Machine vibrations analysis working in non-stationary states

The article presents the examples of practical application of the procedure for non-stationary signals processing. The developed method – Procedure of Linear Decimation (PLD), Short-time PLD and other enhancements to the standard PLD were applied for signal analysis of vibrations of turbine engines and gears in unstable operating conditions. The rotational speed of driving shaft was adapted as a reference signal

Measurement and mathematical function of the actuation force of the rail switch drive

The paper presents results of measuring the force of the adjustment of the rail switch drive by spindle. The actuation force is the maximum force with which setting valve of the drive done to change position of the point. The simulation research requires proper mathematical model of the actuation force of the rail switch drive. Thus, the verification of such model requires real data measured on real object. The paper presents results of measurement and method of real data analysis

Research on influence of damages of car vehicle combustion engine on noise level

The article addresses results of the research on the preliminary research on influence of chosen damages of car vehicle engine on noise generated level. The diagnostics experiment was conducted and the noise levels were measured in defined measure points placed outside the vehicle. For the experiments vehicles with damages of the engine and its equipments were chosen. The measures were conducted before and after the repair. The research had preliminary character, so evaluation of the influence of damages of car vehicle engine on noise generated level have had qualitative dimension

Research on vibroacoustic phenomena of tram vehicles for the changeable dynamics conditions

The article addresses the methodology and the results of studies of vibroacoustic phenomena generated by tram vehicles. While a tram was running at various speeds, both the noise level and surface vibrations were recorded simultaneously. These quantities determine the overall impact of tram cars on their environment. The research assumptions made enable assessment of accretion of these effects in the function of running speed, which may prove particularly for the sake recommendations as to the permissible speed of trams in urban conditions

The study of the dynamic properties of some structural components of harmonic drive

The paper presents the geometric models of flexsplines and wave generators developed based on the actual construction and geometric dimensions of manufactured harmonic drives (type CSD, CSG, HFUS and HFUC). In order to enhance the data preparation process, the model geometry was recorded in a parametrical form. By altering the individual properties of the models, it is possible to automatically generate finite element grids for flexsplines and wave generators of various geometrical and structural properties. The calculations prepared for the sake of the study by application of the finite element method (FEM) were conducted using the Femap/NX Nastran software. A preliminary numerical modal analysis of the structural solutions for the harmonic driver flexsplines and wave generators assumed to be applied was conducted

On-line diagnosis of mechanical defects of the combustion engine with principal components analysis

Vibroacoustic diagnostics of combustion engines might be a complementary tool to OBD systems especially in mechanical defects detection. The presented method allows preliminary diagnosing of the mechanical defects on-line during driving without resampling the signal. The diagnosis is based on statistical features of the vibration signal. Principal components analysis (PCA) offers an approach for linear transformation of the problem variables so that the redundant information is reduced and the diagnostic model is more easily extracted. The product chosen for the investigation presented in this paper is a spark ignition engine. Performing analytical model, which is time consuming and costly, can supplement described method only in chosen cases. It is possible to diagnose of engine from the objective parameters of the specially prepared vibration signal without performing simulation models

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

Advantages of new micro-jet welding technology on weld microstructure control

An innovative apparatus to welding process with micro-jet cooling of the weld made it possible to carry out technological tests, which have proved theoretical considerations about this problem. This project gives real opportunities for professional development in the field of welding with controlling the parameters of weld structure. These tests have proved that the new micro-jet technology has the potential for growth. It may be great achievement of welding technology in order to increase weld metal strength. The new technology with micro-jet cooling may have many practical applications in many fields, for example such as in the transport industry or to repair damaged metal elements. The advantages of the new device over the traditional system are the ability to control the structure of the weld, the weld mechanical performance increases and improve the quality of welded joints

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

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