Papers by Keyword: Testing

Abstract: In the presentation will be presented different additive 3D printing techniques for obtaining different plastic parts using the additive technology. The processes are Stereolithography and Fused deposition modelling After choosing the two processes, the next step is choosing the best material that will have the needed properties. The goal of this paper is to obtain a better gear with improved properties, resistance, and durability. The obtained probes will be tested with a traction device and resilience of the gear. The two parts will be compared, and the best obtained part will be chosen comparing part properties and the production cost

Abstract: An optimized method for assessing the fire protection efficiency of intumescent coatings has been proposed, which can be applied during the development and research of new formulations of fire retardant compositions. To achieve this goal, a critical analysis of existing methods for evaluating the fire protection efficiency of intumescent fire retardant coatings has been conducted, both those approved by regulatory documents and those used by researchers for the fire protection agents effectiveness rapid assessments. Based on the analysis of the studied methods advantages and disadvantages, an optimized method for evaluating the intumescent fire-resistant coatings efficiency has been proposed to reduce the time for preparing and processing experimental results. The proposed optimized method involves the use of an electrical furnace with an insulated test chamber for heat accumulation as a source of thermal radiation, which allows obtaining temperatures on the reverse side of the metal plate exceeding 950 °C. As a criterion for fire protection efficiency, it is proposed to use the comparison of the time to reach the critical temperature (500 °C) on the outer side of metal plates protected by fire retardant coatings. The efficiency of fire protection of the metal plate has been investigated using the proposed method for three samples of intumescent fire protection agents: a coating based on epoxy oligomer, ammonium polyphosphate, aluminum hydroxide, and intercalated graphite, a coating on a styrene-acrylic basis of industrial production, and a well-known coating based on epoxy oligomer filled with monoammonium phosphate and intercalated graphite. The results of the experiment allowed a comparative assessment of the studied coatings fire protection efficiency. The use of the optimized method significantly simplifies the experiment and reduces the time spent on sample preparation and processing of its results.

Abstract: The aim of the work was to determine the possibility of not taking into account the orientation (vertical or horizontal) of the studied elements of steel-reinforced concrete slabs with a corrugated profile during their heating in a modular small-sized fire furnace. The work investigated the temperature distributions on the outer surface of the corrugated ceiling profile of a steel-reinforced concrete slab of horizontal orientation simulated in the fire furnace chamber. To create geometric models of the fire furnace chamber and the studied element, a CAD software complex was used. To solve the heat engineering problem, mathematical (numerical) methods were used, based on solving systems of differential equations of continuous media such as the Navier-Stokes equation and the Fourier heat conductivity equation. According to the results obtained, the temperature distribution on the outer surface of the steel profile of the reinforced concrete slab is uniform, the temperature deviation in different places on the surface does not exceed 7 %. The maximum temperature on the heating surface of the steel profile of the reinforced concrete slab in the last minute of computer simulation reached 921 °С and the average temperature at this time over the entire surface of the structure was 917 °С. To determine the appropriate orientation of the test sample during fire tests, a comparison of the obtained temperature distributions on the outer surface of the corrugated profile of a horizontally placed reinforced concrete slab with the temperature distributions on the outer surface of the corrugated profile of a vertically placed reinforced concrete slab, which were given in the previous work was made. Analysis of the average surface temperatures of the corrugated profile of a reinforced concrete slab of horizontal and vertical orientation showed that the temperature distribution over the surface of the profile was uniform in both cases and the results obtained show good reproducibility of the experiment during computer simulation. And the orientation of the tested elements does not affect the temperature distribution over the outer surface of the corrugated profile of a reinforced concrete slab in the simulated furnace.

Abstract: Material abrasion is a critical consideration in product design, manufacturing, and maintenance because it has a high impact on several properties. When it comes to the abrasion of polymer yarns, insight into the behaviour of yarns due to constant abrasion is important for ensuring final product quality, performance, and customer satisfaction. For this study, a group of polymer yarns is selected. The yarns differ in raw material, as well as the yarn type. Within the experiment selected yarns in both single condition and within the fabric structure were conducted to different abrasion tests. The study findings reveal that yarn type, raw material composition, and additional treatments significantly influence abrasion resistance. Recycled polyester yarns demonstrate comparable, if not superior, abrasion resistance to conventional ones, making them viable for various applications.

Abstract: Increasing usage of the high-strength steels in structural design requires deeper understanding of the residual manufacturing stresses effect on the product service fatigue life. The bending forming process is being examined in this work. High cycle fatigue testing of the specimens before and after the bend shaping is performed by means of the vibrational fatigue method. The manufacturing residual and the fatigue tests stress fields are estimated by means of finite element analysis. The similarity principle is used to compare the fatigue curves constructed for the specimens with different geometries based on their local stress field concentration. A comparison with reference work is provided to support the similarity premise. The implementation of the mean stress correction for the residual stress is evaluated. The goal of this work is to demonstrate a methodological integration of the finite element analysis throughout manufacturing and fatigue testing for accurizing design life estimations. It may also serve as an end-to-end review and provide an outline for similar projects.

Abstract: Health care associated infections or nosocomial infections (NI) is the fourth leading cause of disease and the most common complication affecting hospitalised patients in addition to a minimum of 175,000 deaths every year in industrialised countries. The Center for Disease Control and Prevention (CDC) states that influenza is transmitted from person to person primarily via large virus-laden droplets or through direct or indirect contact with respiratory secretions when touching surfaces contaminated with influenza virus and approximately 80% of the infections are transmitted via touch surfaces. In the year 2020 the Coronavirus (Covid 19) spread has affected the global community and also caused a great concern for the people and health care workers with a global infected population of more than five million. With the ongoing population rise in the cities growing drug resistant bacteria, increasing infection rate in hospitals and communities, ageing world population strongly indicates the need to minimise the spread of infections via touch surfaces. Metals (and products manufactured from them) such as copper and silver are known to exhibit antimicrobial properties. These metals, or composites containing them, can be used as additives and incorporated into other materials such as paints, plastics and powder coatings to imbue these materials with antimicrobial properties. In this paper we present the inherent antimicrobial properties of a copper containing alloy, two alloys of hospital grade steel (304 and 316), extruded aluminium (606013), anodized aluminium (606013) and zinc clad aluminium (3003-7072). Additionally, these materials were coated in epoxy resin powder coating with and without silver based antimicrobial additive. The ability of these metal alloys to reduce the population of inoculated microorganism numbers was assessed via the international standard (ISO) 22196:2011 Measurement of antimicrobial activity on plastics and other non-porous surfaces.

Abstract: Obtaining multi-material parts by material extrusion processes is becoming more interesting as the available materials permit achieving superior properties in the 3D printed products. Combining conductive filament with other with elastomeric properties makes it possible to materialise electrical circuits for introducing active elements in specific parts, such as sensors, triggers or antennas. In this context, a test bench has been designed, manufactured and set-up, to evaluate the electrical behaviour of multi-material 3D printed test samples composed of two or more materials, being one a conductor of electricity (at least) and the other(s) non-conductive but flexible. The functionalities of the test bench include the possibility to apply tensile, compressive, shear, or flexural loads to the test samples. The electrical performance of the samples can be assessed in terms of resistivity and capacitance, in real time, when the test bench stands still and when it conducts the series of movements that produce the elastic deformation of the samples. To achieve this, three electronic circuits have been designed with their own corresponding control with Arduino: a circuit to measure the variation of the resistance of the test samples, a circuit to measure the variation of the capacitance of the test samples, and a circuit controlling the movements of the mechanical set (motor and terminals) that generates the deformation of the test samples. The test bench is connected to a desktop computer to ease the data export, treatment, and visualisation. As a set-up of the test bench, several preliminary experimentation measurements have been done to assess factors of interest such as sensitivity and a correlation index. The present work also frames the requirements of the parts to be tested in the bench and outlines the work procedure to carry out the series of experiments.

Abstract: The use of inorganic matrix in fiber reinforced composites has been studied in the last years for strengthening applications in masonry construction. At the moment different systems are available after a technical qualification that allows a safe and certified use in construction industry. In the field of historical masonry the benefits of such materials are well known respect to the most known Fiber Reinforced Polymers (FRPs), due to a very poor substrate. In this study the experimental results of a larger research program are presented and discussed. A Fiber Reinforced Cementitious Matrix (FRCM) system has been tested in order to measure the tensile mechanical properties and bond properties respect to different substrates: clay masonry and natural tuff masonry. Tensile properties of the FRCM composite were measured in presence of a cement mortar, and results are illustrated. In addition pull-off tests and bond shear lap tests of the FRCM are described and commented respect to the two substrates. Tensile tests on glass fiber mesh and glass FRP (GFRP) connectors were performed and results are presented in the paper.

Abstract: Arch is a structural member which provides aesthetic beauty to architectures and, at the same time, guarantees stability to structures. For this reason, it was largely adopted for masonry building in the past centuries. Nonetheless, the erection of new curved structures is poorly considered in modern time. One of the possible causes is the difficulty of constructing since it requires the use of temporary scaffolding. Thus, it may results time-and cost-consuming. Innovation in the field of arch construction is very rare until now. The present paper aims to validate a novel construction method for curved members by means of small-scaled specimens. The proposed method consists of connecting the stone blocks on one side with Fibre Reinforced Polymer (FRP) and then lift it up. The herein experimental program involved masonry arches loaded at the mid-line in order to compare the behaviour of the traditionally-made and the innovative arches in terms of load-bearing versus deflection. This is a preliminary test within a larger ongoing experimental campaign.

Abstract: UHPC is a material which exhibits excellent mechanical properties and durability. Beside new structures it is also convenient for strengthening of existing structures. The paper investigates the possibilities of strengthening experimentally. A part of the experimental program is presented which is focused on bond of UHPC and existing concrete and on behaviour in bending. Acceptable bond may be achieved when the existing concrete is clean and reasonably rough. Structural elements are exposed to positive and negative bending moments. If UHPC overlay is applied, it works in compression and in tension. The experiments were therefore focused on verification of both alternatives (UHPC in compression and in tension). Finally, the conclusions from the experiments are drawn, which may be applied in practical design.