Experimental probability estimators for Weibull plots

In the present paper, the thermal durability of polyvinyl alcohol fibers (PVA) was studied after fiber samples had been subjected to temperatures ranging from 90°C to 250°C. Residual mechanical properties, such as tensile strength, elastic modulus and elongation at break, and physical properties, such as density were determined. Weibull statistics were used to quantify the degree of variability in fiber strength, at the different temperature. In addition, thermal analysis of PVA fibers were carried out employing thermogravimetry and differential scanning calorimetry up to the temperature of 800°C. SEM analysis of heated and unheated samples had been carried out in order to allow the identification of the changes in the microstructure of the fibers. The degradation process of PVA fibers manifests itself in a significant loss of mass, stiffness and strength of the fibers, which is progressive with increasing temperature. Thermal analysis has shown that the melting point of PVA fibers begins at approximately 200°C and thermal degradation initiates at about 239ºC. However, progressive loss in tensile strength and elastic modulus was observed starting at a temperature as low as 90°C, due to glass transition temperature of PVA fibers at approximately 66°C. At 220°C, the elastic modulus and strength were reduced at about 45% and 52%, respectively, when compared with respective values of unheated samples. With regards to Weibull modulus, the statistical parameter did not exhibit significant influence on temperature for samples heated up to 145°C, which ranged from 23.4 to 28.8. However, samples heated to 220°C showed a sudden reduction in Weibull modulus to 8.6, indicating that a significant change occurred in the populations of fracture inducing flaws at this temperature level, which clearly affect the tensile strength and Weibull modulus.

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“…According to the Weibull analysis [13,14], the failure probability under a uniform stress state is given by:…”

Section: Tensile Testsmentioning

confidence: 99%

“…Probabilities of failure were determined using ranking statistics [13]. Ordering the failure data from smallest to largest and assigning a ranking number i, the probabilities of failure were then assigned by the following relationship:…”

Section: Tensile Testsmentioning

confidence: 99%

Durability under thermal loads of polyvinyl alcohol fibers

2013

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“…The parameter of σμ denotes the stress at which there is no failure possibility and is usually taken to be σμ = 0 [24]. Thus, Equation (3) Compared with a logarithmic normal distribution, a Weibull distribution is more commonly used to evaluate the service reliability of brittle materials.…”

Section: Resultsmentioning

confidence: 99%

Tensile Strength Reliability Analysis of Cu48Zr48Al4 Amorphous Microwires

Sun

Ning

Wang

et al. 2016

Metals

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Uniform Cu 48 Zr 48 Al 4 amorphous microwires with a high surface quality are fabricated by a melt extraction technique. The mechanical property of microwires is evaluated via tensile tests. To estimate the strength scattering, statistical analysis of fracture strengths is conducted using logarithmic normal distribution, and two-and three-parameter Weibull analysis, severally. The results show that the tensile strengths of Cu 48 Zr 48 Al 4 amorphous microwires range from 1724 to 1937 MPa with the arithmetical average value of 1836 MPa, and the arithmetical standard deviation of 56.4 MPa. The geometric mean of fracture strength is 1840 MPa using logarithmic normal distribution statistical analysis. Using two-and three-parameter Weibull analysis, the Weibull modulus and fracture threshold value are respectively calculated for 34.8 and 1483 MPa, which shows the excellent tensile mechanical properties with a high predictability of Cu 48 Zr 48 Al 4 amorphous microwires and further indicates the great potential of application.

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“…O aumento do valor do módulo de Weibull (m) significa menor dispersão dos resultados e maior confiabilidade dos mesmos [16,17]. No presente trabalho, o módulo de Weibull do Grupo I é menor do que aquele do Grupo II (infiltração como recomendado pelo fabricante), o que pode corresponder a uma condição ótima de infiltração (encontrada em pesquisa do fabricante) e provavelmente decorrente do comportamento reológico do vidro de alumino-silicato de lantânio em função da temperatura de infiltração.…”

Section: Discussionunclassified

Caracterização micrográfica de próteses dentais de alumina infiltrada com vidro de lantânio e sua correlação com a resistência à flexão por três pontos

Ogasawara

2008

Matéria (Rio J.)

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Estudou-se a infiltração (em diferentes condições) do vidro de lantânio em alumina parcialmente sinterizada e a sua relação com a resistência à flexão. As barras de In-Ceram Alumina, fraturadas em flexão por 3 pontos, foram lixadas, polidas e caracterizadas por microscopias ótica e eletrônica de varredura (MEV). Foram usadas 10 barras para cada condição operacional. Resultados: (a) A MEV confirma que os núcleos de barras In-Ceram Alumina (sinterizados a 1120ºC durante 2h) infiltrados a 1100ºC durante 6h contém menos vidro de lantânio do que aqueles das barras infiltradas durante 6h a 1110ºC; (b) A micrografia ótica confirma que os núcleos de barras In-Ceram Alumina (sinterizada a 1120ºC durante 2h) infiltrada durante 6h (ou 2h) nas temperaturas de 1100ºC, 1100ºC, 1120ºC e 1130ºC não se diferem notavelmente; (c) A MEV mostra que a microestrutura interna de barras In-Ceram Alumina infiltradas com vidro de lantânio a 1120ºC e 1130ºC é complexa.

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Experimental probability estimators for Weibull plots

Cited by 190 publications

References 3 publications

Durability under thermal loads of polyvinyl alcohol fibers

Durability under thermal loads of polyvinyl alcohol fibers

Tensile Strength Reliability Analysis of Cu48Zr48Al4 Amorphous Microwires

Caracterização micrográfica de próteses dentais de alumina infiltrada com vidro de lantânio e sua correlação com a resistência à flexão por três pontos

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