Papers by Keyword: Testing

Abstract: During cladding an austenitic layer on low-carbon and medium-alloyed steels, the properties of the heat-affected zone, along with the resistance of the surface layer to resist corrosion, largely determine the performance and durability of the surfaced product. The work is devoted to the study of the dependence of the properties of the heat-affected zone during cladding of power equipment with austenitic materials on the parameters of the control mechanical impacts on the strip electrode and determination of their optimal range, which ensures high values of the mechanical properties of the deposited layer.

Abstract: The article gives the description of experimental studies on the assessment of changes in the state of gear teeth of a mechanical transmission during tests on a stand with a closed power flow. Data on the gears made of cast iron materials are presented. The strength characteristics of gear wheel materials and their chemical composition are given. Operational life testing of gear sets with various geometries of gearing and made of gray cast was carried out. According to the conducted studies, it is found that by the optimization of the gearing parameters it is possible to increase the gear life by one and a half to two times without switching to more wear-resistant and durable materials. It is experimentally proved that the influence of geometrical parameters of gearing with combined displacement on the durability of gears is comparable with the replacement of material. When replacing the material of gears made of gray cast iron with alloy grades of cast iron, preference should be given to high-alloy wear-resistant cast iron with a surface hardness above average, and the effect of their use can be comparable to the effect of optimizing the gearing parameters.

Abstract: The paper presents selected results of experimental and computational modelling of composite material samples of tires with cord ply (casing) and breaker textile reinforcement. The computational modelling included applications of finite element methods. The output is to determine and verify the influence of material parameters of textile reinforcement. The results were confirmed by the experiment and computational modelling verification. For elastomeric matrices hyperelastic behavioural patterns of this material were considered.

Abstract: The aim of this paper is to review the literature on Materials science to identify the current research and to provide direction for future research in thermal properties of the concrete block composite, either with Polyethylene Terephthalate (PET) or Polystyrene (PS), presenting the opportunity to make an important methodological contribution by applying systematic review in three areas of Materials science: Composites, Building Materials, as well as Testing and Evaluation of Materials. This is a growing interdisciplinary field since there are no current comparative papers addressing both PET and PS in the same research for concrete composites. Papers investigating to what extent, what type and how academic publications are integrated on the analysis of the characteristics of the two recycled polymers (PET and PS), to improve the thermal properties of the concrete block and contribute to the research of sustainable thermal comfort in homes. They were reviewed, keywords were identified within a framework of composites, building materials, as well as testing and evaluation of materials, and a lexical analysis of the papers was conducted. The results of current research show that both forms of recycling (PS and PET), combined with concrete, have sustainability in thermal comfort. The analysis reveals that previous research has focused on PET-Concrete (i.e., concrete-PET polymer composite) since it is more viable, due to its large amount of recycling. While this has benefited home builders in their ability to respond with some thermal comfort with higher construction efficiency, it also clarifies that there has been research done on PS-Concrete (i.e., concrete-PS polymer composite), presenting greater thermal comfort, because it has lower thermal conductivity. This finding suggests the need for further research within this narrow field, with absence of data, since most prescriptive recommendations have not been tested and lack practical applications, which is why the need for more empirical and experimental studies are identified. Based on the novelty of the PET or PS recycling concepts, we highlight the need of better collaboration between academic disciplines, such as engineering and architecture to provide better experimental evidence for recycling of polymers, including empirical approaches for the different types of composites and aggregate distributions, which can be made with concrete to improve thermal insulation performance and energy savings for manufacturers.

Abstract: CIPP renovation methods are often used for renovation of sewers and water mains. They can also be used for renovation of gas and product pipelines. However, the presence of chemicals in these pipelines cannot be excluded. For this reason, the ability of CIPP liners to resist chemicals should be examined. This paper deals with problematics of influence of chemicals (acids and bases) on CIPP liners. Visual changes can be observed using an optical microscope. Structural changes are evident from the results of short-term bending tests.

Abstract: The paper presents research focused on modeling of lightweight concrete beams combining reinforced and fiber concrete. The paper solves the selected case of the RC beam, which was experimentally tested. The advanced numerical model and calculation used for an experiment into account the non-linear behavior and collapse of the beam. For the experiment, a specific cross-section with an opening that relieves the beam is selected. Non-linear analysis in combination with the finite element method is used for numerical modeling. Specifically, 3D calculation model and fracture-plastic material for concrete are used.

Abstract: In this paper, robustness and reliability differences related to the performance of the gate oxide of commercially-available 1200 V-rated planar and trench SiC MOSFETs have been investigated. Due to a thin gate oxide in SiC MOSFETs and to a naturally imperfect interface of the oxide layer (SiO₂) with the SiC material, its quality and reliability become very important and could be a limiting factor of the SiC technology when compared to the Si one. A dedicated gate oxide step-by-step (V_G SbS) tester has been prepared during which the gate voltage is varied with different profiles. Results of Fowler-Nordheim (FN), Time Dependent Dielectric Breakdown (TDDB) and three test runs of the V_G SbS are presented in this paper. Both technologies show good reliability figures to allow the use in the application. Trench technology shows higher robustness limits whereas the extrapolated reliability at the rated gate voltage is superior for the planar one.

Abstract: The creation of self-compacting concrete (SCC) is associated with the introduction of plasticizing additives based on polycarboxylate esters (PCE). The first patent for a group of substances proposed for use as superplasticizers for concrete, was declared in the early 80-ies of the last century in Japan. In the mid 90-ies superplasticizers based on esters of polycarboxylates began to be used in Europe. In Russia, the use of self-compacting concrete began much later, and in bridge and tunnel construction almost a few years ago. Currently, in the European Union, 70-80% of reinforced concrete structures are made or erected from self-compacting concrete mixtures, and concrete is commonly called self-compacting. In Russia, such concretes are sometimes called self-leveling. The volume of their use is still small.

Abstract: Experimental studies of the influence of the heating temperature on the properties of pipe billets made of titanium alloys OT4 and OT4-1 in the formation of parts for the installation of pipeline systems without a protective atmosphere are presented.

Abstract: The historical masonry buildings are generally characterized by a load-bearing structure constituted by walls that should resist to both gravitational and horizontal actions. In several existing constructions, masonry panels are made by two external leafs with higher mechanical properties and an inner core with very low, or even negligible, mechanical characteristics. In some cases the connection between the external leafs was provided by inserting a certain number of bricks in the transversal direction (namely diatones); while sometimes, the leafs were totally independent. Often in the case of horizontal forces, as those due to earthquakes, the multi-leafs walls collapse has been observed, because of the leafs separation. Nowadays, there are different connecting systems available in the market and utilized to guarantee the collaboration of the external leafs, in order to finally improve the wall bearing capacity.In this scenario, the present paper is aimed to investigate the shear strength of small-scale multi-leafs panels, coupled with different types of connector, such as: diatones, L-shaped glass; glass and steel rope and helical steel bars. In plane shear tests have been performed in order to evaluate the shear stress-strain relationship. The results are herein reported and discussed, aiming to determine the effectiveness of the different connections systems.