One of the most important features of motor vehicles is their steering maneuverability. Ways of determining single axle steering are well known. This paper presents an idea of how to determine maneuverability of motor vehicles with two steering axles. The concept makes use of elements of kinematic analysis as well as of a 3D model of the steering system. It is based on the theoretical analysis of the most unfavorable situations, such as parallel and perpendicular parking techniques, on the basis of which wheel-steering angles are specified. As a result, it was possible to create a 3D model to simulate the actual operation of the steering system. This made it possible to compare the theoretical approach with the actual system design.

Polymer composites with increased utility properties are becoming competition for conventional materials, in conjunction with additive manufacturing techniques. The aim of this study was to evaluate tribological characteristics of fibrous composites produced in fused deposition modeling (FDM) with the use of an innovative head with symmetrical feeding of the matrix material. Analysis of the influence of composite-forming temperature on their tribological properties allowed the determining of the optimal printing process parameters for this group of composites. Significant differences in the friction process of the same reinforced materials were observed in dry and wet environments. Fibrous composites showed 10 times lower wear intensity as well as two times lower friction value in water than in air. Research shows friction in the water environment ensures more even wear of the surface of the composites involved in the work. The article contains 3D microscopic imaging of the friction plane of the tested composites and a description of a typical course of material wear is described.

Abstract:The purpose of this research is unsatisfactory state of knowledge of the abrasive wear of composites with thermoplastic polymer as matrix material and reinforcing material in the form of short and focused carbon fibers that can be used in additive manufacturing technologies. The paper presents a conceptual design of an extrusion head used in Fused Deposition Technology, which allows for the implementation of appropriately stacked fibers at the level of detail production. Finite element simulation was performed to simulate the thermal effect of the system to demonstrate the effect of head cooling on the system. The assumed extrusion temperature of the material was obtained at a uniform nozzle temperature and stable temperature of the entire system. Flow simulation of thermoplastic polymer was carried out in the designed extrusion nozzle. By supplying 0.5 mm wire of 1.75 mm diameter thermoplastic material to the nozzle, the extrusion rate was 0.192 m/s. The proper design of the extrusion head for the intended applications has been demonstrated and the purpose of further research in this field has been confirmed.

The paper presents results of diagnostic tests for a CNC machine tool used for manufacturing elements with restricted freeform surfaces. Some selected errors possible to identify and estimate in numerically controlled machine tools using a QC20-W Ballbar were described and analyzed. The following parameters were subjected to thorough analysis: roundness deviation, perpendicularity and straightness deviation, cyclic error, backlash and reversal spike. The tests made it possible to carry out a correction of selected components of total tool positioning error and their influence on the process of geometric deviations of curvilinear surfaces produced with CNC machine tools.

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