Powder Application in Additive Manufacturing of Metallic Parts

This chapter is going to give up-to-date overview of development in the field of additive manufacturing (AM) of metallic components. There will be briefly mentioned input materials and specific requirement for the input materials (powders and wires). General technology process overview will be presented here, and selective laser melting (SLM) technology and beam melting technologies will be described. Advantages of 3D printing technology will be explained in terms of special designs; special properties and generally multifunctional components of production possibilities will be shown. Postprinting procedures leading to improvement of mechanical properties of printed components like thermal or thermomechanical treatment will also be mentioned here

Study of the microstructure, tensile properties and hardness of AZ61 magnesium alloy subjected to severe plastic deformation

Hot extruded (EX) AZ61 magnesium alloy was processed by the twist channel angular pressing (TCAP) method, which combines equal channel angular pressing (ECAP) and twist extrusion (TE) processes and significantly improves the efficiency of the grain refinement process. Both the initial hot extruded AZ61 alloy and the alloy after completion of TCAP processing were examined by using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) and their corresponding micro-tensile testing (M-TT) and hardness testing at room temperature. The results showed that the microstructure of hot extruded alloy was refined well by TCAP due to dynamic recrystallization (DRX) caused by TCAP. The tensile properties, investigated by micro-tensile testing (M-TT), of the AZ61 alloy were significantly improved due to refined microstructure. The highest tensile properties including YS of 240.8 MPa, UTS of 343.6 MPa and elongation of 21.4% of the fine-grained alloy with average grain size below 1.5 mu m was obtained after the third TCAP pass at 200 degrees C using the processing route B-c.Web of Science810art. no. 77

Thermomechanics fatigue damage methodlogy of the turbine rotor

Příspěvek se zabývá metodikou výpočtu životnosti a stanovením kritických míst rotoru turbíny při zvýšené četnosti teplých i studených startů a následně postupy vyhodnocování únavového poškozování s využitím teorií kombinace nízkocyklové (vysokocyklové) únavy a creepu, zejména potom Sehitoglu modelem a modelem dle Nagodeho. Popisuje potřebné materiálové parametry a schéma programových skriptů a postupu numerických simulací.This paper describes a fatigue life methodology and determination of critical points of the turbine rotor by increased frequency of both hot and cold operational starts, followed by methods of evaluation of fatigue damage using the combination of low cycle (fatigue) and creep theory, especially the Sehitoglu and the Nagode models. It describes the necessary material parameters and schema of the program scripts and the procedure of numerical simulations

THERMO-MECHANICAL FATIGUE ANALYSIS OF A STEAM TURBINE SHAFT

Increasing demands on the flexibility of steam turbines due to the use of renewable energy sources substantially alters the fatigue strength requirements of components of these devices. Rapid start-ups as well as the increased number of the load cycles applied to the turbines must be handled by design methodologies. The goal of the work presented in this paper was to provide a computational framework applicable to the thermo-mechanical fatigue (TMF) prediction of steam turbine shafts. The so-called Damage Operator Approach by Nagode et al. has been implemented to the software codes and applied to fatigue analysis of the thermo-mechanical material response computed numerically by the finite element analysis. Experimental program conducted in order to identify the material thermo-mechanical behavior and to verify numerical simulations is introduced in the paper. Some results of TMF prediction of a sample steam turbine shaft are shown

Damage tolerant design of additively manufactured metallic components subjected to cyclic loading:State of the art and challenges

none21siUndoubtedly, a better understanding and the further development of approaches for damage tolerant component design of AM parts are among the most significant challenges currently facing the use of these new technologies. This article presents a thorough overview of the workshop discussions. It aims to provide a review of the parameters affecting the damage tolerance of parts produced by additive manufacturing (shortly, AM parts) with special emphasis on the process parameters intrinsic to the AM technologies, the resulting defects and the residual stresses. Based on these aspects, basic concepts are reviewed and critically discussed specifically for AM materials: - Criteria for damage tolerant component design; - Criteria for the determination of fatigue and fracture properties; - Strategies for the determination of the fatigue life in dependence of different manufacturing conditions; - Methods for the quantitative characterization of microstructure and defects; - Methods for the determination of residual stresses; - Effect of the defects and the residual stresses on the fatigue life and behaviour. We see that many of the classic concepts need to be expanded in order to fit with the particular microstructure (grain size and shape, crystal texture) and defect distribution (spatial arrangement, size, shape, amount) present in AM (in particular laser powder bed fusion). For instance, 3D characterization of defects becomes essential, since the defect shapes in AM are diverse and impact the fatigue life in a different way than in the case of conventionally produced components. Such new concepts have immediate consequence on the way one should tackle the determination of the fatigue life of AM parts; for instance, since a classification of defects and a quantification of the tolerable shapes and sizes is still missing, a new strategy must be defined, whereby theoretical calculations (e.g. FEM) allow determining the maximum tolerable defect size, and non-destructive testing (NDT) techniques are required to detect whether such defects are indeed present in the component. Such examples show how component design, damage and failure criteria, and characterization (and/or NDT) become for AM parts fully interlinked. We conclude that the homogenization of these fields represents the current challenge for the engineer and the materials scientist.noneZerbst, Uwe; Bruno, Giovanni; Buffiere, Jean-Yves; Wegener, Thomas; Niendorf, Thomas; Wu, Tao; Zhang, Xiang; Kashaev, Nikolai; Meneghetti, Giovanni; Hrabe, Nik; Madia, Mauro; Werner, Tiago; Hilgenberg, Kai; Koukolíková, Martina; Procházka, Radek; Džugan, Jan; Möller, Benjamin; Beretta, Stefano; Evans, Alexander; Wagener, Rainer; Schnabel, KaiZerbst, Uwe; Bruno, Giovanni; Buffiere, Jean-Yves; Wegener, Thomas; Niendorf, Thomas; Wu, Tao; Zhang, Xiang; Kashaev, Nikolai; Meneghetti, Giovanni; Hrabe, Nik; Madia, Mauro; Werner, Tiago; Hilgenberg, Kai; Koukolíková, Martina; Procházka, Radek; Džugan, Jan; Möller, Benjamin; Beretta, Stefano; Evans, Alexander; Wagener, Rainer; Schnabel, Ka

Stavebně technologický projekt - Muzeum rybníkářství Třeboň

Předmětem této diplomové práce je příprava technologického postupu a zpracování rozpočtu k projektu pro stavební povolení rekonstrukce Domu Štěpánka Netolického v Plzni. Další částí práce je provedení výtahové šachty ve dvou variantách a jejich vzájemné porovnání. Cílem je znovuobnovení historické podstaty objektu při respektování současných požadavků na stavby, včetně požadavků na využívání osobami ZTP.ObhájenoThe subject of this thesis is the preparation of the technological procedure and the preparation of the budget, based on the building permission as the resource for this thesis. The object of this thesis is the house of Štěpán Netolický in Třeboň town. The another part of this thesis is the making of two variants of the elevator shaft, one made of steel and another of reinforced concrete. These two versions will be compared in technological terms. The primary aim is the restoration of a historical essence of this building, including requirements for the usability by invalidity persons

The complex reconstruction of an object in Úslavská street 5 in Pilsen "Extension of an existing building"

Předmětem této bakalářské práce je příprava projektové dokumentace pro stavební povolení pro komplexní rekonstrukci objektu v Úslavské ulici v Plzni. Jejím cílem je řešení nové dispozice objektu podle současných požadavků na bydlení, posouzení vybraných částí budovy, zlepšení tepelně-technických vlastností budovy a posouzení únikové cesty.Katedra mechanikyObhájenoThe objective of this Bachelor´s thesis is preparation of project documentation for the building permit for the complex reconstruction of an object in Úslavská street in Pilsen. The aim is a solution of the new disposition of the object with present requirements of the living, assessment of the chosen constructions, improvment of the heat-technical attributes of the building and assessment of the escape path

Praktické poznámky k posouzení únavové životnosti karoserií autobusů a trolejbusů

When developing a new vehicle, the prescribed fatigue criteria must be met in all important structural nodes of the vehicle bodywork. Maximum stress amplitudes (stress ranges) must be lower than permissible values when the vehicle crosses significant road unevenness. The development stages are: 1) projecting and design of vehicle; 2) investigation of vehicle function sample on test stand; 3) measurement of vehicle prototype. In case the prescribed condition is not fulfilled, it is necessary to recommend a modification of the vehicle bodywork. In any case, it is necessary to know the fatigue properties for various structural and technological variants of the body sections. These properties can be determined in advance by laboratory fatigue tests. The paper describes the assessment of fatigue life in successive phases of vehicle development and presents the results of fatigue tests of several variants of welded nodes used in body constructions.Při vývoji nového vozidla musí být ve všech důležitých konstrukčních uzlech karoserie vozidla splněna předepsaná únavová kritéria. Maximální amplitudy napětí (rozsahy napětí) musí být nižší než přípustné hodnoty, když vozidlo přejede významné nerovnosti na silnici. Fáze vývoje jsou: 1) projektování a návrh vozidla; 2) zkoumání funkčního vzorku vozidla na zkušebním stendu; 3) měření prototypu vozidla. V případě, že předepsaná podmínka není splněna, je nutné doporučit úpravu karoserie vozidla. V každém případě je nutné znát únavové vlastnosti různých konstrukčních a technologických variant konstrukčních uzlů karosérie. Tyto vlastnosti lze předem stanovit laboratorními únavovými testy. Článek popisuje hodnocení únavové životnosti v postupných fázích vývoje vozidla a představuje výsledky únavových testů několika variant svařovaných uzlů používaných v konstrukcích karoserie

Focusing High-Resolution Three-Axis Neutron Diffractometer for Investigations of Special Tasks of Powder Diffractometry

Feasibility of focusing high-resolution three-axis diffractometer with the polycrystalline sample between the monochromator and the analyzer was tested for studies of finer effects of powder diffraction lines and for investigations of special tasks of powder diffractometry. The focusing 3-axis diffractometer set-up equipped with bent perfect crystal monochromator and analyzer offers the sensitivity in determination e.g. of strains in polycrystalline materials ε =Δd/d close to 10-5. Together with special tasks of strain/stress studies related namely, to plastic deformation, it permits to study a finer substructure of individual diffraction lines which can appear e.g. in case of polycrystalline alloys where more phases having very close values of the lattice spacing could exist. Resolution properties of the high-resolution diffractometer setting will be documented on several experimental results obtained on unconventional bulk samples