Papers by Keyword: Material

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: Gear wear is the main factor affecting their performance and service life. In addition to the accuracy of production, the quality of the material from which the gears are made also depends on the degree of wear. The article compares the material properties of gears of JAWA motorcycle transmissions. In addition to the original gears, produced at that time in Czechoslovakia, the market also offers gears that are produced today, originally from the Czech Republic and Taiwan. Since the only comparable indicator is their price difference, the question arose whether the new variants can compete with the original part in terms of quality of workmanship. For this finding, the gears were subjected to wear tests and determination of the hardness of the material with the devices intended for this. In this way, valuable data will be obtained that will contribute to a better understanding of the performance and lifetime of these components. The quality of workmanship as well as the price are factors that should always be considered before the final selection of the item.

Abstract: Nutmeg shell waste (CP) has light and hard characteristics which can be used as a replacement material for coarse aggregate for lightweight concrete. The aim of the research is to determine the influence of aggregate characteristics after being mixed with nutmeg shells as a constituent material for concrete and determine the compressive strength value of the concrete. The method used is a laboratory experimental method with CP waste percentages of 2.5%, 5% and 7.5% of the sand volume. The results of the research show the effect of using nutmeg shells in the concrete mixture, where the compressive strength value of the concrete increases along with the increase in CP waste used. The compressive strength values of nutmeg shell concrete (CP) at compositions of 2.5%, 5% and 7.5% were obtained at 234.26, 263.56 kg/cm2, kg/cm2 and 280.14, increasing at 28 days.

Abstract: The advantages of non-contact digitising systems over contact systems are undeniable. They allow capturing more information per unit of time with less accessibility problems and without alter the digitised surface. Although many of these systems have been developed with the aim of replacing contact systems in metrological verification tasks, generalist techniques such as photogrammetry, structured light, etc., have been developed over the years for digitising archaeological remains, works of art or living biological systems, among others. As is the case for non-contact measurement-oriented systems, for these generalist systems there are still difficulties in positioning them along a metrological traceability chain if they are required for any kind of measurement. This is due to the lack of specific standards, as well as the strong influence of the optical properties of the digitised surface on the quality of the results obtained. It is therefore necessary to develop calibration procedures and characterisation work to analyse this influence. The aim of this work is to characterise the metrological performance of one of these generalists structured light devices, Einscan-SP by Shining 3D, in the digitising of different calibration spheres made of different materials (WC, Al₂O₃, ZrO₂, etc.) with different surface finishes (shot-blasted, polished, coated). As quality indicators, the number of points captured, the quality of the point cloud as well as the dimensional and geometrical deviation from the results obtained with a high-performance contact measurement system shall be used. Apart from the raw data, the influence of applying filtering to the captured clouds is analysed. The results of this work allow recommendations to be made regarding the material and finish of the spheres to be used, as well as the filtering to be applied, if necessary, in order to assess the metrological performance of this type of equipment.

Abstract: Fused Deposition Modelling (FDM) is a common technique used when rapid prototyping is needed to perform a preliminary evaluation of the suitability of a part. For this purpose, several materials, as PLA, ABS, PET-G and others, are easily available in the market along with a wide range of commercial 3D printers at affordable prices. Prototypes manufactured under this technique are usually made of a single material and, for most of the applications, it is enough to fulfill the required specifications. However, the increasing demand for the manufacturing of parts made of more than one material suggests that prototyping via FDM using two dissimilar materials should be assessed to assure that such technique is still acceptable to perform a preliminary evaluation of a part. For this purpose, a methodology using a commercial FDM 3D printer is proposed to characterize the flexural and shear bonding behavior of two dissimilar materials. This methodology implements four steps: The selection of the applicable UNE standards as main reference, the design and manufacture of the test specimens based on these standards, the execution of the structural tests to characterize the behavior of those specimens and the analysis of the test data along with the conclusions. This methodology has been validated using ABS and PLA as base materials. The coherence and accuracy of the results obtained from this specific case substantiate that it is a valid methodology to evaluate the structural behavior of the bonding of two dissimilar materials, beyond PLA and ABS, using commercial and affordable off-the-shelf 3D printers.

Abstract: The objective of this study are to isolate lactic acid bacteria from ripe tome-tome fruit (Flacourtia inermis and bacteriocin activity in inhibiting the growth of Staphylococcus aureus and Escherichia coli. The results showed that 10 isolates of lactic acid bacteria were found and have the potential to produce bacteriocins. They were isolates TM1, TM2, TM3, TM4, TM5, TM6, TM7, TM8, TM9 and TM10 and were identified as members of the genus Lactobacillus (TM1,TM2,TM7,TM8,TM9,TM10) and members of the genus Lactococcus (TM3,TM4,TM5,TM6). The ten isolates of lactic acid bacteria were able to produce bacteriocin and were able to inhibit the growth of S. aureus but unable to inhibit the growth of E. coli. Bacteriocins from the ten LAB isolates are expected to be used as raw materials alternative preservatives in food products because of their ability to inhibit growth of food spoilage microbes, resulting in the use of chemical additives can be minimized.

Abstract: The concrete industry in Indonesia is very advanced and developing, so the use of construction materials is increasing. The need for other materials as a substitute for fine aggregate for the manufacture of concrete, namely stone ash comes from the stone slate industry waste. 20% stone ash, 80% sand) and (30% rock ash, 70% sand) with a concrete quality target of Fc' 17.5 Mpa. The method used is the laboratory experimental method referring to the SNI standard. The results showed that the use of stone ash (AB) as a normal concrete mixture affected the compressive strength of concrete. The higher the percentage of stone ash (AB), then the value of the compressive strength of concrete increases. The value of the compressive strength of concrete from stone ash (AB) at the composition of AB 10%, AB 20% and AB 30% was 173.50 kg/cm2, 235.11 kg/cm2 and 239.88 kg/cm2 while normal concrete was 18.59 MPa at 28 days.

Abstract: The purpose of this research of aluminum electroplating with nickel is to improve the value of its tensile strength and hardness. This test was conducted to determine the effect of time towards the tensile strength and hardness of nickel on aluminum 7075 electroplating and the time required to achieve optimum conditions. The materials used in this study are aluminum 7075 and nickel plating. The finishing treatment process used was electroplating method. Fixed variables utilized in this study comprised the voltage (25 V), gap between electrodes (15 cm), amount of water (2400 ml), salt (four spoons), vinegar (1600 ml), aluminum, and nickel for plating. The variations used in immersion time were 30, 40, and 60 minutes for further tensile test and hardness test. The result of this research shows that the highest tensile strength value obtained was 546,155 MPa with 60 minutes coating time. While the value of hardness from time to time varied with the highest rate in of 30-minute coating time was 188.266 kgf/mm. According to the test results, it can be inferred that the longer coating time it takes, the higher the tensile strength rate the material obtains.

Abstract: One of the problems in orthodontic treatment is friction. Some of the factors that support friction are archwire material, archwire dimensions, bracket material, surface roughness, type of ligation, environmental humidity, and bracket position, angulation angle between bracket and wire, changes in the surface of the archwire and bracket. The aim of this study is to analyse the difference in friction between the two branded bracket designs and a new patented bracket (patent no. IDP000069597). The production method for this new bracket is different, however, uses the same material of 17-4 PH stainless steel. There are three groups in this research, one sample of bracket each from two different branded and one sample of a new bracket design. All three groups were tested for microstructure, then tested for measurement of friction between bracket slots and archwire. The microstructure of the two branded brackets has a martensitic phase that is not as dense as the new bracket, which is due to the different manufacturing method processes. The two branded brackets use the metal injection molding method, while the new brackets use the investment casting method. The friction test results show that there are significant differences between the three groups of brackets. One of the branded brackets (A) has the lowest friction, but branded bracket (B) does not have different friction with the new bracket. Differences in design and manufacturing methods of orthodontic bracket affect the friction between orthodontic brackets and archwires even though they use the same material.

Abstract: The performance of the SiO₂ MOSFET-based absorber as a solution to arching within transmission lines (used for RF signal transportation) has been realized and analyzed at 28 GHz using the reflected signal from the R_X branch of 5G massive MIMO base station. The reflected signal from the receiver (R_X) branch of base stations may lead to interference, thus creating a performance reducing condition (arching) within the transmission lines. For optimum performance in the 5G regime, the SiO₂ MOSFET has been used to solve the problem of arching within the transmission line under large field intensities of a standing wave resulting from the impedance. The SiO₂ MOSFET-based absorber has been observed for a reflectivity of -79.5 dB and a rectification efficiency greater than 17 %