Papers by Keyword: Transition Zone

Abstract: This study uses numerical simulation to examine the influence of variations in laser power and transition zone length on the tensile behavior of bimetallic samples designed to be manufactured by selective laser melting (SLM). The materials studied are 316L stainless steel-copper, chosen for their complementary mechanical properties and functional relevance in high-stress applications. The transition between the two materials was modeled by modulating the laser power according to different profiles (linear, concave or convex) and over different lengths (d(x) = 0 mm, 10 mm, 20 mm) in order to evaluate their impact on the simulated mechanical performance. The numerical results show that a gradual transition in laser power, combined with an extended transition zone, significantly improves stress distribution and leads to better mechanical integrity. Simulations performed in ANSYS provide an in-depth analysis of stress fields and highlight the crucial role of manufacturing parameter management. This study thus highlights the importance of precise control of manufacturing parameters in the 3D printing of bimetallic components and demonstrates, through numerical modeling, that optimized transition management can improve the mechanical integrity of parts produced by SLM. Experimental validation of these results will be an essential prospect for future work.

Abstract: The paper compares macromechanical and micromechanical properties of high-performance concrete containing supplementary cementitious materials and basalt aggregate. The aggregate was either a common unprocessed crushed basalt aggregate or crushed basalt aggregate the coarse fractions (4/8 and 8/16 mm) of which were washed by water and dried before use. The observed macro-mechanical properties were compressive strength, tensile strength, elastic modulus and depth of penetration of water under pressure; the paper is focused on the first observed property, which is the basic material characteristic. On the microscale, the thickness of the interfacial transition zone (ITZ) was determined by nanoindentation. The positive influence of supplementary cementitious materials and aggregate washing on compressive strength was confirmed and the correlation between macromechanical and micromechanical characteristics was proved.

Abstract: Concrete on Portland cement and cement modified with expanding additives were studied. The authors present the results of study of the modified concrete with combined aggregate. Combined aggregate is a composition of natural granite and limestone crushed stone mixed with crushed concrete. Structure and properties of concrete with combined aggregate is insufficiently studied, which limits their use in civil engineering Recycling of building materials allows to expand the raw material base, to solve the problems of resource conservation and environmental protection. The regularities and causes of changes (reduction) indicators of the quality of concrete with combined aggregate. Studying of properties and laws of formation of structure of concrete at the same time is a method of control of their production. The valuation of properties of concrete with combined aggregates will allow to use them along with traditional concrete.

Abstract: The transition zone of the road bridges is located right behind the abutment. Function of this structure is to ease the vehicle transition from the bridge on the rigid support to the embankment with much smaller stiffness. The main function of the approach slab is, as a part of the transition zone, helping the backfill to overcome different stiffness of the bridge foundations and embankment. The paper deals with shear resistance of the slabs for different lengths and widths. Parametrical study was performed according to Eurocode loading model 1 (Uniformed distributed load and Tandem system). Each of the analysed slabs was loaded with sets of different TS positions and location of the loading lanes. Envelopes of the shear forces of the approach slabs were analysed for each type of the slab. After that shear resistance of the slab with or without the shear reinforcement was calculated. The slab was divided into areas with same shear reinforcement distribution. The analysis is the part of the engineering tool for the bridge designers. According to length and width of the slab, the engineer can easily choose the shear reinforcement diameter and its distribution. The tool also provides the construction details of the shear reinforcement. There will be also the option for the reinforcement design of the slab, with hints for the structural scheme and calculation method.

Abstract: The paper deals with experimental program concerning transition zone of road bridges with the use of approach slab. The experimental setup was constructed in the laboratory of the Slovak university of technology in the scale 1:2.The main function of the approach slab is to ease the transition from stiff foundation of the abutment to an embankment with much less stiffness. As a part of the transition zone, the slab helps to overcome different stiffness of the foundations. Good design of the approach slab and also the transition zone improves the transit of vehicle and enhances the comfort of the vehicle driver.Main goal of the experimental program is to observe the change of the structural scheme of the approach slab throughout the time via bedding stresses under the slab supported by the gravel soil, and also via the supporting forces in the connection to the abutment. The deflection of the slab is observed to confirm the slab behaviour. The possibility to observe all necessary variables with the option to adjust the height of the slab connection is provided by special construction modifications of slab to abutment joint.Due to the fact, that leading variable loading of the approach slab is traffic, loading of the specimen will be cyclic. This loading type causes dynamic response not only of the approach slab, but also of the experimental setup. Part of the experimental setup design is preliminary numerical, time depended analysis of the experiment. On the basis of results of the preliminary analysis the strain of members of experimental setup was checked to maintain the safety of the experiment during whole time. The analysis also shows predicted behaviour and strain of the approach slab, etc.

Abstract: The work formulates a particular problem on redistribution of an active element from brazing alloy into brazed materials with due account for thermodiffusion effect. The analysis of the solution has demonstrated that thermodiffusion can facilitate the acceleration of mass transfer from brazing alloy into brazed materials and cause the accumulation of components in the vicinity of contact boundaries.

Abstract: The method ofinduction cladding was adopted to make nickel-base layer on the surface ofsteel components in this test, and microstructure morphology, rigiditydistribution of the alloy layer made by cladding were analyzed and studied. Theresults shows that there is obvious bright white transition zone between thecladding alloy layer and the body, which forms an excellent metallurgicalbonding, microstructure of the alloy cladding layer is eutectic structure ofaustenite + carbide (austenite dendrite can be seen at individual parts), axialand radial rigidity are evenly distributed; bonding strength of cladding alloylayer is high without air hole and slag inclusion, with high flatness ofcylindrical surface, small machining allowance and low cost, etc.

Abstract: In this research, a novel hot stamping process to make tailored-properties is proposed. The local areas of blank are heated by induction heating. In the high strength zones, they are heated to austenitizing temperature, and in the absorption zones without heating. The temperature field of transition zone is determined by the thermal conduction between austenitizing temperature and ambient temperature. This novel process can be used for industrialization without changing mold design and stamping process.

Abstract: Super-grade bauxite, pure silicon carbide, andalusite and metal silicon were used as the raw materials to produce plastic phase mullite-SiC bricks. By analysis of the microstructure, physical and chemical properties, it proves that the introduction of metal plastic phase can improve the properties of bricks, such as lower porosity, higher cold crush strength, and wearing resistance. It also can improve the toughness, and effectively relieve the thermal and mechanical stress when using in cement kilns. By analysis of the comparison with MA spinel bricks and ordinary mullite-SiC bricks, the plastic phase mullite-SiC bricks have good thermal shock resistance and lower thermal conductivity. The result shows that the bricks can replace MA spinel bricks using in the transition zone of cement kilns and realizes the aim of saving energy and a long service life.

Abstract: The article gives theoretical solution of the problem of powder particles heating and their transfer to the substrate, considering the impact of transporting gas jet incidence on the substrate. The article also describes the research of layer microstructure, deposited by high power fiber laser cladding, and result of analysis of the dependence metal properties from the transition-layer cladding mode.