Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2018-12-12T11:03:02Z No. of bitstreams: 1 Joao Batista Lamari Palma e Silva.pdf: 6384826 bytes, checksum: 7f07e131301eff9f4bf2ddb19d173b2b (MD5) / Made available in DSpace on 2018-12-12T11:03:02Z (GMT). No. of bitstreams: 1 Joao Batista Lamari Palma e Silva.pdf: 6384826 bytes, checksum: 7f07e131301eff9f4bf2ddb19d173b2b (MD5) Previous issue date: 2018-10-09 / The structures of reinforced concrete, although extremely diffused, require special attention from its conception, utilization its operation. This kind of attention could contribute for developing more useful time of usage, as since, the pathologies could be most varieties in complexes conditions, and so far is to analyze the integrity of the complexity of the structural condition. Structural Heart Monitoring (SHM) seeks the process of monitoring the behavior of the structure in order to assess the structure's conditions verifying the occurrence of damages and eventually in case of need for interventions, aiming at structural rehabilitation. The automated SHM uses data acquisition which acts as an interface between the sensors installed in the structures and the computational systems could be very complex and expensive. This work had the initiative to use the Arduino platform, which one is an electronic prototyping system, which uses an Atmel microcontroller, free hardware and software, with Analog/Digital inputs and outputs, low cost and relative ease of operation. The objective of this research was the development of a structure monitoring system, based on data collection from strain, displacement and force sensors, on reinforced concrete structures, for the acquisition and remote transmission of data, for processing and analysis of information. A data acquisition system was built with the Arduino platform, and this system has been used besides the platform in question, signal amplifiers and Wheatstone Bridge type circuits. A mobile application as a type of software has been developed, compatible with the Android operating system, through a smartphone or tablet, it was possible to control the Arduino through wireless communication via Bluetooth. This application sends and receives data, which is processed and analyzed analytically and graphically, resulting from the information of the sensors installed in the structures, which enables the transmission of the data in real time, via the internet. This system was tested in bending tests of metallic cantilever and reinforced concrete beams, instrumented with electric resistance strain gauges installed in the reinforcement and concrete, as displacement transducers and load cells. In addition to this structure, the system was also tested on a reinforced concrete column supporting a crane, with the installation of strain gauges in the reinforcement. In these tests, the data acquisition was made by two different systems, the first one being a commercial data acquisition purchaser and the second the system object of this research, to compare the data of the readings, obtained between both equipment and analytical values, establishing satisfactory results. / As estruturas de concreto armado, ainda que extremamente difundidas, requerem especial aten??o desde sua concep??o at? sua utiliza??o. Esta aten??o pode ser usada para contribuir com o aumento de sua vida ?til, j? que as patologias podem ser das mais variadas naturezas e causas, o que em muitas vezes torna a an?lise das condi??es de integridade estrutural muito complexa. O Monitoramento da Integridade Estrutural (MIE) busca acompanhar o comportamento da estrutura, para avaliar suas condi??es, inclusive para verificar a ocorr?ncia de danos e das eventuais necessidades de interven??es, visando a reabilita??o estrutural. O MIE automatizado emprega aquisitores de dados que atuam como interface entre os sensores instalados nas estruturas e os sistemas computacionais, tornando sua utiliza??o complexa e cara. Este trabalho teve por iniciativa empregar a plataforma Arduino, que ? um sistema de prototipagem eletr?nica, que utiliza um microcontrolador Atmel, de hardware e software livres, com entradas e sa?das anal?gicas/digitais, de baixo custo e relativa facilidade de opera??o. Com isto, o objetivo da pesquisa foi o desenvolvimento de um sistema de monitoramento de estruturas, baseado em coleta de dados provenientes de sensores de deforma??o, deslocamento e for?a, em estruturas de concreto armado, para aquisi??o e transmiss?o remota de dados, para processamento e an?lise das informa??es. Foi constru?do um sistema de aquisi??o de dados, com a plataforma Arduino, sendo que este sistema emprega al?m da plataforma em quest?o, amplificadores de sinais e circuitos el?tricos do tipo Ponte de Wheatstone. Desenvolveu-se um software do tipo aplicativo mobile, compat?vel com o sistema operacional Android, para que por meio de um smartphone ou tablet, fosse poss?vel controlar o Arduino, mediante comunica??o sem fio via Bluetooth. Este aplicativo envia e recebe dados, que s?o processados e analisados anal?tica e graficamente, decorrentes das informa??es dos sensores instalados nas estruturas, o qual possibilita a transmiss?o dos dados em tempo real via internet. O sistema foi testado em ensaios de flex?o de l?minas met?licas e vigas de concreto armado, instrumentadas com extens?metros de resist?ncia el?trica instalados na armadura e no concreto, como transdutores de deslocamento e c?lulas de carga. Al?m desta estrutura, o sistema tamb?m foi testado em um pilar de concreto armado de sustenta??o de uma ponte rolante, com a instala??o de extens?metros na armadura. Nestes testes, a aquisi??o de dados foi feita por dois sistemas distintos, sendo o primeiro um aquisitor de dados comercial de refer?ncia e o segundo o sistema objeto desta pesquisa, para compara??o dos dados das leituras obtidas entre ambos equipamentos e valores anal?ticos, tendo sido obtidos resultados satisfat?rios.

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-28T12:31:16Z (GMT). No. of bitstreams: 1 Loureiro_Daniel_M.pdf: 3345826 bytes, checksum: a140e145cbae9ae1a5f3f14eaee94c0f (MD5) Previous issue date: 2015 / Resumo: As ligas de níquel são utilizadas em diversos setores industriais sempre que há necessidade de se associar elevada resistência mecânica com resistência à corrosão, ao desgaste e à oxidação. No entanto, as ligas de níquel apresentam baixa usinabilidade, implicando em processos relativamente ineficientes nos quais o desgaste da ferramenta e a integridade superficial são os principais fatores limitantes. A baixa usinabilidade destas ligas está relacionada com as suas características inerentes, tais como: alta dureza e resistência mecânica a quente, altas tensões de cisalhamento durante o processo de corte, alta taxa de encruamento, presença de carbonetos abrasivos na matriz, baixa condutividade térmica e soldagem da peça e da aresta de corte. Dentre as ligas de níquel, uma que apresenta propriedades desejadas para a indústria de exploração de petróleo é a liga 625. O objetivo do presente trabalho é a verificação da integridade da superfície usinada da liga 625, pela caracterização através da rugosidade, microestrutura, microdureza Vickers da superfície e da subsuperfície e da tensão residual de oito diferentes superfícies torneadas com diferentes geometrias da ferramenta (positiva e negativa) e diferentes condições de usinagem. Neste trabalho foram avaliados os danos que o torneamento em condições de acabamento proporciona à superfície usinada e que podem resultar em variação da resistência à corrosão e à fadiga. Dentre os principais resultados destaca-se aquele que aponta que as superfícies torneadas com geometria positiva da ferramenta produziram tensões compressivas na superfície, enquanto aquelas torneadas com ferramentas negativas produziram tensões trativas na superfície / Abstract: The nickel alloys are used in many industrial sectors where there is a need to associate high mechanical strength with resistance to corrosion, wear and oxidation. However, nickel alloys have poor machinability, resulting in relatively inefficient process wherein tool wear and surface integrity are the limiting primary factors. The low machinability of these alloys is related to their inherent characteristics, such as hot hardness and mechanical resistance, high shear rates during the cutting process, high work hardening rate, presence of abrasive carbides in the matrix, low thermal conductivity and welding the workpiece and cutting edge. Among the nickel alloys, one that has desired properties to the oil exploration industry is the alloy 625. The aim of this work is the check of the surface integrity through the characterization by roughness, microstructure, microhardness of the surface and sub- surface and residual stress, of eight turned different surfaces with different geometries tool (positive and negative) and machining conditions. This study evaluated the damage that finish conditions provides to the machined surface and witch can result in variations of resistance to corrosion and fatigue. Among the main results stands out the one who points out that turned surfaces with positive tool geometry produced compressive residual stresses on the surface, while those with negative turned tools produced tensile residual stresses on the surface / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Motor coaches are an integral part of the transportation system. It was observed that occupant fatalities and serious injuries occur in rollover more frequently than in any other type of accidents for these vehicles. Several regulations such as Economic Commission for Europe Regulation 66 (ECE R66) are issued to minimize the catastrophic consequences of rollover accidents. Passing “Motorcoach safety plan” which is based on a complete vehicle rollover test of ECE R66 will be mandatory in North America in the near future. However, the cost of a single physical test encourages researchers to perform numerical simulations prior to a complete vehicle rollover test. In this thesis, the integrity of a coach seat and the effects of different restraint configurations on the safety of passengers in rollover are numerically studied. To perform this research, a new modeling approach, which is computationally effective and highly suitable for parametric studies, is proposed. Firstly, a detailed model of two seats of a coach is developed and validated against experimental results. Anthropomorphic Test Devices are then introduced to the model and acceleration history of a physical rollover test is imposed on the system. The model is solved using non-linear explicit dynamic Finite Element code LS-DYNA®. Injury criteria values are extracted and compared to the experimental results. An acceptable level of correlation is achieved that confirms the validity of the model and the reliability of the modeling approach. The integrity of the seat in a rollover is analyzed showing the necessity of an anchorage test prior to a whole coach rollover test. The results of a parametric study on the safety of passengers reveal the high probability of partial ejection if the retractor does not lock properly in a rollover. It is also shown that the safety of occupants can be improved if retractor pretensioners be introduced to coaches. / February 2017

[pt] O presente trabalho analisa o impacto de uma mossa simples transversal na integridade estrutural de espécimes tubulares de paredes finas com dimensões e características semelhantes aos dutos usados para transporte de óleo e gás. O estudo da mossa simples envolveu as etapas de criação, recuperação elástica e avaliação da sua resistência estática e cíclica. A abordagem do problema fundamentou-se na análise de dados experimentais e na modelagem numérica por elementos finitos. Na análise por elementos finitos foram consideradas: não linearidade por contato, plasticidade, grandes deslocamentos e grandes deformações. Adicionalmente, foram feitas comparações entre os resultados e os procedimentos usados na indústria, de modo a avaliar criticamente eventuais diferenças e semelhanças entre estes. Como resultado, a avaliação da ruptura estática permitiu verificar a pouca influência de mossas, com a geometria estudada, na resistência à ruptura. Entretanto, os códigos de projeto estudados não aceitam mossas com profundidades e deformações menores que as estudadas. A avaliação de resistência cíclica permitiu verificar a influência deste tipo de dano na vida à fadiga. No final foi elaborada uma rotina simples, baseada em fundamentos teóricos, que permite quantificar a vida à fadiga de mossas, com características similares, a partir do seu fator de concentração de tensão. / [en] This work analyzes the impact of transverse plain dents in the structural integrity of thin-thickness pipe specimens with similar dimensions and properties than typical pipelines. The dent analyzes included the following topics: creation, burst and fatigue evaluation and elastic recuperation. The problem was based in the study of experimental data and numerical modeling by finite elements. The numerical modeling considered: non linearity by contact, plasticity, large displacement and large strain. Finally, comparisons were made between the results and the typical industry procedures, in order to identify eventual differences and similarities. The burst evaluation indicated the low influence of the studied plain dents in the burst resistance. Otherwise, the project standards do not accept dents with the depth and strain levels like those studied. The cyclic analyze verified the influence of this type of damage in the fatigue life. At the end of this study, a simple procedure was developed based in theoric fundamentals to quantify the fatigue life of plain dents, with similar characteristics studied above, using their intensity stress factor.

A demanda crescente por energia tem motivado a procura por petróleo e gás natural em ambientes com condições extremas, como operações em águas profundas e o transporte de fluídos corrosivos. Avanços tecnológicos recentes favorecem o uso de tubos de aço contendo uma camada interna resistente a corrosão (comumente chamados de Lined ou Clad Pipes) para o transporte de tais fluidos agressivos. Além disso, as tubulações submarinas são sujeitas a condições de instalação muito severas e, um caso de interesse, é o procedimento de reeling que permite com que a fabricação e inspeção da tubulação seja feita em terra. Apesar de possuir vantagens econômicas, a avaliação da integridade estrutural e especificação dos tamanhos toleráveis de trinca em juntas soldadas, nestas condições, torna-se uma tarefa complexa, devido a natureza dissimilar dos materiais e ao grande nível de deformação plástica no processo. Dessa maneira, este trabalho tem por objetivo o desenvolvimento de um procedimento de avaliação de forças motrizes elasto-plásticas em tubos contendo juntas soldadas circunferenciais sujeitos a flexão, para uma extensa gama de configurações geométricas. Dois métodos distintos foram desenvolvidos e analisados: a metodologia EPRI e o procedimento que utiliza a curva de tensão vs. deformação equivalente. As análises numéricas 3D fornecem os parâmetros de fratura necessários para a resolução do problema e a acurácia dos procedimentos é verificada a partir de estudos de casos e análises paramétricas. / The increasing demand for energy has motivated the oil and natural gas exploration in very hostile environments, including very deep water operation and the transport of corrosive fluids. Technological advances favor the use of high strength steel pipelines either clad or mechanically lined with a corrosion resistant alloy (CRA), such as Alloy 625, for the transport of corrosive hydrocarbons. Moreover, these pipelines are subjected to severe installation conditions and a case of interest is the pipe reeling process, which allows pipe welding and inspection to be conducted at onshore facilities. While cost effective, fracture assessments and specification of critical flaw sizes for the girth welds of lined/clad pipes are more complex due to the dissimilar nature of these materials and the high levels of plastic strain imposed during installation. In particular, effective analyses of crack driving forces in undermatched or partially mismatched pipe girth welds remain essential to determine more accurate acceptable flaw sizes for the piping system based upon conventional ECA procedures. This work focuses on the development of a procedure to determine the elastic-plastic crack driving forces for pipe girth welds with circumferential surface cracks subjected to bending load for a wide range of geometries and weld mismatch levels based upon based methodologies: the GE-EPRI framework and the equivalente stress vs. strain curve. The study also addresses the potential effects of an undermatching girth weld on critical flaw sizes. The extensive nonlinear, 3-D numerical analysis provide the fracture parameters for cracked pipes and cylinders with mismatched girth welds which will be applied in case studies and parametric analyses in order to verify the accuracy of the methods.

Este trabalho busca avaliar o efeito da sobrepressão interna na avaliação crítica de engenharia (ECA) de dutos submersos sujeitos a flambagem lateral controlada, que essencialmente consiste na análise de carregamentos combinados associados a grandes deformações longitudinais. O objetivo principal é avaliar a viabilidade da adoção de corpos-de-prova SENT na avaliação da resistência à fratura em dutos sujeitos a esforços combinados utilizando procedimentos analíticos que incorporam do aumento das forças motrizes devido à sobrepressão interna. Este estudo apresenta uma revisão sobre os procedimentos de ECA utilizados em dutos submersos e sobre o efeito da pressão interna na capacidade de deformação de dutos. Os procedimentos adotados atualmente e procedimentos alternativos são discutidos e implementados em um problema prático envolvendo diferentes razões de diâmetros por espessuras, expoentes de encruamento, níveis de sobrepressão e deformação longitudinal. Alguns casos selecionados são comparados com soluções elasto-plásticas de J, e.g. EPRI. Os resultados apresentados fornecem uma boa compreensão sobre as vantagens e limitações de cada procedimento, incluindo a possibilidade de estender sua aplicação além do limite normativo de 0,4% de deformação longitudinal. / This work aims to evaluate the effect of internal overpressure on the engineering critical assessment (ECA) of submarine pipelines subjected to controlled lateral buckling, which essentially consists of the analysis of combined loading with large longitudinal strains at the buckle crown. The main goal is to evaluate the feasibility of using SENT specimens to characterize the fracture resistance in the assessments of pipelines subjected to combined loadings using analytical procedures that takes into account the increase of crack driving force due to internal overpressure. This study presents a revision about ECA procedures used in submarine pipelines and about the effect of biaxial stresses their tensile strain capacity. Both standard and alternative procedures are discussed and implemented in a practical problem involving different diameter to thickness ratios, hardening exponents, levels of internal pressure and longitudinal strain. Some selected cases are compared with full elastic-plastic J solutions, e.g. EPRI. The results provide useful insights regarding the advantage and limitations of each procedure, including the possibilities to extend their applicability beyond the standard limit of 0,4% of longitudinal strain.

Este trabalho trata sobre o estudo numérico das forças motrizes (J e CTOD) em corpos-de-prova SE(T), usualmente extraídos da junta soldada do componente estrutural defeituoso, especificamente dutos submarinas (risers) com trincas circunferências alocadas no metal de solda. Durante o processo de instalação (reeling method) o duto é submetido a grandes carregamentos cíclicos (principalmente momentos de flexão) os quais introduzem fortes deformações plásticas (~2 e ~3%) afetando diretamente a integridade estrutural e a operação segura do sistema dutoviário. Procedimentos correntes aplicados na determinação da tenacidade à fratura de materiais, frequentemente, baseiam-se no coeficiente adimensional de proporcionalidade plástica (o fator n) e tem se mostrado válido em espécimes homogêneos. Para configurações com dissimilaridade mecânica, a aplicação direta deste método fica comprometida pelo grau de complexidade que existe entre a relação acoplada das forças motrizes (J e CTOD) e carregamento remoto com a dissimilaridade mecânica introduzida pelo processo de soldagem. O objetivo da presente tese é desenvolver um procedimento numérico de estimação de parâmetros de mecânica da fratura aplicáveis em configurações não padronizadas SE(T) para condições de dissimilaridade mecânica (weld strength mismatch). Uma extensiva análise de elementos finitos é desenvolvida na obtenção dos fatores n aplicáveis para espécimes SE(T) com várias profundidades de trincas (a/W) e níveis de dissimilaridade mecânica (My) para dois tipo de carregamento: garra (clamped end) e pino (pin loading). Três diferentes, mas correlatos métodos são aplicados para a obtenção acurada dos fatores n em condição de dissimilaridade mecânica, a saber, são: trabalho plástico, separação de cargas e carga limite. Os efeitos tridimensionais são analisados de forma sistemática para diferentes valores de espessura (B/W) e comprimentos do espécime (H/W) com a finalidade de avaliar a robustez das soluções obtidas das análises em estado plano de deformação. Finalmente, os resultados obtidos fornecem suporte para uso de espécimes SE(T) em procedimentos de avaliação de defeitos em dutos soldados submetidos a carregamento de flexão. / This work focuses on the numerical study of crack driving forces (J and CTOD) on single edge notch in tension (SE(T)) specimens usually extracted from defective structural components, specifically, circumferentially welded cracked pipes. The most efficient procedure to deploy submarine pipes (risers) on the sea floor is the reeling method. This procedure introduces a huge amount of cyclic loading to the girth welded pipe during the installation causing permanent plastic deformation (around ~2 to ~3%), which can affect the structural integrity and safe operation of the pipeline system. Current material fracture toughness procedures rely upon accuracy of proportionality plastic coefficient (also known n factor), which has to be effective for homogeneous condition. For mismatched configurations, where the strength of the weld metal is higher than the strength of base metal (also referred as overmatching), the direct applicability of such procedures remains a key aspect for defect assessment procedures and fitness for service codes, due to the complexity of the univocal relationship between crack driving forces and remote loading and the weld strength mismatch effect. The goal of the present thesis is to develop an estimation procedure of fracture mechanics parameters (J and CTOD) for SE(T) specimens in heterogeneous conditions. Extensive finite element analyses were conducted in order to obtain n factors for mismatched SE(T) specimens with varying crack lengths (a/W), different levels of overmatch (My) and two loading schemes (clamped and pin loading). Three different but related methods are applied to compute the n factor for welded mismatch configurations, namely the plastic work, load separation and limit load method. Also, the 3D effects are systematically analyzed for different thickness (B/W) and different specimen lengths (H/W) in order to prove the robustness of the proposed solutions derived from FE analyses in plane strain conditions. Finally, the results provide strong support for the use of constraint designed SE(T) specimens in fracture assessments of circumferential surface cracks in girth welded pipes subjected to bending moment.

Advances in dynamic fracture modelling have become more frequent due to increases in computer speed, meaning that its application to industrial problems has become viable. From this, the author has reviewed current literature in terms of graphite material properties, structural dynamics, fracture mechanics and modelling methodologies to be able to address operational issues related to the ageing of Advanced Gas-cooled Reactor (AGR) cores. In particular, the experimentally observed Prompt Secondary Cracking (PSC) of graphite moderator bricks which has yet to be observed within operational reactors, with the objective of supporting their plant life extension. A method known as eXtended Finite Element Method with Cohesive Zones (XCZM) was developed within Code_Aster open-source FEM software. This enabled the incorporation of velocity toughening, irradiation-induced material degradation effects and multiple 3D dynamic crack initiations, propagations and arrests into a single model, which covers the major known attributes of the PSC mechanism. Whilst developing XCZM, several publications were produced. This started with first demonstrating XCZM's ability to model the PSC mechanism in 2D and consequently that methane holes have a noticeable effect on crack propagation speeds. Following on from this, XCZM was benchmarked in 2D against literature experiments and available model data which consequently highlighted that velocity toughening was an integral feature in producing energetically correct fracture speeds. Leading on from this, XCZM was taken into 3D and demonstrated that it produced experimentally observed bifurcation angle from a literature example. This meant that when a 3D graphite brick was modelled that the crack profile was equivalent to an accepted quasi-static profile. As a consequence of this validation, the XCZM approach was able to model PSC and give insight into features that could not be investigated previously including: finer-scale heterogeneous effects on a dynamic crack profile, comparison between Primary and Secondary crack profiles and also, 3D crack interaction with a methane hole, including insight into possible crack arrest. XCZM was shown to improve upon previous 2D models of experiments that showed the plausibility of PSC; this was achieved by eliminating the need for user intervention and also incorporation of irradiation damage effects through User-defined Material properties (UMAT). Finally, while applying XCZM to a full-scale 3D graphite brick including reactor effects, it was shown that PSC is likely to occur under LEFM assumptions and that the Secondary crack initiates before the Primary crack arrests axially meaning that modal analysis would not be able to fully model PSC.

En esta Tesis Doctoral se analiza el fenómeno de la pérdida de confinamiento en el plano de aplicación de la carga de componentes industriales y estructuras. El análisis ordinario propuesto por la mecánica de la fractura no tiene en cuenta este fenómeno, dando lugar a resultados que en muchos casos son excesivamente conservadores.Los orígenes de la pérdida de confinamiento son diversos, destacando la superficialidad del defecto, el predominio de cargas de tracción y el efecto entalla. Las distintas teorías existentes analizan estos fenómenos de forma independiente.Este trabajo propone un modelo global justificado teóricamente que analiza de forma conjunta las diferentes fuentes de pérdida de confinamiento. Con objeto de validarlo, se presentan los resultados del programa experimental realizado al efecto y, posteriormente, se comparan dichos resultados con las predicciones del modelo. / This Doctorate Thesis analyses the phenomenon of the loss of constraint on the load application plane on industrial components and structures. The ordinary assessments proposed by the Fracture Mechanics Theory do not take into account this phenomenon, giving many times overconservative results.Two clearly distinct sources of low constraint are distinguished: that caused by the predominance of tensile loads and shallow defects and that produced by the notch effect. Both types of loss of constraint have been analysed by several authors, but in a rather disjointed way and without a global focus that might allow cases in which both situations arise simultaneously to be analysed.This work proposes an overall constraint procedure, theoretically justified, that allows analysing situations where the different sources of constraint coexist. Also, the results of the validation experimental programme are presented and compared to the predictions of the model.

Στην παρούσα διδακτορική διατριβή περιλαμβάνεται το αποτέλεσμα εκτεταμένης συγκριτικής μελέτης των μεθόδων που χρησιμοποιούνται στη διάγνωση της εισαγωγής και της εξέλιξης της οστεοπόρωσης. Η οστεοπόρωση, όπως και όλες οι μεταβολικές νόσοι των οστών, αποτελούν ένα σημαντικό πρόβλημα της παγκόσμιας υγείας. Πολλές τεχνικές έχουν προταθεί και εφαρμόζονται για τη διάγνωση της οστεοπόρωσης αλλά και για την παρακολούθηση της εξέλιξής της, με ταυτόχρονη αξιολόγηση της επίδρασης των θεραπευτικών αγωγών. Η μέθοδος της μέτρησης του Μορφικού Συντελεστή Απόσβεσης αποτελεί μια τεχνική γνωστή στην παγκόσμια βιβλιογραφία για την εκτίμηση της ποιότητας των κατασκευών με μη καταστροφικό τρόπο. Η διερεύνηση της δυνατότητας εφαρμογής της μεθόδου στην αξιολόγηση της δομικής ακεραιότητας των οστών με παράλληλη ανάπτυξη θεωρητικού μοντέλου το οποίο υποστηρίζει την ορθότητα των πειραματικών αποτελεσμάτων αποτέλεσε το βασικό στόχο της έρευνας. Ειδικότερα, περιλαμβάνεται αναλυτική έρευνα βιβλιογραφίας στην περιοχή του μη καταστροφικού ελέγχου συμβατικών κατασκευών και υλικών, και ανάπτυξη των κυριότερων τεχνικών που εφαρμόζονται στην καθημερινή κλινική πρακτική για τον διαγνωστικό έλεγχο της οστεοπόρωσης και γενικότερα των παθήσεων του μυοσκελετικού συστήματος [τεχνικές πυκνομετρίας (pQCT, DEXA, QUS, κ.λ.π) αλλά και τεχνικές που ανιχνεύουν μεταβολές των οστών σε επίπεδο αρχιτεκτονικής (ιστομορφομετρία) και σε μοριακό επίπεδο (βιοχημικοί δείκτες), καθώς και φασματοσκοπία Raman] με τα πλεονεκτήματα και μειονεκτήματα κάθε μεθόδου. Λόγω της πολυπλοκότητας του υλικού του οστού, παρατίθενται αναλυτικά οι μηχανικές του ιδιότητες. Στη συνέχεια αναπτύσσεται το θεωρητικό μοντέλο υπολογισμού του Μορφικού Συντελεστή Απόσβεσης και παρουσιάζεται το εκτεταμένο πειραματικό μοντέλο που εφαρμόστηκε σε επίμυες και γυναίκες. Από τη σύγκριση των πειραματικών αποτελεσμάτων της μεθόδου του Συντελεστή Απόσβεσης και των συμβατικών τεχνικών που χρησιμοποιούνται για τη διάγνωση της οστεοπόρωσης με τις αναλυτικές τιμές υπολογισμού του Συντελεστή Απόσβεσης αναδεικνύεται η υψηλή ευαισθησία της προτεινόμενης μεθόδου και τεκμηριώνεται η ωριμότητά της για αποτελεσματική, επαναλήψιμη, έγκυρη και αξιόπιστη αξιολόγηση της δομικής ακεραιότητας των οστών. / Extended comparative study of the methods used in the diagnosis of osteoporosis is included in this thesis. Osteoporosis, as well as all metabolic diseases of bones, consist an important health problem. Many techniques have been proposed and are applied for monitoring of osteoporosis with simultaneous assessment of the effect of therapeutical treatment. Measurement of Modal Damping Factor is a worldwide known technique for the non destructive assessment of structural integrity. The potential of application of this method on the assessment of structural integrity of bones, in combination with development of theoretical model supporting the experimental results has been the main target of this research. Specifically, in the frame of the research, a thorough state of the art has been elaborated in the domain of non destructive testing of conventional structures and materials, as well as on the main techniques applied on everyday clinical practice for diagnosis of osteoporosis and of metabolic diseases of bones [bone density techniques (pQCT, DEXA, QUS), techniques detecting architectural changes (histomorphometry), molecular changes (biochemical markers) and Raman Spectroscopy], accompanied by the advantages and disadvantages of each approach. Due to the complexity of bone structure, its mechanical properties are presented, accompanied by the theoretical model, from which the Modal Damping Factor is calculated, and the experimental model that was applied on osteoporotic rats and women. The comparison between experimental results of Modal Damping Factor and of data from conventional methods used for diagnosis of osteoporosis with the analytical values of Modal Damping Factor permits for elevating the high sensitivity of the proposed method and documenting its maturity for effective, repetitive, and accurate assessment of bone structural integrity.