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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Mechanical Behaviour under Tensile Loading of Textile Reinforced Concrete with Short Fibres

Barhum, Rabea, Mechtcherine, Viktor January 2011 (has links)
This treatise addresses the influence of the addition of short dispersed and integral fibres made of alkali-resistant glass on the fracture behaviour of textile-reinforced concrete (TRC). A series of uniaxial, deformation-controlled tension tests was performed to study the strength-, deformation-, and fracturebehaviour of thin, narrow plates made of TRC both with and without the addition of short fibres. Furthermore, uniaxial tension tests on specimens reinforced with only short fibres and single-fibre pullout tests were carried out to gain a better understanding of crack-bridging behaviour, which suppresses crack growth and widening. Various effects of the addition of short fibre on the stress-strain relationship and cracking behaviour of TRC were observed and discussed with reference to microscopic investigation of fractured surfaces.
72

An experimental-analytical scale-linking study on the crack-bridging mechanisms in different types of SHCC in dependence on fiber orientation

Curosu, Iurie, Muja, Erjon, Ismailov, Mansur, Hamza Ahmed, Ameer, Liebscher, Marco, Mechtcherine, Viktor 04 March 2023 (has links)
A scale-linking, experimental study complemented by an analytical model was carried out to investigate the influence of fiber orientation on the crack-opening behavior of strain-hardening cement-based composites (SHCC). Three SHCC compositions were investigated with polyvinyl alcohol (PVA) and ultra-high molecular weight polyethylene (UHMWPE) fibers in combination with normal- and high-strength matrices. The micromechanical experiments with fiber inclinations of 0◦, 30◦, 45◦, and 60◦ involved fiber embedment in plain and fiber-reinforced specimens. The experimentally derived micromechanical parameters were input into an analytical crack-bridging model to assess the upscaling accuracy of the micromechanical results by comparing the predicted crack-bridging laws to the single-crack opening behavior of equivalent miniature SHCC specimens with controlled fiber orientation. This study yields new insights into the effect of fiber orientation on the crackbridging properties of different types of SHCC, assesses the link between micromechanical and composite scale properties, offers a solid experimental basis for refining the analytical models, and developing anisotropic materials models for SHCC in dependence on fiber orientation.
73

Optimization of Pedicle Screw Depth in the Lumbar Spine: Biomechanical Characterization of Screw Stability and Pullout Strength

Buckenmeyer, Laura 14 June 2013 (has links)
No description available.
74

A GFRP Bar Bond Stress and Strength: Comparison of Beam-bond and Pullout Tests Results

Makhmalbaf, Elyas January 2015 (has links)
Four beam-bond test specimens, two in accordance with RILEM TC-RC5 recommendation, labelled as RILEM and two based on a modified form of the ACI 208 beam-bond test method, labelled as Notched, were tested in four-point bending to investigate the bond stress distribution and values along the bar embedment length of a 15 𝑚𝑚 nominal diameter GFRP rebar. The beams experienced failure through the rupturing of the longitudinal GFRP tensile reinforcement. In addition, two Modified and ten Standard pullout specimens were tested using the same bar. The beam-bond and the Modified pullout specimens had embedment length of 600 𝑚𝑚 while the Standard pullout specimens had, in accordance with CSA S806, 60 𝑚𝑚 embedment, or four times the bar nominal diameter. The first Modified pullout specimen experienced concrete splitting failure and as a result, the second was lightly confined and failed by GFRP bar rupture. All ten Standard pullout specimens failed due to bar pullout. It was determined that the actual bond stress distribution as a function of the embedment length is practically parabolic and can be described by the derivative of a modified form of the logistic growth function used to approximate the strain distribution along the embedment length. Furthermore, the maximum bond stress location progressively moves from the loaded-end towards the unloaded-end as the bond continues to deteriorate with increasing GFRP stress levels. The development length recommendations by ACI 440.1 and to a lesser degree, CSA S806 and CSA S6 are quite conservative compared to that which is required. It is observed that pullout tests alone cannot provide sufficient knowledge regarding the bond behaviour of FRP reinforcement; consequently, the results of beam-bond testing are more appropriate. Standard pullout tests may be incorporated into quality assurance programs with the understanding that they cannot provide valuable information regarding bond stress distribution and required development length in real structural elements with large embedment lengths. In terms of the beam-bond test method, the RILEM TC-RC5 design recommendation appears to be superior since it eschews severe stress perturbation caused by incidence of flexural cracks at beam midspan. As a result, it produces stability in the terms of the data gathered from the strain gauges placed on the GFRP bar. This benefit outweighs the ease of constructability of the Notched beams as well as their resemblance to real beams. / Thesis / Master of Applied Science (MASc) / The force that bonds a reinforcing rod to concrete is determined using three test methods. Each method is recommended by some design standards, but it is unclear how the results of these tests compare to each other. To shed light on the issue, a 15 𝑚𝑚 fibre glass rod was tested using three well-known test methods. It was discovered that two of the methods give results that are reasonably close while the third gives variable results that generally do not agree with the results of the other two. It was also discovered that the required embedment length recommended for such a bar by design codes and standards are relatively excessive because they underestimate the actual bond strength of the rod. Since sometimes it may be difficult to provide such long length in practice, it is recommended that the code requirements be revisited.
75

Bond and Material Properties of Grade 270 and Grade 300 Prestressing Strands

Loflin, Bryan 28 July 2008 (has links)
The first objective of this thesis was to determine the material properties of grade 270 and grade 300 prestressing strand of various sizes. Tension tests were performed on each type of strand. The data from these tests was used to determine modulus of elasticity, yield stress, ultimate stress, and ultimate elongation for each strand. The yield stresses and ultimate stresses for many of the strands did not meet the requirements found in ASTM A416. The ultimate elongation results far exceeded the requirements and the measured elastic moduli were near the modulus recommended by AASHTO LRFD. A secondary objective from the tension tests was to evaluate a gripping method which used aluminum tubing to cushion the strands against notching. The grips performed very well. Most of the strand breaks did not occur in the grips and when a strand did break in the grips, the failure occurred after significant post-yield elongation. The second objective was to evaluate the bond properties of grade 270 and grade 300 prestressing strands. The North American Strand Producers (NASP) Bond Test and Large Block Pullout Test (LBPT) were performed on six different strand grade and strand size combinations. Both of the tests are simple pullout tests on untensioned strand. The results for each strand type were compared to one another as well as to measured transfer and development lengths from beams using the strand from the same reel. All of the strands showed sufficient bond in the beams, but one strand type did fail both the NASP Test and the LBPT. Both pullout tests were acceptable methods to evaluate strand surface condition and the benchmarks set for 0.5 in. diameter regular strand were conservative for the strands used in this thesis. Little difference was evident in the bond performance of grade 270 and grade 300 prestressing strand. / Master of Science
76

[en] EXPERIMENTAL AND NUMERICAL INVESTIGATION OF DAMAGE AND STRESS TRANSFER MECHANISMS IN CEMENT MATERIALS / [pt] INVESTIGAÇÃO EXPERIMENTAL E NUMÉRICA DO DANO E MECANISMOS DE TRANSFERÊNCIA DE TENSÃO EM MATERIAIS CIMENTÍCIOS

MARCELLO CONGRO DIAS DA SILVA 13 June 2024 (has links)
[pt] A interação entre o cimento e outros constituintes desempenha um papel importante em várias aplicações de Engenharia, como nas indústrias de construçãocivil e de óleo e gás (OeG). Na indústria da construção, os compósitos cimentícios reforçados com fibras (CRF) ganharam grande destaque por suas excelentes propriedades mecânicas. As fibras podem aumentar a resistência crítica à fissuração do compósito, melhorando a durabilidade do concreto convencional e controlando a propagação de fissuras na matriz cimentícia. Além disso, as fibras desenvolvem um mecanismo de ponte de transferência de tensões na interface, alterando o comportamento pós-pico do compósito. Por outro lado, na indústria de OeG, cimento e aço são elementos estruturais essenciais que devem garantir a integridade de poços e fornecer isolamento para a passagem de fluidos, especialmente em cenários de abandono. Esse mecanismo na interface é considerado crítico, uma vez que uma interação não eficaz pode permitir a formação de caminhos de vazamento no microanular ao longo da interface cimento-aço, gerando a formação de fissuras. Neste sentido, um estudo abrangente dos mecanismos de dano desenvolvidos na interface do cimento é essencial em ambas as aplicações para entender o comportamento mecânico do material. Portanto, faz-se necessário o desenvolvimento de modelos de elementos finitos que considerem os mecanismos de pullout (descolamento, adesão e atrito) e os parâmetros de interface que governam o comportamento mecânico local do cimento. Embora existam numerosos estudos experimentais e modelos numéricos na literatura, o estado-da-arte atual carece de formulações que investiguem os mecanismos de mapeamento de dano e as interações de transferência de tensão na interface do cimento, especialmente considerando diferentes tipos de matriz de cimento e geometrias de fibra de aço.Esta tese aborda uma lacuna crítica na literatura ao propor a modelagem numérica do descolamento interfacial e mecanismos de evolução de dano para materiais cimentícios avançados e em aplicações de integridade de poços. Modelos de elementos finitos elastoplásticos, incorporando formulações coesivas baseadas em superfícies de contato, são empregados para simular o comportamento da interface do cimento. Além disso, ensaios experimentais de caracterização mecânica e análises de microtomografia são realizados para validar e apoiar os resultados do modelo numérico, avaliando a resistência ao cisalhamento e a propagação de dano na interface do cimento. Assim sendo, esta pesquisa pode oferecer contribuições para engenheiros de diferentes áreas aprimorarem o desempenho mecânico e prototipar novos materiais avançados por meio da investigação da evolução do dano. Os modelos de elementos finitos desenvolvidos emergem como ferramentas valiosas para avaliações de desempenho do cimento de maneira eficaz, simulando confiavelmente o comportamento de pullout/pushout. / [en] The interaction between cement and other constituents plays an important role in several engineering applications, such as in the construction and oil and gas (OandG) industries. In the construction industry, fiber-reinforced cementitious composites (FRC) have gained wide prominence for their excellent mechanical properties. Fibers can increase the post-cracking strength of the composite, improving concrete durability and controlling crack propagation in the cement matrix. Moreover, they perform a bridging mechanism at the interface, changing the material post-peak behavior. On the other hand, in the OandG industry, cement and steel are essential structural elements that should ensure well integrity and provide zonal isolation. This interaction is considered critical since a strong bond may prevent the generation of microannulus leakage paths along the cement and steel interface, which also can lead to crack propagation. In this sense, a comprehensive study of the damage mechanisms developed at the cement interface is essential in both applications to understand the material mechanical behavior. Therefore, it is possible to develop finite element models that consider the pullout mechanisms (debonding, adhesion, and friction) and the interface parameters that govern the local mechanical behavior of cement. While numerous experimental studies and numerical models exist, the current state-of-the-art lacks formulations investigating damage mapping and stress transfer interactions at the cement interface, particularly considering different cement matrix types and steel fiber geometries. This thesis addresses a critical gap in the literature by proposing the numerical modeling of interfacial debonding and damage evolution mechanisms for cement advanced materials and well integrity applications. Elastoplastic finite element models, incorporating surface-based cohesive formulations with contact, are employed to simulate cement interface behavior. Additionally, mechanical characterization tests and microCT analyses are conducted to validate and support the numerical model results, assessing shear strength and damage propagation at the cement interface. Therefore, this research can offer insights for engineers across disciplines to enhance mechanical performance and prototype new advanced materials by damage evolution investigation. The developed finite element models emerge as valuable tools for cost-effective evaluations of cement performance through reliably simulating pullout/pushout behavior.
77

Estudo comparativo da interação solo-geogrelha por meio de ensaios de arrancamento monotônico e cíclico utilizando equipamentos de pequenas e grandes dimensões / Comparative study of soil-geogrid interaction through monotonic and cyclic pullout tests using small and large dimensions equipments

Rincón Barajas, Sergio Arturo 02 August 2016 (has links)
O melhor comportamento de uma estrutura de solo reforçado com geossintéticos não depende só da elevada resistência à tração da inclusão, mas também da sua rigidez e do nível de carregamento sob o qual a estrutura está submetida. Dessa maneira, a interação entre o reforço e as respectivas camadas de solo ao seu redor torna-se de grande importância, pois a mobilização cisalhante combina a deformação da interface solo-reforço e o alongamento do geossintético. Sendo que a melhor forma de avaliar a interação entre o solo e a geogrelha é por meio de ensaios de arrancamento, pensa-se na realização de ensaios de arrancamento cíclico para analisar a interação dinâmica entre o solo e a inclusão quando certas estruturas são submetidas a esse tipo de solicitação. Por causa disso, o objetivo principal deste trabalho é analisar o efeito produzido por carregamentos monotônicos e cíclicos de interface numa geogrelha biaxial de polipropileno, quando inserida na interface de um solo argiloso e um solo arenoso sob diferentes tensões de confinamento. Para isso, são utilizados os equipamentos de pequenas e grandes dimensões do Laboratório de Geossintéticos da EESC-USP, visando avaliar a sua relação e a viabilidade de uso do equipamento de pequenas dimensões. Inicialmente foram realizados ensaios de arrancamento monotônico em ambos os equipamentos sob tensões de confinamento de 25, 50 e 100 kPa, sendo que as resistências obtidas com as tensões de 25 e 100 kPa permitiram definir as amplitudes do carregamento cíclico correspondentes ao 20% de tais valores. Adicionalmente, após a aplicação dos 10.000 ciclos de carga correspondentes à capacidade do equipamento, foi aplicado novamente um carregamento monotônico com o intuito de determinar o efeito do carregamento dinâmico na resistência ao arrancamento e assim poder realizar as respectivas comparações com os valores iniciais. Com base nos resultados obtidos, foi possível observar a diferença no grau de confinamento entre ambos os equipamentos, sendo maior no de grandes dimensões por causa da melhor distribuição das tensões sobre a área ocupada pela geogrelha. Adicionalmente, o grau de confinamento em ambos os equipamentos também influenciou a diferença no efeito do carregamento dinâmico, sendo de desconfinamento no de grandes dimensões e de densificação no de pequenas dimensões. / The best behavior of a reinforced soil structure with geosynthetics not only depends on the high tensile strength of the inclusion, but also on its rigidity and the loading level in which the structure is subjected. Thus, the interaction between the reinforcement and the respective layers of soil around, becomes very important because the shear mobilization combines the deformation of the soil-reinforcement interface and the lengthening of the geosynthetic. Since the best way to assess the soil-geogrid interaction is through pullout tests, it is thought in performing cyclic pullout tests to examine the dynamic soil-inclusion interaction when some structures are submitted to that kind of loads. Because of that, the main objective of this work is to analize the effect that is produced by monotonic and cyclic interface loading on a biaxial polypropylene geogrid, when it is inserted into the interface of a clayey soil and a sandy soil under different confinement stresses. For that, the small and large dimensions equipments of the Geosynthetics Laboratory at EESC-USP are used, looking to evaluate their relationship and the feasibility of using a small dimensions equipment. Initially, they were performed monotonic pullout tests in both equipments under confinement stresses of 25, 50 and 100 kPa, wherein the pullout strengths obtained with 25 and 100 kPa allowed the definition of the load cyclic amplitudes, which corresponded to 20% of such values. Additionally, after applying 10.000 load cycles, corresponding to the capacity of the equipment, it was applied a monotonic loading in order to determine the dynamic loading effect on pullout strength, being useful to compare such values with the initial response. Based on the obtained results, it was possible to observe the difference in the confinement degree between both equipments, being higher in the large one because of the better stress distribution on the geogrid area. Aditionally, the confinement degree in both equipments also influenced the difference in the dynamic loading effect, being deconfinement in the soil-geogrid interface of the large one and densification in the other one.
78

Estudo comparativo da interação solo-geogrelha por meio de ensaios de arrancamento monotônico e cíclico utilizando equipamentos de pequenas e grandes dimensões / Comparative study of soil-geogrid interaction through monotonic and cyclic pullout tests using small and large dimensions equipments

Sergio Arturo Rincón Barajas 02 August 2016 (has links)
O melhor comportamento de uma estrutura de solo reforçado com geossintéticos não depende só da elevada resistência à tração da inclusão, mas também da sua rigidez e do nível de carregamento sob o qual a estrutura está submetida. Dessa maneira, a interação entre o reforço e as respectivas camadas de solo ao seu redor torna-se de grande importância, pois a mobilização cisalhante combina a deformação da interface solo-reforço e o alongamento do geossintético. Sendo que a melhor forma de avaliar a interação entre o solo e a geogrelha é por meio de ensaios de arrancamento, pensa-se na realização de ensaios de arrancamento cíclico para analisar a interação dinâmica entre o solo e a inclusão quando certas estruturas são submetidas a esse tipo de solicitação. Por causa disso, o objetivo principal deste trabalho é analisar o efeito produzido por carregamentos monotônicos e cíclicos de interface numa geogrelha biaxial de polipropileno, quando inserida na interface de um solo argiloso e um solo arenoso sob diferentes tensões de confinamento. Para isso, são utilizados os equipamentos de pequenas e grandes dimensões do Laboratório de Geossintéticos da EESC-USP, visando avaliar a sua relação e a viabilidade de uso do equipamento de pequenas dimensões. Inicialmente foram realizados ensaios de arrancamento monotônico em ambos os equipamentos sob tensões de confinamento de 25, 50 e 100 kPa, sendo que as resistências obtidas com as tensões de 25 e 100 kPa permitiram definir as amplitudes do carregamento cíclico correspondentes ao 20% de tais valores. Adicionalmente, após a aplicação dos 10.000 ciclos de carga correspondentes à capacidade do equipamento, foi aplicado novamente um carregamento monotônico com o intuito de determinar o efeito do carregamento dinâmico na resistência ao arrancamento e assim poder realizar as respectivas comparações com os valores iniciais. Com base nos resultados obtidos, foi possível observar a diferença no grau de confinamento entre ambos os equipamentos, sendo maior no de grandes dimensões por causa da melhor distribuição das tensões sobre a área ocupada pela geogrelha. Adicionalmente, o grau de confinamento em ambos os equipamentos também influenciou a diferença no efeito do carregamento dinâmico, sendo de desconfinamento no de grandes dimensões e de densificação no de pequenas dimensões. / The best behavior of a reinforced soil structure with geosynthetics not only depends on the high tensile strength of the inclusion, but also on its rigidity and the loading level in which the structure is subjected. Thus, the interaction between the reinforcement and the respective layers of soil around, becomes very important because the shear mobilization combines the deformation of the soil-reinforcement interface and the lengthening of the geosynthetic. Since the best way to assess the soil-geogrid interaction is through pullout tests, it is thought in performing cyclic pullout tests to examine the dynamic soil-inclusion interaction when some structures are submitted to that kind of loads. Because of that, the main objective of this work is to analize the effect that is produced by monotonic and cyclic interface loading on a biaxial polypropylene geogrid, when it is inserted into the interface of a clayey soil and a sandy soil under different confinement stresses. For that, the small and large dimensions equipments of the Geosynthetics Laboratory at EESC-USP are used, looking to evaluate their relationship and the feasibility of using a small dimensions equipment. Initially, they were performed monotonic pullout tests in both equipments under confinement stresses of 25, 50 and 100 kPa, wherein the pullout strengths obtained with 25 and 100 kPa allowed the definition of the load cyclic amplitudes, which corresponded to 20% of such values. Additionally, after applying 10.000 load cycles, corresponding to the capacity of the equipment, it was applied a monotonic loading in order to determine the dynamic loading effect on pullout strength, being useful to compare such values with the initial response. Based on the obtained results, it was possible to observe the difference in the confinement degree between both equipments, being higher in the large one because of the better stress distribution on the geogrid area. Aditionally, the confinement degree in both equipments also influenced the difference in the dynamic loading effect, being deconfinement in the soil-geogrid interface of the large one and densification in the other one.
79

Avaliação da interação solo-fitas metálicas e poliméricas para soluções em terra armada em solos não convencionais / Evaluation of the interaction of soil and metal strips and soil and polymeric strips applied to mechanically stabilized earth with concrete wall facing reinforce with unconventional soil

Maparagem, Albano Sâlzon 22 August 2011 (has links)
Grande percentagem do território brasileiro é coberta por solos finos (% passando peneira # 200 > 50%), geralmente de origem tropical, que poderiam ser classificados como solos de baixa capacidade de drenagem. Estes solos não atendem às recomendações técnicas para solos de aterro de estruturas reforçadas, conforme exigido pela AASHTO e BS 8006. Neste trabalho foi avaliado experimentalmente um dos parâmetros mais importantes de projeto de Terra Armada, que condiciona o mecanismo de transferência de carga, o coeficiente de atrito aparente solo-fita metálica (f*). Foi avaliada a influência das características dos solos para as classes de solos estabelecidas pela NBR 9286/86 para o caso de fitas metálicas, e, dos critérios que sustentam o uso de fitas poliméricas, sob diversas tensões verticais atuantes nas fitas, simulando o efeito da profundidade. As informações foram obtidas através de ensaios de arrancamento de fitas metálicas e poliméricas realizados em laboratório e depois comparadas aos resultados teóricos da norma e àqueles preconizados para o uso de fitas poliméricas. Os ensaios realizados com as fitas em solo não convencional 1 e em areia mal graduada, mostraram que para profundidades equivalentes a tensões verticais até 50 kPa, os dois tipos de inclusões possuem valores de coeficiente de interação com o solo maiores que a unidade, isso tornaria razoável o seu uso sob o ponto de vista deste parâmetro e nas condições da realização dos ensaios, quando comparado com a norma, e com os critérios que sustentam o uso das fitas poliméricas em técnica de solo armado. No entanto, para maiores profundidades, a interação apresenta uma tendência de diminuição. O solo não convencional 2 valores da interação muito baixos. Foram instalados strain gages ao longo do comprimento das fitas para monitoramento dos esforços no maciço. Nota-se que esforços elevados ocorreram nas regiões mais próximas do ponto de aplicação da força de arrancamento. / A large percentage of Brazil\'s territory is covered with fine tropical soil (50% passing #200) which can be classified as soils with low drainage capacity. These soils do not meet the technical recommendations for backfill of reinforced soil structures by AASHTO and BS 8006. This paper presents the result of an experimental evaluation of one of the most important design parameters of mechanically stabilized earth with concrete wall facing. The apparent friction coefficient of soil-steel strips and soil-polymeric strips is the project parameter. Also was evaluated the influence of soil characteristics for soil types listed by the NBR 9286/86 for metal strips and for the criteria that support the use of polymeric strips. The evaluation included the application of different vertical stresses on the strips simulating the effect of depth. The information obtained from pullout tests performed in laboratory was compared to the standard theoretical values and design values for polymeric strips. Tests performed on strips in nonconventional soil (1) and poorly graded sand showed that at depths equivalent to vertical stresses up to 50 kPa the two types of inclusions have coefficients of interaction greater than unity, which appears reasonable. Therefore, such soils can be used as backfill soils in the conditions tested and at equal or lesser stress levels. Nonconventional soil (2) showed low value of the friction coefficient. The strain gages installed along the length of the strips recorded the distribution of tensile stress in pull-out tests. Higher tensile stress was recorded by the gages nearest the point of application of the pull-out force.
80

Avaliação da estabilidade primária de implantes convencionais e modificados por meio de ensaios de desempenho, frequência de ressonância e análise microestrutural / Evaluation of primary stability of conventional and modified implants by the performance tests, resonance frequency and microstructural analysis

Valente, Mariana Lima da Costa 09 October 2014 (has links)
A estabilidade primária dos implantes odontológicos é determinante para a osseointegração e depende dos fatores qualidade, quantidade óssea e tipo de implante. O objetivo desse estudo foi avaliar a influência do formato de implantes convencionais e modificados e do tipo de substrato na estabilidade primária por meio da correlação de ensaios de desempenho e frequência de ressonância e análise microestrutural. No estudo foram utilizados 54 implantes Neodent®: 27 cilíndricos, sendo 9 hexágono externo (Titamax Ti Cortical - 4,0 mm x 11 mm), 9 hexágono interno (Titamax II Plus - 3,75 mm x 11 mm) e 9 cone morse (Titamax CM - 4,0 mm x 11 mm); e 27 implantes cônicos de 4,3 mm x 10 mm, sendo 9 hexágono externo (Alvim Ti), 9 hexágono interno (Alvim II Plus) e 9 cone morse (Alvim CM). Os implantes foram inseridos em osso artificial da marca Nacional® nas densidades de 15, 20 e 40 PCF e osso de costela suína. Para os ensaios de desempenho foi quantificado o torque de inserção com um torquímetro digital e a força máxima de arrancamento utilizando uma Máquina Universal de Ensaios. Para avaliar a frequência de ressonância foi utilizado o aparelho Ostell® e para a análise morfológica um Microscópio Eletrônico de Varredura, sob aumentos de 40 e 100 vezes. Após a realização dos ensaios com os implantes convencionais, os modelos Alvim CM e Titamax Ti Cortical (n=9) tiveram sua morfologia externa alterada com a prolongação dos chanfros desde o terço apical até o nível da plataforma protética e foram submetidos aos mesmos testes propostos para os parafusos originais. Verificada a normalidade dos dados utilizou-se o teste de análise de variância ANOVA, comparação de médias Tukey (α=5%) e correlação de Pearson. Para os implantes convencionais, o Alvim CM apresentou maior média em todos os ensaios realizados, sendo estatisticamente diferente dos implantes cilíndricos quando analisado o torque de inserção no osso (73,33 N.cm) e força de arrancamento na poliuretana de 40 PCF (910,36 N) e osso (553,79 N). Os implantes Titamax II Plus tiveram as menores médias, diferente estatisticamente dos cônicos quando analisado o torque de inserção (22,22 N.cm) e frequência de ressonância no osso (72,83 ISQ) e força de arrancamento na poliuretana de 40 PCF (61,97 N) e osso (86,40 N). A análise dos ensaios de desempenho e frequência de ressonância apresentou correlação moderada de acordo com o p de Pearson (0,30 a 0,70) e a comparação entre as fotomicrografias não mostrou alteração morfológica dos implantes. A modificação realizada no parafuso Alvim CM proporcionou um aumento significativo no torque de inserção (p=0,000), diminuição das médias de arrancamento (p=0,000) e manteve semelhança com as médias de frequência de ressonância (p=0,169) quando comparado ao implante convencional. O Titamax Ti modificado aumentou significativamente o torque de inserção (p=0,043) e provocou diminuição significativa para a frequência de ressonância (p=0,002) e ensaio de arrancamento (p=0,000). Conclui-se que o formato dos implantes interfere na estabilidade primária, sendo os implantes cônicos indutores de maior estabilidade. A análise de correlação das metodologias empregadas demonstrou a associação positiva das mesmas para complementação da análise da estabilidade primária / The primary stability of dental implants is critical for osseointegration and depends on factors quality, bone quantity and type of implant. The aim of this study was to evaluate the influence of conventional and modified implants and the type of substrate shape on primary stability through the correlation of performance tests and frequency of resonance and microstructural analysis. In the study 54 Neodent® implants were used: 27 cylindrical, 9 hexagonal (Titamax Ti Cortical - 4.0 mm x 11 mm), 9 internal hexagon (Titamax II Plus - 3.75 mm x 11 mm) and 9 morse taper (Titamax CM - 4.0 mm x 11 mm); and 27 tapered implants of 4.3 mm x 10 mm and 9 external hexagon (Alvim Ti), 9 internal hexagon (Alvim II Plus) and 9 morse taper (Alvim CM). The implants were inserted into artificial bone of National ® brand at densities of 15, 20 and 40 PCF and pork rib bone. For testing the performance was quantified insertion torque with a digital torque meter and the maximum pullout strength using a universal testing machine. To evaluate the resonance frequency was used Ostell ® device and the morphological parsing an Scanning Electron Microscope under increases of 40 and 100 times. After the tests with conventional implants, models CM Alvim and Titamax Cortical Ti (n=9) had their external morphology changed with the prolongation of the bevels from the apical to the level of prosthetic platform and underwent the same tests proposed for the original screws. Checked for normality of the data used in the test of ANOVA, Tukey comparison (α=5%) and Pearson correlation. For conventional implants, the CM Alvim showed higher average in all tests, with statistically different when analyzed cylindrical implant insertion torque on bone (73.33 N.cm) and pullout strength in polyurethane 40 PCF (910.36 N) and bone (553.79 N). Implants Titamax II Plus had the lowest average, statistically different when analyzed the tapered insertion torque (22.22 N.cm) and resonance frequency in bone (72.83 ISQ) and pullout strength in 40 PCF polyurethane (61.97 N) and bone (86.40 N). The analysis of the performance tests and had moderate resonance frequency correlation according op Pearson (0.30 to 0.70) and comparing the photomicrographs showed no morphological alteration of the implants. The modification made to the screw Alvim CM provided a significant increase in insertion torque (p=0.000), decrease of average pullout (p=0.000) and remained similar to the average resonance frequency (p=0.169) when compared to the implant conventional. The Titamax Ti modified significantly increased insertion torque (p=0.043) and caused a significant decrease in the resonance frequency (p=0.002) and pullout test (p=0.000). It is concluded that the shape of the implants interfere with the primary stability, with the inductors tapered implants stability. Correlation analysis of the methodologies used showed a possible association of these for further analysis of primary stability

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