Stålindustrin står för 7 % av världens koldioxidutsläpp. För att minska industrins miljöpåverkan är ett alternativ att introducera konstruktioner i höghållfasta stål eftersom det ger möjlighet till slankare konstruktioner och därmed mindre materialåtgång. Användning av höghållfasta stål i svetsade konstruktioner kan dock vara problematiskt då de utsätts för utmattningslaster vilket kan leda till oanade brott i konstruktionen. För att förbättra svetsade konstruktioner mot utmattning kan PWT tillämpas.I arbetet undersöktes möjligheterna till implementering av PWT i tillverkningsstadiet samt eventuella hinder till varför metoden inte används. För att bilda en uppfattning om möjligheten till alternativa metoder för att öka utmattningshållfastheten för en svets har gällande myndighetskrav samt normer för utförande av vanliga svetsar undersökts. Genom intervjuer har åsikter från olika aktörer inhämtats för att besvara frågeställningarna.Efter genomförd undersökning konstaterades att den bristande förmågan att kontrollera spänningar i en svets är en bidragande faktor till varför PWT i dagsläget inte används i tillverkningsstadiet inom byggbranschen. Intervjun med Trafikverket resulterade i alternativet att ta fram en särskild kravspecifikation enligt Krav Brobyggande, som vid godkännande skapar möjlighet för implementering av PWT. Krav Brobyggande är Trafikverkets dokument men krav och råd för brobyggande i Sverige. / The steel industry stands for 7 % of the worlds emission of carbon dioxide. An alternative to reduce the environmental impact of the industry is to introduce structures of high strength steel since it provides opportunity for slimmer structures and thereby less material consumption. However, the use of high strength steel in welded structures can be problematic when exposed to fatigue loads, which can lead to unsuspected breaks in the structure. To improve welded structures against fatigue PWT can be implemented.The possibilities for implementation of PWT during manufacturing and possible obstacles as to why it should not be used was investigated in this thesis. To form a perception for the possibilities of alternative welding methods to increase fatigue strength the existing regulations and norms of execution for as welded conditions was examined. Opinions from different participants in the construction process were interviewed to answer the questions at issue.The lacking ability to verify stress in a weld was concluded to be a contributing factor as to why PWT is not currently used during the manufacturing process in the construction industry. The interview with Trafikverket resulted in the alternative to create a specific requirement specification according to demands in Krav Brobyggande. Approval of the specific requirement specification could lead to possibility to implement PWT in the construction industry. Krav Brobyggande is Trafikverkets document with demands and advice for bridge construction in Sweden.

Performance of indexable insert cutting tools is not only about the performance of cutting inserts. It is also about the cutting tool body, which has to provide a secure and accurate insert positioning as well as its quick and easy handling under severe working conditions. The common damage mechanisms of cutting tool bodies are fatigue and plastic deformation. Cutting tools undergo high dynamic stresses going in and out cutting engagement; as a result, an adequate level of fatigue strength is the essential steel property. Working temperatures of tool bodies in the insert pocket can reach up to 600°C, why the tool steel requires high softening resistance to avoid plastic deformation. Machinability is also essential, as machining of the steel represents a large fraction of the production cost of a cutting tool. The overall aim of the study is to improve the tool body performance by use of an advanced steel grade with an optimized combination of all the demanding properties. Due to the high-temperature conditions, the thesis concerns mostly hot-work tool steels increasing also the general knowledge of their microstructure, mechanical properties and machinability. Knowing the positive effect of sulphur on machinability of steels, the first step was to indentify a certain limit of the sulphur addition, which would not reduce the fatigue strength of the tool body below an acceptable level. In tool bodies, where the demand on surface roughness was low and a geometrical stress concentrator was present, the addition of sulphur could be up to 0.09 wt%. Fatigue performance of the cutting tools to a large extent depended on the steel resistance to stress relaxation under high dynamic loading and elevated temperatures. The stress relaxation behaviour, material substructure and dislocation characteristics in low-alloyed and hot-work tool steels were studied using X-ray diffraction under thermal and mechanical loading.  Different tool steels exhibited different stress relaxation resistance depending on their microstructure, temper resistance and working temperature. Hot-work tool steels showed to be more preferable to low-alloyed tool steels because of their ability to inhibit the rearrangement and annihilation of induced dislocations. High-temperature softening resistance of the hot-work tool steels was investigated during high-temperature hold-times and isothermal fatigue and discussed with respect to their microstructure. Carbide morphology and precipitation were determined using scanning and transmission electron microscopy. Machinability of a prehardened hot-work tool steel of varying nickel content from 1 to 5 wt% was investigated in end milling and drilling operations. Machining the higher nickel containing steels resulted in longer tool life and generated lower cutting forces and tool/workpiece interface temperature. The difference in machinability of the steels was discussed in terms of their microstructure and mechanical properties.

This master’s thesis describes the design of wall mobile crane and its railway. At the beginning of the work research of suitable hoists is conducted according to important parameters. Following the calculation of basic loads applied during crane operation. Furthermore the determination of the static load and fatigue strength of selected part which is verified by MKP simulation. The work continues with design of selected parts of crane and its railway. This design is solved with respect to relevant standards. In conclusion the final design of machine is drawn.

The master’s thesis deals with the fatigue life prediction under multiaxial cyclic loading. First, the fatigue process is discussed and the methods for fatigue life prediction under uniaxial and multiaxial loading are described. In the practical part, the accuracy of selected criteria is assessed based on experimental data obtained on cylindrical samples made of 1.2210 steel that were tested under synchronous symmetric axial-torsion loading. Application of criteria requires to determine the fatigue strength under pure axial and torsional loading.

This master’s thesis describes the design of two-girder overhead crane. At the beginning of the work are designed sectional characteristics of the girder and the crossbeam. Furthermore, they are calculated loads applied during crane operation. Following the determination of the static load and fatigue strength. All calculations are solved with respect to relevant standards relating to overhead cranes. The work also includes analysis of purchased components, which are geared motors, bumpers and drive (no drive) wheels.

Ermüdungsanalyse mit Pro/Mechanica am Beispiel einer Förderschnecke

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No description available.

<p>Disertacija obrađuje problematiku praktičnog uvođenja opterećenja izazvanih<br />zako&scaron;avanjem dizalice u normiranu proceduru dokaza zamorne čvrstoće njene noseće<br />konstrukcije. U prvom delu rada koncizno je izložena teorijska podloga zako&scaron;avanja<br />mosne dizalice, neophodna za potpunije razumevanje relevantnih obeležja predmeta<br />istraživanja. Predložene su metode za eksperimentalnu determinaciju bočnih sila u<br />interakciji točak &ndash; &scaron;ina, odn. vodeća rolna &ndash; &scaron;ina. Testiranje predloženih metoda<br />spovedeno je kroz eksperimente na realnom objektu &ndash; jednogredoj električnoj mosnoj<br />dizalici nosivosti 3,2 t i raspona 8,91 m. Komentarisani su reprezentativni rezultati i<br />date su smernice za sprovođenje dokaza zamorne čvrstoće detalja noseće konstrukcije<br />dizalice, uzimajući u obzir pri tom i spektre sila zako&scaron;enja. Takođe je ukazano i na<br />neke nejasnoće i nedorečenosti u važećim standardima, a u vezi proračunskog<br />određivanja sila zako&scaron;enja.</p> / <p>The dissertation deals with the problem of practical application of loadings caused by<br />crane skewing, in normative procedures of fatigue strength proof calculations of crane<br />supporting structure. In the first part, the theoretical framework of bridge crane<br />skewing, necessary for better understanding of relevant characteristics of the research<br />topic, has been concisely elaborated. Methods are proposed for experimental<br />determination of lateral forces in wheel/rail and guiding roller/rail contacts. These<br />methods were tested through a series of experiments on a real object &ndash; an electrically<br />driven single girder bridge crane with a capacity of 3.2 t, and span 8.91 m. Some<br />representative measurement results are discussed and guidelines are given for<br />performing the fatigue strength proof calculation of crane supporting structure details,<br />taking into account skewing forces spectra, too. Also, attention has been drawn to<br />certain unclear points and inconsistencies in norms in force, concerning calculative<br />determination of skewing forces.</p>

Ce mémoire présente une méthode visant à mettre en évidence l’influence de l’intégrité de surface obtenue en tournage, sur la fatigue de l’acier 15-5PH. Le travail réalisé consiste à développer des moyens d’obtention de surfaces à intégrités maitrisées, puis à réaliser des essais de fatigue pour observer l’influence des paramètres d’intégrité. Les procédés de tournage et de galetage sont utilisés pour obtenir des lots d’éprouvettes possédant différentes intégrités de surfaces. Ces éprouvettes sont ensuite toutes caractérisées, en rugosité et contraintes résiduelles, de manières non destructives. Certaines éprouvettes font l’objet d’analyses complémentaires pour caractériser l’état de la matière sous la surface. Ces analyses permettent de constituer des lots d’éprouvettes possédant des caractéristiques de surfaces très proches. Toutefois, il a été mis en évidence une très grande sensibilité de l’intégrité de surface générée, vis-à-vis du diamètre de la pièce usinée, ce qui se traduit par une dispersion importante des intégrités de surface obtenues. Les lots constitués sont ensuite testés en fatigue sur une machine de flexion rotative (R = -1) selon la méthode Staircase. Cette méthode permet de déterminer la limite d’endurance avec 50 % de probabilité de rupture pour un nombre de cycles donné. Les résultats sont ensuite confrontés aux intégrités de surface des lots pour déterminer les caractéristiques les plus influentes. Une comparaison des données expérimentales est réalisée avec les modèles de la littérature. Il est montré que ces modèles ne parviennent pas à décrire de manière satisfaisante le comportement en fatigue vis à vis de la rugosité ou du niveau de contraintes résiduelles. L’analyse de ces résultats montre que le profil de contraintes résiduelles, dans le cas du 15-5PH, est la caractéristique la plus influente sur la tenue en fatigue. La rugosité n’apparait pas comme un facteur d’influence notable, à l’exception des cas où les contraintes résiduelles ont un niveau très faible. Des pistes d’améliorations sont enfin suggérées pour améliorer la prise en compte de l’intégrité de surface dans le cadre d’un dimensionnement en fatigue. / This thesis aims to show a method to highlight the influence of surface integrity obtained by turning on the fatigue of a 15-5PH steel. Several ways are developped to obtain desired surface integrities, then fatigue test are performed to observe the influence of surface integrity parameters'. Turning and ball burnishing were used to achieve specimens with differents surface integrities. Theses samples are then fully characterized in term of surface roughness and residual stresses, in a non-destructive way. Some specimens are subject to further analysis to characterize the state of the material under the surfaece. These analyses are used to create batches of specimens with very close surfaces characteristics. However, it has been shown a high sensitivity of the generated surface integrity, with respect to the workpiece diameter, which result in a significant dispersion of surface integrities obtained. Batches are then tested on a rotating bending test machine (Stress ration R=-1) thanks to the Staircase method, in order to determine the fatigue limit at two billion cycle with a 50% failure probability. The results are then compared with the surface integrities in order to determine the most influencial parameter. A comparison of the experimental datas with models in the literature is performed. It is shown that models are unable to describe the fatigue behavior with respect to the roughness or the residual stress state. The results analysis shows that residual stresses profile, in the case of 15-5PH steel, is the most influencial parameter on the fatigue life. Roughness does not appears as a factor of major influence, except in cases where residual stresses have a very low level. Prospects for improvement are finaly suggested in order to improve the consideration of surface integrity during the fatigue design of parts.