Abstract. The article deals with modal analysis of light racing car. The objective of the modal analysis was to obtain a mathematical model of the structure that matches as closely as possible to the experimental results achieved in the tests. The post-processing stage encompasses the use of the results to update theoretical predictions, optimization via structural modification, subsystem coupling, calculation of real modes from complex modes, etc. So, modal analysis has been used as a simple way to calculate the natural frequencies of the system and as the technique for finding out, which frequencies can be destructive and dangerous for it. Within the article, the verification of boundary conditions of virtual FEM analysis was done using the experimental modal analysis. It was performed on a simple fixed beam. After the results comparison, it could be stated that the values of natural frequencies correspond each other, so the virtual lightweight racing car could be analyzed in software Autodesk Inventor Professional. The analysis has helped to improve the stiffness of the car to be more stable on the wavy surface of the racing road.

The paper deals with the bending tests of new designed joints for bus skeletons. The frames of buses have to satisfy various demands, but the safety of the passengers is the priority. The actual welded joints should be replaced by new type of profiles connections in the future. Finite elements method was used for the bending test simulation and for the stress investigation; the real experiments were done using the universal test equipment ZD10/90. Obtained results are comparable, so authors aim to realize next experiments in next days at which other shapes of the joints will be tested.

The article deals with application of theory related to kinematic analysis of mechanism into educational process. The article describes basic principles of three approaches to the kinematic analysis of mechanism, such are graphical, analytical and computer aided solution. Results obtained by individual methods can be compared, if the same input parameters are used. The modern and most popular method for students is the analysis with computer aid, at which a special software is used. This approach enable not only visualization of mechanism motion, but it allows also to define the position, velocity, acceleration, forces, moments and other parameters in every moment of time of movement. However, at definition of boundary conditions and verification of results obtained by means of computer, students need to know the theory and understand the laws of mechanics.

The article deals with the investigation of chip dimensional characteristics that are created by the tool with linear cutting edge nonparallel to the workpiece axis. It is the tool with special geometry that was designed by authors in order to improve product quality and shorten the time of its production. Aim of the research has been focused on the obtaining of dependencies of the chip dimensions on both feed per revolution and setting of tool corner height in relation to the workpiece axis during machining of 12 050 steel. Measured data were processed statistically and they were evaluated by means of regression analysis in matrix expression. Measured data have indicated that with the increasing of feed per revolution, the chip width and chip thickness are increasing, too. As for the depth of cut, if it is increasing, the width of chip is also increasing, but chip thickness is not changing. The experiments have shown that the shape of chips at the machining by tool with linear cutting edge is not suitable for usage in production without direct control by operator. Therefore, when considering usage of this tool, it will be necessary to design the tool with chip breaker.