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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

Mechanical properties of trabecular structures produced by SLM, as a function of the trabecular morphology

Johansson, Frida, Klarin, Johanna January 2017 (has links)
Eurocoating, Italy, is a company that works in the biomedical sector. They have for a long time created prostheses from CAD files achieved from customers, and now they want to build their own expertise about the design. The thesis work was a part of a three year long collaborative research project between Eurocoating and University of Trento that was aiming to investigate the prostheses with open-porous surface and trabecular structure, created by Selective Laser Melting. The purpose of the thesis was to investigate and characterize 30 different trabecular structures of Ti-6Al-4V, fabricated by Selective Laser Melting. That includes investigation the effect on the morphology and porosity fraction caused by the manufacturing and the effect on mechanical and physical properties due to the different characterizations of the structures. The thesis work had its foundation in literature studies to receive deep knowledge about the subject. Practical tests were performed to investigate mechanical behaviour under compressive and tensile loading, static friction and wear resistance. The findings from these tests were compared to the porosity fraction and the morphological characterizations. The result stated that the porosity fraction was lower than the designed porosity, and that is was strongly influenced by size of the voids and struts. The strut thickness was higher than the design values, especially on the lateral surface, while the voids size were approximately as designed. Result from the compression test showed a trend of decreasing stiffness and strength with increasing porosity fraction. Also structures with same porosity fraction could have a wide range in mechanical properties which indicates high dependence on the morphological geometry i.e. pore size and shape, strut size and pore distribution. Comparisons between tensile and compression behaviour stated that the structures had a lower strength but a significant higher stiffness in tensile load. All structures from the wear test showed a good resistance while the results from the friction test needs further investigation to be fully understood. The physical and mechanical properties of the trabecular structures was found to be close to those of cortical and trabecular bone in porosity, stiffness and strength. There is a range of variations leading to possibilities to adopt the application depending on customer. Thus, these can be considered as promising structures used biomedical application to optimize osseointegration and secondary long term fixation.
432

Modifikace povrchu materiálu vytvořeného technikou SLM / The use of surface modification for enhancing mechanical properties of SLM bulk materials

Barinka, Michal January 2021 (has links)
This diploma thesis deals with the surface modification of 3D printed metallic materials. The research part presents the most used methods of additive manufacturing and their process parameters influencing the quality of printed components. Defects arising during these processes and the techniques used to eliminate them are also described. In the experimental part of the work, the optimization of electrochemical polishing parameters was performed. The aim was to modify the rough surface of the components and thus prevent the formation of defects on the surface. The mechanical properties were investigated by means of three-point bending under static and dynamic loading. Fractographic analysis was performed on the quarry surfaces.
433

Optimalizace parametrů SLM procesu při zpracování hliníkové slitiny AW2618 / SLM process parameters optimization for processing of AW2618 aluminum alloy

Těšický, Lukáš January 2017 (has links)
The diploma thesis deals with possibilities for processing aluminium alloy EN AW 2618 using Selective laser melting (SLM). The theoretical part contains basic knowledge about production by this technology and possibilities of evaluation of relative density of samples. It also contains an overview of the current state of knowledge about the processing of aluminium alloys by SLM technology. Above all, aluminium alloys of the series 2000, where the main alloying element is copper. In the experimental part testing samples were designed based on the research. These samples can be divided into three areas: single-track specimens, volume samples and samples for tensile testing. Single-track and volume samples were used to find appropriate processing parameters to achieve a relative density close to full volume of material. For this purpose, the effect of the different scanning strategies on the relative density of the sample were examined. The limiting factor has been the occurrence of small cracks in the broad range of parameters studied. Mechanical properties of samples produced by SLM were compared with extruded material. It was found that the material processed by SLM achieves only half the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks and other defects in the structure of the material.
434

Zpracování Al-Sc hliníkové slitiny technologií SLM / Processing of Al-Sc aluminum alloy using SLM technology

Skulina, Daniel January 2017 (has links)
Master's thesis deals with the experimental determination of process parameters reaching densities >99 % for scandium modified aluminium alloy (Scalmalloy®) processed by SLM. The alloy achieves higher mechanical properties than the AlSi10Mg aluminum alloy commonly used. The theoretical part deals mainly with the results of Scalmalloy® alloys. Experimental bodies, testing methodology and evaluation method were designed on the basis of the theoretical parts,. The practical part is divided into four main stages: experimental determination of process parameters, a description of the effect of the parameters used on the relative density achieved, examination of the influence of process parameters on surface quality and mechanical testing. The mechanical properties were determined for the best parameters.
435

Univerzální úsťové zařízení na útočnou pušku / Universal muzzle device for an assault rifle

Rušar, Filip January 2017 (has links)
This diploma thesis deals with the design of a universal muzzle device for the assault rifle. The device is designed to produce Selective Laser Melting. The main objective is the elimination negative effects of gunshot. The paper explores possibilities of using porous structures for this type of equipment. The influence of individual types of porous structures on the flow of gases is monitored. The universal muzzle device itself is optimized using CFD analyzes. The device was made using SLM technology and experimentally verified. His impact on the impact, gun lift, noise and flame elimination was investigated.
436

Mechanické vlastnosti Al slitiny připravené pomocí procesu SLM / Mechanical properties of Al alloy prepared by SLM process

Vitásek, Ladislav January 2017 (has links)
The master's thesis deals with properties of aluminium alloys prepared by SLM process. The teoretical part of thesis is focused on decribtion of selective laser melting technology, metallurgical defects and mechanical properties of aluminium alloys processed by this technology. The experimental part of this thesis deals with selections of the SLM process parameters suitable for samples preparation in bulk. Tensile testing at room temperature was used for evaluation of basic mechanical properties. Metallographic and fractographic analyses were performed for evaluation of the microstructure and fracture mechanisms. The materials characteristics obtained on SLM samples were compared with the properties of the same materials grade produced by conventional technologies.
437

Vývoj procesních parametrů slitiny mědi pro 3D tisk tenkostěnných struktur / Process parameters development for copper thin walls manufacturing via 3D printing

Klimek, Ľubomír January 2018 (has links)
In the work is used the processing of metallic material by the method of Selective Laser Melting. The main objective is to verify and describe the influence of the individual process parameters entering the production process when processing the alloy Cu7.2Ni1.8Si1Cr with SLM. This alloy contains 90 % copper. The first theoretical part of the thesis describes so far processed copper alloys with a high content of copper using the method of Selective Laser Melting. The practical part then deals with the specification of the main process parameters, which are optimized in the next part of the work solution. On the basis of the information obtained experimental bodies have been created, which will be tested and analyzed in several steps. The work focuses on thin-walled samples, which have a perspective use in the creation of highefficiency heat exchangers. The main results that the work deals with are the relative density and mechanical properties of the material. Also, great emphasis is placed on the resulting surface quality
438

Vývoj procesních parametrů technologie Selective laser melting pro výrobu tenkostěnných dílů z práškového železa / Development of process parameters of Selective laser melting technology for the production of thin-walled iron parts

Šreibr, Vít January 2018 (has links)
The thesis deals with the processing of pure iron by Selective laser melting technology as a material with good electromagnetic properties. The main area is the optimization of the production of thin-walled samples, which monitor the influence of process parameters on the thickness and quality of the wall surfaces. In addition to the perpendicular walls, walls built at an angle of 45° are also examined. Another phase of the thesis is the determination of process parameters for bulk bodies to achieve the lowest porosity and high surface quality. An important part of the research is the application of acquired knowledge in the production of samples designed to test magnetic properties as well as part for a specific application. These considerations concern not only the setting of the printing parameters, but also the heat treatment and its influence on the magnetic and mechanical properties of the material. Mechanical properties were determined by tensile tests and hardness tests. All samples were made on a SLM 280HL using a 400W ytterbium laser.
439

Konstrukce nanášecího systému pro zpracování dvou kovových prášků pomocí 3D tisku / Design of recoating system for processing of two metal powders using 3D Printing

Guráň, Radoslav January 2019 (has links)
The thesis deals with the design, construction and testing of two different metal powder coating equipment, which is able to work with SLM 280HL metal 3D printer. Since the field of multimaterial metal printing by selective laser melting (SLM) has not been significantly investigated yet, an overview of existing patents and possible approaches to the solution has been developed. The device has been successfully designed and a series of tests was carried out defining the issue of applying an improved head that uses a nozzle and an eccentric vibration motor. Based on the experiments performed, the coating parameters of the multimaterial layer of FeAm and 316L materials were defined. A control system for the partial process automation was created for the proposed device. The device was implemented in a printer that demonstrated both the ability to apply a single multimaterial layer of at least 50 m thickness, and the ability to produce a 3D multimaterial component comprised of up to 200 layers and containing material change across all axes.
440

Návrh aditivně vyráběného tepelného výměníku olej-voda pro formuli student / Design of additively manufactured oil-water heat exchanger for formula student

Březina, Josef January 2019 (has links)
Diploma thesis deals with a design and manufacture of oil cooler by technology Selective Laser Melting for Formula Student. The main goal of the design is to ensure optimal oil circuit cooling at a minimal mass. The design of manufactured oil cooler is based on a plate heat exchanger concept with optimized intakes by CFD simulations and heat exchange body with fins of thickness 0.17 mm. An analytical model was created. SLM process parameters were optimized for a thin walls printing, Subsequently, a fabrication of testing parts was finished for measuring pressure drops and performances of micro heat exchangers. Results were used for an accuracy improvement of the analytical model and for consequent optimization of heat exchange surface. Afterwards optimization was executed for inlets and outlets by using flow simulations. A prototype was built and verified on a test stand. Performance of the designed oil cooler is 4.5 kW for race mode, where temperature drop of oil circuit is 22 °C. The lightweight design weighs 320 g, which reduces more than 47 % of a current oil-air cooler weight. Furthermore, a centre of gravity is decreased by designed placement of the cooler.

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