Дисертації з теми "Defects in welding"
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Auger, Marc. "Detection of laser-welding defects using neural networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65599.pdf.
Повний текст джерелаHunt, Johnathon Bryce. "Defect Detection in Friction Stir Welding by Measureable Signals." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8676.
Повний текст джерелаDa, Costa S. C. "The prediction of risk of welding defects at the procedure stage using computer knowledge based systems." Thesis, Cranfield University, 1992. http://dspace.lib.cranfield.ac.uk/handle/1826/4446.
Повний текст джерелаDolejský, Tomáš. "Porovnání nákladů na svařování a Virtual Welding." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-231042.
Повний текст джерелаZareie, Rajani Hamid Reza. "Development of a three-dimensional multi-scale model to study the formation of solidification defects in fusion welding." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57601.
Повний текст джерелаApplied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
Li, Peigang. "Cold lap formation in Gas Metal Arc Welding of steel : An experimental study of micro-lack of fusion defects." Doctoral thesis, Högskolan Väst, Avd för maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5596.
Повний текст джерелаMaia, Ivan Gonçalves. "Efeito da camada de nitreto na porosidade em soldas de eixos automotivos." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263152.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Visando solucionar o problema da ocorrência de poros em um cordão de solda de um eixo automotivo, o presente trabalho apresenta um estudo da influência de diferentes fatores na ocorrência de porosidade em juntas de aço soldadas pelo processo MIG/MAG robotizado. Basicamente, foi estudada a influência de três fatores na ocorrência dos poros. São eles, a presença de uma camada rica em nitretos na extremidade de um dos tubos que compõe a junta, a limpeza das superfícies a serem soldadas e a vazão do gás de proteção. Após a soldagem dos corpos de prova foram retiradas de cada um deles, três amostras da seção transversal do cordão de solda. A porosidade foi quantificada pela técnica de análise metalográfica por microscopia ótica. Os resultados de porosidade foram apresentados de duas maneiras, uma sem qualquer tipo de restrição quanto aos poros encontrados, e outra em que houve distinção quanto à localização dos poros na seção transversal do cordão de solda. Quando a porosidade foi quantificada de maneira geral, sem qualquer tipo de distinção quanto à localização dos poros, dois fatores influenciaram a ocorrência de poros na junta soldada. São eles, a presença da camada rica em nitretos e a vazão do gás de proteção. No outro caso, levando em consideração a localização dos poros na seção transversal do cordão de solda, foi constatado que para o caso dos poros localizados na raiz da junta, a presença da camada rica em nitretos gerada pelo processo de corte a plasma na extremidade do tubo correspondente ao metal-base 1 afetou significativamente a porosidade resultante no cordão de solda. Além dos ensaios experimentais, ensaios práticos foram realizados no próprio chão de fabrica de produção dos eixos. A realização de ensaios práticos visou avaliar a solução proposta para eliminação da ocorrência de porosidade no cordão de solda dos eixos. Os resultados destes ensaios comprovaram que a substituição do gás utilizado para o corte a plasma na extremidade do tubo correspondente ao metal-base 1, de ar comprimido por oxigênio puro, inibiu a formação dos poros
Abstract: In order to solve the occurrence of pores in weld beads of an automotive axle, the present work studies the influence of three different factors on the occurrence of porosity in joints welded by robotized GMAW process. The factors analyzed were: the presence of a region enriched by nitrides on the surface of the tube related to the base metal 1, the surface cleanliness of the joint components, and the shielding gas flow. Three samples of the weld bead transversal section were retired in each specimen. The porosity was quantified by metalographic analysis technique using an optical microscope. The results were presented by two different ways. In one of this ways, pores were quantified without any kind of distinction. In the other way, pores were grouped in accordance of their location in the weld bead transversal section. The pores quantified without any kind of distinction were affected by the ¿presence of the coat¿ and by the shielding gas flow. The pores located near the joint root were affected only by the ¿presence of the coat¿. In addition to the experimental specimens, practical experiments were made in the axles line production. These practical experiments were developed to evaluate a proposed solution to prevent the occurrence of the pores on the weld bead of the axles. The results of these practical experiments proved that changing the compressed air used in the plasma cut of the extremities of the tube related to the base metal 1 by pure oxygen gas inhibited the pores formation
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
Yeh, Felipe Wu Tzong. "Avaliação de descontinuidades no reparo em placas de aço por "Friction Hydro Pillar Processing" (FHPP) via ultrassom e micrografia." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/75898.
Повний текст джерелаFriction welding processes have several advantages in the union of metallic materials. The friction processing of pins or Friction Hydro Pillar Processing (FHPP), is an example of friction welding technology that can be used in the repair of metallic structures in hostile environments. Depending on the welding parameters and materials used (consumable pins and base material), the FHPP welds can present defects like cracks in the bond surface and the presence of inclusions. Such inclusions and defects compromise the mechanical integrity of the weld and therefore a inspection using nondestructive evaluation is justified. Using ultrasonic testing, FHPP welds using ASTM A36 steel plates and ASTM A36 and SAE 8620 steel pins were surveyed, varying only the axial forces in the welding process: 200, 250, 300 and 350kN. It was possible to relate the ultrasound testing results with the location of defects and inclusions in the specimens and those signals were validated by the micrography of the joints studied.
CARVALHO, GILBERTO. "Determinacao de defeitos em profundidade (estereoradiografia)." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10938.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Brehovský, Patrik. "Svařování hlubokotažných ocelí s ochrannou vrstvou hybridní technologií Laser-TIG." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417119.
Повний текст джерелаRepper, Elias, and Amanda Carsbring. "Defect formation in laser welded steels after use of corrosion protection coating." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209805.
Повний текст джерелаDauskurdis, Kęstutis. "R65 tipo bėgio kontaktinio suvirinimo jungties tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140619_144302-31757.
Повний текст джерелаIn 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.
Barsoum, Zuheir. "Residual Stress Analysis and Fatigue Assessment of Welded Steel Structures." Doctoral thesis, Stockholm : Farkost och flyg, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4687.
Повний текст джерелаMěřičková, Petra. "Svařování rámu výtahové kabiny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231112.
Повний текст джерелаZíka, Luboš. "Lokalizace vad svarů jeřábů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230002.
Повний текст джерелаWilson, Raymond A. "Towards a zero defect welding system." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321249.
Повний текст джерелаSilva, Francisco EstÃnio da. "Reconhecimento de PadrÃes AtravÃs de AnÃlises EstatÃsticas e Fractais Aplicadas a Dados de Ensaios NÃo-Destrutivos." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7330.
Повний текст джерелаConselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
In this work a procedure is studied for pattern classification related to different types of data, namely: (1) signals obtained from ultrasonic testing ( pulse-echo technique) and magnetic signals obtained from BarkhÃusen noise in samples of ferritic-pearlitic carbon steel tubes which, due to temperature effects, have shown microstructural changes as consequence of the total or partial transformation of the pearlite into spherodite; (2) images built from TOFD ultrasonic testing and 8 bit digital radiographic images obtained from carbon steel 1020 sheets, with different welding defects. From the data obtained, images have been considered with the defects as lack of fusion, lack of penetration, porosity and images without defect. For this aim, non-conventional mathematical techniques have been used for the preprocessing of the data, namely, the statistical analyses, Hurst analysis (RSA) and detrended fluctuation analysis (DFA), and fractal analyses, box counting analysis (BCA) and minimal cover analysis (MCA). The curves obtained with the initial mathematical treatment, discrete functions of the temporal window width, have been handled with the supervised and non-supervised pattern recognition techniques known as principal component analysis and Karhunen-LoÃve (KL) transformation analysis respectively. With respect to the magnetic signals, the KL classifier has been shown to be very efficient when applied to DFA obtained from the magnetic flux, with a success rate around 94%. On the other hand, for the magnetic noise signals we have not obtained an acceptable success rate independently of the pre-processing used. However, when were considered the curves obtained by concatenating all curves of the pre-processing was obtained a consistent average success rate of 85%. As far as the rate of success of the PCA classifier is concerned, an excellent success of 96% has been reached for concatenated curves of selected data of magnetic noise only. As far as the analyses of the backscattered ultrasonic signals is concerned, it was not possible to classify the different stages of the microstructural degradation by using KL or PCA independently of the pre-processing used. As far as the analyses of the D-scan images are concerned, by applying PCA a rate of success of 81% has been obtained with MCA data, 73% has been obtained by concatenating all curves from the different fractal and statistical analyses and around 85% when concatenating the best individual results (DFA and MCA). On the other hand, considering the KL classifier, high success rates have been verified for the training stage, between 96% and 99%, and a maximum success rate (100%), when concatenating all analyses. With respect to the testing results, the best success rate which has been reached was approximately 77%, when concatenating all the curves obtained from the statistical and fractal pre-processing. For the digitalized radiographic images, relevant individual rates of success (between 70% and 90%) for the training set (consisting of all data) have been obtained for the classifier KL only, and a 100% success rate, when concatenating all the curves obtained from the pre-processing of the images.
Neste trabalho estudou-se uma metodologia de classificaÃÃo de padrÃes relacionados a dois tipos de dados: (1) sinais obtidos atravÃs dos ensaios ultrassÃnicos (tÃcnica pulso-eco) e sinais magnÃticos obtidos atravÃs de ruÃdo Barkhausen realizados em amostras de tubos de aÃo carbono ferrÃtico-perlÃtico que devido aos efeitos da temperatura de trabalho apresentaram mudanÃas microestruturais decorrentes da transformaÃÃo parcial ou total da perlita em esferoiditas; e (2) imagens construÃdas a partir de ensaios ultrassÃnicos (tÃcnica TOFD) e imagens radiogrÃficas digitais de chapas de aÃo carbono 1020 soldadas, obtidas com resoluÃÃo de 8bits, nas quais foram inseridos diversos tipos de defeitos de soldagem. Dos dados gerados, foram estudadas as imagens com os defeitos de falta de fusÃo (FF), falta de penetraÃÃo (FP), porosidade (PO) e uma classe designada como sem defeito (SD). Para tanto, utilizaram-se de tÃcnicas matemÃticas nÃo convencionais no prÃ-processamentos dos dados conhecidas como anÃlises estatÃsticas de Hurst (RSA) e flutuaÃÃo sem tendÃncia (DFA) e as anÃlises fractais de contagem de caixas (BCA) e de mÃnima cobertura (MCA). Em seguida as curvas obtidas desse tratamento matemÃtico inicial, funÃÃes discretas da largura da janela temporal, foram utilizadas na alimentaÃÃo das tÃcnicas de reconhecimento de padrÃes nÃo supervisionada e supervisionada conhecidas, respectivamente, como anÃlise de componentes principais (PCA) e anÃlise da transformaÃÃo de Karhunen-LoÃve (KL). Em relaÃÃo aos estudos dos sinais magnÃticos, o classificador KL mostrou-se eficiente quando aplicado Ãs DFA do fluxo magnÃtico, com uma taxa de sucesso em torno de 94%. JÃ para os sinais do ruÃdo magnÃtico nÃo se obteve uma taxa de sucesso aceitÃvel, independente do prÃ-processamento utilizado. Entretanto quando todas as curvas de todas as anÃlises, dos dois tipos de sinais magnÃticos (ruÃdo e fluxo), foram concatenadas, obteve-se uma taxa mÃdia de sucesso consistente de aproximadamente 85%. No tocante Ãs taxas de sucesso do classificador PCA, somente para o ruÃdo magnÃtico e considerando todas as curvas concatenadas para um grupo de dados selecionados, conseguiu-se uma taxa de sucesso de 96%. A respeito das anÃlises dos sinais ultrassÃnicos retroespalhados, tambÃm nÃo foi possÃvel classificar, nem com a KL e nem com a PCA, os diferentes estÃgios de degradaÃÃo microestrutural, independemente do prÃ-processamento utilizado. No tocante Ãs analises das imagens D-scan, obteve-se com a PCA, taxas de sucesso de 81% considerando apenas os dados das MCA, 73% quando as curvas de todas as anÃlises estatÃsticas e fractais foram concatenadas, e em torno de 85%, quando apenas as curvas das melhores anÃlises (DFA e MCA) foram concatenadas. JÃ considerando o classificador KL, verificaram-se taxas de sucesso na etapa de treinamento, entre 96% e 99%, e mÃxima taxa de sucesso (100%) no caso dos vetores de todas as anÃlises concatenados. Em relaÃÃo aos resultados dos testes, a melhor taxa de sucesso alcanÃada foi aproximadamente de 77% quando se concatenaram todas as curvas oriundas dos prÃ-processamentos estatÃsticos e fractais. Com respeito Ãs imagens radiogrÃficas digitalizadas somente com o classificador KL (na etapa de treinamento, com 100% dos vetores) obtiveram-se taxas de sucesso individuais entre 70 e 90% de acertos e 100% de sucesso na classificaÃÃo quando se concatenaram as curvas de todos os prÃ-processamentos das imagens.
Kocak, Okan Okay. "Defect Assessment Of Spot Welds By Ndi." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1027382/index.pdf.
Повний текст джерелаProcházka, Jan. "Vliv opravného zavařování za tepla na změnu struktury a tvrdost odlitků z litiny s lupínkovým grafitem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400486.
Повний текст джерелаDasari, Vinod Kumar. "Machine Learning to Detect Anomalies in the Welding Process to Support Additive Manufacturing." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176357.
Повний текст джерелаFelisberto, Marcelo Kleber. "Técnicas automáticas para detecção de cordões de solda e defeitos de soldagem em imagens radiográficas industriais." Universidade Tecnológica Federal do Paraná, 2007. http://repositorio.utfpr.edu.br/jspui/handle/1/95.
Повний текст джерелаThis work proposes a new method for the automatic detection of the weld seam in radiographic images of pipeline welded joints. The proposed methodology is based on the optimization of parameters that are used to control and modify the position, size and shape of an image window, in order to enclose the image region that best matches the radiographic representation of a reinforced weld seam. The search for the best matching is managed by a genetic algorithm and uses an image similarity concept that is commonly applied on template matching procedures. The proposed technique solved weld seam detection problems for which no other automatic detection method was successful. The test results achieved an accuracy between 93% and 100%, regarding different tests circumstances, for a total of 478 radiographic images. The images data set included radiograph samples that cover all the recommended radiographic exposure techniques that are recommended, in the ASME V code, for inspection of pipeline welded joints. Meanwhile, a known image segmentation technique was modified and applied to perform the automatic detection of welding defects. For that test series, radiographic patterns from the International Institute of Welding (IIW) were used, including samples of the most popular classes of welding defects. After the used segmentation technique has been properly modified, defect detection samples were achieved for all the tested defect classes. Such results contribute with advancements in the automatic analysis of industrial radiographs and, as a final goal, aim at aggregating quality and efficiency to the radiographic inspection of welded joints.
Schneider, Guilherme Alceu. "Segmentação e extração das características de defeitos em imagens radiográficas de juntas soldadas e tubulações." Centro Federal de Educação Tecnológica do Paraná, 2005. http://repositorio.utfpr.edu.br/jspui/handle/1/113.
Повний текст джерелаThe visual inspection of radiographic images of welds and pipelines is a very repetitive task, very hard for humans. However, using digital radiographic images, it is possible to develop computational tools to be applied in the inspection process and to decrease the risks of inconsistent evaluations. This work presents a methodology to be applied in the automatic segmentation of defects in welds and pipes radiographic images, as well as to extract characteristics for the defects recognition. The tests and results, using the proposed methodology, show that it is possible to automatically perform the defect segmentation and characteristic extraction. As a result, some defects, difficult to be visually detected, were automatically segmented by the proposed method. Using some adjusting parameters, also proposed in this work, it is possible to adjust the method performance, obtaining more flexibility in the method applications. Two groups of images, originating from different sources, were tested and the results were satisfactory, since the defects, in almost all images, were segmented by the proposed method. A connected region labeling algorithm was used in order to make possible the automatic characteristics extraction for each detected defect. Besides, the proposed methodology shows to be robust also in some situations where other undesirable objects are presented in the image.
Marconato, Eduardo Amado. "Influência de defeitos nas propriedades mecânicas de juntas soldadas por FSW da liga AA6013-T6." Universidade Federal de São Carlos, 2009. https://repositorio.ufscar.br/handle/ufscar/852.
Повний текст джерелаFinanciadora de Estudos e Projetos
In 1991, it was developed a solid state welding process called Friction Stir Welding - FSW, intended to increase the number of applications for the aluminum and its alloys. As every welding process the presence of defects should be avoided to not compromise the quality of the welded joint. Some typical defects originating from FSW process are found in some joints depending of the welding parameters. Thus, this study has the purpose to evaluate the quality of welded joints in 3 mm thick 6013-T6 friction stir welded joints in function of the obtained defects, using different welding parameters. The characterization was based on metallography by OM and SEM of the welded joints in order to analyze the obtained defects. The mechanical properties were evaluated by tensile, microhardness and fatigue tests.Welds joints were intentionally produced to contain inner defects in the weld nugget like tunnel shaped along the joint and lack of root penetration of the welding tool. All welded conditions, the microhardness profiles show a big drop in hardness when crossing from the HAZ zone into the center of each weld, while the tensile and fatigue tests showed a strong defects influence in the mechanical properties. The lack of penetration weld defect had the worst results of mechanical properties compared to tunneling defects, and the sound weld joint exhibited the best results of mechanical properties for all conditions investigated.
Visando ampliar o número de aplicações para o alumínio e suas ligas, foi desenvolvido em 1991, um processo de soldagem no estado sólido denominado Friction Stir Welding. Como em todo processo de soldagem a presença de defeitos deve ser evitada, pois compromete a qualidade da junta soldada. Alguns defeitos típicos oriundos do processo FSW são encontrados em algumas juntas dependendo dos parâmetros de soldagem escolhidos. Assim sendo, este trabalho teve como principal objetivo estudar a influência de defeitos nas propriedades mecânicas de juntas soldadas pelo processo Friction Stir Welding da liga de alumínio 6013-T6, correlacionando as variações microestruturais obtidas com os diferentes parâmetros de soldagem adotados. Para tanto foram utilizados diferentes parâmetros de soldagem para a obtenção de juntas soldadas que apresentem defeitos distintos. A caracterização metalográfica se baseou em macrografias e micrografias via M.O. e MEV das juntas soldadas, de forma a analisar os defeitos obtidos. As propriedades mecânicas foram avaliadas por ensaios de tração, microdureza e fadiga. Foram obtidas soldas com defeitos internos a lente de soldagem em forma de vazios ao longo do cordão e soldas com falta de penetração na região da raiz. Em todas as condições foi observada uma redução brusca nos valores de microdureza na região da junta soldada, enquanto os ensaios de tração e fadiga revelaram forte influência da presença de defeitos na junta. A solda que apresentava como defeito a falta de penetração na raiz apresentou resultados de propriedades mecânicas muito inferiores às condições que apresentaram vazios internos a lente de soldagem. A solda que não continha defeitos apresentou os melhores resultados de propriedades mecânicas em relação a todas as condições investigadas.
Rašek, Ondřej. "Svařování rámu z hliníkových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231110.
Повний текст джерелаBoaretto, Neury. "Classificação de defeitos de soldagem em imagens radiográficas PDVD de tubulações de petróleo: uma abordagem com ensemble de Extreme Learning Machines." Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/2890.
Повний текст джерелаThe inspection of radiographic images of welded joints is very subjective and is subject to errors of interpretation by the inspector. In this context, a great effort has been made in the last years to develop automatic and semiautomatic methods for detecting defects in welded joints. This research work presents an automated method for the detection and classification of defects in radiographic images of welded joints of pipes obtained by the double wall double image (DWDI) exposure technique obtained in real field situations and which generally have a lower quality than the images used in other studies. The proposed methos identifies the region of the weld bead, detects the discontinuities and classifies them as defects and non-defects, highlighting in the image the result. Classifiers are evalueted using methods of classification by multilayer perceptron (MLP) neural networks, extreme learning machines (ELM) neural networks, and Support Vector Machines (SVM). The proposed method for identifying the region of interest reached 100% precision in the segmentation od the weld bead. The SVM classifier performed better than the MLP and ELM classifiers in all scenarios tested. Using ELM ensembles, an F_score of 85,7% was obtained for a test patterns database, satisfactoryresults when compared to similar works. The use of ensembles of ELMs represents a gain of only 0,5% in the F-score compared to the best result of the individually trained network, however, with the use of ensemble decision threshold ranges, the presented method allows to show the discontinuities about which the ensemble is not sure, highlighting in the image these discontinuities as a region of uncertainty, leaving to the specialist the final evaluation of these discontinuities. The image resulting from the application of the method serves as an aid to the expert in the elaboration of reports.
Henon-Vernet, Christine. "Contribution à l'étude métallurgique d'une liaison bimétallique soudée 16MND5/309/308." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0021.
Повний текст джерелаCao, Xiaochao. "WELD READ-THROUGH DEFECTS IN LASER TRANSMISSION WELDING." Thesis, 2010. http://hdl.handle.net/1974/5916.
Повний текст джерелаThesis (Master, Chemical Engineering) -- Queen's University, 2010-07-02 14:34:41.201
Lin, Hwang-Fuu, and 林皇甫. "Study of Inspection of Welding Steel Plate Defects Using Ultrasonic Testing." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/09269188065553987947.
Повний текст джерела國立海洋大學
河海工程學系
83
Welding is the most important problem in the steel structures. It is always of defect no matter how to use artificial or automatic welding steel structures.The motivation of this investigation is to evaluate the integrity and safety of welding steel plate by using the fast,portable and reliable nondestructive testing.The main purpose of this study is to detect the defect of welding steel plate by using ultrasonic testing.The method of experiment use SM41A steel,welding producer is GMAW(Gas Metal Arc Welding) and SMAW(Shielded Metal Arc Welding),specimen size is 30cm×20cm×15mm,welding condition are perfect、 porosity、incomplete penetration、 incomplete fusion、crater crack and slag inclusion,using portable ultrasonic flaw detector associated with singnal analysis and display(ver.4.0) of programme to detect the welding integrity and comparing to the results obtained from X- ray photograph.The results of this investigation show that A- scan is not accurate and time consuming.The B-scan is more reliable.The C-scan is very accurate in 70o transducer.The point of wave incident and direction is very important relatively to detecting the welding defect.In this investigation ,the result of ultrasonic detecting the welding defect is very wonderful except crater crack.Thus ,it is a powerful and useful tool to detect the welding steel plate by means of ultrasonic technique.
Liu, Terence, and 劉立仁. "Study of Control of Welding Defects by Using Externally-Applied Compressive Mechanism." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/65558431660740804284.
Повний текст джерела長庚大學
機械工程研究所
92
Arc welding has been proven to be a very economical and efficient manufacturing technology, and is widely used in various industries. However, there might still be some unexpected welding defects occurring during welding. In addition to human errors, the most noticeable defects are weld cracking, which are primarily caused by both microstructural changes and thermal stresses during welding. The formation of thermal stresses is due to the abrupt heating and cooling, and the non-uniform cooling of the weldments. The thermal stresses can be roughly divided into the thermal stress during cooling and the residual stress after the weldment being completely cooled. Weld cracking is directly related to these stresses, which are tensile in nature. It is probable to lower the cracking susceptibility such as fusion zone solidification cracking and heat-affected zone liquation cracking by reducing the thermal stresses during cooling. Moreover, the residual stress of the weldments may also be lowered and consequently result in better fatigue strength and resistance to stress corrosion cracking. The major goal of this study is to design an externally-applied compressive mechanism, which is based on the concept of shot peening, to produce a series of impacts or presses at various locations of the weld metal or HAZ. The impacts should be able to produce minor plastic deformation and also lower the tensile thermal stresses, which may even become compressive momentarily. Consequently, most tensile stress-related weld cracking may be prevented. In order to perform a systematic optimization study of each experimental variable, the following procedures will be conducted including FEM simulation. In addition, measurements of welding thermal cycles and residual stresses will be conducted. The welding defects to be evaluated in this study include HAZ liquation cracking, repair welding defects in extensively radiated materials, and ductility dip cracking.
Antunes, João Dias. "FSW de Materiais Poliméricos." Master's thesis, 2021. http://hdl.handle.net/10316/96070.
Повний текст джерелаO objetivo desta dissertação é estudar a influência dos parâmetros de Friction Stir Welding (FSW) na qualidade de soldaduras de topo em placas de Polietileno (PE) e Acrilonitrila Butadieno Estireno (ABS) com 6 mm de espessura. As soldaduras foram realizadas com uma ferramenta de base estacionária e pino cónico, sem aquecimento externo. Os parâmetros estudados foram a velocidade de rotação da ferramenta, com valores de 870, 1140 e 1500rpm, e a velocidade de soldadura, com 60 e 120mm/mim. Durante a soldadura foram registados os ciclos térmicos na vizinhança da soldadura. Depois de ser feita a inspeção visual, as soldaduras foram submetidas a microscopia ótica e a análise tomográfica, para caraterizar a morfologia das soldaduras, e a ensaios de microdureza, e a testes de tração, para caraterizar as propriedades mecânicas das soldaduras. Verificou-se que a morfologia das soldaduras, e em particular, a presença de defeitos, é muito influenciada pelo calor adicionado no processo. O aumento do rácio entre a velocidade de rotação e avanço da ferramenta (w/v) aumenta a temperatura na soldadura, principalmente nas soldaduras em ABS. O aumento de temperatura local facilita o fluxo de material e reduz a formação defeitos. O aumento do rácio w/v não alterou sensivelmente a dureza das soldaduras, mas aumentou a eficiência de soldadura. A resistência das soldaduras foi sempre inferior aos respetivos materiais de base, mas as soldaduras em PE apresentaram eficiência superior às realizadas em ABS. A eficiência de soldadura é muito condicionada pela presença de defeitos.
The aim of this dissertation is to study the influence of Friction stir Welding ( FSW ) parameters on the quality of butt welds in 6 mm thick Polyethylene ( PE ) and Acrylonitrile butadiene styrene ( ABS ) plates. The welds were carried out using a tool with a stationary shoulder and conical pin, without external heating. The parameters studied were the tool rotation speed, with values of 870, 1140 and 1500 rpm, and the welding speed, with 60 and 120 mm/min. During welding, thermal cycles in the vicinity of the weld were recorded. After visual inspection, the welds were submitted to optical microscopy and tomographic analysis, to characterize the morphology of the welds, and microhardness tests and tensile tests, to characterize the mechanical properties of the welds. It was found that the morphology of the welds, and in particular the presence of defects, is greatly influenced by the heat input in the process. Increasing the ratio between rotation speed and tool feed ( w/v ) increases the temperature in the weld, especially in ABS welds. On-site temperature rise facilitates material flow and reduces the formation of defects. Increasing the w/v ratio did not noticeably change the hardness of the welds, but it did increase the welding efficiency. The strength of the welds was always lower than the respective base materials, but the PE welds showed greater efficiency than those made in ABS. Welding efficiency is greatly affected by the presence of defects.
Shan, Yi-Pan, and 單亦磐. "The Influence of Welding Defects on the Mechanical Behavior of Ti-6Al-4V Laser Weld." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/11774504078726722252.
Повний текст джерела國立臺灣海洋大學
材料工程研究所
92
The influence of weld defects on the undercut properties of Ti-6-4 laser welds was investigation in this work. Experimental results indicated the presence of undercut on the weld surfaces inevitably played an important role on the reduced weld’s ductility, regardless of post-weld treatment. For the weld consisting of a large amount of porosity during tensile straining may lead to a great decrease in ductility. Moreover, the existence of porosity in the weld metal will deteriorate the impact toughness of the weld significantly. The result of fatigue crack growth tests revealed environments have a great influence on the fatigue crack growth rate (FCGR) of Ti-6-4 alloy. As a whole, the FCGR was lower for the specimens tested in vacuum and gaseous hydrogen than the counterpart tested in laboratory air. In general, the defect-free laser weld showed a higher resistance fatigue crack growth than the base plate, owing to the combined microstructural and residual stress effects. The presence of porosity in the weld metal did not accelerate the fatigue crack growth . Although the erratic change of FCGR as the crack tip met the porosity occurred, the blunting of crack tip should be the main causes for the weld with relatively high resistance to crack growth as compared with the defect-free weld.
Carvalho, Diogo Albano Cavaleiro Ventura de. "Comportamento mecânico de juntas T soldadas por fricção linear na liga AA6082." Master's thesis, 2015. http://hdl.handle.net/10316/38975.
Повний текст джерелаA soldadura por fricção linear (FSW), surge atualmente como um processo de ligação, de grande interesse na produção de juntas T. Estas soldaduras apresentam, frequentemente, defeitos como cavidades e linhas de óxidos, além da redução da espessura na pele da junta T. Neste trabalho estudou-se a solução para o problema de redução de espessura, a otimização da geometria de ferramenta e de parâmetros de soldadura para a obtenção de soldaduras sem defeitos e a possível melhoria do comportamento mecânico de juntas T na liga de alumínio 6082-T6. Para o efeito foram realizadas análises morfológicas, ensaios de dureza, tração e fadiga seguida de análise fratográfica, para soldaduras nos dois tipos de configuração de junta, T-Butt e T-Lap. Concluiu-se que, com a ferramenta progressiva usada na configuração T-Butt é possível eliminar a linha de óxidos e que a configuração T-Lap elimina totalmente a redução de espessura da pele.
Nowadays, friction stir welding (FSW) appears as a joining process of increasing interest in the production of T joints. This type of welds frequently present defects such as cavities or oxides lines, besides the thickness reduction in the skin of the T joint. This paper work will try to present a possible solution to the thickness reduction problem, an optimization of welding parameters to obtain defect free welds and a possible improvement in mechanical behavior of this type of joint in the 6082-T6 aluminum alloy. In order to do that, several analysis and tests will be conducted, ranging from morphologic analysis to hardness, stress and fatigue tests followed by fracture analysis, in two types of joint configurations, T-Butt and T-Lap. It was concluded that the removal of the oxide lines are possible using the progressive tool design and also that the joint configuration, T-Lap, was able to completely eliminate the thickness reduction problem.
Dunstone, Alexander. "Numerical modelling of pipeline construction / Alexander Dunstone." 2004. http://hdl.handle.net/2440/22098.
Повний текст джерелаBibliography: leaves 231-249.
xxvii, 261 leaves : ill. (some col.), plates, photos (col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Examines ways of reducing the risk of hydrogen assisted cold cracking in pipeline construction by modifying the construction procedure to reduce residual stress and hydrogen concentration. A numerical model of the pipeline construction procedure capable of modelling the process in a transient sense was created. Experimental validation of the model involved using the "blind hole drilling" strain gauge method of residual stress measurement. The diffusion of hydrogen during welding was modelled using a scheme based on Fick's Second Law of Diffusion, finding that the parameters which dominate the rate of diffusion are the timing of the weldment process, joint geometry, pre-heating and post-heating.
Thesis (Ph.D.)--University of Adelaide, School of Mechanical Engineering, 2004
Dunstone, Alexander. "Numerical modelling of pipeline construction / Alexander Dunstone." Thesis, 2004. http://hdl.handle.net/2440/22098.
Повний текст джерелаBibliography: leaves 231-249.
xxvii, 261 leaves : ill. (some col.), plates, photos (col.) ; 30 cm.
Examines ways of reducing the risk of hydrogen assisted cold cracking in pipeline construction by modifying the construction procedure to reduce residual stress and hydrogen concentration. A numerical model of the pipeline construction procedure capable of modelling the process in a transient sense was created. Experimental validation of the model involved using the "blind hole drilling" strain gauge method of residual stress measurement. The diffusion of hydrogen during welding was modelled using a scheme based on Fick's Second Law of Diffusion, finding that the parameters which dominate the rate of diffusion are the timing of the weldment process, joint geometry, pre-heating and post-heating.
Thesis (Ph.D.)--University of Adelaide, School of Mechanical Engineering, 2004
Melo, Joao Carlos Simões. "Comportamento à fadiga de ligações T em ligas de alumínio dissimilares, soldadas por laser." Master's thesis, 2017. http://hdl.handle.net/10316/83422.
Повний текст джерелаEste trabalho foi feito com o objetivo de estudar a influência dos parâmetros de soldadura na morfologia e no comportamento à fadiga de juntas T de ligas de alumínio dissimilares soldadas a laser, com o fim da sua aplicação na indústria aeronáutica.Utilizando a soldadura laser, foram fabricadas juntas T em chapas com 2 mm de espessura das ligas AA2024-T4 (Skin) e AA7075-T6 (Stringer) e elétrodo da liga AA4047 como material de adição. Foi feita a variação de parâmetros de soldadura como o diâmetro de spot, o ângulo e posição de incidência do feixe laser e velocidade de soldadura. As soldaduras foram feitas sequencialmente de um e outro lado do Stringer. Foi então analisada a influência dos vários parâmetros de soldadura na geometria de cordões de soldadura, na sua microestrutura e resistência mecânica, recorrendo à microscopia ótica e eletrónica (SEM), à medição de microdurezas, à radiografia, aos ensaios de tração e fadiga e, por fim, à análise de elementos finitos. Observou-se que estes parâmetros influenciaram a penetração e distância entre os pés dos dois cordões e na formação de poros no interior da zona fundida. Conseguiu-se ainda evitar a fissuração a quente. Nos ensaios de arrancamento e tração do Skin, a penetração e a distância entre os pés dos cordões não tiveram grande influência na resistência mecânica. Nos ensaios de fadiga estudou-se a influência da amplitude de tensão nominal na vida total dos provetes tendo-se por fim comparado as curvas S-N das várias séries entre si. Utilizando a análise de elementos finitos construíram-se as curvas S-N para as tensões locais das várias séries de soldadura tendo-se comparado as várias curvas entre si e com as curvas S-N para a tensão nominal, concluindo-se por fim que o parâmetro com maior influência no comportamento à fadiga foi a presença de defeitos.
This paper was made to evaluate the influence of welding parameters on the morphology and fatigue behaviour of laser welded dissimilar aluminium alloys T joints for aeronautical industry application.T joints of 2mm thick sheets were produced with AA2024-T4 as skin, AA7075-T6 as Stringer and AA4047 as filler metal. The variation of welding parameters such as the spot diameter, the angle and position of incidence of the laser beam and the welding speed was made. The influence of the various welding parameters on the weld bead geometry on its microstructure and mechanical strength using optical and electronic microscopy (SEM), micro hardness measurement, radiography, tensile and fatigue tests and, finally, analysis of finite elements was studied.It was observed that these parameters influenced the penetration and distance between the two weld bead toes and the formation of pores within the molten zone. It was still possible to avoid hot cracking. In the T-pull and skin traction tests, the penetration and distance between the welding bead toes did not have great influence on mechanical resistance. In the fatigue tests the influence of the nominal stress amplitude on the total life of the test specimens was studied, comparing the S-N curves of the various welding series with each other. Using the finite element analysis, the SN curves for the local stress of the various welding series were constructed by comparing the various curves with each other and with the curves SN for the nominal stress, finally concluding that the parameter with greater influence on fatigue behaviour was the presence of defects.
Chien, Kun-Chieh, and 簡昆傑. "Applications of Acoustic Emission and Sound Signal for Welding Defect Monitoring in Nd:YAG Laser Thin Plate Butt Welding." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91274181705613641718.
Повний текст джерела國立中興大學
機械工程學系所
101
In recent years, laser welding has been increasingly used in different industrial applications because of its deep penetration, high depth to width ratio, high speed and high precision with low heat effects. However, due to some defects might occurs during processes such as the partial penetration and cavity generation to lower down the strength of the welded parts and deteriorate the surface quality, the real-time quality monitoring for laser welding plays an important role to improve the production rate and to decrease cost. This thesis is to develop a laser welding monitoring system which using acoustic emission and sound signal for detecting the welding quality. 0.2mm thin plate stainless steel welded in type of butt joint and conduction mode will be implemented on a Nd-YAG laser welding system integrated with two acoustic emission (AE) sensors and two free-field condenser microphones. Acoustic emission sensors were placed on two different locations, one on the stainless steel workpiece and the other one on the aluminum fixture for holding the workpiece. Two different microphones were installed in the system, including the one with a frequency response between 3.15Hz and 20kHz and high sensitivity, and the other one with a frequency response between 4Hz and 80kHz and low sensitivity. Five experimental setups were conducted to create various qualities including the ideal welding and the welding with partial penetration, cavity generation, standard trapezoid weld pool and non-standard trapezoid weld pool. The class-mean-scatter criteria were used to select the proper features correlated to the welding quality and the Fisher linear discriminant function was developed to classify the defect or quality. The results show that higher than 77% of classification rate for the detect detection can be obtained for AE sensors by developing the system independently for each defect monitoring, and higher than 95% of classification rate for the detect detection can be obtained for Microphone for each defect monitoring. By considering the sensor location effect on the system performance, the AE signal on workpiece shows the better ability to detect the welding with partial penetration and non-standard trapezoid weld pool than the AE signal on fixture. However, the counterpart demonstrates the higher capability in detecting the welding qualities with cavity generation and standard trapezoid weld pool. By considering the sound signal for welding quality monitoring, the 20k microphone shows a better ability to detect the welding with partial penetration and standard trapezoid weld pool. On the other hand, the 80k microphone demonstrates the higher capability in detecting the welding with cavity generation. By the way, both of them show the same ability to detect the non standard trapezoid weld pool. To improve the reliability of the developed system, a decision fusion algorithm based on the results obtained from all four sensors was implemented and the results shows that 100% for all defect detection excepting for the welding with cavity generation (92.5%) can be obtained. Finally, a multiple defect classification algorithms were proposed and the result shows that the mixed signals corresponding to the ideal welding and all defects can be mapped successfully to the ideal welding, the welding with cavity generation, and the welding with two types of trapezoid weld pool. 90% classification can also be obtained for the welding with partial penetration.
SHUN, WANG HSIANG, and 王湘順. "A Case Study for Defect Prevention Management of Submerged Arc Welding of Pipeline." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/17475641847320291756.
Повний текст джерела義守大學
工業工程與管理學系
92
ABSTRACT From the years supervision experience on the pipeline Submerged Arc Welding (SAW), the author found that even utilized the similar welding equipment it doesn’t mean a same high quality SAW product level could be achieved. The reasons can be due to the technique issues and engineering management issues. Traditional pipeline SAW processes, the engineering management applied is loose, hence, the variation in quality is significantly. There have no means to raising the yield rate and then to decreasing the welding cost systematically. Upon this observation, a prevention management model for pipeline SAW welding was proposed on this study to improve the quality of SAW. The methodology of Analytic Hierarchic Process (AHP) was used to analyze the four management factors of welding operations of the case study company. Through the calculation of the weighting for management factors, the ranking of management performance can exposure the poorest management section of the target case company. This weighting will be also a cross reference for defect analysis of SAW product later. On the other hand, through the literature review and the experiences in SAW operation supervision, the key factors and event frequency of major defects of SAW welding were summarized. Consequently, two key concepts that (1) Reasonableness of the management process to prevent the occurrence of defect and, (2) Tracing the reasons of defects quickly and applying the solutions immediately are implemented to develop a defect prevention management model with the weighting of engineering management performance. The study indicated that the smallest weighting in AHP analysis could exposure the poorest management section. The superviser should request the company to correct the faults and improve the performance immediately. Otherwise, once the welding defect occurs, the causes due to this management section will take high probability.Consequently the engineer can trace the caures easily and provide the solut quickly. The case study shows well consistency with this finding. At similar situation, the occurrence frequency of defect type that summarized via the literature review and supervision experiences is also consistency with the case well. It is conclused that introduces a well construction defect prevention management model to undertake welding process management can lower the total welding defect counts, therefore, the management performance is remarkable. However, the ratio of the defect types are still kept the same trend as the very beginning, the defect type ratio cannot be changed significantly due to the defect type is determined by the technique characteristics that adopted.
Tseng, Kuo-Hsing, and 曾國興. "Analyses of defect patterns of butt welding using multi-angle detector ultrasonic tests." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/48314846517846273483.
Повний текст джерела國立屏東科技大學
機械工程系所
100
Ultrasonic testing (UT) is one of the main approaches for inspecting weld quality, and has advantages such as simple equipment, fast inspections, and easy operation. But in the applications of inspection, the inspectors usually cannot judge the type of defects by the defect echo waves. Different defect shapes inside the welds may generate noise waves and cause direct influences on the judgment of the ultrasonic inspectors or even mislead them. This research explores the currently most popular ultrasonic testing techniques applied in welds according to the sound wave principle and characteristics of ultrasound. The main purpose is to inspect the integrity and safety inside the welds with the most fast, convenient and reliable approach without destroying the welds. The research method uses the SN490-B plate to weld the 25 mm and 60 mm butt test pieces by flue cored arc welding and considers the classical and actual defects of welds including cluster porosity, defective fusion, incomplete penetration, slag inclusion and cracks. Moreover, the ultrasonic testing is applied with different angles of probe scanning to judge the type of defects by echo wave characteristics, wave shape analysis and rich experiences, and then the results are verified with X-ray testing and Chipping. The results of this research show that probes with small angels are suitable for thick steel plates, high-frequency probes with centralized sound beam are with high attenuation, and the incident angles of sound waves are closely related to the shapes, sizes and directions of defects. As a result, using the ultrasound to test the welds can effectively improve the inspection ability of engineering inspectors and ensure the welding quality of buildings, factories, roads and bridges.
Malik, Vinayak. "Studies on the Effect of Process Aspects on Material Mixing and Defect Formation in Friction Stir Welding." Thesis, 2017. http://etd.iisc.ernet.in/2005/3646.
Повний текст джерелаSheng, Chen Jyh, and 陳志聖. "Application of Digital Signal Processing and Artificial Neutral Network to Defect Recognition in Acoustic Emission Testing during Laser Welding Process." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/72797464992602429095.
Повний текст джерела