Correlation between changes in mechanical strength and damping of a high alumina refractory castable progressively damaged by thermal shock

Pereira, A. H. A.; Fortes, Gustavo Mattos; Schickle, Benjamin; Tonnesen, Thorsten; Musolino, B.; Maciel, Carlos Dias; Rodrigues, J. A.

doi:10.1590/s0366-69132010000300016

Cited by 4 publications

(5 citation statements)

References 5 publications

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“…Similar recoveries, as found for Young's modulus, have been related on previous works. [28][29][30][31][32] Comparing the results obtained from the impulse excitation technique with DMA and ILSS results, it can be observed that all of them presented a decrease of strength values after 1000 thermal cycles followed by a recovery, when exposed during 2000 thermal cycles. However, at all the tests the specimens were evaluated in the longitudinal and not at transversal direction, as it was done in the torsion mode to obtain shear modulus.…”

Section: Thermal Shock Weatheringmentioning

confidence: 99%

Evaluation of weather influence on mechanical and viscoelastic properties of polyetherimide/carbon fiber composites

Batista

Iha

Botelho

2013

Journal of Reinforced Plastics and Composites

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In order to investigate how environmental degradation affects the mechanical and thermal performance of polyetherimide/carbon fiber laminates, in this work different weathering were conducted. Additionally, dynamic mechanical analysis, interlaminar shear strength tests and non-destructive inspections were performed on this composite before and after being submitted to hygrothermal, UV radiation and thermal shock weathering. According to our results, hygrothermally aged samples had their glass transition temperature and elastic and storage moduli reduced by plasticization effect. Photooxidation, due to UV radiation exposure, occurred only on the surface of the laminates. Thermal shock induced a reversible stress on the composite’s interface region. The results revealed that the mechanical behavior can vary during weather exposure but since this variation is only subtle, this thermoplastic laminate can be considered for high-performance applications, such as aerospace.

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Section: Thermal Shock Weatheringmentioning

confidence: 99%

Evaluation of weather influence on mechanical and viscoelastic properties of polyetherimide/carbon fiber composites

Batista

Iha

Botelho

2013

Journal of Reinforced Plastics and Composites

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“…Contudo estes sistemas também podem apresentar mecanismos de amortecimento não-viscosos, por exemplo, mecanismos anelásticos dependentes da frequência ou da amplitude de vibração. Esta simplificação por um lado desconsidera a possibilidade de ocorrência de mecanismos não-viscosos, mas por outro viabiliza caracterizações experimentais comparativas para corpos de prova com faixa de frequência de ressonância e dimensões similares [18].…”

Section: Modelo Viscoelástico Equivalenteunclassified

Algoritmo para determinação do amortecimento de materiais cerâmicos pela técnica das freqüências naturais de vibração via excitação por impulso

Pereira

Musolino²,

Maciel³

et al. 2012

Cerâmica

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O amortecimento ou atrito interno é uma das propriedades mais sensíveis de materiais e estruturas tanto em escala macro como microscópica e um bom indicador para a caracterização de danos estruturais, sendo particularmente sensível à presença de trincas e micro-trincas. O objetivo deste trabalho foi desenvolver um algoritmo que permitisse incorporar a caracterização do amortecimento à técnica das freqüências naturais de vibração via excitação por impulso, já bem estabelecida pela norma ASTM E1876 e amplamente empregada na determinação não-destrutiva dos módulos elásticos de materiais cerâmicos. Foi desenvolvido um algoritmo para a determinação do amortecimento fundamentado na análise de sinal no domínio de tempo-freqüência, no método do decremento logarítmico e no modelo viscoelástico equivalente. O algoritmo foi validado empregando um gerador de ondas de formato arbitrário e aplicado na caracterização de dois materiais, sendo um concreto refratário de alta alumina, com e sem dano por choque térmico, e um aço SAE 1020. O algoritmo foi eficiente ao determinar a frequência e o amortecimento de sinais arbitrários e dos corpos de prova, e em limitar a análise ao modo de vibração de interesse, minimizando assim a interferência de outros modos. O algoritmo permitiu integrar com eficiência o cálculo do amortecimento à técnica de excitação por impulso.

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“…Thermal shock induces crack nucleation and propagation through thermal stress (2-4) resulting in a decrease of elastic moduli and mechanical strength and in an increase of damping (5)(6)(7)(8)(9). Taking this into account, it is interesting to understand in more depth the differences between cooling and heating thermal shock types, since both are present in applications of refractories.…”

Section: Introductionmentioning

confidence: 99%

“…To evaluate the thermal shock damage, the most common ways are the retained module of rupture and the retained dynamic Young's modulus characterizations after heatingcooling thermal shock cycles (1,(5)(6)(7). Damping, shear modulus and Poisson's ratio are also used for that purpose, however to a lesser extent.…”

Section: Introductionmentioning

confidence: 99%

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Elastic moduli, damping and modulus of rupture changes in a high alumina refractory castable due to different types of thermal shock

Pereira¹,

Nascimento²,

Exposito³

et al. 2012

Bol. Soc. Esp. Ceram. Vidr.

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The work herein verifies the changes of the elastic moduli, damping and modulus of rupture (MOR) of a high alumina refractory castable due to heating, cooling and heating-cooling thermal shock damage. Twelve prismatic specimens were prepared for the tests and divided into four groups. The thermal shocks were performed on three groups, each containing three specimens having abrupt temperature changes of 1100°C during heating in the first group, during cooling in the second and during heating followed by cooling in the third group. The fourth group, which was taken as a reference did not receive any thermal shock. The elastic moduli were measured after each thermal shock cycle. After 10 cycles, the MOR, the damping and the damping dependence on excitation amplitude were measured at room temperature for all specimens. The elastic moduli showed a similar decrease and the damping a similar increase due to the cooling and heating-cooling thermal shocks. The heating thermal shocks caused no significant changes on the elastic moduli and damping. However, the MOR appeared to be sensitive to the heating thermal shock. This work also shows that the damping for the studied refractory castable is non-linear (i.e., amplitude of excitation sensitive) and that this non-linearity increases when the damage level rises. Keywords: refractories, thermal shock, mechanical properties, non-destructive tests, Young's modulus.Alteraciones de los módulos elásticos, del amortiguamiento y del módulo de rotura provocado por diferentes tipos de choques térmicos en material refractario moldeable de alta alúmina En este trabajo se investigaron las alteraciones de los módulos elásticos dinámicos, del amortiguamiento y del módulo de rotura (MOR) de un material refractario moldeable de alta alúmina después de recibir choques térmicos de calentamiento, enfriamiento y calentamiento seguido de enfriamiento (calentamiento-enfriamiento). Para ello se prepararon doce cuerpos prismáticos dividiéndolos en cuatro grupos. Los choques térmicos se le aplicaron a sólo tres grupos, cada uno con tres muestras. Al primer grupo se le aplicó un cambio brusco de temperatura de 1100 °C en calentamiento, en enfriamiento al segundo grupo y calentamiento seguido de enfriamiento al tercer grupo. El cuarto grupo no recibió choque térmico. Los módulos elásticos se midieron después de cada ciclo de choque térmico. Después de 10 ciclos, el MOR, el amortiguamiento, y la dependencia de la amortiguación de la amplitud de la excitación fueron caracterizados a temperatura ambiente en todos los cuerpos de prueba. Como resultado se obtuvo que los cuerpos sometidos a cambios bruscos de temperatura por enfriamiento y calentamientoenfriamiento presentaran una reducción similar en los módulos elásticos y aumento similar en la amortiguación mientras que el calentamiento no causó cambios significativos en estos parámetros. Sin embargo, el MOR pareció ser sensible a los cambios bruscos de temperatura por calentamiento. Este estudio también mostró que la amortiguación para el material refr...

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Correlation between changes in mechanical strength and damping of a high alumina refractory castable progressively damaged by thermal shock

Cited by 4 publications

References 5 publications

Evaluation of weather influence on mechanical and viscoelastic properties of polyetherimide/carbon fiber composites

Evaluation of weather influence on mechanical and viscoelastic properties of polyetherimide/carbon fiber composites

Algoritmo para determinação do amortecimento de materiais cerâmicos pela técnica das freqüências naturais de vibração via excitação por impulso

Elastic moduli, damping and modulus of rupture changes in a high alumina refractory castable due to different types of thermal shock

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