One of the main directions in the development of modern mechanical engineering consists in the use of novel materials and technological processes for the production of parts and products, in ...particular additive technologies. Nowadays, dozens of technological processes and additive manufacturing plants based on a number of physical and chemical effects have been developed and implemented. A brief history, the basic principles, and the features and advantages of additive technologies are considered, and a system for their classification, based on a generalized morphological approach, is proposed. All the known and promising technologies are placed in a morphological matrix; further a space of possible technical solutions is analyzed and formed. The number of potential variants amounts to 276 420. The proposed classification of additive technologies is the most complete at the moment.
Heat exchangers make it possible to utilize energy efficiently, reducing the cost of energy production or consumption. For example, they can be used to improve the efficiency of gas turbines. ...Improving the efficiency of a heat exchanger directly affects the efficiency of the device for which it is used. One of the most effective ways to intensify heat exchange in a heat exchanger without a significant increase in mass-dimensional characteristics and changes in the input parameters of the flows is the introduction of turbulators into the heat exchangers. This article investigates the increase in efficiency of heat exchanger apparatuses by introducing turbulent lattice structures manufactured with the use of additive technologies into their design. The study is carried out by numerical modeling of the heat transfer process for two sections of the heat exchanger: with and without the lattice structure inside. It was found that lattice structures intensify the heat exchange by creating vortex flow structures, as well as by increasing the heat exchange area. Thus, the ratio of convection in thermal conductivity increases to 3.03 times. Also in the article, a comparative analysis of the results obtained with the results of heat transfer intensification using classical flow turbulators is carried out. According to the results of the analysis, it was determined that the investigated turbulators are more effective than classical ones, however, the pressure losses in the investigated turbulators are much higher.
Display omitted
•Laser printing in amorphous rare-earth microwires.•Fast local crystallization under laser heat.•Enhanced radial local magnetization.•Magnetically modulated microwires.
Magnetically ...modulated PrDyFeCoB microwires containing periodical local magnetic labels of ~ 10 μm length are imprinted by single 120 ns laser impulse. Initially amorphous microwires is locally transformed by laser irradiation to nanocrystalline (PrDy)2(FeCo)14B1, and (PrDy)1(FeCo)2, (PrDy)1(FeCo)4B1 magnetic phases, possessing enhanced magnetic anisotropy. Alternating magnetic patterns imprinted by laser irradiation have magnetization component perpendicular to the microwire main axis. Fast imprinting of the magnetic microlabels allows one to design programmable microstructures.
The main aim of the presented tests was to assess the possibility of using 3D printing and casting material to produce casting molds and prototypes, especially in production of existing models. The ...analysis was based on the assessment of dimensional accuracy and quality of the surface layer of a finished prototype and the intermediate elements made during the production process. The mold was made using the PolyJet Matrix additive technology, and then a silicone mold was cast which was used to prepare a finished sample for testing in accordance with the design assumptions. Based on the results of metrological measurements, the phenomenon of technological inheritance in terms of error transfer in the foundry industry was evaluated. The measurements obtained suggest that in case of casting process, the hereditary features are transferred from individual casting processes, which is especially prominent in the case of surface texture quality. This confirms the occurrence of the phenomenon of the so-called technological inheritance and the need to analyze it. The results of the tests can be a guide for technologists who design molds, core boxes, and casting models, concerning the corrections (shrinkage) that need to be introduced at the design stage in order to obtain a product (casting) of satisfactory dimensional accuracy and quality of the surface layer. The result can also be useful for casting materials reinforced with glass fiber, carbon fiber, which are common materials in 3D printing and textile industry.
The results of creating an experimental model of a mobile ropeway consisting of two base stations is under consideration in this article. The model was made by 3D printing technology in the ...laboratory of additive technologies of the Research and innovation center of digital technologies Industry 4.0 of Bryansk state University named after academician I. G. Petrovsky. The article provides a detailed overview of the stages of the model manufacturing, analyzed the typical problems and solutions. Models of base stations on wheeled chassis are made of ABS plastic with subsequent processing and painting of surfaces with acrylic paint. An electric motor connected to the control system based on the Arduino Nano microcontroller is used to drive the ropeway. The dynamic processes in the cable system are investigated by video fixation.
•Ti-6Al-4V DED samples with different heat treatment observed evolution of structure and phase composition.•Improvement in the quality of the DED samples with different heat treatment modes was ...determined.•The mechanism of electrochemical corrosion is considered.•Electrochemical properties of the DED samples with different heat treatment modes was demonstrated.•Increasing in heat treatment temperature leads to increasing of the facets size on the fracture surface.
Display omitted
Additive technologies are actively implemented in various industries. The actual task is a complex study of the properties of the products. In the present work, electrochemical studies of the heat-treated Ti-6Al-4V alloy manufactured by Direct Energy Deposition were carried out to determine the evolution of electrochemical and mechanical properties. The analysis of the structure and phase composition were compared with the results of electrochemical and mechanical properties. The effect of the lamellae size and phase composition on corrosion and mechanical properties is more pronounced for the DED Ti-6Al-4V alloy. It was determined that the best electrochemical properties are possessed by a heat treated sample at 800 °C. With an increase the temperature of the heat treatment up to 900 °C, the corrosion resistance decreases, however, the values of relative elongation increase.
Events related to climate change and the increase in the occurrence of natural disasters, as well as the increasing incidence of new diseases, have all caused the prominence of regional security and ...crisis management around the world to rise. Three-dimensional printing, which has seen noteworthy developed in recent years, both in terms of print parameters, and the magnitude of the production potential, may prove helpful in this matter. Enormous opportunities have arisen which, if properly directed, can save human life and preserve health in crisis situations, when traditional supply chains could be disrupted or even prevented. The use of additive technologies, however, has its limitations and in order to be able to take full advantage of the opportunities they offer, a legitimate functional system should be created and embedded within proper structures to support crisis management. This paper presents the advantages and disadvantages of using 3D printers and the possibility of their implementation as part of the current crisis-response systems. The article proposes a model for incorporating additive technologies into the crisis-management system.
Purpose
3D printing technologies have become an integral part of modern life, and the most routinely used materials in reconstructive surgery in children are biodegradable materials. The combination ...of these two technologies opens up new possibilities for the application of innovative methods in neurosurgery and a patient-centered approach in medical care. The aim of the study was to determine whether a physician without specialized programming and printing skills could independently create materials in a clinical setting for the treatment of patients.
Methods
We conducted a preclinical study on 15 male Balb-C mice. Cylindrical materials made of polylactic acid (PLA) plastic were 3D printed. Sterilization of the obtained material was performed using a cold plasma sterilizer with hydrogen peroxide vapor and its plasma. The sterile material was implanted subcutaneously into the mice for 30 days, followed by histological examination. Using open-source software for modeling and printing, plates and screws made of PLA plastic were manufactured. The produced components were tested in the biomedical laboratory of the institute.
Results
The histological material showed that no inflammatory changes were observed at the implantation site during the entire observation period. The cellular composition is mainly represented by macrophages and fibroblasts. There was a gradual resolution of the material and its replacement by native tissues. Research conducted to assess the effectiveness of material sterilization in a cold plasma sterilizer demonstrated its high bactericidal efficiency.
Conclusion
The method we developed for obtaining biodegradable plates and fixation elements on a 3D printer is easy to use and has demonstrated safety in a preclinical study on an animal model.
Finite element modeling of ballistic impact of inserts containing titanium structures were presented in the article. The inserts containing an additional layer made using additive manufacturing ...technology were analyzed. The layer was created from repetitive elements made without connections (adjacent cells were inseparable). Four variants of printed titanium structures were placed between layers of Twaron CT 750 aramid fabric to create ballistic inserts. In order to assess the ballistic resistance of the inserts, numerical simulations of ballistic impact phenomenon were carried out using LS-Dyna software. In the simulations the inserts were placed on a steel box filled with ballistic clay and were fired at with the 9 × 19 mm full metal jacket (FMJ) Parabellum projectile. The main aim of the work was to check the effectiveness of such solutions in soft ballistic protection applications and to select the most effective variant of 3D printed structure. Results of the numerical analysis showed a high potential for 3D printed structures made of titanium alloys to be used for bulletproof vest inserts. In all analyzed cases the projectile was stopped by the armor. In addition, thanks to the cooperation of adjacent cells, the projectile energy density was distributed over a large area, as evidenced by large volumes of hollows in the ballistic clay. The indentations in the ballistic clay obtained in the simulations were significantly lower than the acceptable value for the back face deformation (BFD) parameter required by international body armor standards.
Introduction. 3D printing is a promising technology to improve the efficiency of construction. At the present time, one of the main disadvantages of this technology remains the low functionality of ...printed products, in particular, traditional methods are used for thermal insulation and conditioning of printed buildings, which reduces the productivity of the technology. In this regard, the use of thermal accumulative materials (TAM) with phase transition function in building 3D printing to ensure a constant comfortable temperature in the building seems promising. A paraffin-based composite TAM has been investigated for the development of “smart” construction “ink” that will provide printed buildings operating in a temperate climate zone with a passive thermoregulation function.Materials and methods. Differential scanning calorimetry method was used to study the thermal effects of phase transitions of composite TAM consisting of paraffin, paraffin oil and petroleum jelly.Results. A decrease in the peak temperatures of TAM phase transitions was recorded from 53.8 to 32 °C during melting and from 47.6 to 32.6 °C during crystallization. For the two-component composition, the maximum enthalpy reduction was from 102.4 to 27.0 J/g during melting and from 47.7 to 8.5 J/g during crystallization; for the three-component composition, the enthalpy was 60.6 J/g during melting and 20.6 J/g during crystallization. The peak melting temperature for mixtures with 60 and 40 % paraffin is 39.4 and 39.9 °C, the peak crystallization temperature is 43.5 and 33.8 °C, respectively.Conclusions. The conducted studies have shown that the use of paraffin oil and petroleum jelly allows to shift the temperature boundaries of thermal effects of paraffin-based TAM towards lower values. At the same time, a decrease in the intensity of the corresponding peaks on thermograms is recorded, which indicates a decrease in the enthalpy of phase transition processes. Obtaining three-component TAM makes it possible to maintain a higher enthalpy by providing a sequential phase transformation of each of them.
PDF
