87 research outputs found

    Dwell Sensitivity Behavior and Modeling

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    Since engineering materials are exposed to dwell-times in service, it is important to understand the effects of dwell times on the fatigue life. The mechanisms controlling deformation and failure under dwell conditions are in terms of metallographic damage namely; transgranular fracture, intergranular fracture, mixed intergranular transgranular fracture modes, surface striated damage, creep damage and oxidation. These mechanisms are very difficult to include in a quantitative model to predict the dwell sensitivity behavior of high temperature materials. Published creep-fatigue data were compiled from various sources for a number of materials such as copper alloys (NARloy-Z, AMZ1RC), steel alloys (9Cr-lMo), and nickel based alloys(lN 100, Rene 95, Waspaloy). In general, dwell-times were found to be detrimental to the fatigue life of materials, but the exact extent of the effect varies depending on the material, duration of the dwell, and the direction in which a dwell was applied. In this research an attempt has been made to further develop the models of the senior author and include such concepts as stress relaxation with respect to a particular dwell time. Very limited data sets are available in the literature showing all the test details needed for developing a model for this research. However, the initial trials show stress relaxation as a result of a dwell cycle may exhibit an effect that may describe dwell. A dwell sensitivity damage mechanistic map and a new dwell sensitivity damage parameter were developed

    Trichinae Certification in the United States Pork Industry

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    We report here on progress in the Trichinae Certification pilot program. This program uses an on-farm auditing system to document good production practices (GPPs) for swine relative to the risk of exposure to Trichinella spiralis. The pilot phase of this program continues while regulations to establish it as an official USDA program are being developed. Launch of the Trichinae Certification Program in the United States is expected to take place when regulations are finalized within the next year. The Trichinella certification program establishes a process for ensuring the quality and safety of animal-derived food products from the farm through slaughter

    Risk Factors for Swine Infection with Toxoplasma gondii

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    The objective of this study was to evaluate the association between the seroprevalence of Toxoplasma gondii antibodies in swine in commercial pork production systems in Iowa, USA and the source of water (surface water vs. well water vs. rural processed water) and method of water delivery (surface or trough vs. nipple vs. cup). Also the study evaluated the association between T. gondii seroprevalence and other selected potential farm variables

    Trichinella Certification in the U.S. Pork Industry

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    We report here on a certification pilot study using an on-farm auditing system to document good production practices for swine relative to the risk of exposure to Trichinella spiralis. Based on the results, improvements in the program have been made and further piloting of the program is being undertaken prior to launching the Trichinae Certification Program in the United States. The Trichinella certification mechanism will establish a process for ensuring the quality and safety of animal-derived food products from the farm through slaughter

    Introduction: Toward an Engaged Feminist Heritage Praxis

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    We advocate a feminist approach to archaeological heritage work in order to transform heritage practice and the production of archaeological knowledge. We use an engaged feminist standpoint and situate intersubjectivity and intersectionality as critical components of this practice. An engaged feminist approach to heritage work allows the discipline to consider women’s, men’s, and gender non-conforming persons’ positions in the field, to reveal their contributions, to develop critical pedagogical approaches, and to rethink forms of representation. Throughout, we emphasize the intellectual labor of women of color, queer and gender non-conforming persons, and early white feminists in archaeology

    Finite Element Analysis of Femoral Components Paper III – Hip Joints

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    Finite element analysis of the hip implant is conducted in this paper for representative femoral cross-section geometries and development of stress in the presence of bone cement is elucidated. Differences in cement stresses generated by varying implant cross-sections were compared with conventional features derived from representative implants. The analysis was performed under idealized implant assemblies by constraining the implant movement in the assembly. The cross-sections and implant geometries used are generic and intended to be representative of available geometries. This paper is a part of student research projects, prepared from a series of activities in biomedical implant research currently underway at Ohio Northern and Arkansas Tech Universities

    Dwell Sensitivity Behavior and Modeling

    No full text
    Since engineering materials are exposed to dwell-times in service, it is important to understand the effects of dwell times on the fatigue life. The mechanisms controlling deformation and failure under dwell conditions are in terms of metallographic damage namely; transgranular fracture, intergranular fracture, mixed intergranular transgranular fracture modes, surface striated damage, creep damage and oxidation. These mechanisms are very difficult to include in a quantitative model to predict the dwell sensitivity behavior of high temperature materials. Published creep-fatigue data were compiled from various sources for a number of materials such as copper alloys (NARloy-Z, AMZ1RC), steel alloys (9Cr-lMo), and nickel based alloys(lN 100, Rene 95, Waspaloy). In general, dwell-times were found to be detrimental to the fatigue life of materials, but the exact extent of the effect varies depending on the material, duration of the dwell, and the direction in which a dwell was applied. In this research an attempt has been made to further develop the models of the senior author and include such concepts as stress relaxation with respect to a particular dwell time. Very limited data sets are available in the literature showing all the test details needed for developing a model for this research. However, the initial trials show stress relaxation as a result of a dwell cycle may exhibit an effect that may describe dwell. A dwell sensitivity damage mechanistic map and a new dwell sensitivity damage parameter were developed

    Finite Element Analysis of Femoral Components Paper III – Hip Joints

    No full text
    Finite element analysis of the hip implant is conducted in this paper for representative femoral cross-section geometries and development of stress in the presence of bone cement is elucidated. Differences in cement stresses generated by varying implant cross-sections were compared with conventional features derived from representative implants. The analysis was performed under idealized implant assemblies by constraining the implant movement in the assembly. The cross-sections and implant geometries used are generic and intended to be representative of available geometries. This paper is a part of student research projects, prepared from a series of activities in biomedical implant research currently underway at Ohio Northern and Arkansas Tech Universities

    Social learning: a construction of reality

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