The paper presents a method of modal parameter estimation based on RLS (Recursive Least Square) algorithm, and wavelet filtering. The wavelet filtering gives possibility to decoupling frequency components of signal response of structure. This operation can also reduce the order of the signal model estimated by RLS algorithm. An additional advantage of this method is the possibility of adapting the wavelet filter parameters to the changing parameters of the system. Reduced model order significantly reduces the time of estimation of modal parameters, which enables the real – time implementation of the method. Due to recursively updated covariance matrix of model parameters, the confidence intervals of modal parameters can be also estimated. All routines have been implemented and tested in MATLAB®. The method have been tested on simulated data delivered by an AIRBUS team and on the test bed with a variable stiffness.
The paper presents an experimental study to identify the dynamic parameters of a water-filled tank model. The experimental modal analysis approach involving the excitation at one point of the structure and acquisition of vibrations at selected points distributed over the tank surface allowed to determine the resonance frequencies, mode shapes and damping ratios. The main aim of the research was to examine the influence of the level of liquid on the modal parameters. The experimental study showed that the level of water in the tank had an important impact on the values of natural frequencies and damping ratios.
Measurement and determination of the corrosion in the material is an important aspect of the structure safety. For that purpose article presents amplitude and time-of-flight C-scan method for thickness evaluation with single ultrasonic transducer. Test was performed using immersion setup with automated two-axis scanner.
Fundamental issues of electromagnetic interference influencing transport electrical equipment used for railway purposes were presented in this paper. Train call recorder is an example of such equipment and it is the focal point here. In its daily operation it is exposed to electromagnetic environment. That interference may originate from both intended and unintended (static and mobile) electromagnetic interference spanning across vast areas of railway activity. Hence the importance of uninterrupted and undisrupted functioning of train call recorders under conditions of electromagnetic environment present over areas of railway activity.
In last few decades it can be observed that there is a significant growth of the interest in the structural health monitoring (SHM) systems development and applications. Unfortunately many authors focuses only on the damage detection and other activities related with diagnosis of fault. Meanwhile, classical SHM system by definition should have in addition to a diagnostic module also module for load monitoring. This load can be measured, but easier and cheaper is to identify it from the measured response of the object. Often it is the only practical possibility to monitor the excitation. The paper presents a trial to apply a spatial filter based on operational deflection shapes (ODS) to force identification. The idea of spatial filter will be shown together with the method of force reconstruction. The simulation verification and comparison with classical modal filter will be also provided.
The stringent worldwide CO2 limit values are the primary requirement for future mobility. So the environmentally vehicle’s drivetrain is element of energy efficiency worldwide mobility. Hence, the development of efficient drivetrain is the top priority. We can also follow the optimization of existing system and introduction of completely new system. According to the various experts, these new trends have expressive effect on torsional vibration in drivetrain. For this reason, many elements such as the clutch disc equipped with a torsional vibration dampers and dual mass flywheels are posed higher and higher requirements for minimizing vibration, and that, in the case of research of mentioned elements are required the application of methods of design diagnostics. In order to accomplish the growing requirements we need to know the basic dynamic properties, torsional stiffness and damping. Therefore, we decided to study of these properties of a dual mass flywheel in our laboratory. Mentioned properties were evaluated from measurements on the experimental stand for measuring by forced vibration and they were monitored at various conditions.
At our department we deal with continuous tuning of torsional oscillating mechanical systems during their operation, mainly in terms of torsional oscillation size, whereby we use the methods and means of technical diagnostics. One of the manners of continuous tuning realization is the application of the extremal control – experimental optimization. The main advantage of this is that we need not know the mathematical model of the mechanical system. Actuating variable in this regulation is the pressure of gaseous medium in the pneumatic flexible shaft coupling – pneumatic torsional oscillation tuner. By changing the pressure of the gaseous medium in pneumatic flexible elements of the coupling we change its torsional stiffness and thereby dynamic properties of the mechanical system too. The objective of this paper is to present partial results of extremal control operation on the newly built mobile torsional oscillating mechanical system.
The paper contains a strength analysis of gears in a dual-path gearing made of plastic. Computation was carried out using Abaqus program by means of finite elements method (FEM). The results of calculations allow the interpretation of the results of diagnostic tests. Due to the fact that the dual-path gearing had wheels with straight teeth, it was possible to simplify the computation using two-dimensional models. The paper shows activities related to preparation of models, defining boundary conditions, the process of computation and the presentation and interpretation of obtained results. In the carried out FEM analysis, stress distribution was determined on models of pinions and gears, paying particular attention to key points like teeth feet or their flanks. In order to improve readability of these solutions and to ease interpretation, some results were also presented in a form of charts. Conclusions drawn from the analysis will make it possible to introduce conceivable changes in the structure of designed gearing already at the stage of modelling.
Air gears must meet high performance criteria for accuracy, therefore quality control is necessary for their production. CMM Software determines the capabilities and scope of the measuring machines. The choice of measurement method should be carried out taking into account the accuracy of gear and taking into account the capabilities of the system and measurement needs. Item will present the methodology of measurement of cylindrical gears using a standard CMM software. The results of these diagnostic tests to prevent the need to purchase additional software, the measuring machine and its setup. You should only choose a method of analysis that will be carried out directly in the environment measuring machine, or will be made in the CAD system based on the geometry acquired during the measurement with respect to the virtual model. In the second case export is needed in the appropriate format measurement data to CAD software.
Accuracy diagnostics bevel gears of aircraft gearbox has become a key component in today’s manufacturing process. Properly prepared and carried out the measurement process of bevel gears determines its accuracy, productivity and the production costs of aeronautical gearbox.
In the process of assessing the accuracy of manufacturing, majority of manufacturers of bevel gears use specialized contact coordinate measuring machines. Therefore, this article depicts different perspective on measurements of bevel gears using a universal measuring device, which is an optical 3D scanners ATOS, using in the process of measuring white and blue light.
Due to the use of the optical scanners ATOS in measurement process, it was necessary to develop a methodology dealing with the process of assessing and accuracy, in order to achieve the desired results of measurement. The studies take into account the economic aspects of the use of technical diagnostics in the production process.
The article presents an analysis of conditions and developed rules concerning the preparation of a model for measurement. It also contains hints and a description of the measurement process. Furthermore, it depicts the rules specifying the interpretation of measurement results as well as the technical rules of their realization.
The project involved developing a mathematical model of machining teeth of a spiral bevel gear and a mathematical model of the gear pair. The mathematical model of machining was based on generative machining with a single indexing system (face milling). On the basis of tool geometry, technological settings, kinematics of the process based on the vector and matrix calculus and differential machining geometry, a tooth model was built and tooth surfaces were obtained. The mathematical model of the gear pair was developed with the use of the gear geometry and the obtained tooth surfaces of the pinion and the gear. The model allows for the possibility of introducing errors due to gear settings and tolerances of the manufacturing errors in housings and other transmission components. The mathematical model of the gear pair was used to obtain the contact pattern and the transmission error graph. An analysis of the results and the application of meshing quality indicators allowed us to improve the gear transmission. This process was carried out in an iterative cycle by changing the set-up (by modifying technological machining) parameters of the machined surfaces of the teeth. The application of both models, i.e. the mathematical model of machining teeth of a spiral bevel gear and a mathematical model of the gear pair, was presented using the example of aircraft gear 18:43.
Adam MARCINIEC, Grzegorz BUDZIK, Tomasz DZIUBEK, Bartłomiej SOBOLEWSKI, Małgorzata ZABORNIAK
Designing and manufacturing of aeronautic bevel gearbox is a complicated and time-consuming process due to complex kinematics of the machining process and numbers of manufacturing methods. Algorithms used in manufacture process are usually provided by machine manufacturers. Using other and commonly available calculation algorithms requires a lot of studies to verify whether the proposed gearbox works correctly. In order to reduce the manufacturing costs of prototypes, it is possible to use Rapid Prototyping methods.
Using coordinate optical measurements enables to determine the accuracy of prototypes manufactured by selected methods using and introduce such changes in the model to get the best accuracy of mapping models. Increasing the accuracy of the models enables to verify the correctness of assumptions made in the initial stage of product designing. This approach reduces significantly both prototyping time and manufacturing costs.
The article presents the model ling and manufacturing process of aeronautic bevel gear taking into consideration the accuracy of selected Rapid Prototyping methods. The gear modeling is based on machining simulation method conducted in Autodesk Inventor software. The measurement results are shown in displacement maps obtained with an optical scanner Atos II Triple Scan and universal GOM Inspect Professional software, which determines the prototype accuracy in relation to 3D-CAD models.