Noise is a mixture of sounds of various frequencies that irritate human beings. Today, noise is considered an “invisible” pollutant that raises great concern, especially in cities. Prolonged exposure ...to noise, either in everyday life or at the workplace, may cause health problems including high blood pressure and heart diseases. Noise may have negative impacts on reading, attention, problem-solving, and memory. One of the solutions to this problem is the reduction of the decibel level (dB).
This article studies the noise-absorbing characteristics of polymer materials used in shoe sole production. The authors suggest producing noise-absorbing caps from the FLEX material. Additive technologies were used in cap production. This article presents the results of the research on the use of the FLEX plastic for noise-absorbing shoe heel caps. When using the shoes with heel caps made of FLEX plastic, the noise level on porcelain stoneware reduced 5.61 times, and 12.79 times on laminate flooring. The authors prove that noise-absorbing heel caps can reduce the noise levels at workplaces and public organizations, which may have a positive effect on the environment.
•Optical measurement of geometric slope deviations of specimens made by 3D printing.•Determination of optimal 3D printing parameters based on optical measurements.•Determination of suitable method of ...slope’s measuring in additive technology.•Determination of effects of deformation using optical measurement.•Finding out the best geometric deviations of the slope.
The paper aims to research optical measurements of geometric slope deviations and their differences on two types of experimental specimens. The two types of specimens have plane segments inclined in the angular range of 0°- 45° and 0°- 90°, graded after 10° and 15°. Specimens were produced as six different combinations of printing parameters of a Renishaw AM500E 3D printer. At the same time, the 3D models of specimens obtained by scanning serve as a standard for inspection. A coordinate measuring machine Wenzel LH 65 with a Shapetracer 2 optical head and an Atos Gom MV 300 scanner were used for evaluation. Based on the research, best 3D printing parameters were decided, position in the printing space of the printer and the effects of deformation triggered by supports at different inclinations of the plane segments. The analysis of experiments supplied the best geometric deviations of the slope for specimens.
Display omitted
•WAAM manufacturing steps from a CAD model to the final geometry of the part.•Optimal deposition parameters and mechanical properties for four metallic alloys.•The WAAM process ...reduces the component buy-to-fly ratio, rationalizing resource use.•A monitoring method is developed to obtain a unique fingerprint of each part.•A matrix manufacturing strategy is used to increase the productivity of the process.
WAAM (Wire Arc Additive Manufacturing), an additive manufacturing technology with high deposition rates, can produce metallic components, layer by layer, from different alloys, yielding high mechanical performance. Customized AM machines with monitoring and control systems are necessary to facilitate automated manufacture of different types of components through WAAM technology. In this paper, a methodology for the validation of additive manufacturing is presented as an alternative to industrial machining, for the manufacture of medium-sized aeronautical parts. To begin with, the most appropriate welding technology and adequate parameters for four different metal alloys are selected. Successively, a characterization wall is manufactured with each of the four metal alloys, for metallographic and mechanical characterization, concluding that the material deposited utilizing the WAAM process is adequate for the fabrication of medium-sized aeronautical parts. Consecutively, machine paths are defined under conditions that consume the least possible amount of material for the manufacturing of the aeronautical part. Several aspects -manufacturing times, deposition rate, material efficiency ratio- of each component are then analyzed, relating them to the properties obtained in each alloy. The manufacturing process is supervised and controlled by online monitoring. The novelty of this paper consists in establishing unique dataset for each component that is defined as a unique additive manufacturing Fingerprint as baseline for in process defect detection. Finally, the unique contribution of stablishing a matrix-strategy for the manufacture of multiple parts with the same tooling to optimize the use of resources is presented.
This research addresses the metallurgical and mechanical response during the annealing of Ti6Al4V parts fabricated by selective laser melting. The as-manufactured Ti6Al4V exhibited a very fine α´ ...martensitic structure with low ductility of less than 10%. It was observed that the fine α´ martensitic structure transformed into two phases of α and β by applying heat treatments at 850 and 1020 °C followed by furnace cooling. The experimental results demonstrated that 850°C/2h/FC heat treatment has optimum mechanical performance in terms of tensile strength and ductility.
PAW (Plasma Arc Welding), a WAAM (Wire Arc Additive Manufacturing) technology with high deposition rates, can produce metallic components, layer by layer, of varied sizes, from different alloys, ...yielding high mechanical performance. Two Ti6Al4V walls are manufactured in an inert argon atmosphere using WAAM-PAW to analyze the deposition process in terms of growth in height per layer, deposition process temperature, and cooling times. The properties of the walls are compared with the values obtained from a thermo-mechanical simulation and both the microstructural and mechanical properties of the annealed WAAM-PAW wall are studied. Moreover, the effect of the media on the oxidation layer and on the mechanical properties are also analyzed throughout the heat treatment process, as well as the microstructure of Ti6Al4V. Stable deposition rates were achieved for a high deposition ratio of Ti6Al4V at 2 kg/h, restricting the oxygen levels to under 100 ppm. No significant differences were found in either the microstructural or the mechanical properties following heat treatments in a vacuum, in air or in argon. All the heat-treated samples met the AMS4928 standard for Yield Strength (YS) and Ultimate Tensile Strength (UTS).
FDM 3D printed honeycombs are investigated. A honeycomb is composed of regular hexagonal cells. A honeycomb is 3D printed so that the fused filament runs along the walls of its cells. We emphasize ...that the thickness of these walls is one or two times the thickness of the fused filament. When calculating the mechanical properties of a honeycomb, its walls are considered as a Euler-Bernoulli beam bending in one plane. To describe honeycombs, a homogenization procedure is used, which reduces a honeycomb to a homogeneous orthotropic medium. An adequate analytical calculation of the mechanical properties of this medium is the subject of our research. Analytical formulae for calculating the mechanical properties of honeycombs are presented. To assess the adequacy of the calculation results, the analytical data are compared with the results of simulation in the commercial ANSYS package. For this, the mechanical properties of the honeycombs made of the ULTEM 9085 material are determined numerically. To assess these properties, from a large number of analytical formulae are selected those that predict them adequately. As a result of calculations, an analytical prediction of all mechanical properties is obtained, with the exception of the in-plane shear modulus of a honeycomb. This is due to the fact that to simulate such a shear modulus one has to use a three-dimensional theory that does not have an adequate analytical description. A thin aluminum honeycomb was considered. In the future, three-layer structures with such a honeycomb will be investigated. Analytical results for ULTEM 9085 and aluminum honeycombs are similar.
Abstract Objectives The aim of this study was to compare the physical and mechanical properties of stereolithography (SLA)- manufactured alumina ceramics of different composition to those of ...subtractive- manufactured ceramics and to produce suitable dental crown frameworks. Methods The physical and mechanical properties of a control and six experimental SLA ceramics prepared from slurries with small (S) and large (L) particles (0.46 ± 0.03 and 1.56 ± 0.04 μm, respectively) and three dry matter contents (70%, 75%, 80%) were evaluated by dynamic rheometry, hydrostatic weighing, three3-point flexural strength measurements, and Weibull analyses, and by the micrometrics measurement of shrinkage ratio before and after the heat treatments. Results S75 was the only small particle slurry with a significantly higher viscosity than L70. The viscosity of the S80 slurry made it impossible to take rheological measurements. The viscosities of the S75 and S80 slurries caused deformations in the printed layers during SLA manufacturing and were excluded from further consideration. SLA samples with low dry matter content had significantly lower and densityflexural strengths. Only SLA samples with a large particle size and high dry matter content (L75 and L80) were similar in density and flexural strength to the subtractive- manufactured samples. The 95% confidence intervals of the Weibull modulus of the L80 ceramic were higher (no overlap fraction) than those of the L75 ceramic and were similar to the control (overlap fraction). The Weibull characteristics of L80 ceramic were higher than those of L75 ceramic and the control. SLA can be used to process suitable crown frameworks but shows results in anisotropic shrinkage. Significance The hH High particle size and dry matter content of the L80 slurry allowed made it possible to produce a reliable ceramic by SLA manufacturing with an anisotropic shrinkage, and a density, and flexural strength similar to those of a subtractive-manufactured ceramic. SLA allowed made it possible to build up a dense 3D alumina crown framework with controlled shape. Further studies on the marginal adaptation and shrinkage model of alumina crown frameworks will be required to optimize the process.
Background: 3D printing technology is replacing manual fabrication in all fields. 3D-printed impression trays should be assessed as they could replace conventional impression trays in the future. ...Aim: In-vitro comparison and evaluation of the dimensional stability and retention strength of impressions to custom impression trays fabricated using conventional method and additive technology. Materials and Methods: A maxillary edentulous auto-polymerizing acrylic resin model served as the master model. Two moulds were prepared from the master model in order to obtain 12 casts. One cast was scanned for 3D printing digital light processing (DLP) and fused deposition modelling (FDM) 24 impression trays using polylactic acid (PLA). Twelve casts were used to fabricate light cure impression trays. Polyvinyl-siloxane impressions were made on the master model using 36 impression trays and 18 trays each were used to assess dimensional stability and retention strength. Results: In dimensional stability analysis, one sample t -test revealed a statistically significant difference between each group and the master model followed by a one-way ANOVA. There were significant differences, but the difference was less with FDM trays ( P < 0.05). In retention strength analysis, one-way Analysis of variance (ANOVA) revealed statistically significant difference between each group and post-hoc test revealed specific difference, the highest with FDM trays ( P < 0.05). Conclusion: Dimensional changes were observed at 30 minutes and 72 hours. Lesser dimensional changes were observed when impressions were made using FDM trays followed by DLP and light cure trays. The mean retention strength seen in descending order was FDM, followed by DLP and light cure trays. The best retention strength was noticed when impressions were made using FDM trays.
Metal products manufactured by means of additive technologies are usually characterized by unfavorable mechanical properties. Laser shock processing is mechanical processing of surfaces at a high ...strain rate, which hardens the near-surface layer and creates favorable mechanical properties. This work discusses the development of hybrid additive technology in combination with laser shock processing with additive technologies, and the role of laser shock processing in hybrid additive technology is analyzed using the finite element method. The results obtained demonstrate that the frequency of the hardened layer is a critical technological parameter influencing the redistribution of residual stresses, which strongly depends on the amount of heat released during 3D printing. Due to the results obtained, the hybrid additive technology developed occupies a position in various additive technologies and is promising for practical implementation as a new method for manufacturing high-quality metal products.
Metal structures, pipelines and dies are used for a long time wear out and deteriorate. At the end of the service life it is necessary to repair or replace the metal component. The article discusses ...the method of applying nickel super-alloy Inconel 625 by direct laser deposition on high-alloy austenitic Mn-Cr steel. The article discusses the method of applying nickel super-alloy Inconel 625 by direct laser deposition on high-alloy austenitic Mn-Cr steel. Inconel 625 alloy is used as a buffer layer or repair material. But there is a high probability of cracks in the cladding material and the substrate material when the DLD method is used. One of the frequent causes of these cracks is high tensile stresses and oxides. To eliminate defects, the substrate was heated with resistive heaters to 400 °C. The result was a defect-free adhesion of the cladding material and the substrate. The hardness of the substrate before and after heating has not changed (312 HV 0,5/10). After heating the hardness of the substrate in the heat-affected zone decreased by 14% and was equal to 267 HV 0,5/10. The hardness of the cladding decreased by 12% and was equal to 230 HV 0,5/10.
PDF
