ABSTRACT
The experimental stress-strain curves from the standardized tests of Tensile, Plane Stress, Compression, Volumetric Compression, and Shear, are normally used to obtain the invariant λi and constants of material Ci that will define the behavior elastomers. Obtaining these experimental curves requires the use of expensive and complex experimental equipment. For years, a direct method called model updating, which is based on the combination of parameterized finite element (FE) models and experimental force-displacement curves, which are simpler and more economical than stress-strain curves, has been used to obtain the Ci constants. Model updating has the disadvantage of requiring a high computational cost when it is used without the support of any known optimization method or when the number of standardized tests and required Ci constants is high. This paper proposes a methodology that combines the model updating method, the mentioned standardized tests and the multi-response surface method (MRS) with desirability functions to automatically determine the most appropriate Ci constants for modeling the behavior of a group of elastomers. For each standardized test, quadratic regression models were generated for modeling the error functions (ER), which represent the distance between the force-displacement curves that were obtained experimentally and those that were obtained by means of the parameterized FE models. The process of adjusting each Ci constant was carried out with desirability functions, considering the same value of importance for all of the standardized tests. As a practical example, the proposed methodology was validated with the following elastomers: nitrile butadiene rubber (NBR), ethylene-vinyl acetate (EVA), styrene butadiene rubber (SBR) and polyurethane (PUR). Mooneyâ»Rivlin, Ogden, Arrudaâ»Boyce and Gent were considered as the hyper-elastic models for modeling the mechanical behavior of the mentioned elastomers. The validation results, after the Ci parameters were adjusted, showed that the Mooneyâ»Rivlin model was the hyper-elastic model that has the least error of all materials studied (MAEnorm = 0.054 for NBR, MAEnorm = 0.127 for NBR, MAEnorm = 0.116 for EVA and MAEnorm = 0.061 for NBR). The small error obtained in the adjustment of the Ci constants, as well as the computational cost of new materials, suggests that the methodology that this paper proposes could be a simpler and more economical alternative to use to obtain the optimal Ci constants of any type of elastomer than other more sophisticated methods.
ABSTRACT
Resumen En la actualidad hay suficiente evidencia científica que relaciona directamente la adquisición, exposición y prevalencia del virus del papiloma humano (VPH) con el cáncer del cuello de uterino. Por ello, el artículo aborda el VPH en la mujer teniendo en cuenta la naprotecnología, que permite conjugar evidencia científica y planteamientos éticos. Se busca que se tengan en cuenta tanto el aspecto biológico de la sexualidad como la capacidad de hacerse persona en su núcleo sexual. De ahí que se analicen programas dirigidos a la educación sexual, basados tanto en la prevención sanitaria como en la antropología de la sexualidad, y apoyados por las instituciones familiares, que han demostrado una mejor acogida ante los riesgos de las enfermedades de transmisión sexual, y entre ellas la infección por el VPH.
Abstract There currently is sufficient scientific evidence directly linking acquisition, exposure and prevalence of the human papillomavirus (HPV) to cervical cancer. The article addresses HPV in women by taking NaProTechnology into account, which makes it possible to combine scientific evidence with ethical approaches. It looks at both the biological aspect of sexuality and the ability to become a person within one's sexual nucleus. There is an analysis of sex education programs based on preventive health and on the anthropology of sexuality, and supported by family institutions, that have demonstrated better acceptance in dealing with the risk of sexually transmitted diseases, including HPV infection.
Resumo Na atualidade, há suficiente evidência científica que relaciona diretamente aquisição, exposição e prevalência do Papilomavírus Humano (HPV) com o câncer do colo do útero. Por isso, este artigo aborda o HPV na mulher considerando a naprotecnologia, que permite conjugar evidência científica e proposições éticas. Procura-se que sejam levados em conta tanto o aspecto biológico da sexualidade quanto a capacidade de se fazer pessoa em seu núcleo sexual. A partir disso, são analisados programas dirigidos à educação sexual, baseados tanto na prevenção sanitária quanto na antropologia da sexualidade, e apoiados pelas instituições familiares, que têm demonstrado uma melhor acolhida diante dos riscos das infecções de transmissão sexual e, entre elas, a infecção pelo HPV.
