G. Peruń

The Method for Identification of Damping Coefficient of the Trucks Suspension

The modern commercial vehicle with a weight of more than 3,5 [Mg] is a complex design solution, which contains many of mechatronic systems. The standard equipment are the ability of the driver assistance systems such as ABS (Anti-Lock Braking System), ESP (Electronic Stability Program), ASR (Acceleration Slip Regulation). The technical condition of the modern cars suspension determines the value of the indicators of road safety. An essential element of the suspension system, whose function is to change the mechanical vibration energy into thermal energy, is the shock absorber. Incorrect functioning of shock absorbers affects the quality of the operation of these systems improve safety. In the case of gradually wears of shock absorber even an experienced driver is able to notice this phenomenon. For this reason it becomes necessary the need for regular technical condition monitoring of dampers. Diagnostic dampers on buses and trucks are limited to the organoleptic examination and propose based on intermediate symptoms such as accelerated tire wear. The paper describes the method for estimating the suspension damping characteristics of commercial vehicle in operating conditions.

Simulation and Laboratory Studies on the Influence of Selected Engineering and Operational Parameters on Gear Transmission Vibroactivity

The optimization of the construction of gears leading to the minimization of dynamic effects and to meet all basic criteria is in many cases only possible by applying numerical methods. The models allow determining the influence of a range of factors on the dynamic phenomena. Proper experimental tests are often not possible because the number of options of influencing factor sets is very large. Using simulation models allows limiting the volume of experimental studies to the necessary minimum, and hence is beneficial from the economic standpoint. The paper describes numerical and laboratory researches on the influence of selected construction, technological and operational factors on the dynamic effects and vibroactivity in gears. Numerical analyses were performed using a custom-developed dynamic model of a test stand with the gears operating in the circulating power system. The models details were presented at the International Congress on Technical Diagnostics in 2008. The idea behind this article is to present selected results of simulation calculations and laboratory tests to determine the possibility of minimizing the noise and vibration of gears. Selected results of the calculations were also compared with the results of laboratory tests to demonstrate the high compatibility of the two test methods.

Modelling of Power Transmission Systems for Design Optimization and Diagnostics of Gear in Operational Conditions

This article presents the authors dynamic model of power circulating gear test stand. It was assumed, that properly defined and next identified model can be used to analyze dynamic phenomena in meshing and bearings of gears and allows optimizing their construction, especially to minimize their vibroactivity. The article includes description of the construction of a test-stand, as well as short characteristic of the dynamic model. Afterwards it was presented verification, whether the model was correctly fine tuned. For verification purpose, were conducted laboratory measurements of velocity of transversal vibrations at the test-stand using laser vibrometer. Results of laboratory examinations were compared with the results achieved during computer simulation. Developed and presented dynamic model take into account a number of design, technological and operational parameters of gear. It was also presented algorithm of researches aimed at minimizing the vibroactivity of gear.

MODELLING AND SIMULATION OF POWER TRANSMISSION SYSTEM ORIENTED ON DIAGNOSIS OF FAILURES IN TOOTHED GEAR

In the article are presented chosen research results of influence of local defects in toothed gear on the vibroacoustic signal. Vibroacoustic methods of diagnostics are perfectly suitable to the task of monitoring the status of devices during their normal work. Monitoring of vibrations during operation is particular importance for industrial toothed gear as well gears working in the power transmission systems of aircrafts. Taken into account negative consequences of damages in toothed gears, determination of changes in vibroacoustic signal can prevent possible failures, and is therefore very important. Researches were performed with use residual signals created from synchronously averaged time signals generated by identified dynamic model of toothed gear working in circulating power system. Superior purpose of work is development of effectively methods of damage detection, especially in its early stages, what has great importance during operating aircrafts. The study shows that local damage of the wheels affects changes in the frequency distribution of vibroacoustic signals energy. The degree of damage significantly impacts to the possibility of detecting it on the basis of time signals analyses.

Simulation Investigations of Influence of Tooth Depth Coefficient on Dynamic Phenomena in Toothed Gear

The increase of transverse contact ratio (εα) value usually allows reducing general level of gear vibroactivity. Article put to the test influence of coefficient εα value on dynamic forces in mesh zone with use of dynamic model of toothed gear. From theoretical point of view, the optimum value of transverse contact ratio is equal 2, what mean, that in mesh are always two pair of teeth. Obtainment such value of coefficient εα requires another construction of toothed wheels – wheels with HCR (High Contact Ratio) profile teeth. On result of occurrence of different deviations in toothed gears, as well as the dynamic phenomena, obtainment of continuous two-pair cooperation of gear pair is impossible and when this necessary is, solutions with near or exceed optimum value of coefficient are applied.

Toothed Gear Dynamic Model as a Tool for Assist Diagnosis its Technical Condition

This article presents the results obtained with use of authors dynamic model of gears working on power circulating test stand. It was assumed, that properly defined and next identified model can be used to analyze dynamic phenomena in meshing and bearings of gears.The article includes results of simulations of gear with chipped tooth and with partial crack of the pinion. Results of analysis shown, that the occurrence of meshing deviations, makes the detection of damages in the early stages of their growth difficult and the detection may be not possible without using methods of advanced signal analysis.

Possibilities of Using Vibration Signals for the Identification of Pressure Level in Tires with Application of Neural Networks Classification

The article provides a discussion on the studies comprising active experiments conducted on passenger car and analytical experiment on application of neural networks in the identification of pressure level in tires of a vehicle based on vibration signals. The purpose of research was to analyze the possibilities of monitoring of pressure in tires during the diagnostics tests of shock absorbers. The paper presented on last International Congress on Technical Diagnostics in 2008 examined the influence of changes of pressure in tires on the results of diagnostics test of shock absorbers. Those influences were observed in typical test methods used in vehicles service stations and even in new vibration methods. The article presents some results of research on neural network classification method of pressure in tires level. Tested solutions can be used as the preliminary module of diagnostics system during the shock absorber test. The signal processing methods were based on application of time, frequency and time-frequency transformations which enables obtaining the signals information carried in one or two domains simultaneously, namely those of time and frequency.