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Djahansouzi, B. "Effect of dynamic response on impact damage". Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47033.
Pełny tekst źródłaTappert, Peter M. "Damage identification using inductive learning". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-05092009-040651/.
Pełny tekst źródłaGe, Ma. "Structural damage detection and identification using system dynamic parameters". Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.
Pełny tekst źródłaQuiroz, Laura Maria. "Probabilistic assessment of damage states using dynamic response parameters". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36955.
Pełny tekst źródłaMao, Lei. "Frequency-based structural damage identification and dynamic system characterisation". Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7945.
Pełny tekst źródłaUwayed, Ahmed Noori. "Damage detection in laminated composite structures using dynamic analysis". Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/42921.
Pełny tekst źródłaLacruz, Alvarez Alfonso de. "Damage response of sandwich plates subject to dynamic loads". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35040.
Pełny tekst źródłaTondreau, Gilles. "Damage localization in civil engineering structures using dynamic strain measurements". Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209466.
Pełny tekst źródłamonitoring of civil engineering structures in order to locate small damages automatically. A
review of the very wide literature on Structural Health Monitoring (SHM) points first out that
the methods can be grouped in four categories based on their need or not of a numerical model,
as well as their need or not of information of the damaged structure to be applied. This state
of the art of the SHM methods highlights the requirement to reach each levels of SHM, which
is in particular for the localization of small damages in civil engineering structures the needs
for a non-model based output-only damage sensitive feature extraction technique. The origin of
the local sensitivity of strains to damages is also analyzed, which justifies their use for damage
localization.
A new method based on the modal filtering technique which consists in combining linearly
the sensor responses in a specific way to mimic a single degree of freedom system and which
was previously developed for damage detection is proposed. A very large network of dynamic
strain sensors is deployed on the structure and split into several independent local sensor networks.
Low computational cost and fast signal processing techniques are coupled to statistical
control charts for robust and fully automated damage localization.
The efficiency of the method is demonstrated using time-domain simulated data on a simply
supported beam and a three-dimensional bridge structure. The method is able to detect and
locate very small damages even in the presence of noise on the measurements and variability
of the baseline structure if strain sensors are used. The difficulty to locate damages from acceleration
sensors is also clearly illustrated. The most common classical methods for damage
localization are applied on the simply supported beam and the results show that the modal filtering
technique presents much better performances for an accurate localization of small damages
and is easier to automate.
An improvement of the modal filters method referred to as adaptive modal filters is next
proposed in order to enhance the ability to localize small damages, as well as to follow their
evolution through modal filters updating. Based on this study, a new damage sensitive feature
is proposed and is compared with other damage sensitive features to detect the damages with
modal filters to demonstrate its interest. These expectations are verified numerically with the
three-dimensional bridge structure, and the results show that the adaptation of the modal filters
increases the sensitivity of local filters to damages.
Experimental tests have been led first to check the feasibility of modal filters to detect damages
when they are used with accelerometers. Two case studies are considered. The first work
investigates the experimental damage detection of a small aircraft wing equipped with a network
of 15 accelerometers, one force transducer and excited with an electro-dynamic shaker. A
damage is introduced by replacing inspection panels with damaged panels. A modified version
of the modal filtering technique is applied and compared with the damage detection based principal
component analysis of FRFs as well as of transmissibilities. The three approaches succeed
in the damage detection but we illustrate the advantage of using the modal filtering algorithm as
well as of the new damage sensitive feature. The second experimental application aims at detecting
both linear and nonlinear damage scenarios using the responses of four accelerometers
installed on the three-storey frame structure previously developed and studied at Los Alamos
National Labs. In particular, modal filters are shown to be sensitive to both types of damages,
but cannot make the distinction between linear and nonlinear damages.
Finally, the new method is tested experimentally to locate damages by considering cheap
piezoelectric patches (PVDF) for dynamic strain measurements. Again, two case studies are investigated.
The first work investigates a small clamped-free steel plate equipped with 8 PVDFs sensors, and excited with a PZT patch. A small damage is introduced at different locations by
fixing a stiffener. The modal filters are applied on three local filters in order to locate damage.
Univariate control charts allow to locate automatically all the damage positions correctly.
The last experimental investigation is devoted to a 3.78m long I-steel beam equipped with 20
PVDFs sensors and excited with an electro-dynamic shaker. Again, a small stiffener is added to
mimic the effect of a small damage and five local filters are defined to locate the damage. The
damage is correctly located for several positions, and the interest of including measurements
under different environmental conditions for the baseline as well as overlapping the local filters
is illustrated.
The very nice results obtained with these first experimental applications of modal filters
based on strains show the real interest of this very low computational cost method for outputonly
non-model based automated damage localization of real structures.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Elbadawy, Mohamed Mohamed Zeinelabdin Mohamed. "Dynamic Strain Measurement Based Damage Identification for Structural Health Monitoring". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/86167.
Pełny tekst źródłaPh. D.
All modern societies depend heavily on civil infrastructure systems such as transportation systems, power generation and transmission systems, and data communication systems for their day-to-day activities and survival. It has become extremely important that these systems are constantly watched and maintained to ensure their functionality. All these infrastructure systems utilize structural systems of different forms such as buildings, bridges, airplanes, data communication towers, etc. that carry the service and environmental loads that are imposed on them. These structural systems deteriorate over time because of natural material degradation. They can also get damaged due to excessive load demands and unknown construction deficiencies. It is necessary that condition of these structural systems is known at all times to maintain their functionality and to avoid sudden breakdowns and associated ensuing problems. This condition assessment of structural systems, now commonly known as structural health monitoring, is commonly done by visual onsite inspections manually performed at pre-decided time intervals such as on monthly and yearly basis. The length of this inspection time interval usually depends on the relative importance of the structure towards the functionality of the larger infrastructure system. This manual inspection can be highly time and resource consuming, and often ineffective in catching structural defects that are inaccessible and those that occur in between the scheduled inspection times and dates. However, the development of new sensors, new instrumentation techniques, and large data transfer and processing methods now make it possible to do this structural health monitoring on a continuous basis. The primary objective of this study is to utilize the measured dynamic or time varying strains on structural components such as beams, columns and other structural members to detect the location and level of a damage in one or more structural elements before they become serious. This detection can be done on a continuous basis by analyzing the available strain response data. This approach is expected to be especially helpful in alerting the owner of a structure by identifying the iv occurrence of a damage, if any, immediately after an unanticipated occurrence of a natural event such as a strong earthquake or a damaging wind storm.
Vongbandit, Pratip. "Morphology of surface damage resulting from static and dynamic contacts". Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/3215.
Pełny tekst źródłaGANDINO, EDOARDO. "Diagnostics of machines and structures: dynamic identification and damage detection". Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506356.
Pełny tekst źródłaHardy, Michael Stuart Anthony. "The response of flexible pavements to dynamic tyre forces". Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385406.
Pełny tekst źródłaMartinez-Flores, Rene. "DAMAGE ASSESSMENT POTENTIAL OF A NOVEL SYSTEM IDENTIFICATION TECHNIQUE - EXPERIMENTAL VERIFICATION". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1028%5F1%5Fm.pdf&type=application/pdf.
Pełny tekst źródłaLestari, Wahyu. "Damage of composite structures : detection technique, dynamic response and residual strength". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12072.
Pełny tekst źródłaGonzalez, Ignacio. "Application of monitoring to dynamic characterization and damage detection in bridges". Doctoral thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150804.
Pełny tekst źródłaQC 20140910
Richards, Victor Mark. "Damage identification in engineering structures from changes in measured dynamic response". Thesis, University of South Wales, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325901.
Pełny tekst źródłaCundy, Amanda L. "Use of Response Surface Metamodels in Damage Identification of Dynamic Structures". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/30842.
Pełny tekst źródłaMaster of Science
Aravindababu, Sumanth Ram. "Investigation of sources of wheel-rail impact force deviation through dynamic simulations". Thesis, KTH, Fordonsdynamik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302783.
Pełny tekst źródłaPå grund av den ökade efterfrågan på godstransporter är det nödvändigt attundvika förseningar för att säkerställa att varorna når sin destination i tid. Deviktigaste faktorerna som orsakar störningar i trafiken på huvudlinjen är stopp ispår av fordon, främst på grund av skadade hjul. De skadade hjulen identifierasmed hjälp av mätningar av slagkraft mellan hjul och spår som tillhandahållsav hjulbelastningsdetektorer (WILD). Detta kräver ett optimerat schema förunderhåll av hjulsatser och vagnar i allmänhet. Under underhållet kontrollerartjänstemännen manuellt för defekta hjul och utbytet av hjulsatser utförs baserat på typen av skada. Klassificeringen av hjulskador spelar en viktig roll närdet gäller att underlätta identifiering av skador och ge insikt för att bedöma enstrategi för hjulbyte. I den här studien görs ett försök att klassificera de skadade hjulsatserna genom att analysera data från slagkraften mellan spår ochhjul från detektorer. Uppgifterna från detektorerna hämtas från PredgeAB, enLuleå-baserad uppstartsbolag som är pionjärer för att ge beslutsstöd om optimala underhållsscheman och prediktivt underhåll av järnvägshjul. Genom sinadetekterings- och prediktiva lösningar observerades att 10% av alla hjul märktasom skadade av detektorerna var oskadade. Källan till avvikelsen i slagkraftavläsningarna kan hjälpa Predge att göra bättre uppskattningar när det gällerupptäckning och förutsägelse av skador. I den här studien studeras de källorsom bidrar till avvikelsen med simuleringar av flera kroppar i GENSYS. En nymetod för modellering av hjulskador har utvecklats för att övervinna programvarans brister. Resultaten av denna studie skulle kunna användas på lämpligtsätt för att göra klassificeringar av hjulskador.
Sanchez, Gabriel Sabino. "AN INVESTIGATION OF DAMAGE ARRESTMENT DEVICES ON CARBON FIBER SANDWICH SPECIMENS UNDER DYNAMIC LOADING". DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/821.
Pełny tekst źródłaMehdizadeh, Mohammad, i n/a. "Curvature Mode Shape Analyses of Damage in Structures". RMIT University. Aerospace, Mechanical & Manufacturing Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091022.154814.
Pełny tekst źródłaLu, Kan. "Dynamics Based Damage Detection of Plate-Type Structures". University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133818717.
Pełny tekst źródłaCole, David James. "Measurement and analysis of dynamic tyre forces generated by lorries". Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334095.
Pełny tekst źródłaHassan, Noha Mohamed. "Damage Development in Static and Dynamic Deformations of Fiber-Reinforced Composite Plates". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30171.
Pełny tekst źródłaPh. D.
Tan, Hock Chuan. "Load-induced damage evaluation in reinforced concrete structures using dynamic response signatures". Thesis, University of Aberdeen, 2000. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602019.
Pełny tekst źródłaWaltering, Markus. "Damage assessment of civil engineering structures and bridges using nonlinear dynamic characteristics". Aachen Shaker, 2009. http://d-nb.info/998626988/04.
Pełny tekst źródłaLi, Tianyi. "Gradient-damage modeling of dynamic brittle fracture : variational principles and numerical simulations". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX042/document.
Pełny tekst źródłaIn civil engineering, mechanical integrity of the reinforced concrete structures under severe transient dynamic loading conditions is of paramount importance for safety and calls for an accurate assessment of structural behaviors in presence of dynamic crack propagation. In this work, we focus on the constitutive modeling of concrete regarded as an elastic-damage brittle material. The strain localization evolution is governed by a gradient-damage approach where a scalar field achieves a smeared description of dynamic fracture phenomena. The contribution of the present work is both theoretical and numerical. We propose a variationally consistent formulation of dynamic gradient damage models. A formal definition of several energy release rate concepts in the gradient damage model is given and we show that the dynamic crack tip equation of motion is governed by a generalized Griffith criterion. We then give an efficient numerical implementation of the model based on a standard finite-element spatial discretization and the Newmark time-stepping methods in a parallel computing framework. Simulation results of several problems are discussed both from a computational and physical point of view. Different damage constitutive laws and tension-compression asymmetry formulations are compared with respect to their aptitude to approximate brittle fracture. Specific properties of the dynamic gradient damage model are investigated for different phases of the crack evolution: nucleation, initiation, propagation, arrest, kinking and branching. Comparisons with experimental results are also performed in order to validate the model and indicate its further improvement
Tondi, Michele <1990>. "Innovative model updating procedure for dynamic identification and damage assessment of structures". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8617/1/Tondi_Michele_tesi.pdf.
Pełny tekst źródłaLa procedura di model updating è una tecnica alquanto datata che permette di comprendere il comportamento dinamico di un sistema e il suo stato di danno. Negli ultimo anni, il monitoraggio strutturale ha incrementato la sua applicabilità grazie al ridotto costo dei sensori e al miglioramento della potenza computazionale. Sempre più strutture sono oggi strumentate per valutare i loro danni e capire il comportamento dinamico stesso. La valutazione in tempo reale dei parametri strutturali e dello stato di danno è oggigiorno non più irraggiungibile. La valutazione delle incertezze sui parametri è, inoltre, richiesta ai moderni algoritmi di model updating. La combinazione della valutazione in tempo reale e dell'incertezza possono portare a un giudizio di situazioni potenzialmente pericolose in strutture esistenti con possibile evacuazione e messa in sicurezza delle strutture stesse. Questa valutazione è sempre più richiesta ai sistemi di monitoraggio strutturale. L'algoritmo sviluppato in questo lavoro è incentrato su questi aspetti, in particolare sulla rapida valutazione dei parametri strutturali e delle relative incertezze. La velocità dell'algoritmo permette l'uso dello stesso per il monitoraggio in tempo reale delle strutture. L'algoritmo è basato su una procedura innovativa a due fasi, con valutazione dell'incertezza, risolvendo un problema inverso agli autovalori. La prima fase è risolta con formulazione chiusa del problema (senza considerare le equazioni ai determinanti). Se la soluzione non soddisfa delle soglie prefissate per i parametri di controllo, la seconda fase, iterativa, deve essere eseguita in modo da migliorare la corrispondenza tra risultati sperimentali e numerici. La procedura permette, inoltre, di scrivere le derivate parziali del problema stesso, rispetto ai risultati sperimentali, in formulazione chiusa; pertanto le incertezze sui parametri sono calcolate mediante la teoria della propagazione degli errori. Una seconda procedura è sviluppata affrontando il problema completamente in forma iterativa, usando un algoritmo genetico con superfici di risposta.
Gbetchi, Kokouvi. "Multi-scale modeling of thermo-mechanical dynamic damage in quasi-brittle materials". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0049.
Pełny tekst źródłaUnder impact mechanical loadings, structural components made of brittle materials may be exposed to dynamic failure. The appropriate modeling of the failure mechanisms at different scales of observation and the prediction of the corresponding thermomechanical damage evolution in such materials is essential for structural reliability predictions. Experimental observations on dynamic failure in brittle materials report important cooling and heating effects in the vicinity of the crack tip. Theoretical modeling of the thermo-mechanical coupling during fracture have been generally undertaken without accounting for microstructural aspects. The objective of the present thesis is to develop a procedure to obtain macroscopic thermo-mechanical damage laws in which the damage evolution is deduced from the propagation of microcracks and the associated small-scale thermal effects in the material. We use the asymptotic homogenization method to obtain the macroscopic thermo-mechanical and damage response of the solid. A Griffith type criterion is assumed for microcracks propagating in modes I or II. Heat sources at the tips of microcracks are considered as a consequence of the energy dissipated during propagation. Frictional heating effects are also considered on the lips of microcracks evolving in the shear mode. An energy approach is developed in combination with the homogenization procedure to obtain macroscopic damage laws. The resulting thermoelastic and damage system involves strong couplings between mechanical and thermal fields. Computation of the effective coefficients allowed us to study the local response predicted by the new models. The macroscopic response exhibits strain-rate sensitivity, microstructural size effects, degradation of thermoelastic properties and specific thermal evolutions due to microcracking and frictional effects at the small scale. Distributed heat sources are present in the macroscopic temperature equation linked to damage and frictional dissipations. The implementation of the proposed damage models in a FEM software allowed us to perform numerical simulations at the structural level. We reproduced numerically experimental tests reported in the literature concerning the rapid failure of PMMA samples impact. The results obtained in the simulations are in good agreement with the experimental observations
Oruganti, Krishna, i krishnaov@yahoo com. "Evaluation of Damage in Structures using Vibration-based Analyses". RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091002.143408.
Pełny tekst źródłaAykan, Murat. "Identification Of Localized Nonlinearity For Dynamic Analysis Of Structures". Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615596/index.pdf.
Pełny tekst źródłaCullen, Daniel Kacy. "Response of neurons cultured in two-and-three-dimensions to dynamic shear deformation". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17520.
Pełny tekst źródłaSarego, Giulia. "Structural material damage: novel methods of analysis". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3427223.
Pełny tekst źródłaNella teoria classica della meccanica dei solidi, la formulazione matematica include derivate parziali, grazie alle quali si possono rappresentare stati di deformazione come funzioni degli spostamenti relativi dei nodi in cui è discretizzato il sistema continuo. Una carenza rilevante dovuto all’utilizzo delle derivate è legato ai risultati privi di significato fisico ottenuti in prossimità delle discontinuità perché le derivate non sono definite laddove manca un campo di spostamenti continuo, come può capitare in presenza di dislocazioni, vuoti, cricche, interfacce tra fasi differenti nello stesso corpo e bordi dei grani. Dato che la formazione spontanea e la crescita di discontinuità sono di grande importanza in meccanica dei solidi, diverse tecniche sono state utilizzate per superare questa incapacità della teoria di descrivere il comportamento dei materiali in tali condizioni, perché situazioni in cui le strutture sono incapaci di continuare a svolgere la propria funzione devono essere evitate, specialmente per strutture aerospaziali, in primo luogo, per ragioni di sicurezza ed, in secondo luogo, per motivi economici. Uno di questi nuovi approcci riguarda l’utilizzo di teorie non locali basate su formulazioni integrali (più precisamente formulazioni integro-differenziali), definite anche quando campi di spostamento non derivabili sono presenti. La teoria “Peridynamics” è una di queste teorie: è stata proposta da Stewart Silling nel 2000 [1] così da adottare una formulazione unica e coerente capace di descrivere i comportamenti dei materiali in corpi sia continui che discontinui, evitando l’uso di equazioni alle derivate parziali o la definizione a priori di alcune condizioni che possono influenzare (e in un certo senso favorire) dei risultati. Ci sono due versioni di modelli peridinamici: la state-based, e un suo caso particolare, la bond-based, che è stata introdotta per prima (vedi [1, 2]). Nella versione bond-based, le forze tra due punti materiali dependono unicamente dal loro spostamento relativo e dalla loro posizione relativa iniziale, oltre che dalle proprietà del materiale. Vista la sua semplicità a confronto con la seconda versione, la maggior parte delle applicazioni e degli articoli sulla Peridynamica ha adottato la formulazione bond-based. Tuttavia, i modelli nella formulazione bond-based sono caratterizzati da alcune limitazioni (le stesse dei modelli di altre teorie atomistiche e dei modelli di dinamica molecolare [3], anche se la Peridinamica è una teoria del continuo, non discreta), la più notevole di queste è il modulo di Poisson fisso: 1/4 nelle simulazioni 3D oppure in caso di deformazione piana 2D, e 1/3 nelle simulazioni in stato di tensione piana 2D (si veda per esempio [1, 4]). Questa particolarità implica altre restrizioni, come l’impossibilità di riprodurre la condizione di incomprimibilità plastica in maniera accurata. Tuttavia, per la maggior parte degli scopi, la formulazione bond-based è sufficiente e fornisce risultati approssimati soddisfacenti. I modelli della versione state-based rimuovono queste restrizioni, permettendo che le interazioni tra due punti possano dipendere da tutte le interazioni (i “bond”) connessi ad almeno uno dei due punti, tramite delle mappe avanzate chiamate “states”. Inoltre, ci sono due tipi di formulazioni state-based: la ordinary e la non-ordinary [2, 5, 6]. Nella formulazione ordinary, le forze tra due punti materiali agiscono lungo la congiungente i due punti nella configurazione deformata, mentre nella formulazione non-ordinary, questa caratteristica non è più vera. La formulazione ordinary della state-based necessita di modelli costitutivi appositamente derivati, come per esempio i modelli di viscoelasticità e platicità in [7, 8]. Per la formulazione non-ordinary della state-based, due approcci sono stati proposti: lo sviluppo di un modello esplicito per l’espressione dello state della forza peridinamica [2] e lo sviluppo di una mappa grazie alla quale le relazioni costitutive della meccanica classica sono incorporate per stabilire indirettamente la relazione tra la forza d’interazione e la deformazione. I modelli derivanti dal secondo approccio sono chiamati modelli correspondence [2]. L’argomento di questa tesi è lo sviluppo di modelli per particolari tipi di analisi e la ricerca di possibili vantaggi e inconvenienti di questa teoria nuova ed inesplorata, così da identificare alcune linee guida per la scelta di parametri fondamentali per le analisi. Durante il primo anno del corso di dottorato, lo stato dell’arte relativo a questa teoria è stato studiato e i solutori statici lineari e non lineari nella formulazione bond-based sviluppati precedentemente in ambiente Matlabr sono stati analizzati, usati e migliorati. Durante il secondo anno, l’autrice di questa tesi si è concentrata sulla seconda versione, basata su concetti di matematica avanzata con cui ha preso dimestichezza grazie al corso di analisi funzionale seguito il primo anno. Uno dei principali contributi originali alla letteratura esistente presenti in questa tesi è lo sviluppo dei modelli linearizzati 2D del modello solido lineare nella formulazione state-based. Questi modelli sono particolarmente utili quando semplificazioni di stato piano di tensione o di deformazione possono essere assunte per la simulazione di un sistema tridimensionale, che altrimenti verrebbe descritto da un modello 3D che necessiterebbe di risorse computazionali più elevate (in termini di tempo e memoria). Una particolare attenzione è richiesta per quest’aspetto, perché, essendo un approccio non locale, implementare un codice basato sulla teoria peridinamica richiede in generale più risorse computazionali di un codice basato su un approccio locale. Lo studio della versione state-based è iniziato prima di andare all’estero e lo sviluppo dei modelli 2D si è poi completato durante il soggiorno di sei mesi alla University of Nebraska-Lincoln negli Stati Uniti. Sono stati sviluppati sia un codice dinamico che uno statico. I parametri principali di questi modelli sono stati analizzati e i modelli linearizzati si possono trovare descritti nel capitolo 1.2.2. Lo studio dei criteri di frattura adottabili nella formulazione state-based e il miglioramento degli algoritmi in Matlabr per accelerare i codici e ottimizzare le risorse di memoria e gestione dei dati sono stati gli argomenti principali del terzo anno. Alcuni criteri di frattura, presentati nel capitolo 1.2.3, sono stati proposti per materiali lineari elastici omogenei e caratterizzati da frattura fragile. Sono criteri basati sul massimo allungamento: un’interazione non locale (“bond”) viene meno quando un valore critico di allungamento è raggiunto; questo valore di allungamento critico è calcolato dal lavoro richiesto per rompere il bond e questo lavoro è a sua volta legato all’energia di frattura. I risultati ottenuti sono stati confrontati con dati sperimentali per casi sia statici che dinamici, sia nella formulazione bondbased che in quella state-based. La descrizione dettagliata degli algoritmi si trova nel capitolo 3, mentre i risultati sono riportati nei capitoli 4 e 5.
Marpaung, Fivman. "Investigation of the effect of gel residue on hydraulic fracture conductivity using dynamic fracture conductivity test". Texas A&M University, 2007. http://hdl.handle.net/1969.1/85866.
Pełny tekst źródłaWade, James. "Contact damage of ceramics and ceramic nanocomposites". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24932.
Pełny tekst źródłaZhang, Ming. "On the changes in dynamic behavior produced by the hydraulic turbine runner damage". Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667319.
Pełny tekst źródłaLa energía hidroeléctrica juega un papel muy importante en la generación de electricidad hoy en día. La energía hidroeléctrica es la única fuente de energía renovable que puede proporcionar gran regulacion de potencia con una respuesta rápida, que es precisamente lo que demanda la red eléctrica. El elemento más importante en plantas hidroeléctricas es la turbina hidráulica. La concentración de potencia en turbinas hidráulicas está aumentando muy rápido hoy en día. Como consecuencia, las presiones y velocidades son mayores, y por lo tanto las fuerzas de excitación aumentan. Por otro lado, para mejorar la eficiencia de las turbinas hidráulicas, así como para lograr mayores aceleraciones durante las variaciones de carga, el grosor / peso del rodete se disminuye tanto como es posible, lo que también aumenta es estrés que recibe el rodete. Además, el rango de operación de las turbinas hidráulicas se está viendo ampliado para satisfacer la demanda de los usuarios proporcionando una mayor capacidad de regulación. La operación de las turbinas en condiciones fuera de diseño conlleva todavía a mayores fuerzas y esfuerzos en el rodete. Debido a estas razones, han habido muchos fallos por fatiga de componentes de turbinas hidráulicas en los últimos años. En algunos casos se encontraron grandes fisuras en la estructura, lo que indica que son difíciles de detectar con los actuales sistema de monitoreo de estas máquinas. Para controlar la aparición de fisuras en turbinas hidráulicas, es imprescindible estudiar el efecto de estas fisuras en el comportamiento dinámico de turbinas hidráulicas. El comportamiento dinámico de turbinas hidráulicas se ha estudiado en detenimiento durante la última década.. Sin embargo, la mayoría de estos estudios se centraron en turbinas Francis y bomba turbinas, mientras que el comportamiento dinámico de otros tipos de turbinas hidráulicas, como por ejemplo, las turbinas Kaplan, no ha sido estudiado todavía con detalle. Además, todos estos estudios se realizaron en rodetes sin fisuras, con lo que el efecto de una fisura en el comportamiento dinámico de turbinas hidraulicas todavía no se conoce. En esta tesis se ha estudiado el efecto de una fisura en el comportamiento dinámico de turbinas Kaplan y Francis. El énfasis de la investigación está puesto sobre todo en turbinas Kaplan. Primero se ha estudiado el comportamiento dinámico de un rodete de turbina Kaplan intacto. Luego, basándose en el comportamiento dinámico de los rodetes intactos, se ha investigado el efecto de una fisura en una pala. Para realizar la investigación se ha realizado un estudio sistemático: las investigaciones parten de modelos numéricos, y luego los resultados se han validado con experimentos. Los estudios con los modelos numéricos se han llevado a cabo paso a paso, desde modelos de álabes simplificados hasta un modelo de un álabe de turbina Kaplan o del rodete entero. El conocimiento obtenido en las turbinas Kaplan también se ha aplicado a un rodete de turbina Francis, cuyo comportamiento dinámico se había estudiado previamente.
Wu, Chunquan. "Fault zone damage, nonlinear site response, and dynamic triggering associated with seismic waves". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41143.
Pełny tekst źródłaZumpano, Giuseppe. "Development of damage detection algorithms for structural systems based on structural dynamic data". Thesis, Cranfield University, 2005. http://hdl.handle.net/1826/4231.
Pełny tekst źródłaGemkow, Karla Simone. "Modelling of Damage in Orthotropic Materials: Including Strain-Softening Effects in Dynamic Problems". Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/9302.
Pełny tekst źródłaElmukashfi, Elsiddig. "Modeling of fracture and damage in rubber under dynamic and quasi-static conditions". Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-178048.
Pełny tekst źródłaQC 20150203
Chen, Yanyun. "Stress-induced Damage and Post-fire Response of Aluminum Alloys". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51187.
Pełny tekst źródłaPh. D.
Luo, Huageng. "Damage detection and health monitoring of structures using dynamic response and neural network techniques". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12929.
Pełny tekst źródłaDavies, Rosemary Carolyn. "The effects of exercise-induced muscle damage on the human response to dynamic exercise". Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/111454.
Pełny tekst źródłaWaltering, Markus [Verfasser]. "Damage Assessment of Civil Engineering Structures and Bridges using Nonlinear Dynamic Characteristics / Markus Waltering". Aachen : Shaker, 2009. http://d-nb.info/1161301380/34.
Pełny tekst źródłaMcKenna, Alice J. "Ab initio and molecular dynamic models of displacement damage in crystalline and turbostratic graphite". Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809906/.
Pełny tekst źródłaHtet, Yar Zar Moe. "An Assessment of Moisture Induced Damage in Asphalt Pavements". Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-theses/516.
Pełny tekst źródłaJumpathong, Watthanachai. "The dynamic interplay between DNA damage and metabolism : the metabolic fate and transport of DNA lesions and novel DNA damage derived from intermediary metabolism". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93772.
Pełny tekst źródłaThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
The work presented in this thesis explores two novel and complementary facets of endogenous DNA damage: the development of biomarkers of inflammation based on metabolites of DNA damage products and the formation of DNA adducts by electrophilic products of intermediary metabolism. From the first perspective, endogenous DNA damage generated by reactive oxygen and nitrogen species from inflammation and oxidative stress has shown strong mechanistic links to the pathophysiology of cancer and other human diseases, with the damage products reflecting all types of damage chemistries including oxidation, deamination, halogenation, nitration and alkylation. However, the use of DNA damage products as biomarkers has been limited by poor understanding of the damage actually arising in tissues and a lack of appreciation of the fate of DNA damage products from the moment of formation at the site of damage to release from cells to final excretion from the body. The goal of the work presented in the first part of this thesis was to investigate the metabolic fates of the base propenal products arising from 4'-oxidation of 2'-deoxyribose in DNA, one of the most common products of DNA oxidation, and to define base propenal metabolites as potential biomarkers of oxidative stress. This project was approached with systematic metabolite profiling, starting with prediction of potential base propenal metabolites based on a priori knowledge of its chemical reactivity as an [alpha],[beta]-unsaturated aldehyde toward glutathione (GSH) in non-enzymatic reactions and in rat liver cell extracts. Of 15 potential candidates predicted and identified from these in vitro studies, analysis of urine samples from rats given intravenous doses (IV) of thymine propenal revealed three major metabolites: thymine propenoic acid and two mercapturic acid derivatives, which accounted for ~6% of the injected dose. An additional four metabolites, including conjugates with GSH, cysteinylglycine and cysteine, were observed in bile and accounted for ~22% of the dose. One of the major metabolites detected in urine and bile, a bis-mercapturic acid adduct of reduced thymine propenal was detected as a background excretory product in saline-treated rats and was significantly elevated after oxidative stress caused by treatment with bleomycin and CCl₄. Our observations suggest that metabolism and disposition of damaged biomolecules should be considered as crucial factors in the development of biomarkers relevant to inflammation and oxidative stress. The second part of this thesis addresses the complementary hypothesis that electrophilic metabolites generated endogenously from intermediary metabolism can react with DNA to form adducts. This concept is illustrated here with glyoxylate from the glyoxylate metabolic cycle, whicvh plays a key role as an alternative to the TCA cycle in plants, bacteria, protists and fungi under changing conditions of environmental nutrients. The goal of this project was to characterize DNA adducts caused by glyoxylate in the mycobacterium M. smegmatis, with the studies motivated by the higher-than-expected mutation rate of mycobacteria during dormancy induced by nutrient deprivation and a shift to utilization of the glyoxylate cycle. Initially, in vitro reactions of 2'-deoxyguanosine (dG) with glyoxylate yielded N²-carboxyhydroxymethyl dG (N²-CHMdG) as the only adduct. However, the adduct proved to be unstable, so a reduction-based analytical method was developed to yield the stable amine derivative, N2-carboxymethyl dG (N²-CMdG). This stable adduct was used to develop an isotope-dilution chromatography-coupled tandem mass spectrometry method to quantify N²-CHMdG as N²-CMdG in calf thymus DNA treated with glyoxylate in vitro. This analytical method was then applied to quantify and compare the level N2-CMdG in (1) wild-type M. smegmatis grown in rich medium (7H9) or in minimal M9 medium supplemented with acetate, the latter inducing a switch from the TCA cycle to the glyoxylate cycle; and (2) the isocitrate dehydrogenase (ICD)-deficient mutant of M. smegmatis. Mycobacteria grown in the acetate medium experienced a 2-fold increase in the adduct compared to those grown in 7H9. Similarly, the adduct increased 2-fold in the ICD mutant compared to wild-type M. smegmatis grown in 7H9. The results support the idea that shifts in intermediary metabolism can lead to DNA damage that may cause mutations associated with nutrient deprivation in mycobacteria, with implications for the genetic toxicology of other metabolism-derived electrophiles.
by Watthanachai Jumpathong.
Ph. D.
Bedouet, Sylvain. "Study of damage evolution in a titanium matrix composite under quasi-static and dynamic loading". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/18225.
Pełny tekst źródłaBrown, Graham. "A study of the effect of damage on the dynamic response of masonry arch bridges". Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246045.
Pełny tekst źródłaAl, Mamun Abdullah. "Seismic Damage Assessment of Reinforced Concrete Frame Buildings in Canada". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36188.
Pełny tekst źródłaFerrante, Cavallaro Giovanni. "Pseudo dynamic tests and numerical analysis of free from damage multistorey steel buildings with innovative connections". Doctoral thesis, Universita degli studi di Salerno, 2019. http://elea.unisa.it:8080/xmlui/handle/10556/4277.
Pełny tekst źródłaOne of the most widespread structural systems is represented by Moment Resisting Frames (MRFs). resistant seismic frames. This structural system is made up of frames capable of resisting seismic actions through predominantly flexural tension states. The stiffness and lateral resistance of the system depend on the flexural strength of the members and the type of connection, while the development of the plastic hinges guarantee the dissipation of the seismic input energy. The location of the dissipative zones varies according to the design approach adopted, typically they develop in beams, columns and connections. The most widespread design philosophy is to have strong columns, weak beams and full-strength rigid connections with complete resistance restoration, in this way all the seismic energy tends to be dissipated by the plastic hinges at the ends of the beams and at the base of the columns of the first level. In order to overcome the traditional design approach, the present research work introduces a new type of beam-column connection capable of exhibiting a remarkable rigidity in service conditions (SLE) and able to exhibit a remarkable dissipative capacity when a rare seismic event occurs. The codes currently in force provide that for seismic events characterized by a period of return comparable with the useful life of the structure (frequent or occasional events) the structures remain in the elastic field ensuring that the seismic energy is completely dissipated through viscous damping. Vice versa, the seismic energy must be dissipated through plastic engagement of parts of the structure, with wide and stable hysteresis cycles, for rare and very rare seismic events with a return period of about 500 years. The development of the hysteresis involves structural damage that have to be such as not to lead to the collapse of the structure in order to guarantee the protection of the life of those who occupy the building. The prediction of the behaviour of the structure in non-linear field for rare seismic events represents an aspect that only experimental research can describe in depth by developing new analytical models and innovative design philosophies. The execution of quasi-static tests can provide useful information in order to investigate the nonlinear behaviour of the members and the assemblages even if the forces or the displacement histories applied during the tests do not correspond exactly to the actions that occur during a real seismic event. The information obtained through these test procedures is however useful for calibrating analytical models and comparing the behaviour of structural components. The execution of tests on real scale structures is the best way to investigate the global behaviour of a structural system. For a more complete knowledge about the response in the dynamic field, the pseudo-dynamic tests represent a test protocol able to provide information of the structural response of a component or of a structure in a dynamic field through a static test. The main purpose of this work, developed within the FREEDAM research project financed by the European Community, is to develop an innovative beam-column connection. These innovative connections are equipped with an additional damper able to dissipating the energy deriving from destructive seismic events. The FREEDAM beam-column connection, through an appropriate design of the various components, is able to withstand frequent earthquakes and rare events without causing damage to the structural elements. The thesis is divided into six chapters. The Chapter 1 reports a brief introduction to the traditional beam-column connections, specifying the characteristics of the different types of connection and their influence on the behaviour of the Moment Resisting Frames. In the last part of the chapter the FREEDAM dissipative connection is presented, specifying its peculiarities and the benefits that its introduction into the structural system brings. The Chapter 2 is devoted to the description of the results obtained from an extensive experimental campaign developed at the STRENGTH laboratory of the University of Salerno, for the choice of material for the friction dampers used in the FREEDAM connections by carrying out a statistical characterization of the static and dynamic friction coefficients. The Chapter 3 collects the results of a further experimental campaign carried out at the University of Salerno laboratory and aimed at studying the tightening losses for pre-loading bolt systems equipped with different washers. In Chapter 4 a design procedure has been define for the FREEDAM beam-column connections, then this procedure has been applied in order to design two different types of connections that have been experimentally tested at the University of Coimbra Laboratory (PT). In the same chapter, the test layouts and the results obtained from the cyclic tests carried out on the nodes equipped with FREEDAM friction dampers have been described, finally developing models to the finite elements and comparing the experimental results with the computerized models. Finally, the Chapter 5 shows the results of the pseudo-dynamic tests carried out on a full-scale steel Moment Resistant Frame equipped in a first case with traditional full strength beam-column connections (dogbone) and in a second case equipped with the innovative connections proposed. These results have been compared to each other and with the results obtained from finite element models. [edited by Author]
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