Identification of structure and directional distribution of vibration transferred to car-body from road roughness

The article presents results of the research on identification of structure and directional distribution of vibration transferred to car-body from road roughness. It is the case study of multiple sources of vibration interacting on vehicle and vibration transfer into driver and passengers. During the research the passenger car was driven on special test track. It were recorded the vibration signals in 3 orthogonal axes. The sensors were mounted at the floor panel in locations where the vibration are transferred into the human organism. For the purpose of analysis of vibration transfer in term of human perception it is necessary to correlate the vibration energy, frequency and time of exposition. It allows to evaluate exposure on vibration in frequency bands close to natural frequency of chosen human organs. The analysis of time-frequency distribution of the vibration allow to separate the main components of the signal. The paper presents the results of comparison of RMS value of vibration for different axes in measurement points on floor panel

Research on the influence of engine rotational speed to the vibration penetration into the driver via feet – multidimensional analysis

The manuscript provides a discussion on the studies and analysis of influence of engine rotational speed to the vibration penetration into the driver via feet. For the driving safety and comfort it is very important what kind and values of vibration are transferred to car body. The motor-engine was chosen as the vibration source. The paper presents some results of investigation on influence of idle gear rotational speed of engine to the vibration registered at place for driver feet. Changes of the values of the influence of vibration on human were presented as RMS and Awmax distribution or proposed estimator of spectrum Tabs(FFT). The changes of the vibration signals and its spectrums were observed in orthogonal 3 axes. The complementary analysis was conducted as time-frequency distribution of the vibration. The experiments were conducted on the car vehicle which was placed on the special test racks. It allows to lessen the road roughens impact on the suspension and the car body

Frequency analysis decimation vibration signals of passenger car’s suspensions

The paper presents possibilities of applying linear decimation procedure in frequency analysis of non-stationary signals. It shows the results of analytical experiments conducted with vibration signals registered during examination of car suspension which was activated to vibration on harmonic stand research. Working cycles identification algorithm was helpful to make LDP of working cycles parts of a signal. Signals spectrum results confirm amplitude selectivity for typical frequency ofresearching dynamic system

Modern suspension systems for automotive vehicles and their test methods

This article provides a discussion on various solutions used in modern suspension systems of automotive vehicles. The mechanical dependent suspension system and some solution of adaptive, semi-active and active suspension system has been described. The paper also presents shortly test methods used to evaluation of technical conditions of this system

Research on vibration of steering gear of automotive vehicle

The paper presents chosen solutions and technical elements for minimising of vibration effects in special vehicles. Due to volume and scope of the impact, forces and load generated in special vehicle during operating these elements are extremely important for isolation and absorbing of vibration affecting human or load. As the example of such solutions frame, suspension of car-body and cabin adopt in high mobility wheeled platform were described

Research on structure, propagation and exposure to general vibration in passenger car for different damping parameters

The article addresses results of the research on the structure and propagation of vibration of vehicle for different parameters of suspension damping system. Long term exposure to whole-body vibration in transport may cause health risk and many diseases. Suspension is the most important system of vehicle for vibration control of level of wave emission to car-body and passengers. Thus the research on structure and propagation of vibration were conducted for different damping parameters of shock absorbers. For the sake of the analysis of exposure to whole-body vibration signals of general vibration were recorded at locations where vibration penetrated the human organism by the feet inside the vehicle. The vibrations have to be analyzed in the domains of amplitudes, time, frequency and time-frequency. Chosen estimators were defined and compared for the sake of the analysis of vibration propagation in terms of energy and dynamics. To evaluate the exposure to vibration it is important to analyse the dynamics of phenomena and main frequency components of vibration. For the spine response in vertical direction calculation of the model presented in ISO 2631 was used. The calculations of acceleration dose and equivalent static compressive stress for the assessment of health effects were done. Due to the large capacity of information in vibration signal the scope of presented research can be used for active diagnostics experiments on determining of estimators of technical condition of suspension elements

Analysis of vibration propagation in the human body

The human vibration is a multi-disciplinary subject involving many disciplines. A special area in the field of vibration research is the transport system. The paper presents the results of preliminary tests, the aim of which was to analyze the propagation of vibrations forced by the movement of the vehicle floor on persons sitting in a car. During research vibration were registered in measurement nodes, in which the composition always included the signal of oscillation of the enforcing plate and specific locations on the human body. This paper presents results of vibration recorded on the extinction plate and on the head of the passenger

Probability of transmission of SARS-CoV-2 virus pathogens in long-distance passenger transport

This paper presents a description of the methodology developed for estimation of pathogen transmission in transport and the results of the case study application for long-distance passenger transport. The primary objective is to report the method developed and the application for case studies in various passenger transport services. The most important findings and achievements of the presented study are the original universal methodology to estimate the probability of pathogen transmission with full mathematical disclosure and an open process formula, to make it possible to take other specific mechanisms of virus transmission when providing transport services. The results presented conducted an analysis on the mechanisms of transmission of SARS-CoV-2 virus pathogens during the transport process, to examine the chain of events as a result of which passengers may be infected. The author proposed a new method to estimate the probability of transmission of viral pathogens using the probability theory of the sum of elementary events. This is a new approach in this area, the advantage of which is a fully explicit mathematical formula that allows the method to be applied to various cases. The findings of this study can facilitate the management of epidemic risk in passenger transport operators and government administration. It should be clearly emphasised that the developed method and estimated values are the probabilities of pathogen transmission. Estimating the probability of transmission of the SARS-CoV-2 virus pathogen is not the same as the probability of viral infection, and more so the probability of contracting COVID-19. Viral infection strongly depends on viral mechanisms, exposure doses, and contact frequency. The probability of contracting COVID-19 and its complications depends on the individual characteristics of the immune system, even with confirmed viral infection. However, it is undoubtedly that the probability of transmission of the SARS-CoV-2 virus pathogen is the most reliable measure of infection risk, which can be estimated according to the objective determinants of pathogen transmission

Estimation of engine piston system wear using time-frequency method

The paper presents the fault diagnosis technique for internal combustion engines using time-frequency representations of vibration signal. Engine block vibration results as a sum of many excitations mainly connected with engine speed and their intensity increases with the appearance of a fault or in case of higher engine elements wearing. In this paper an application of acceleration signals for the estimation of the influence of piston skirt clearance on diesel engine block vibrations has been described. Engine body accelerations registered for three simulated cases representing piston skirt clearance variations were an object of preliminary analysis. The presented procedures were applied to vibration and pressure signals acquired for a 0.5 dm3 Ruggerini, air cooled diesel engine. Reciprocating machines are difficult to diagnose using traditional frequency domain techniques because of generate transient vibration. In conducted experiments wavelet transform has been chosen

Application of the vibration test in the evaluation of the technical condition of shock absorbers built into the vehicle

The paper presents an assessment of the technical condition of the vehicle shock absorbers built into the vehicle on the basis of the signals recorded during the vibration test. The test was performed on a test stand with kinematic harmonic forcing. The test stand can enforce vibrations in the range of 0-21 Hz and amplitude of 6 mm. The shock absorbers with indicated technical condition were built into the vehicle (the new shock absorber and the one with oil leak). The research was conducted on the twin-tube hydraulic shock with a modified structure that allows to change the amount of the fluid. The study was conducted for the front suspension shock absorber of passenger car with an independent McPherson front suspension. Acceleration was measured using capacitive sensors of accelerations type ADXL. Acceleration was recorded on test stand platform and near the axis of the wheel and on the upper point of attachment of the McPherson strut. Registered acceleration diagrams were subject to further treatment consisting of filtration and analysis. The results were compared for selected technical states