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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.
21

R65 tipo bėgio kontaktinio suvirinimo jungties tyrimas / Research of the Flash Welding of the R65 Type Rail Joint

Dauskurdis, Kęstutis 19 June 2014 (has links)
Šiame baigiamajame magistro darbe tiriama R65 tipo bėgio kontaktinio suvirinimo jungtis. Supažindinama su pagrindiniais mokslininkų parašytais straipsniais, bėgių kontaktinio suvirinimo tematika. Pateikiama tyrimų metodika, kurią sudaro šios dalys: apžiūrimasis paviršiaus tyrimas, ultragarsinės kontrolės tyrimas, važiuojamasis paviršiaus kiečio bandymas, sulydimo zonos nustatymas, termiškai suminkštintos zonos kiečio matavimas, mikrokietumo matavimas, mikroskopinis jungties matomosios terminio poveikio ir sulydymo zonų tyrimas, smūginio tąsumo bandymas, cheminė analizė, aširačio bandažo ir bėgio sąveikos tyrimas baigtinių elementų metodu (BEM). Išanalizuoti gauti tyrimo rezultatai, kurie įvertina suvirinimo siūlės kokybę. Pateiktos tiriamojo darbo išvados. / In the final thesis of masters degree I analyze the R65 type rail joint that were welded flash butt. Introducing with scientific articles about flash butt welding of rails. Survey methodology of the research, which consists of the following parts: visual surface review of welded joint, ultrasonic rail inspection, hardness test of upper part of the rail, fusion area research, the measurement test hardness of heat-softened area, the measurement test microhardness, microstructure research of the welded joint, impact strenght experiments, chemical analysis of welded joint, wheel-rail interaction research of the finite element method (FEM). Analyzes the results of the research, who assess the quality of weld. The conclusion is based on the results of this research.
22

Caracterização mecânica e metalúrgica de um elo de corrente de amarra em aço para aplicação naval na indústria do petróleo

Santos, Rafael Eugenio dos January 2017 (has links)
As amarras de correntes de aço para aplicação naval utilizadas na indústria de óleo e gás são fabricadas para atender elevadas exigências operacionais. Com a prospecção de petróleo em águas profundas e ultraprofundas o conhecimento de suas propriedades torna-se relevante. Frente a essa necessidade foi realizado o estudo das propriedades mecânicas e metalúrgicas de um elo de corrente de amarra naval na indústria do petróleo proveniente de operação. Esse estudo teve como objetivo principal identificar e avaliar as propriedades mecânicas e metalúrgicas das regiões resultante do processo de soldagem por centelhamento frente ao material de base. Como objetivo secundário foi classificado o material de acordo com algumas propriedades mecânicas recomendadas pela IACS UR W22. Para isso foram realizados ensaios de tração, microdureza, tenacidade ao impacto Charpy e à fratura CTOD, com avaliações metalúrgicas no material de base e região de união por centelhamento. Como resultado foi verificado que o processo de soldagem por centelhamento produziu zonas de extensões reduzidas e com menores valores de tenacidade à fratura e ao impacto. O processo de centelhamento produziu união com espessura de 0,375 mm, com uma zona de solda revelada por ataque químico e duas zonas afetadas pelo calor caracterizadas apenas por perfil de microdureza, com 0,150 mm e 0,300 mm, respectivamente. Os menores valores de tenacidade ao impacto Charpy e à fratura CTOD foram medidos nos corpos de prova posicionados na zona afetada pelo calor. Os resultados obtidos em todos os ensaios foram comparados com as recomendações técnicas IACS UR W22, onde caracterizou o elo como grau R4. / Mooring chains of offshore systems anchors are design to be used under extreme environment operation. New fields of exploration have been operated in deep water and ultra-deep water, wherefore, require more knowledge of the mechanical and metallurgical properties. Hence a study of a studless link of offshore chain from the operating service component was carried out. The main goal of this work was to determine and evaluate the properties of the base material and the zones produced by Flash Butt Welding Process. Furthermore, the material was characterized by the IACS UR W22 standard recommendation. In this study tests of tensile test, microhardness, Charpy and CTOD toughness, mechanical and metallurgical evaluation were performed in the base material and welding zones. The results showed small welding zones with reduced impact and fracture toughness. The lowest values were seen in specimens from the heat affect zone. The weld zone thickness observed by chemical etching extend 0,375 mm and the microhardness profile indicated a Heat Affected Zone (HAZ) with 0,150 and 0,300 mm. The lowest Charpy and CTOD toughness tests were measured in the HAZ specimens. These results were compared with IACS UR W22 standard recommendation and the link chain was characterized as R4 grade.
23

Caracterização mecânica e metalúrgica de um elo de corrente de amarra em aço para aplicação naval na indústria do petróleo

Santos, Rafael Eugenio dos January 2017 (has links)
As amarras de correntes de aço para aplicação naval utilizadas na indústria de óleo e gás são fabricadas para atender elevadas exigências operacionais. Com a prospecção de petróleo em águas profundas e ultraprofundas o conhecimento de suas propriedades torna-se relevante. Frente a essa necessidade foi realizado o estudo das propriedades mecânicas e metalúrgicas de um elo de corrente de amarra naval na indústria do petróleo proveniente de operação. Esse estudo teve como objetivo principal identificar e avaliar as propriedades mecânicas e metalúrgicas das regiões resultante do processo de soldagem por centelhamento frente ao material de base. Como objetivo secundário foi classificado o material de acordo com algumas propriedades mecânicas recomendadas pela IACS UR W22. Para isso foram realizados ensaios de tração, microdureza, tenacidade ao impacto Charpy e à fratura CTOD, com avaliações metalúrgicas no material de base e região de união por centelhamento. Como resultado foi verificado que o processo de soldagem por centelhamento produziu zonas de extensões reduzidas e com menores valores de tenacidade à fratura e ao impacto. O processo de centelhamento produziu união com espessura de 0,375 mm, com uma zona de solda revelada por ataque químico e duas zonas afetadas pelo calor caracterizadas apenas por perfil de microdureza, com 0,150 mm e 0,300 mm, respectivamente. Os menores valores de tenacidade ao impacto Charpy e à fratura CTOD foram medidos nos corpos de prova posicionados na zona afetada pelo calor. Os resultados obtidos em todos os ensaios foram comparados com as recomendações técnicas IACS UR W22, onde caracterizou o elo como grau R4. / Mooring chains of offshore systems anchors are design to be used under extreme environment operation. New fields of exploration have been operated in deep water and ultra-deep water, wherefore, require more knowledge of the mechanical and metallurgical properties. Hence a study of a studless link of offshore chain from the operating service component was carried out. The main goal of this work was to determine and evaluate the properties of the base material and the zones produced by Flash Butt Welding Process. Furthermore, the material was characterized by the IACS UR W22 standard recommendation. In this study tests of tensile test, microhardness, Charpy and CTOD toughness, mechanical and metallurgical evaluation were performed in the base material and welding zones. The results showed small welding zones with reduced impact and fracture toughness. The lowest values were seen in specimens from the heat affect zone. The weld zone thickness observed by chemical etching extend 0,375 mm and the microhardness profile indicated a Heat Affected Zone (HAZ) with 0,150 and 0,300 mm. The lowest Charpy and CTOD toughness tests were measured in the HAZ specimens. These results were compared with IACS UR W22 standard recommendation and the link chain was characterized as R4 grade.
24

Caracterização mecânica e metalúrgica de um elo de corrente de amarra em aço para aplicação naval na indústria do petróleo

Santos, Rafael Eugenio dos January 2017 (has links)
As amarras de correntes de aço para aplicação naval utilizadas na indústria de óleo e gás são fabricadas para atender elevadas exigências operacionais. Com a prospecção de petróleo em águas profundas e ultraprofundas o conhecimento de suas propriedades torna-se relevante. Frente a essa necessidade foi realizado o estudo das propriedades mecânicas e metalúrgicas de um elo de corrente de amarra naval na indústria do petróleo proveniente de operação. Esse estudo teve como objetivo principal identificar e avaliar as propriedades mecânicas e metalúrgicas das regiões resultante do processo de soldagem por centelhamento frente ao material de base. Como objetivo secundário foi classificado o material de acordo com algumas propriedades mecânicas recomendadas pela IACS UR W22. Para isso foram realizados ensaios de tração, microdureza, tenacidade ao impacto Charpy e à fratura CTOD, com avaliações metalúrgicas no material de base e região de união por centelhamento. Como resultado foi verificado que o processo de soldagem por centelhamento produziu zonas de extensões reduzidas e com menores valores de tenacidade à fratura e ao impacto. O processo de centelhamento produziu união com espessura de 0,375 mm, com uma zona de solda revelada por ataque químico e duas zonas afetadas pelo calor caracterizadas apenas por perfil de microdureza, com 0,150 mm e 0,300 mm, respectivamente. Os menores valores de tenacidade ao impacto Charpy e à fratura CTOD foram medidos nos corpos de prova posicionados na zona afetada pelo calor. Os resultados obtidos em todos os ensaios foram comparados com as recomendações técnicas IACS UR W22, onde caracterizou o elo como grau R4. / Mooring chains of offshore systems anchors are design to be used under extreme environment operation. New fields of exploration have been operated in deep water and ultra-deep water, wherefore, require more knowledge of the mechanical and metallurgical properties. Hence a study of a studless link of offshore chain from the operating service component was carried out. The main goal of this work was to determine and evaluate the properties of the base material and the zones produced by Flash Butt Welding Process. Furthermore, the material was characterized by the IACS UR W22 standard recommendation. In this study tests of tensile test, microhardness, Charpy and CTOD toughness, mechanical and metallurgical evaluation were performed in the base material and welding zones. The results showed small welding zones with reduced impact and fracture toughness. The lowest values were seen in specimens from the heat affect zone. The weld zone thickness observed by chemical etching extend 0,375 mm and the microhardness profile indicated a Heat Affected Zone (HAZ) with 0,150 and 0,300 mm. The lowest Charpy and CTOD toughness tests were measured in the HAZ specimens. These results were compared with IACS UR W22 standard recommendation and the link chain was characterized as R4 grade.
25

Tensile Strength of Bonded Lap-mitered Butt-Joints between Layered CFRP Bands : -In collaboration with RUAG Space AB

Zeeshan, Muhammad January 2014 (has links)
Joints in structures always cause strength reduction. The percentage of strength reduction depends upon the selection of several factors such as: type of joint (i.e. adhesive or mechanical), technique of joint (i.e. lap joint, butt joint etc.), geometry of joint, mode of load application etc. Here in this research, the strength of adhesively bonded butt joints with several geometries, later referred as joint angles, is investigated under uniaxial tension loading. Adhesively bonded simple butt joints, where joints are placed perpendicular to the loading direction are in common practice mainly because of ease in manufacturing process. But when the joint is fabricated with an angle respective to the loading direction, the geometry of the joint itself affects the strength of the joint significantly. Without going too deep into other factors that affects the joint strength such as manufacturing techniques, manufacturing defects, material behavior etc. only the geometry of the joint is considered and it is evaluated whether it is worth to change the joint geometry or not. The significant issue in adhesive joint technology is the prediction of joint strength. However, an approach similar to plastic yield criterion later referred as elastic limit offset method (attempted for 0.025% offset) is considered to estimate the linear elastic limit. Since RUAG Space AB (the industry for which this project is performed) is only interested in the linear elastic regime of the stress-strain curve, therefore the elastic limit offset method is considered to be the suitable one. The present work is concerned with the study of adhesively bonded angled butt joint vs. strength behavior. The strength of adhesively bonded butt joints is examined for several butt joint angles under uniaxial tensile loading. The employed butt joint angles are: 0°, 30°, 45°, 60° and 75°. The main objective of the current investigation is to find the joint angle that has the highest strength or the highest capability of load transfer. In addition to the above, the influence of the joint on the stress field, joint strength and type of failure is also evaluated using DSP (Digital Speckle Photography) technique and simulated using well known finite element tool, ABAQUS. It is observed that specific strength of the joint is greatly influenced with joint angle. The 45° joint showed the highest elasticity and failed like ductile behavior whereas 75° joint showed the lowest elasticity and failure was purely brittle. Moreover, post-failure inspection of fractured surfaces showed cohesive failure (failure within adhesive layers) for 0°, 30°, 45° and 60°whereas 75° showed composite or adherend failure. The simulation is performed for each joint angle. However to validate the model only 45° and 75° joints results are compared with experimental results and plotted in the report. The simulation results of these angles showed good agreement with the experimental ones. Moreover, the stress fields for each joint angle are captured (from ABAQUS), showing that all joints are susceptible to inter-laminar shear. Besides, the relative slip between the top and middle adherends is also calculated, the results show that, the 45° joint has higher tendency of relative slip than others.
26

COSMETIC ENHANCEMENTS IN BLACK AND BROWN COMMUNITIES: AN ANALYSIS ON THE DANGERS AND IMPLICATIONS OF ILLEGAL BUTTOCK INJECTIONS AND THE BRAZILIAN BUTT LIFT PROCEDURE

Johnson, Rowena January 2021 (has links)
Modifications, alterations, and enhancements to the body have been a practice forvarious ethnic, religious, and cultural groups across the globe for centuries. Over recent years, augmentations to the buttocks have become increasingly popular amongst women in Black and Brown communities. It is necessary to examine the health concerns, medical neglect, and societal influences that have contributed to the alarming increase of health complications and fatalities within these communities as a result of the procedures. Specifically, the administration of illegal injectable substances to the buttocks and the “Brazilian Butt Lift” procedure are in need of serious ethical focus and concern. In addition to the harmful health effects that result from these procedures, it is also important to recognize relevant societal and structural factors that intersect this rising issue. To fully comprehend the magnitude of the ongoing concerns, the history of buttock augmenting will be thoroughly discussed, other serious contributing factors, accessibility to adequate healthcare, and health knowledge. Cosmetic enhancements should come from a place of both empowerment and wellbeing, however the current conditions in the industry as it pertains to marginalized communities reflect otherwise. There are several contextual aspects as to why the ramifications of these procedures are so detrimental and it is my intention to highlight these issues, discuss the ethical implications, implore further research efforts, and then provide possible solutions to help address this growing issue. / Urban Bioethics
27

System för minskad fimpnedskräpning / System for reduced butt littering

Berg, David January 2012 (has links)
Fimpnedskräpning är ett problem ur flera aspekter. Fimparnas filter har en lång nedbrytnings­tid och innehåller tungmetallen kadmium, den lagras i allt organiskt. Med den största andelen av den totala mängden skräp har samhället varken råd att låta fimparna ligga kvar i naturen eller att plocka upp alla från densamma. Kemiskt och estetiskt såväl som ekonomiskt är fimp­ned­skräpningen ett dåtida, ett nutida och ett framtida problem. Lösningsförslag handlar ofta om restriktioner, ökade investeringar i renhållning eller tillgänglighet. Men en skräpig miljö behöver inte fler skräpinsamlare och botskrivare, utan färre nedskräpare. Filtren på cigaretter består av en plast kallad cellulosaacetat. Pressas de ihop ordentligt är de­formationen plastisk, ett faktum efter utförda experiment. Det konstaterades att bestående tryckmönster i relief kan inpräntas i fimparnas filterplast. Detta ska uppfyllas via mobila ask­koppar, kallade LitterPress. Dessa släcker, kom­primerar och förvarar fimpar samtidigt som de omvandlar dess filter till lottsedlar. Vid användning märks filtren med respektive rökares person- eller telefonnummer i ett pressmoment. Alla ciga­retter är därmed potentiella lotter som kan spåras tillbaka till inlämnarna. Förslaget uppmuntrar rökarna att tömma sina mobila askkoppar i numrerade stationära ask­koppar, kallade LitterBox. Dessa fördelar slump­mässigt fimparna mellan två fack, ett huvudfack där de flesta hamnar och ett mindre fack där betydligt färre hamnar. Varje vecka slumpar ett dataprogram fram ett nummer mellan 1 och antalet uppsatta stationära askkoppar. De som har märkta fimpar, i den utlottade stationära ask­koppens mindre fack, erhåller en kännbar ekonomisk utdelning. Det ska gå att tilldela en eventuell utdelning till en specifik verksamhet. Detta uppfylls genom att den mobila askkoppen ställs in på att märk­a filtren med ett organisationsnummer. Oberoende av märkning kan det parallellt ske en fortlöpande utdelning till välgörande ända­mål, där en bestämd summa skänks för varje fimp i det mindre facket. Detta utgör konceptet Litter­Lott, ett skräplotteri med LitterPress och LitterBox som kompo­nenter. Alla deltagare har en chans att ta del av de skräpkostnader och miljöbelastningar de besparar samhället. Innovativt och pedagogiskt ökar medvetenheten kring både återvinning och kostnader kopplade till nedskräpning. En hemsida annonserar aktuell LitterBox och veckans ”återvinnare”. Där ska det gå att regi­strera medlemskap, följa utvecklingen av LitterLott och delta i ämnes­relaterade diskussioner. Företag, kommunala verksamheter, stiftelser och organisationer kan också anmäla sitt intresse i att vara med och samarbeta för en mer hållbar miljö. Projektets intention är att väcka debatt med fokus på viktiga frågor angående miljö, nedskräp­ning och återvinning. Frågor som är relevanta i dagens samhälle och nödvändiga för morgon­dagens. / Butt littering is a problem in several ways. The filter of the cigarette butts have long degrada­tion time and contain cadmium, a heavy metal stored in organic tissues. With a large fraction of the total amount of litter the society can neither afford to ignore or collect every cigarette butt dropped in the environment. Chemically and esthetically as well as economi­cally butt littering is a past, a present and a future problem. Suggestions of solutions often in­volve re­strictions, increased investments in cleaning efforts or in accessibility. But a littered environ­ment doesn’t need more bins or stricter laws, it needs less littering. Cigarettes have filters that contain a plastic fiber called cellulose acetate. If they are enough compressed the deformation is plastic, a fact after empirical experiments. Definite permanent patterns in relief could be formed within the plastic fiber of the filters. This will be achieved through mobile ashtrays, called LitterPress. These stub out, compress and store cigarette butts along with transforming its filters to lottery tickets. In use, a press motion marks the filters with the social security number or the phone number of each user respectively. In other words, all cigarettes are potential lottery tickets which can be traced to its recycler. The proposition encourages the smokers to empty their mobile ashtrays into numbered sta­tionary ashtrays, called LitterBox. These will randomly di­vide the butts between two com­partments. One is large where the majority end up and one is small, enclosing significantly fewer. A computer program will weekly and randomly pick a number between 1 and the num­ber of stationary installed ashtrays. Those who have their marked cigarette butts in the smaller compartment, of the stationary ashtray of the week, will collect a noticeable economic payoff. There will be possible to allocate any payoff to a specific business. This is done by adjusting the mobile ashtray to mark the filters with an organization number. Irrespective of marking there can also be a continuously payoff to charity, where a fixed amount is allocated for each cigarette butt in the smaller compartment. In action the two physical products are components in the concept of LitterLott, a lottery out of litter. Participants have a chance to receive a part of the litter ex­penses and environmental impositions they spare the society. In an innovative and pedagogic way the awareness in­creases around recycling and what the costs are to refrain. A homepage will announce current LitterBox along with the fortunate recyclers. One may register membership, follow the development of LitterLott and participate in discussions re­lated to the subject. Also companies, municipal businesses and organizations can declare their interests in being a part of the concept and co­operate towards a healthier environment. The intention is to start a debate focusing on important environmentally related questions, litter­ing in general and recycling. Those questions are relevant in today’s society and neces­sary for tomorrows.
28

Numerical simulation of residual stresses in a weld seam : An application of the Finite Element Method

Maczugowski, Maciej January 2017 (has links)
Articulated haulers are fundamental equipment to transport material. The load carrying structure on a hauler consists mainly of welded frames. During welding of the frames high residual stress will be introduced. These stresses may have a significant impact on the fatigue life of the frames. This is the reason for having good knowledge of the weld residual stresses. The finite element method was used to calculate the residual stress distributions in a butt weld and a T-join weld. Simulation of the welding process with thermal and mechanical analysis was prepared by means of welding GUI implemented in LS-PrePost. The welding simulation is a computer intensive operation with high CPU time. That is why it is important to investigate which process factors that have the largest impact on welding simulation results. The aim of this thesis is to investigate the correlation between designed models in FEA software with published results of weld residual stress measurements and conclude which parameters should be mainly taken into consideration.
29

Analýza svarových spojů z termoplastů / Analysis of Thermoplastic Welded Joints

Procházka, Martin January 2018 (has links)
This thesis deals with analyses of thermoplastic welded joints. Experiments were performed, in which the not-welded specimens and specimens with cruciform welded joints were tested by tensile and three-point bending test. For these measurements, polypropylene and polyethylene specimens were used. Afterwards, the analyses of specimen models were made in the ANSYS programme. The results of the analyses were compared with figures of the analytic calculations and measurements.
30

Isotope

Ladrick, Alice 21 August 2012 (has links)
No description available.

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