Advanced Materials Research Vol. 1036

Abstract: The author of the article applied the boundary element method (BEM) to determine stresses occurring in a toothed rim of a flexspline. The relevant numerical calculations were conducted using software developed at the Faculty of Transport of the Silesian University of Technology. The numerical analysis conducted for flexsplines entailed the impact exerted by parameters of an indented toothed flexspline rim (number of teeth, addendum modification coefficient) and of a gear tool (gear tool head curve radius, pressure angle) on values of the stresses occurring at the tooth space bottom. Results of the said calculations have been depicted as curves of dependences between stresses at the tooth space bottom in the function of the number of flexspline rim teeth on constant values of the addendum modification coefficient. The cumulative diagrams developed based on the results of the calculations conducted may provide guidelines as to the manner of designing flexsplines for harmonic drives.

Abstract: This article is dedicated to analysis of the impact of lightening holes (performed in the webs of girders, ribs, etc. elements of thin-walled structures) on the value of the critical forces and local effort of the material webs girders. Paper presents the results of typical analysis of two flanges thin-walled girders. Calculations was performed for one of the three most common ways of making lightening holes which differ in the way the edge of the hole shaping. Analysis includes the most common case of work of this construction type - that is the case in which the load acts in the plane of web girder. The article presents a comparison of the results of girders with holes with the results for the full girders (without holes). Particular attention was paid to the significant increase the stress concentration caused by the occurrence of holes.

Abstract: The paper presents results of the active diagnostics experiments on influence of fatigue metal damage of the inner race of bearing and unbalance of rotating masses on vibration generated by the machine. Analysis of vibration related phenomena is a solution commonly applied in Structural Health Monitoring (SHM) systems. The application of vibroacoustics methods for technical condition monitoring has been developed in the past years in many systems of manufacturing processes. Vibroacoustic methods, based on the analysis of vibration or acoustic signals perceived as residual processes of non-invasive nature, is becoming more and more important in this respect. The scope of its application as well as the applicability of methods in numerous diagnostic systems also results from the capabilities of advanced methods of signal analysis and identification of numerous characteristics of technical condition. One of the most common operation damages are caused by rolling bearings wear. The scope of research contains tests on bearing damage and the unbalance of disc. The wear processes and unbalance are closely related to the vibration levels (arising from the mass loss of plastic deformation, and the fatigue damage). The research was conducted on special research test bench for vibration monitoring for rotating machinery. Structural health monitoring of machinery has to be conducted in different states and working conditions of the manufacturing system. Thus for simulating of different operating conditions the experiments have been conducted during run up of the machine which consist the transient states of working and during work on constant rotational speed of the power generate engine. For the identification of the symptoms of the machinery and equipments health monitoring the vibration signal have been analysed in time domain and frequency transformation as well. The performed signals are not stationary. Thus it is better to observe the signal simultaneously in time and frequency domains. For this purpose the spectrograms were determined. Spectrograms computes the short-time Fourier transform of a signal by default divided into segments. During the transformation the Hamming window and noverlap were used. For the comparison of the vibration of good and damage bearings signals registered for different frequencies have been presented in form of spectrograms and RMS distributions.

Abstract: The rapid prototyping with ice is a new manufacturing technology that can generate three-dimensional objects from ice by depositing and rapidly freezing water layer by layer. In order to freeze the water droplets, the plate must meet certain conditions, among those it is worth to be mentioned, the surface temperature, which should not surpass 0°C. The equipment presented in the paper is a part of rapid freeze prototyping equipment, designed and built by the authors. The authors analysed various freezing systems and they discovered that the classical cooling systems are not appropriate to be used in rapid freeze prototyping technology. The unique solution is the utilisation of thermoelectric cells, generic named as Peltier cells. The modern technology can be used in obtaining Peltier cells, with a high degree of reliability, electrical consumption and yield. This can be successfully used as heat pumps in industry. The author developed an original system that permitted to implement the Peltier cells. The cold plate was designed by using CAD software. In addition, the cold plate was produced and tested. The equipment obtained, has a greater power in comparison with the classical ones, even if it has smaller dimensions. The electrical power supply has to be well filtered in order to generate a higher efficiency. Through the main advantages of the Peltier cells can be mentioned: no maintenance have to be performed as this type of cells have no moving parts, thus having a major advantage; no CFC or other consumables parts have to be used, thus proving to be more economical than other systems; the heat regulation can be performed easier compared with the classical systems offering a better control and precision; it can be used in severe environments where conventional cooling systems can fail, being successfully used in the presence of liquid nitrogen; it can perform in various positions and is reversible similar to heat pumps. The main drawback of this system is that it uses a great amount of electrical energy, consequently can have a low yield.

Abstract: In order to prepare a refurbishing process of an element that characterize with a material loss which is a result of worn process or damage could be 3D scanned. Then it 3D model is gained after triangularization process and surface fitting. This model is compared with a CAD model which is an element design representation. In order to provide such comparison, the proper implementation of the MLDMCS (Material Loss Detection Method for Cylindrical Shape parts) in to the software is needed. The software is prepared in Visual Studio environment (.NET) with C# programing language (the algorithm code and the interface), SQL server (database) and Siemens NX software (PARASOLID internal libraries). MLDMCS is implemented as the one of the author Computer Aided Overhaul software modules (CAO). The implementation is a complex task, according to: interface preparation, data collecting, data presentation an input data form, proper set of input data configuration, preparation of 3D graphics processing an analysis algorithms, preparation of output data form and interpretation. The result of software algorithm should be an easy to interpret set of data with a possibility of automatic rapport generation. Furthermore the data should be collected in a data base for future analysis of element worn and damage repeatable progression. Data collected each time from a element during it technical state examination gives also an answer to future proceeding according critical quantity of refurbishing processes in recirculation of technical mean. Additionally collected data gives suggestion of it repeatability in worn or damage after various technologies of refurbishing. Future systems probably will be set on such solution and MLDMCS will be one of typical method used in industry oriented to overhaul of machines parts. Previously presented article, shows only pure method with it foundations. Nowadays solutions are mainly based on a metrology, also supported with CMM (Coordinate Measuring Machines) and offline measuring paths generating systems. The accuracy of proposed solution (3D scanning and transformation of point clouds to solid model) is less accurate than typical measuring methods; however foresights of application are promising. The demand accuracy is sufficient in order to prepare a cladding process by turning worn-out or damaged surface layer.

Abstract: The Material Loss Detection Method for Cylindrical Shape parts (MLDMCS) was presented in the previous article. The verification of the method was executed on two different samples, manufactured from different materials and with different geometries. The main goal of research was to set the diameter tolerance for a detection process. The first sample was examined nine times with a modification of one parameter diameter tolerance. The results interpretation gives a possibility to check the proper set of data for future cylindrical shape examinations according to accuracy class of manufacturing. Preparation of the first sample was done in order to check: centricity of compared models, uniform material los detection mechanical friction worn, various distribution and shape of material loss, various depth of material loss. Second sample was prepared in order to check correct detection of material loss in case when element have a feature (like key slot), that is in a part but simultaneously it exist according to design. The main target is to recognize with the algorithm: what is, what is not and properly classify material loss. Furthermore second examination sample was damaged in a border area of the mentioned feature. The presented verification proves that is possible to apply the proposed MLDMCS in industry to support overhaul process of technical means. The important part of examination preparation is a set of a technological base that is used to fit together sample model (from 3D scanning) and the design pattern model (from CAD design). The main result is a material loss digital presentation, 3D and 2D simplified distribution. Groups of material loss can be assigned to specific areas in order to prepare refurbishing process turning surface layer before laser cladding is applied. The distribution map (2D and 3D) fully corresponds to material loss distribution on samples. Time of element examination with MLDMCS is strictly related to accuracy in angle division and axial division in distribution of singular volume. The verification proves that the 3^rd generation of refurbishing process operation preparation is possible to put in to practice. However it has to be prepared with proper methods and equipment. The method should be applied especially in situation when an element is: refurbished in series, elements that are refurbished have similar design, elements characterizes with same accuracy class of manufacturing and similar diameters, but with various designs.

Abstract: Geneva mechanism is used as a mechanism for transforming rotary motion into intermittent motion and is able to achieve a precise movement and its lock, which makes it usable in many areas, particularly in timer devices, measurement devices, feed mechanisms, positioning mechanisms, pick-up and transport machinery, textile machinery etc. The studied literature showed that, although it has long been known, this mechanism is still interesting for contemporary researchers. The present paper proposes a method of synthesis and a computer-aided kinematic and dynamic analysis for this mechanism. Based on input data, it was developed a computer program that computes the dimensions of components of Geneva mechanism and determines velocity acceleration and displacement of Geneva wheel. The dimensional calculated data were also used to obtain 3D model of the mechanism.

Abstract: In this paper are described fatigue physical tests that were performed on a great number of riveted specimens with different constructive and technological parameters. Some of the purposes of the experimental tests, they were: determining the number of load cycles at which cracks by fatigue occurred, determining the moment of initiation, the location and propagation speed of the fatigue crack. For fatigue crack evolution study numerical models were designed. A simplified model for FEM analysis was proposed that reduced considerable the calculus effort and allows models for complex riveted joints. From the described experiments on specimens and numerical simulations there are some important conclusions regarding the fatigue phenomenon in riveted joints such as: important peculiarity of damage by multiple cracks is the cracks junction of adjacent rivet holes, which contributes, by jumping, to increase the degradation rate of assembly; the riveted joint model can be applied with good accuracy to estimate the durability of the structures inclusively to identify and prevent the cases of widespread fatigue damage.

Abstract: "The Greenpower Corporate Challenge" is an annual race of four-wheeled electric vehicles organized on the tracks in the UK. Participants of the "The Greenpower Corporate Challenge" contest are students of high schools and universities which are involved in designing and construction process of an electric race car. The basic goal of GPCC competition is making the largest possible number of laps on the race track - for a limited time of 90 minutes. The main restriction is imposed by the organizers, the power source and type of the motor driving the car, which increases competition level and equalize the chances of teams. The design process of the vehicle was followed by the drawn intuitively, an iterative procedure. A simplified methodology for the design and construction of the vehicle has been adopted, which was based on a cyclic process of designing every mechatronic subsystems and gathering them all in one CAD model. During all designing and engineering tasks a mathematical model of the vehicle has been used. With using finite element method (FEM) and studies using an anthropometric drivers model there was a continuous control of the correctness of the solutions and results. This article describes the computer research methods used in the design process of selected systems and components of the vehicle Silesian Greenpower and their adequacy in relation to traditional methods.

Abstract: The paper presents the puncture resistance of the material, that is under the influence of highly deformable projectile, depending on changes of material’s yield strength. The simulation has been conducted using mobile cellular automata (MCA) with authors’ own software. The simulation took into account the elasto-plasto-viscous properties of the material as well as surface and internal friction. The selected results are illustrated in terms of piercing the multilayer material with chosen projectiles of kinetic influence in the range of impact velocity between 300 and 1000 m/s.