Applied Mechanics and Materials Vol. 693

Abstract: The contribution deals with verification of tin car body production using single action experimental stamping die. Two methods of car body production were verified - the first one used open die made of tool steel and the second one used closed die made of tool steel with Fibroflex at the bottom of the die. The tin steel sheet TS 245 with thickness 0.28 mm had been used for the car body production. The shapes of pressings were evaluated using the photogrammetric 3D measuring system ARGUS. The ARGUS optical system allowed evaluating the wall thickness change and the deformation on the surface of pressings as well. These values had been compared for both method of the tin car body production.

Abstract: Redistribution of residual stresses in a stamped sheet metal leads to the springback phenomenon. Springback phenomenon is well predicted for some mild steel materials, but not for steels with higher strengths. Nowadays, one of the most used tools to stamping optimization is usage of numerical simulations. In this paper was investigated sheet metal behavior under cyclic tension-compression test. Special fixture which serves as a buckling prevention of sheet metal in the compression phase of measuring stress-strain curve was designed. Obtained stress-strain curve was used to the definition of kinematic hardening model in numerical simulation. This model was verified with the real experiment in deep drawing process.

Abstract: Explosion and high velocity impact are typical ballistic loads of structures. This paper describes the problem of wave propagation in solid rocket booster part. Such waves originate by acting of explosion waves or by high velocity impact of solid parts on the structure. Computational simulations are applied to the problem of propagation of shock waves in a composite material reinforced by carbon fibres which are supposed to be much stiffer than the matrix. The shock wave in such material is influenced by reflexion and refraction on the interface between fibres and the matrix and by the interaction of then waves. The shock wave is strongly damped in such composites in this way. In the present study, the response of composite laminates under velocity impact loading will be investigated using MATLAB and ABAQUS software.

Abstract: The paper deals with comparison of the failure micromechanisms of nodular cast iron at static, impact and fatigue stress. Several specimens of ferrite-pearlitic nodular cast irons with different content of ferrite in a matrix were used for metallographic analysis, mechanical tests and microfractographic analysis. Mechanical properties were found out by static tensile test, impact bending test and fatigue tests. The microfractographic analysis was made with use of scanning electron microscope on fracture surfaces of the specimens fractured by these mechanical tests. Fracture surfaces of analysed specimens are characteristic of mixed mode of fracture. Failure micromechanism of nodular cast irons is dependent on mode of stress.

Abstract: The article describes the deep drilling tests of internal company research, which is aimed to determine the geometric tolerances as run-out, roundness and roughness, but also the shape and size of chips depending on cutting parameters. Further exploration subject was recorded using the actual engine power to determine the torque and axial force required for removing particles at the given cutting parameters. The results served to increase the productivity of deep drilling operations within the optimization process.

Abstract: The paper is focused on the design of the electrode for needleless coaxial electrospinning. This method allows to produce core/shell nanofibers from the free surface of a polymeric two-layer. The geometry of the designed model of electrode was analyzed using the software Autodesk Simulation Multiphysics. The results of electrostatic field simulation indicate the sharp edges of the electrode as the source of high electric intensity. These sharp edges lead to the loss of the electric energy during the electrospinning process. Based on that, the new cylindrical geometry of the electrode was developed. The results of carried out experiments clearly demonstrate the enhancement of the electrospinning process stability.

Abstract: This article is focused on analysis of impacts of cellular structure on even heat distribution and heat removal rate from surface of the bi-component experimental part with using cooling potential of liquid technical gases. Experimental part had bi-component core/shell structure and both components were made of the same metal material. The only difference between them was their structure. The shell component of experimental part had compact and consistent structure. The core either had the same structure as the shell layer or it was created using fractal patterns with microporous structure of open cell character. Porosity influence on temperature field distribution on the part surface was assessed in two levels distinguished by different sizes of fractal patterns.

Abstract: This work deals with a development of a tool for ear ventilation tube production. Ear tubes are medical devices, which allow ventilation and provide pressure equalization in the middle ear cavity for prolonged period of time; in case of repetitive inflammation. These implants are normally made from metals or classical polymeric materials. Whereas, today, the effort is to develop bioresorbable tubes based on polylactic acid, which could replace currently used material. The benefit provides no requirement of secondary surgery for their removal. The size of ear implants is only in millimetres and the tool for their manufacturing requires a special technology. In this paper, two tubes and a transfer mold for their production was designed using 3D CAD software Catia V5R18. Subsequently, the special manufacturing process for the mold cavity plates using the rapid prototyping and electroforming technology was proposed. The designed tool is intended for biodegradable tubes, which will be further tested in the laboratory.

Abstract: The modern investigation of the topography of cut surfaces is nowadays usually performed by three-dimensional surface roughness indexes. The goal of this work was to determine a theoretical roughness index for face milled surfaces. The calculated values were compared with real surface roughness data obtained by performing cutting experiments and the relation was determined between these two datasets.

Abstract: The main goals of the improvements of manufacturing procedures are the increase of the material removal rate, the enhancement of the accuracy of the parts and the improvement of the surface quality. The specifications of the surface quality contain the requirements which ensure the proper functional conditions as well. An example among these is the twist-free surface on some special rotating shafts. In this paper we investigate the generated twist on surfaces machined by longitudinal and rotational turning and analyse the effects of the geometric parameters of rotational turning.