary calculations. Apart from the scientific objectives, an important utilitarian goal may also be pointed out. The data and methods presented may be used by automotive technology experts in their accident reconstruction work. The paper shows seven methods that enable the taking into account of the uncertainty of the data used for calculations, i.e. extreme values method, total differential method, higher-order total differential method, finite-difference method, Gauss method, method based on the description of stochastic processes, and Monte-Carlo method. Apart from formal (mathematical) descriptions of the methods, an example of their use for the estimation of uncertainty of selected quantities that describe an accident situation has been demonstrated. The bad and good points of individual methods have been shown in the context of the application considered.

The paper presents the optimization of damping in the passive suspension system of a motor vehicle moving rectilinearly with a constant speed on a road with rough surface of random irregularities, described according to the ISO classification. Two quarter-car 2DoF models, linear and non-linear, were used; in the latter, nonlinearities of spring characteristics of the suspension system and pneumatic tyres, sliding friction in the suspension system, and wheel lift-off were taken into account. The smoothing properties of vehicle tyres were represented in both models. The calculations were carried out for three roads of different quality, with simulating four vehicle speeds. Statistical measures of vertical vehicle body vibrations and of changes in the vertical tyre/road contact force were used as the criteria of system optimization and model comparison. The design suspension displacement limit was also taken into account. The optimum suspension damping coefficient was determined and the impact of undesirable sliding friction in the suspension system on the calculation results was estimated. The results obtained make it possible to evaluate the impact of the structure and complexity of the model used on the results of the optimization.

The aim of the study was to verify whether simultaneous responses from the muscular and circulatory system occur in the driver’s body under simulated conditions of a crash threat. The study was carried out in a passenger car driving simulator. The crash was included in the driving test scenario developed in an urban setting. In the group of 22 young male subjects, two physiological signals — ECG and EMG were continuously recorded. The length of the RR interval in the ECG signal was assessed. A HRV analysis was performed in the time and frequency domains for 1-minute record segments at rest (seated position), during undisturbed driving as well as during and several minutes after the crash. For the left and right side muscles: m. trapezius (TR) and m. flexor digitorum superficialis (FDS), the EMG signal amplitude was determined. The percentage of maximal voluntary contraction (MVC) was compared during driving and during the crash. As for the ECG signal, it was found that in most of the drivers changes occurred in the parameter values reflecting HRV in the time domain. Significant changes were noted in the mean length of RR intervals (mRR). As for the EMG signal, the changes in the amplitude concerned the signal recorded from the FDS muscle. The changes in ECG and EMG were simultaneous in half of the cases. Such parameters as mRR (ECG signal) and FDS-L amplitude (EMG signal) were the responses to accident risk. Under simulated conditions, responses from the circulatory and musculoskeletal systems are not always simultaneous. The results indicate that a more complete driver’s response to a crash in road traffic is obtained based on parallel recording of two physiological signals (ECG and EMG).

W pracy wykorzystano ponad 40-letnie osiągnięcia wielu autorów zagranicznych i polskich w zakresie metod optymalizacji parametrów zawieszenia samochodu. Zaprezentowano, rozwiniętą przez autora, metodykę obliczeń optymalizacyjnych na przykładzie tłumienia wiskotycznego pasywnego zawieszenia pojazdu poruszającego się po nierównej, losowej nawierzchni drogi. Wykorzystano liniowy model zawieszenia ćwiartki samochodu oraz analizę transmitancji widmowych w wyznaczaniu wskaźników dyskomfortu i niebezpieczeństwa. Wyniki zaprezentowano w postaci bezwymiarowej funkcji celu, która stanowiła kryterium optymalizacji ze względu na komfort jazdy i bezpieczeństwo. Uwzględniono także ograniczenie ugięć zawieszenia. Graficzna postać tej funkcji, gdzie zmienną niezależną jest bezwymiarowy współczynnik tłumienia zawieszenia, przypomina poglądowe, jakościowe zależności przytaczane w wielu pracach innych autorów, co ułatwia interpretację wyników końcowych optymalizacji.

The article demonstrates selected issues related to assessment of computational accuracy in accident analysis. The hereto presented theoretical grounds of the methods make it possible to consider uncertainties in the assessment of input data values. The methods were compared on the basis of their exemplary application in the case of braking process study of a vehicle in rectilinear motion. Also for the aforementioned case, the results obtained by means of various computational methods of vehicle motion (analytical and simulation models) were compared with the outcome of the experimental study.