Дисертації з теми "Multiaxial fatigue of rubber"
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Hallett, Joseph F. "Multiaxial strength and fatigue of rubber compounds." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/6759.
Повний текст джерелаWarneboldt, Iona. "Multiaxial fatigue design of elastomeric parts using Equivalent Fatigue Loads." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0002.
Повний текст джерелаThis thesis introduces an Equivalent Fatigue Load (EFL) approach for the multiaxial fatigue design of elastomeric parts. As direct Finite Element Analysis (FEA) calculations of automotive in-service loads (Road Load Data (RLD)) are too expensive, the objective is to derive simplified load blocks as a realistic input for numerical damage calculations. Three streps are applied for this method: the localization method, the material damage function and the EFL determination process. Various fatigue tests have been conducted (415 samples) to study the fatigue behavior of this complex type of relaxing and non-relaxing multiaxial loading on natural rubber specimens. Lifetime and crack features are analyzed to eventually introduce an appropriate critical planebased fatigue measure and to establish a novel mean strain effect model. This criterion is generalized throughout an original critical plane search method. To estimate the local mechanical response (localization method), this thesis identifies an axes-coupling method that is fitted for the nonlinear nature of elastomeric structures. It is based on the multiplicative decomposition of the deformation gradient tensors. These two steps are then implemented in the framework of the EFLdetermination process. For this, a global optimization method is added to determine the simplified load blocks, causing locally the same fatigue behavior in the given structure. The computational costs of this optimization are reduced by only considering a subset of the most damaged material points for EFLdetermination. Finally, the method has been challenged on a specimen to outline its capabilities and to validate the approach
Saintier, Nicolas. "Fatigue multiaxiale dans un élastomère de type NR : mécanismes d'endommagement et critère local d'amorçage de fissure." Phd thesis, Paris, ENMP, 2001. https://pastel.archives-ouvertes.fr/tel-00397910.
Повний текст джерелаLiu, Mu-Hsin. "Multiaxial Fatigue Testing Machine." Ohio University / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1266241731.
Повний текст джерелаSwalla, Dana Ray. "Fretting fatigue damage prediction using multiaxial fatigue criteria." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17033.
Повний текст джерелаFEIFERIS, ANDRE DOS REIS. "STRUCTURAL EVALUATION OF CRANKSHAFT UNDER MULTIAXIAL FATIGUE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35967@1.
Повний текст джерелаCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTITUIÇÕES COMUNITÁRIAS DE ENSINO PARTICULARES
Eixos de virabrequim estão sujeitos a carregamentos multiaxiais quando em serviço. Por se tratar de um estado complexo de tensões, os modelos aplicados na determinação da vida em fadiga de tais componentes devem permitir, também, uma abordagem multiaxial, mais avançados do que aqueles adotados para carregamentos uniaxiais. O objetivo deste trabalho foi prever a falha em serviço de eixos virabrequins de unidades geradoras Diesel ou gás de plantas termoelétricas. Falhas recentemente ocorridas em eixos virabrequins no parque termoelétrico nacional justificam o presente estudo, para garantir eficiência e segurança nas operações industriais. Com base no método de elementos finitos, foram calculadas as tensões atuantes em um eixo virabrequim de unidade geradora a gás, com 10 mancais, duas bielas por mancal e fabricado com aço estrutural DIN 34CrNiMo6. Em sequência, adotando-se estas tensões atuantes calculadas, foram aplicados diversos critérios de fadiga para prever sua falha. Para tal, adotaram-se os modelos de Papadopoulos, Findley, Matake, McDiarmid, Carpinteri e Spagnoli, Liu e Mahadevan, Mises, Sines e Crossland, todos de fadiga de alto ciclo, baseados no plano crítico ou na tensão de von Mises. Propriedades de resistência à fadiga do material foram retiradas da literatura. Os resultados obtidos indicaram que o componente é seguro quando avaliado usando tais critérios.
Crankshaft axles are subject to multiaxial loading when in service. Because the resulting state of stresses is complex, models applied to determining the fatigue life of such components employ a multiaxial approach as well, more advanced than those adopted for uniaxial loads. The objective of this work is to predict the failure in service of crankshafts of diesel or gas generating units of thermoelectric plants. Crankshafts reported recent failures in the national thermoelectric power plant justifies the present study, to guarantee efficiency and safety in such industrial operations. Based on the finite element method, the resulting stresses on a DIN 34CrNiMo6 structural steel gas generating unit crankshaft, with 10 bearings, two connecting rods per bearing were calculated. Using these finite element calculated stresses, several fatigue criteria were applied to predict this cranckshaft structural failure. Models due to Papadopoulos, Findley, Matake, McDiarmid, Carpinteri and Spagnoli, Liu and Mahadevan, Mises, Sines and Crossland, all of high cycle fatigue based on the critical plane or von Mises strain, were adopted. Material fatigue properties used in the analyses were compiled from specidized literature. Obtained results indicated that the component considered is safe regarding fatigue loadings, as evaluated using such criteria.
Bold, P. E. "Multiaxial fatigue crack growth in rail steel." Thesis, University of Sheffield, 1990. http://etheses.whiterose.ac.uk/14807/.
Повний текст джерелаKawamoto, Jiro. "Fatigue of rubber composites." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14566.
Повний текст джерелаJuneja, Lokesh Kumar. "Multiaxial fatigue damage model for random amplitude loading histories." Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/41522.
Повний текст джерелаThe minimum of the two life values obtained from SWT model and the shear
strain model is compared with the life estimated by the proposed model with the
modified Morrow's mean stress model. The former is essentially the life predicted by
Socie. The results of the proposed model, as reduced to the uniaxial case, are also
compared with the experimental data obtained by conducting one-channel random
amplitude loading history experiments.
Master of Science
Sharifimehr, Shahriar. "Multiaxial Fatigue Analysis under Complex Non-proportional Loading Conditions." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544787705876488.
Повний текст джерелаCarraro, Paolo Andrea. "Multiaxial fatigue behaviour of composite materials: characterisation and modelling." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423782.
Повний текст джерелаGrazie alla loro leggerezza e versatilità combinate ad eccellenti proprietà meccaniche, i materiali compositi hanno acquisito un'importanza sempre maggiore negli ultimi vent'anni in molti settori industriali, anche per applicazioni strutturali. A fronte dei numerosi vantaggi offerti da questa classe di materiali vi è un costo che rimane ancora piuttosto elevato rispetto ai più tradizionali materiali da costruzione. Una delle ragioni è la mancanza di procedure di progettazione affidabili e riconosciute, nonché l'assenza, in letteratura, di estese caratterizzazioni sperimentali da cui acquisire informazioni di carattere generale. Ciò è particolarmente evidente in riferimento al comportamento a fatica multiassiale di lamine, laminati e giunzioni incollate in composito. Al fine di sopperire alla mancanza di informazioni sul comportamento a fatica multiassiale di lamine unidirezionali, nonché all'assenza di una procedura adeguata di test, è stata inizialmente definita una configurazione di provini adatta a caratterizzare la risposta matrix-dominated (particolarmente significativa per il danneggiamento a fatica di laminati) di materiali compositi unidirezionali (capitolo 2). Provini tubolari soggetti a carichi ciclici di trazione e torsione combinati sono stati identificati come il miglior compromesso tra affidabilità dei risultati, semplicità di testing e possibilità di ottenere condizioni multiassiali di interesse. Nel terzo capitolo sono riportati i risultati di un'estesa campagna sperimentale su tali provini tubolari in presenza di diversi rapporti di biassialità (tensione di taglio su tensione trasversale) e rapporti di ciclo (rapporto tra il minimo e il massimo carico di fatica). É stata riscontrata una notevole influenza di tali parametri sull'innesco e propagazione di cricche off-axis, nonché sui meccanismi di danneggiamento su scala microscopica. Sono poi stati testati a fatica uni-assiale dei laminai piani multi-direzionali progettati per avere condizioni di multiassialità locali simili a quelle ottenute sui provini tubolari tramite carichi esterni in diverse direzioni. L'attività, presentata al quarto capitolo, ha permesso di verificare l'equivalenza tra condizioni multiassiali ti tipo esterno (carichi in più direzioni) e interno (dovute all'anisotropia di lamine e laminati in composito). Ciò rappresenta uno step fondamentale per l'estensione di risultati sperimentali e modelli previsionali a condizioni di carico generiche. L'attività sperimentale sviluppata sui tubi ha fornito informazioni sui meccanismi di danneggiamento a livello microscopico che sono responsabili del cedimento a fatica della lamina unidirezionale. Sulla base di tali meccanismi è stato proposto un criterio per l'innesco di cricche a fatica multiassiale in lamine in composito basato su un approccio multiscala (capitolo 5). Il criterio è risultato in ottimo accordo con i nuovi dati sperimentali sui campioni tubolari, con dati disponibili in letteratura riguardanti lamine unidirezionali piane e con i dati ad innesco sugli strati off-axis dei laminati testati al capitolo 4. Parlando quindi di laminati multi-direzionali, un aspetto fondamentale è la diminuzione di rigidezza di questi ultimi dovuto all'innesco e propagazione di cricche multiple negli strati off-axis. A tal proposito è stato proposto un modello analitico in grado di legare la densità di cricche in ciascuno strato di un laminato alla diminuzione di rigidezza globale considerando anche l'interazione tra cricche presenti su strati diversi (capitolo 6). Tale modello fornisce anche le distribuzioni di tensione dovute alla presenza delle cricche stesse. Questo è un aspetto di fondamentale importanza per lo sviluppo di una procedura per prevedere l'evoluzione della densità di cricche in laminati multi-direzionali sollecitati a fatica, presentata al capitolo 7. A tale scopo le osservazioni sperimentali, i modelli analitici e i criteri sviluppati in precedenza, combinati ad un approccio di tipo statistico, vengono utilizzati per prevedere l'innesco e propagazione di cricche multiple in un laminato. Di conseguenza, combinata con il modello precedentemente illustrato, la procedura consente di prevedere sia la diminuzione di rigidezza di laminati sia la ridistribuzione delle tensioni per effetto del danneggiamento rappresentando quindi uno strumento utile anche alla stima della vita a fatica totale di un laminato. Quando i laminati in composito sono utilizzati come aderendi in giunzioni incollate, l'interfaccia di incollaggio rappresenta una zona particolarmente critica per l'innesco di cricche a fatica. Di conseguenza è stata analizzata sperimentalmente la propagazione di cricche in giunzioni incollate soggette a carichi ciclici di modo misto I + II (apertura + scorrimento). Ancora una volta i meccanismi osservati su scala microscopica sono stati utilizzati per la formulazione di un criterio damage-based per la previsione della velocità di propagazione di cricche in giunzioni incollate sollecitate in modo misto (capitolo 8). In fine, in Appendice A è presentato un modello analitico sviluppato per la previsione dell'innesco di una cricca di debonding tra fibra e matrice in condizioni di carico statico biassiale. Il modello è utile per trarre informazioni sull'influenza dei principali parametri geometrici e interfacciali sulla resistenza dell'interfaccia fibra-matrice.
Ninic, Dejan Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Fatigue in automatic transmissions." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2006. http://handle.unsw.edu.au/1959.4/28056.
Повний текст джерелаAsare, Samuel. "Failure of rubber components under fatigue." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8407.
Повний текст джерелаPIRES, FERNANDO SALLES DA SILVA. "NUMERICAL STUDY ON THE PREDICTION OF FRETTING FATIGUE CRACK NUCLEATION VIA MULTIAXIAL FATIGUE MODELS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34764@1.
Повний текст джерелаCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Esta dissertação revisita quatro modelos multiaxiais de dano por fadiga (SWTD, SWT, Findley e Crossland) e discute a sua aplicação na previsão do risco de nucleação de trinca sob solicitações de fadiga por fretting segundo as abordagens local e não-local. As previsões do risco de nucleação de trinca obtidas através dos modelos estudados foram confrontadas com dados experimentais disponíveis na literatura para o contato cilindro/plano em aços AISI 52100 e AISI 1034 respectivamente. As melhores previsões foram obtidas através da versão desviadora SWTD. Segundo a abordagem local, o modelo SWTD fez previsões menos conservativas que os demais, sendo estas com erros conservativos inferiores a 15 porcento. Segundo a abordagem não-local, os quatro modelos geram previsões com erros inferiores a 15 porcento se os mesmos forem calibrados de forma independente. É importante mencionar que as melhores previsões obtidas através da abordagem não-local (que requer a calibração de um parâmetro adicional) são similares àquelas obtidas por SWTD local. Especificamente para os testes de fadiga por fretting com carga remota, o modelo SWTD não-local gerou previsões com 100 porcento de acertos (13 testes). Segundo a abordagem não-local, foi verificado que, para o conjunto de testes estudado, a precisão nas previsões é mais influenciada pela dimensão característica (que deve ser calibrada) que pelo modelo de fadiga multiaxial ou método de integração considerado. Por fim, verificou-se que previsões não conservativas podem ser obtidas ao se considerar uma dimensão característica assumida como parâmetro material (sem calibração) tal qual a distância crítica proposta por Taylor, definida em termos do método do ponto.
This work presents and discusses four multiaxial fatigue damage models (SWTD, SWT, Findley and Crossland) applied to crack nucleation prediction under fretting fatigue loadings according to the local and the non-local approaches. The predictions have been compared with experimental data available in the literature for the cylinder on flat configuration made of 52100 and 1034 AISI steel s respectively. In particular, for the data set analyzed, SWTD parameter (deviatoric version of SWT model) predictions were less conservative than the ones made by the other three models and have better correlated the experimental results. Considering the local approach, the error observed on the SWTD predictions was lower than 15 percent. On the other hand, for the non-local approach, it has been demonstrated that the four multiaxial fatigue models can provide crack nucleation predictions with similar level of accuracy (error lower than 15 percent) if the characteristic dimension is calibrated model-by-model. Note that this same level of accuracy was obtained with SWTD parameter defined in terms of the local approach, which requires one less parameter to be calibrated (characteristic dimension). In particular, considering only the fretting fatigue tests with bulk stresses, SWTD non-local (area method) prediction accuracy was 100 percent (13 tests). For the material studied, it has also been concluded that the non-local predictions accuracy depends more on the calibrated characteristic dimension than on the multiaxial model or integration method considered. Moreover, it has been verified that non-conservative predictions can be made if the characteristic dimension is assumed as a material property as proposed by Taylor on the critical distances theory (point method).
Bennett, Valerie P. "A microscale study of small crack propagation in multiaxial fatigue." Diss., Atlanta, Ga. : Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/23957.
Повний текст джерелаEl-Hage, Hicham. "Multiaxial fatigue analyses and life predictions using finite element method." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62209.pdf.
Повний текст джерелаWavish, Paul M. "Representative specimen for multiaxial fretting fatigue in a splined coupling." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438306.
Повний текст джерелаSuman, Sandip Kumar. "Nonlinear Fatigue Damage Accumulation in Aircraft Engine Alloys Multiaxial Loading." Diss., North Dakota State University, 2013. https://hdl.handle.net/10365/26885.
Повний текст джерелаGeneral Electric (Aviation)
Airforce Office of Scientific Research
Bulusu, Prashant. "Rolling contact fatigue predictions based on elastic-plastic finite element stress analysis and multiaxial fatigue /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1437664.
Повний текст джерела"August, 2006." Includes bibliographical references (leaves 38-45). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
Mustafa, Zaleha Binti. "Multiaxial fatigue characterization of self-reinforced polylactic acid-calcium phosphate composite." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/3876/.
Повний текст джерелаPoisson, Jean-Louis. "Détermination d'un critère de fatigue multiaxial appliqué à un élastomère synthétique." Phd thesis, Université François Rabelais - Tours, 2012. http://tel.archives-ouvertes.fr/tel-00780307.
Повний текст джерелаSum, Wei Siang. "FE-based multiaxial fatigue life prediction of spline couplings undergoing fretting." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420357.
Повний текст джерелаGONCALVES, ROBERTA AMORIM DE MAGALHAES MONTEIRO. "CONTRIBUTION IN THE USEFUL LIFE EVALUATION OF CRANKSHAFT UNDER MULTIAXIAL FATIGUE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36348@1.
Повний текст джерелаCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
As previsões de falhas por fadiga tornam-se críticas sob condições multiaxiais de carregamento, uma vez que a complexidade do estado de tensões requer uma análise com base em modelos mais avançados do que aqueles adotados para carregamentos uniaxiais. Neste contexto, alguns critérios foram desenvolvidos para tentar prever a falha de componentes submetidos a carregamentos cíclicos multiaxiais. Um exemplo de componente mecânico sujeito a fadiga multiaxial quando em serviço são os eixos virabrequim de unidades geradoras de plantas termoelétricas. Usualmente projetados segundo o critério de Findley, falhas recentes de eixos virabrequim ocorridas no parque termoelétrico nacional, tem provocado o questionamento da eficiência de tal critério. Desta forma, o presente estudo teve como objetivo analisar a aplicabilidade de seis modelos (Papadopoulos, Findley, Matake, McDiarmid, Carpinteri e Spagnoli e Liu e Mahadevan) de fadiga multiaxial de alto ciclo, baseados no plano crítico, para prever a falha de eixos virabrequim de unidades geradoras. Para aplicação dos modelos, adotaram-se diferentes parâmetros de carregamento (tensão média e defasagem de aplicação das tensões normais e cisalhantes) e propriedades de material (resistência à fadiga), partindo de valores encontrados na literatura. Observou-se uma divergência entre os resultados de cada modelo estudado, sendo uns mais conservadores do que os outros, em função do carregamento e propriedades do material. Entretanto, o modelo de Papadopoulos, com base na facilidade de aplicação e sensibilidade de previsão da falha, mostrou-se mais adequado.
The fatigue failure prediction becomes critical under multiaxial loading conditions, since the complexity of the stress state requires analysis based on models more advanced than those adopted for uniaxial loads. In this context, some criteria were developed in an attempt to predict the failure of components subjected to multiaxial cyclic loads. An example of mechanical component subject to multiaxial fatigue is the crankshaft of thermoelectric plants. It is usually projected according to the Findley criterion. However, recent failures of crankshafts occurring in the national thermoelectric park, put on doubt the efficiency of such criterion. In this way, the present study aimed to analyze the applicability of six models (Papadopoulos, Findley, Matake, McDiarmid, Carpinteri e Spagnoli and Liu e Mahadevan) of high cycle multiaxial fatigue, based on the critical plane, to predict failure on crankshaft of generating units. For the models application, different loading parameters (medium stress and out-of-phase stresses) and material properties (fatigue limit) were adopted, starting from values found in the literature. A divergence between the results of each model was observed, some of them were more conservative than the others, depending on the loading and material s properties. However, the Papadopoulos model, based on easy application and failure prediction sensitivity, proved to be more suitable than the others.
Nasr, Anouar. "Fiabilité en fatigue polycyclique des matériaux à défaut sous chargement multiaxial." Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2009. http://www.theses.fr/2009ESMA0020.
Повний текст джерелаIn many casting mechanical components, the fatigue microcracks initiate from surface defects. The process conditions and technology are being improved but they still cannot avoid these defects inherent to casting. Such defects were reported in different materials: cast irons, various steels and aluminium alloys. Different kinds of defects have been studied, namely, shrinkages, pores, inclusions and surface oxides. They have different shapes (spherical for the case of a pore and a complex 3D shape for shrinkage) and sizes (from several micromillimetres to millimetres ). It is well established that crack initiation occurs around the defect when components are submitted to multiaxial high cycle loading. For a given size, surface defects are much more harmful than those located in the bulk. The most influencing paérameters are the size and the distribution density of those defects
Adams, Charles Edward. "Influence of the Biaxiality Ratio on Multiaxial Fatigue of Metallic Materials." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27247.
Повний текст джерелаRoy, Alexander M. "Prediction of low and high cycle multiaxial fatigue of superelastic nitinol stents via uniaxial fatigue based equations." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527412.
Повний текст джерелаMička, Jan. "Únavová životnost ocelových vzorků při axiálním, torzním a kombinovaném axiálně-torzním namáhání." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241133.
Повний текст джерелаShamsaei, Nima. "Multiaxial Fatigue and Deformation Including Non-proportional Hardening and Variable Amplitude Loading Effects." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1279760342.
Повний текст джерелаGates, Nicholas R. "Fatigue Behavior under Multiaxial Stress States Including Notch Effects and Variable Amplitude Loading." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1469637495.
Повний текст джерелаBäckström, Mika. "Multiaxial fatigue life assessment of welds based on nominal and hot spot stresses /." Espoo : Technical Research Centre of Finland, 2003. http://www.vtt.fi/inf/pdf/publications/2003/P502.pdf.
Повний текст джерелаMaragoni, Lucio. "Influence of manufatcuring-induced defects on the multiaxial fatigue behaviour of composite materials." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422888.
Повний текст джерелаIn questo lavoro si è studiato l’effetto di difetti indotti dal processo produttivo, ed in particolare della porosità, sul comportamento a fatica multiassiale di materiali compositi. Estese campagne sperimentali hanno mostrato che nonostante i vuoti non alterino i meccanismi di danno su scala microscopica che portano alla formazione di una cricca visibile, la loro presenza causa un innesco prematuro del danneggiamento ed una sua più rapida evoluzione, evidenziando quindi la necessità di tenere debitamente conto della difettologia del materiale in fase di progettazione. È stato quindi proposto un modello, basato sulle tensioni locali all’interno del materiale calcolate mediante Elementi Volumetrici Rappresentativi (RVEs), per prevedere la formazione di cricche a fatica in laminati porosi a partire dal comportamento del materiale “void-free”. Infine, si è sviluppata una procedura di tipo Monte-Carlo per prevedere l’evoluzione della densità di cricche durante la vita a fatica in laminati sia “void-free” che porosi, ottenendo previsioni in ottimo accordo con i dati sperimentali.
Ma, Zepeng. "Fatigue models for life prediction of structures under multiaxial loading with variation in time and space." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX117/document.
Повний текст джерелаThe aim of this work is to propose a multi-scale approach to energy-based fatigue, which can estimate lifetimes associated with variable multidimensional loading. The foundation of the approach is to assume that the energy dissipated on a small scale governs the fatigue behavior. Each material point is associated to a stochastic distribution of weak points that are likely to plasticize and contribute to the dissipation of energy without affecting global macroscopic stresses. This amounts to adopting Dang Van's paradigm of high cycle fatigue. The structure is supposed to be elastic (or adapted) on a macroscopic scale. In addition, we adopt on the mesoscopic scale an elastoplastic behavior with a dependence of the plastic load function not only of the deviatoric part of the stresses, but also of the hydrostatic part. Linear kinematic hardening is also considered under the assumption of an associated plasticity. Instead of using the number of cycles as an incremental variable, the concept of temporal evolution of the load is adopted for a precise follow-up of the history of the actual loading. The effect of mean stress is taken into account in the mesoscopic yield function; a law of nonlinear accumulation of damage is also considered in the model. Fatigue life is then determined using a phenomenological law based on mesoscopic energy dissipation from the plastic accommodative cycle. The first part of the work focused on a proposal for a fatigue model with a simpler implementation gradient than the previous models
Nadjitonon, Ngarmaïm. "Contribution à la modélisation de l'endommagement par fatigue." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-01017174.
Повний текст джерелаBrunac, Jean-Baptiste. "Modélisation numérique du comportement en fatigue des élastomères chargés de noir de carbone." Paris 6, 2006. http://www.theses.fr/2006PA066511.
Повний текст джерелаBonnen, John Joseph Francis. "Multiaxial fatigue response of normalized 1045 steel subjected to periodic overloads, experiments and analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0008/NQ38224.pdf.
Повний текст джерелаJohansson, Nils. "Estimation of fatigue life by using a cyclic plasticity model and multiaxial notch correction." Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158095.
Повний текст джерелаOba, Takeshi. "The fatigue behaviour of toughened epoxy polymers." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/11431.
Повний текст джерелаFumes, Fabiano Gonzaga 1986. "Estudo comparativo entre critérios de fadiga multiaxial aplicados ao contato roda-trilho : A comparative study of multiaxial fatigue criteria applied to the wheel-rail contact." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265955.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Este trabalho apresenta a comparação entre os diversos critérios de fadiga multiaxial de alto ciclo aplicados ao problema de contato roda-trilho. Para isto, é utilizado um modelo elastoplástico tridimensional de elementos finitos capaz de permitir o cálculo tanto das tensões geradas pelo rolamento de uma roda livre de tensões residuais de fabricação como de uma roda que contenha as tensões residuais provenientes do processo de tratamento térmico, obtidas através de uma simulação térmico-estrutural. Estes dois cenários são avaliados segundo critérios de fadiga multiaxial baseados tanto em planos críticos, como Dang Van, Matake e McDiarmid, quanto nos baseados em invariantes do tensor de tensões, como Sines, Crossland e Kakuno Kawada. Pela natureza da fadiga de contato, que não possui condição de vida infinita, é estimado para cada critério um número de ciclos para o aparecimento das trincas. Como resultado, observa-se que para alguns critérios como Dang Van, Sines e Kakuno-Kawada, a vida em fadiga é beneficiada pelo processo de tratamento térmico, enquanto para os demais, as tensões residuais de fabricação provocam uma redução no número de ciclos para o aparecimento das trincas
Abstract: This work presents a comparison of different high cycle multiaxial fatigue criteria, applied to wheel- rail contact. For this, it is used a three-dimensional elastoplastic finite element model able to calculate stresses generated by the rolling of a wheel free of residual stresses from manufacturing process and also by a wheel containing the residual stresses from heat treatment process, generated by a thermal-structural simulation. These two scenarios are evaluated according to multiaxial fatigue criteria based on critical planes, as Dang Van, Matake and McDiarmid, and also based on the invariants of the stress tensor, as Sines, Crossland and Kakuno Kawada. Due to the nature of rolling contact fatigue, which has no condition of infinite life, a number of cycles for crack appearance are estimated for each criterion. It can be notice that for some criteria, such as Dang Van, Sines and Kakuno-Kawada, fatigue life is benefited by the heat treatment process, while for others the residual stresses from manufacturing promote a reduction in the number of cycles
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
Perez, Romero Roberto, and Ramirez Alvaro Lazuen. "Analysis of rubber adhesive : FE simulation of damage propagation over rubber adhesive under fatigue in mixed-mode loading." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-10522.
Повний текст джерелаBerrehili, Abdelmoutalib. "Comportement cyclique et tenue en fatigue sous chargement multiaxial d'un polyéthylène : expériences et critère d'endurance." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2010. http://tel.archives-ouvertes.fr/tel-00517401.
Повний текст джерелаLiao, Kin. "Tensile and uniaxial/multiaxial fatigue behavior of ceramic matrix composites at ambient and elevated temperatures." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40047.
Повний текст джерелаPh. D.
Raoult, Ida. "Structures élastomères sous chargement cyclique : comportement, fatigue, durée de vie." Phd thesis, Ecole Polytechnique X, 2005. http://tel.archives-ouvertes.fr/tel-00521633.
Повний текст джерелаAttari, Nordine. "Etude en fatigue oligocyclique multiaxiale d'un alliage de magnésium GA3Z1." Vandoeuvre-les-Nancy, INPL, 1991. http://www.theses.fr/1991INPL010N.
Повний текст джерелаMelnikov, Alexei. "Damage and Fatigue in Cross-Linked Rubbers." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1280198428.
Повний текст джерелаNingre, Corado. "Modélisation du comportement élastoplastique cyclique multiaxial par une approche multisurface dans l'espace des déformations." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALI053.
Повний текст джерелаThis work deals with the theoretical, numerical and experimental study of the elastoplastic mechanical behavior of metallic materials in complex multiaxial cyclic loadings. The elastoplastic behavior is described by a multisurface model, within the finite strain theory. This model is written in the five-dimensional Ilyushin strain space. The resulting model is capable of describing the multiaxial behavior of metallic materials, in complex cyclic loadings, in particular non-proportional, taking into account finite strain, time-independent irreversibility, cumulative second order effects (Poynting-Swift effect) and cyclic hardening. The model has been implemented in a commercial finite element calculation code, in order to produce an operational tool for calculating structures such as mechanical equipment and internal components of hydroelectric power plants (turbines, alternators, etc.). The proposed model was validated by comparison with combined tensile-torsion biaxial test results obtained on stainless steel. This model has been completed by an energy and thermodynamic analysis that allows the implementation of a relevant energy approach for the monitoring of fatigue damage. As part of this work, this approach was illustrated by the proposal of a fatigue criterion, validated by the comparison of its predictions with those of other classical fatigue criteria proposed in the literature
ARGENCE, DIDIER. "Endommagements couples de fatigue et de fluage sous chargement multiaxial applique a un acier inoxydable austenitique." Paris, ENMP, 1996. http://www.theses.fr/1996ENMP0796.
Повний текст джерелаBaumard, Thomas Louis Marie. "Investigation on fatigue failure in tyres." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24553.
Повний текст джерелаBarros, Cainã Bemfica de. "Fatigue and cyclic plasticity of 304L stainless steel under axial, torsional and proportional axial-torsional loading." reponame:Repositório Institucional da UnB, 2018. http://repositorio.unb.br/handle/10482/31953.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).
Os objetivos deste trabalho são investigar o comportamento tensão-deformação cíclico e a fadiga multiaxial do aço inoxidável 304L por meio de ensaios axiais, torsionais e axiais-torsionais proporcionais totalmente alternados controlados por deformação à temperatura ambiente e avaliar os modelos de fadiga do tipo plano crítico propostos por Smith, Watson e Topper (1970), e Fatemi e Socie (1988) em relação à previsão de vida à fadiga e à orientação das trincas macroscópicas. Corpos de prova tubulares com paredes finas usinados após o tratamento térmico de normalização foram submetidos a amplitudes de deformação equivalente de von Mises tais que 0,20% ≤ Δ/2 ≤ 1,00%. Devido à dependência da taxa de carregamento do comportamento tensão deformação do aço inoxidável 304L, todos os ensaios foram realizados com frequências (0,30-2,00 Hz) tais que a taxa de deformação equivalente de von Mises fosse igual a 10-2 s-1. Observou-se que o endurecimento secundário nos ensaios proporcionais só ocorreu para amplitudes de deformação equivalente Δ/2 ≥ 0,80% enquanto todos os ensaios axiais-torsionais apresentaram endurecimento secundário. Baseado na comparação entre os estados de tensão, concluiu-se que há falha por fadiga antes que o endurecimento secundário se torne significativo para os ensaios proporcionais cuja Δ/2 ≤ 0,60%. Observou-se um comportamento do tipo Masing para uma faixa de deformação axial Δ/2 ≤ 0,40% e torsional Δ/2 ≤ 0,61% para ensaios axiais, torsionais e proporcionais. A deformação equivalente de von Mises não pode ser usada como parâmetro limite para o comportamento Masing já que o ensaio proporcional cuja Δ/2 = 0,50% apresenta comportamento semelhante àquele de ensaios cuja Δ/2 ≤0,50%, o que não ocorre para o ensaio axial de mesma amplitude de deformação equivalente. Observou-se não proporcionalidade nos espaços das tensões desviadoras e das deformações plásticas para os ensaios proporcionais no espaço das deformações totais. No entanto, não se observou um aumento na amplitude de tensão destes ensaios quando comparados a ensaios axiais e torsionais, o que sugere que o endurecimento não proporcional está associado à não proporcionalidade no espaço das deformações totais. Não houve influência significativa do endurecimento secundário na análise de fadiga, já que não houve diferença significativa entre as estimativas de vida realizadas com constantes materiais obtidas de diferentes ciclos de referência para os dois modelos. Os modelos investigados previram a vida à fadiga com boa acurária, mas falharam em prever a orientação das trincas para todas as três histórias de deformação.
The goals of this work are to investigate the cyclic stress-strain behaviour and the multiaxial fatigue of the 304L stainless steel through fully reversed strain-controlled axial, torsional and proportional axial-torsional experiments at room temperature and to evaluate the critical plane fatigue models proposed by Smith, Watson and Topper (1970), and Fatemi and Socie (1988) regarding the fatigue life and the macroscopic fatigue crack orientation. Thin-walled tubular specimens machined after a normalization heat treatment were submitted equivalent von Mises strain amplitudes such that 0:20% "eq=2 1:00%. Due to the rate-dependent cyclic stressstrain behaviour of the 304L stainless steel, all experiments were performed with frequencies (0.30{2.00 Hz) such that the equivalent von Mises strain rate was equal to 102 s1. It was observed that the secondary hardening upon proportional loads occurred only for "eq=2 0:80%, whilst it occurred for all axial and torsional experiments. Based upon the comparison between stress states, it was concluded that fatigue failure occurs before the secondary hardening becomes important for proportional experiments whose "eq=2 0:60%. A Masing-type behaviour was observed for a range of axial strain "=2 0:40% and torsional strain sur=2 0:61% for axial, torsional and proportional experiments. The equivalent von Mises strain amplitude cannot be used as a threshold since the proportional experiment whose "eq=2 = 0:50% exhibits a behaviour similar to experiments whose "eq=2 < 0:50%, which does not occur for the axial experiment with the same equivalent strain amplitude. non-proportionality upon deviatoric stress and plastic strain spaces was observed for proportional experiments upon total strain space. Nonetheless, an increase in stress amplitude was not observed for those experiments when compared to axial and torsional ones, which suggests that non-proportional hardening is related to non-proportionality upon the total strain space. There was no signi cant inuence of secondary hardening upon fatigue analysis since there was no signi cant di erence between life predictions generated from material constants obtained from di erent reference cycles for both models. The investigated models predicted accurately fatigue life, but failed to predict crack orientation for all the three strain histories.
Giordani, Felipe André. "Estudo de metodologias para medir a vida em fadiga multiaxial não proporcional." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/118864.
Повний текст джерелаIt is known throughout human history the large amount of accidents linked to action of cyclic loading. For over 100 years, methodologies take into account the fatigue phenomenon of new components projects. Existing methodologies for assessing the fatigue life are empirical and have been successfully applied in the determination of fatigue life of the component when it is subjected to uniaxial loading or proportional multiaxial loading. But the experimental evidence has shown that when the request is multiaxial and not proportional, the laws mentioned above are no longer adequate. Thus the classical criteria used not correctly predict component life. In this context, this paper analyzes some of the methodologies of multiaxial fatigue non proportionate available in the relevant literature. The results obtained with these methods are compared with the results so obtained and using the proportional multiaxial fatigue methodology. To compare the methods mentioned is an example of simple request, and also the analysis component of an agricultural machine requested by a history of typical strains, obtained from the machine field testing on a test track. Finally conclusions on the methodologies used and the importance of taking into account the non-proportionality of a state of oscillating multiaxial stresses are presented.
Malek, Benaïssa. "Etude et modélisation du comportement en fatigue de l'alliage d'Aluminium 2618 anodisé soumis à des chargements multiaxiaux." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30016.
Повний текст джерелаAnodized aluminum alloys are widely used in aircraft construction because of their mechanical properties, corrosion resistance and low density. However, the anodizing process often leads to a reduction in fatigue strength. In addition, the parts are generally subjected to multiaxial fatigue loadings in service. Therefore, it is necessary to study, not only the effect of the anodization, but also to correlate it to the nature of the loading.The objective of the thesis is to identify and characterize the different mechanisms involved in the anodizing effect of the alloy 2618-T851 on the fatigue strength and to determine the impact of the nature of the loading. On the one hand, uniaxial tensile and torsional fatigue tests have been carried out on specimens in the bare state with different surface roughness levels and under different stress ratios. It was found that the surface roughness had no effect whatever the nature of the loading. On the other hand, a non-zero normal mean stress or mean shear stress reduces fatigue life.The tests carried out on pickled, anodized, impregnated and finally sealed specimens showed that, in tension, the reduction in fatigue life is mainly due to the anodic oxidation step. On the other hand, in torsion, the fatigue strength of the alloy is not sensitive to the anodizing process. Then, the material was studied in multiaxial fatigue, tensile-torsion under different stress ratios and different phase angles in the machined and anodized state. We have found that anodizing has a detrimental effect as in the case of pure tension and that the material is not sensitive to phase angle whatever the stress amplitude ratio. The alloy has been studied under multiaxial loadings integrating the internal pressure to analyze the fatigue behavior of the alloy under this type of loading. Surface fracture analysis has shown that, in general, cracks initiated from Al9FeNi intermetallic particles with the presence of a single site for the alloy in the bare state and from the oxide layer with the presence of multi-sites in the case of anodized specimens. For life-time predictions, we have used different critical-plane approaches (Morel, Fatemi-Socie, Findley, Kluger and Macha) to predict fatigue life under different loading combinations. Finally, a model inspired by the Kluger model has been proposed