Key Engineering Materials Vol. 635

Abstract: Spinal implants are mechanical equipments that facilitate fusion, correct deformities, and stabilize and strengthen the spine. To make an implant efficient, it has to endure without any failure, especially mechanical damage, stand all the static and dynamic loads incurred in spine during everyday activities, and maintain the necessary position of motive segments during the bone adhesion. [1] Human spine is exposed to the highest load in the lumbar section [2]; therefore, lumbar bilateral implants require higher attention in terms of mechanical parameters verification. The main objective of this paper was to compare mechanical properties of lumbar bilateral systems using the spinal implants manufactured by the conventional method and the Direct Metal Laser Sintering method (DMLS). Detection of mechanical properties enables the assessment of possible replacement of commercial manufacture with the DMLS manufacture. On the basis of the ASTM F1717 standards providing the essentials for the comparison of mechanical properties of spinal systems, twenty mechanical compression tests were carried out. Mechanical tests were carried out using 20 spinal bars with the diameter of 11 mm and the fastening length of 260 mm, manufactured by the DMLS technology while using the EOSINT M280 equipment (EOS, Germany), and 20 identical spinal bars manufactured by the conventional technology. Results obtained in mechanical compression tests indicate that both manufacture methods are comparable and there are no significant differences between them, as for the strength characteristics. Other trials will be focused on static tensile tests and cyclical tests of lumbar bilateral systems.

Abstract: Advanced high-strength dual-phase steel was developed specifically for automotive industry in order to benefit from its excellent formability and great crash absorption ability in comparison with conventional AHSS. Resistance spot welding is the dominant and effective method of joining metal sheets in automobile industry. After spot welding, important changes occur in mechanical and metallurgical properties of the spot welded areas and heat affected zones. The investigation into these changes is very important for safety, which depends on the strength of the welded joints. Weldability of the DP steel is one of the key factors governing its application in automotive industry. The influence of the primary welding parameters, especially welding current, on the weld quality was investigated by testing microhardness and tensile shear load bearing capacity of resistance spot welds of DP600 steel sheets.

Abstract: Ground-supported tanks are used to store a variety of liquids. This paper deals possibility numerical modelling reciprocal interaction moving container with fluid in under consideration horizontal harmonic motion reservoirs. It clarify watched phenomenon, illustrate pressure process at a walls of container, from witch it results action of force at a container. The numerical problem analysis is comparing with realised experiment, where steady state motion of fluid was watched and his maximum wave of fluid on the walls of reservoirs.

Abstract: In the stamping operation, springback causes geometrical inaccuracies and defects in final shape of metal stampings. This defect is actual problem in stamping production. Nowadays the detailed description of the springback is not clarified well regarding production of more complicated shape. To eliminate springback problem in stamping production there are methods, discovered and approved by advanced procedures. However applying these methods, particularly in drawing operations is much more complicated. The research describes theoretical analysis of springback phenomenon and possible experiments for the springback compensation. The research also describes analysis of springback using software for numerical simulation AutoFormplus R5 which is currently used to design the process of stamping production in company ŠKODA AUTO.

Abstract: The article deals with the comparison of thickness change of spherical cup made from TRIP steel RAK40/70 after hydraulic bulge test. The thickness has been measured by timing gauge and by apparatus Argus. Experimental material thickness has been 0.75 mm. From measured values of thickness of experimental material has been calculated the dependence stress-strain by models of several authors.

Abstract: This paper analyses a failure of the micro alloyed steel (R_e= 500MPa) at a temperature range 400 - 500 ^oC in the tensile test conditions and in the creep conditions. The failure character in condition tensile test was changeless and the fraction was transcrystalline ductile. The structure near a fraction showed a considerable deformation texture (reduction of area = 76%). The contraction and the fraction stress considerable was decreased by the increase of the time up to the fraction and the by the increase of temperature in the creep conditions. There were formed secondary intercrystalline cracks except the central crack in the area fraction. Intercrystalline cracks were started step by step to be connected each other. The fraction was started to obtain a mixed status alike and the intercrystalline (creep) fraction part was started to increase.

Abstract: Nowadays, heating energy demand has become a significant estimator used during the design stage of any new building. The residential building sector consumes a significant amount of fossil fuel energy and thereby produces a large percentage of greenhouse gas emissions that contribute to global warming and climate change. The aim of the paper is analysis of thermo-physical and environmental parameters of proposed versions of exterior wall structures.

Abstract: The rapid prototyping (RP) process is capable of building parts of any complicated geometry in least possible time without incurring extra cost due of absence of tooling. Fused deposition modeling (FDM) is a fast growing RP technology due to its ability to build functional parts having complex geometrical shape in reasonable time period. The quality of built parts depends on many process variables. The presented study focus on assessment of mechanical property flexural strength of part fabricated using fused deposition modeling (FDM) technology. The 3-point bending test was used, to determine flexural strength. Samples were made of polycarbonate on Fortus 400 mc machine from polycarbonate with slice height 0.127mm. The experiment was focused on influence of air-gap size between fibers and number of outline contours on selected mechanical properties of FDM prototypes determined 3-point bending test. The results show possibility to obtain weight reduction in printed parts with sparse structure with sufficient flexural strength and with reduced build time, compared to structure printed with default machine setting,. To obtain optimal processing parameters for 3D printing prototypes, it is necessary to execute further experiments, which could verify gathered results.

Abstract: Protection and safety of workers in plants with the danger of fire is always the first place. They are currently used in devices that are designed to quickly separate the fire residues from workers such as steel fire doors filled with non-combustible materials that insulate the prescribed time up to 600 ° C. As the demands for safety was the requirement for resistance to temperatures higher than 600 ° C. [1, 2]. Post relates to improvements refractory properties of steel gates based geopolymer matrix composites. They are analyzed the properties of different materials such as fillers geopolymer matrix, durability and affinity to steel parts of the door structure.

Abstract: Cast iron with spheroidal graphite is a very good constructional material. Production of castings from standard kinds of nodular cast irons is quite good managed, but manufacturing of mark GJS 400-18 LT with excelent strength and plastic properties by minus temperatures is complicated, because it reacts very sensitively on the changing of melting conditions and metallugical treatment. The contribution is focused on an observation of changing of structure and mechanical properties by different ways of metallurgical treatment. In operating conditions of foundry three series of melts were made. From every melt the mould with testing pieces „Y“ with dimensions 25 x 40 x 140 mm was poured. Tensile test, impact test and metalographic analyse were realized on the test samples.