WorldWideScience

Sample records for environment fatigue design

  1. Effects of LWR coolant environments on fatigue design curves of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1998-03-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the code specify fatigue design curves for structural materials. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data indicate that the Code fatigue curves may not always be adequate in coolant environments. This report summarizes work performed by Argonne National Laboratory on fatigue of carbon and low-alloy steels in light water reactor (LWR) environments. The existing fatigue S-N data have been evaluated to establish the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, temperature, orientation, and sulfur content on the fatigue life of these steels. Statistical models have been developed for estimating the fatigue S-N curves as a function of material, loading, and environmental variables. The results have been used to estimate the probability of fatigue cracking of reactor components. The different methods for incorporating the effects of LWR coolant environments on the ASME Code fatigue design curves are presented

  2. Interim fatigue design curves for carbon, low-alloy, and austenitic stainless steels in LWR environments

    International Nuclear Information System (INIS)

    Majumdar, S.; Chopra, O.K.; Shack, W.J.

    1993-01-01

    Both temperature and oxygen affect fatigue life; at the very low dissolved-oxygen levels in PWRs and BWRs with hydrogen water chemistry, environmental effects on fatigue life are modest at all temperatures (T) and strain rates. Between 0.1 and 0.2 ppM, the effect of dissolved-oxygen increases rapidly. In oxygenated environments, fatigue life depends strongly on strain rate and T. A fracture mechanics model is developed for predicting fatigue lives, and interim environmentally assisted cracking (EAC)-adjusted fatigue curves are proposed for carbon steels, low-alloy steels, and austenitic stainless steels

  3. Fatigue management considering LWR coolant environments

    International Nuclear Information System (INIS)

    Park, Heung Bae; Jin, Tae eun

    2000-01-01

    Design fatigue curve for structural material in the ASME Boiler and Pressure Vessel Code do not explicitly address the effects of reactor coolant environments on fatigue life. Environmentally assisted cracking (EAC) of low-alloy steels in light water reactor (LWR) coolant environments has been a concern ever since the early 1970's. And, recent fatigue test data indicate a significant decrease in fatigue lives of carbon steels, low-alloy steels and austenitic stainless steels in LWR coolant environments. For these reasons, fatigue of major components has been identified as a technical issue remaining to be resolved for life management and license renewal of nuclear power plants. In the present paper, results of recent investigations by many organizations are reviewed to provide technical justification to support the development of utility approach regarding the management of fatigue considering LWR coolant environments for the purpose of life management and license renewal of nuclear power plants. (author)

  4. Fatigue design 1998

    Energy Technology Data Exchange (ETDEWEB)

    Marquis, G.; Solin, J. [eds.] [VTT Manufacturing Technology, Espoo (Finland)

    1998-12-31

    These preprints contain the presentations to be delivered at the Fatigue Design 1998 symposium held on May 26-29, 1998 in Espoo. Fatigue Design 1998 is the tenth in a series of VTT symposia addressing the challenge of fatigue of materials, components and structures. Previous international events were in 1992 and 1995. The key theme of the current meeting is `RELIABILITY`. The two volumes (VTT symposium 181-182) represent 56 contributions by authors representing 26 countries. Emphasis has been given to application oriented research topics that report new technologies, new uses of existing methods and case studies. The objective of the symposium is to bring together researchers and engineers to share experiences and new innovations in designing reliable components to resist alternating loads. (orig.)

  5. Fatigue impact on Mod-1 wind turbine design

    Science.gov (United States)

    Stahle, C. V., Jr.

    1978-01-01

    Fatigue is a key consideration in the design of a long-life Wind Turbine Generator (WTG) system. This paper discusses the fatigue aspects of the large Mod-1 horizontal-axis WTG design starting with the characterization of the environment and proceeding through the design. Major sources of fatigue loading are discussed and methods of limiting fatigue loading are described. NASTRAN finite element models are used to determine dynamic loading and internal cyclic stresses. Recent developments in determining the allowable fatigue stress consistent with present construction codes are discussed relative to their application to WTG structural design.

  6. Fatigue data compilation and evaluation of fatigue on design

    International Nuclear Information System (INIS)

    Nyilas, A.

    1985-05-01

    The aim of this report is a review of the available fatigue data of various materials necessary for the design of large superconducting magnets for fusion. One of the primary objectives of this work is to present a broad outline of the low temperature fatigue data of relevant materials within the scope of available data. Besides the classical fatigue data of materials the fatigue crack propagation measurements are outlined widely. The existing recommendations for the design of cryogenic structures are described. A brief introduction of fracture mechanics as well as a historical background of the development of our present day understanding of fatigue has been done. (orig.) [de

  7. Design fatigue curve for Hastelloy-X

    International Nuclear Information System (INIS)

    Nishiguchi, Isoharu; Muto, Yasushi; Tsuji, Hirokazu

    1983-12-01

    In the design of components intended for elevated temperature service as the experimental Very High-Temperature gas-cooled Reactor (VHTR), it is essential to prevent fatigue failure and creep-fatigue failure. The evaluation method which uses design fatigue curves is adopted in the design rules. This report discussed several aspects of these design fatigue curves for Hastelloy-X (-XR) which is considered for use as a heat-resistant alloy in the VHTR. Examination of fatigue data gathered by a literature search including unpublished data showed that Brinkman's equation is suitable for the design curve of Hastelloy-X (-XR), where total strain range Δ epsilon sub(t) is used as independent variable and fatigue life Nsub(f) is transformed into log(log Nsub(f)). (author)

  8. Interconnect fatigue design for terrestrial photovoltaic modules

    Science.gov (United States)

    Mon, G. R.; Moore, D. M.; Ross, R. G., Jr.

    1982-03-01

    The results of comprehensive investigation of interconnect fatigue that has led to the definition of useful reliability-design and life-prediction algorithms are presented. Experimental data indicate that the classical strain-cycle (fatigue) curve for the interconnect material is a good model of mean interconnect fatigue performance, but it fails to account for the broad statistical scatter, which is critical to reliability prediction. To fill this shortcoming the classical fatigue curve is combined with experimental cumulative interconnect failure rate data to yield statistical fatigue curves (having failure probability as a parameter) which enable (1) the prediction of cumulative interconnect failures during the design life of an array field, and (2) the unambiguous--ie., quantitative--interpretation of data from field-service qualification (accelerated thermal cycling) tests. Optimal interconnect cost-reliability design algorithms are derived based on minimizing the cost of energy over the design life of the array field.

  9. High temperature creep-fatigue design

    International Nuclear Information System (INIS)

    Tavassoli, A. A. F.; Fournier, B.; Sauzay, M.

    2010-01-01

    Generation IV fission and future fusion reactors envisage development of more efficient high temperature concepts where materials performances are key to their success. This paper examines different types of high temperature creep-fatigue interactions and their implications on design rules for the structural materials retained in both programmes. More precisely, the paper examines current status of design rules for the stainless steel type 316L(N), the conventional Modified 9Cr-1Mo martensitic steel and the low activation Eurofer steel. Results obtained from extensive high temperature creep, fatigue and creep-fatigue tests performed on these materials and their welded joints are presented. These include sequential creep-fatigue and relaxation creep-fatigue tests with hold times in tension, in compression or in both. Effects of larger plastic deformations on fatigue properties are studied through cyclic creep tests or fatigue tests with extended hold time in creep. In most cases, mechanical test results are accompanied with microstructural and fractographic observations. In the case of martensitic steels, the effect of oxidation is examined by performing creep-fatigue tests on identical specimens in vacuum. Results obtained are analyzed and their implications on design allowable and creep-fatigue interaction diagrams are presented. While reasonable confidence is found in predicting creep-fatigue damage through existing code procedures for austenitic stainless steels, effects of cyclic softening and coarsening of microstructure of martensitic steels throughout the fatigue life on materials properties need to be taken into account for more precise damage calculations. In the long-term, development of ferritic/martensitic steels with stable microstructure, such as ODS steels, is proposed. (authors)

  10. High temperature creep-fatigue design

    Energy Technology Data Exchange (ETDEWEB)

    Tavassoli, A. A. F.; Fournier, B.; Sauzay, M. [CEA Saclay, DEN DMN, F-91191 Gif Sur Yvette (France)

    2010-07-01

    Generation IV fission and future fusion reactors envisage development of more efficient high temperature concepts where materials performances are key to their success. This paper examines different types of high temperature creep-fatigue interactions and their implications on design rules for the structural materials retained in both programmes. More precisely, the paper examines current status of design rules for the stainless steel type 316L(N), the conventional Modified 9Cr-1Mo martensitic steel and the low activation Eurofer steel. Results obtained from extensive high temperature creep, fatigue and creep-fatigue tests performed on these materials and their welded joints are presented. These include sequential creep-fatigue and relaxation creep-fatigue tests with hold times in tension, in compression or in both. Effects of larger plastic deformations on fatigue properties are studied through cyclic creep tests or fatigue tests with extended hold time in creep. In most cases, mechanical test results are accompanied with microstructural and fractographic observations. In the case of martensitic steels, the effect of oxidation is examined by performing creep-fatigue tests on identical specimens in vacuum. Results obtained are analyzed and their implications on design allowable and creep-fatigue interaction diagrams are presented. While reasonable confidence is found in predicting creep-fatigue damage through existing code procedures for austenitic stainless steels, effects of cyclic softening and coarsening of microstructure of martensitic steels throughout the fatigue life on materials properties need to be taken into account for more precise damage calculations. In the long-term, development of ferritic/martensitic steels with stable microstructure, such as ODS steels, is proposed. (authors)

  11. Automated corrosion fatigue crack growth testing in pressurized water environments

    International Nuclear Information System (INIS)

    Ceschini, L.J.; Liaw, P.K.; Rudd, G.E.; Logsdon, W.A.

    1984-01-01

    This paper describes in detail a novel approach to construct a test facility for developing corrosion fatigue crack growth rate (FCGR) properties in aggressive environments. The environment studied is that of a pressurized water reactor (PWR) at 288 0 C (550 0 F) and 13.8 MPa (200 psig). To expedite data generation, each chamber was designed to accommodate two test specimens. A common water recirculation and pressurization system was employed to service two test chambers. Thus, four fatigue crack propagation rate tests could be conducted simultaneously in the pressurized water environment. The data analysis was automated to minimize the typically high labor costs associated with corrosion fatigue crack propagation testing. Verification FCGR tests conducted on an ASTM A469 rotor steel in a room temperature air environment as well as actual PWR environment FCGR tests performed on an ASTM A533 Grade B Class 2 pressure vessel steel demonstrated that the dual specimen test facility is an excellent system for developing the FCGR properties of materials in adverse environments

  12. Effects of LWR environments on fatigue life of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    SME Boiler and Pressure Vessel Code provides construction of nuclear power plant components. Figure I-90 Appendix I to Section III of the Code specifies fatigue design curves for structural materials. While effects of environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A 106-Gr B carbon steel and A533-Gr B low-alloy steel in water

  13. Effects of LWR coolant environments on fatigue lives of austenitic stainless steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Gavenda, D.J.

    1997-01-01

    The ASME Boiler and Pressure Vessel Code fatigue design curves for structural materials do not explicitly address the effects of reactor coolant environments on fatigue life. Recent test data indicate a significant decrease in fatigue life of pressure vessel and piping materials in light water reactor (LWR) environments. Fatigue tests have been conducted on Types 304 and 316NG stainless steel in air and LWR environments to evaluate the effects of various material and loading variables, e.g., steel type, strain rate, dissolved oxygen (DO) in water, and strain range, on fatigue lives of these steels. The results confirm the significant decrease in fatigue life in water. The environmentally assisted decrease in fatigue life depends both on strain rate and DO content in water. A decrease in strain rate from 0.4 to 0.004%/s decreases fatigue life by a factor of ∼ 8. However, unlike carbon and low-alloy steels, environmental effects are more pronounced in low-DO than in high-DO water. At ∼ 0.004%/s strain rate, reduction in fatigue life in water containing <10 ppb D is greater by a factor of ∼ 2 than in water containing ≥ 200 ppb DO. Experimental results have been compared with estimates of fatigue life based on the statistical model. The formation and growth of fatigue cracks in austenitic stainless steels in air and LWR environments are discussed

  14. Low cycle corrosion fatigue properties of F316Ti in simulated LWR primary environment

    International Nuclear Information System (INIS)

    Xu Xuelian; Ding Yaping; Katada, Y.; Sato, S.

    1998-11-01

    Environment effect on fatigue performance of materials used for Pressurized boundary, including fatigue life and crack growth rate, are of importance to nuclear safety. To predict the fatigue life of nuclear materials and to improve the design of nuclear materials, it is necessary to investigated the material fatigue performances in corrosive environment and to get the fatigue data under its environment to be used in. Low cycle corrosion fatigue (CF) performance investigation of domestic F316Ti in simulated BWR and PWR primary environment was carried out. The result shows that the high temperature water environment is one of the most important factors on CF properties. For the same material, the low cycle fatigue life in high temperature air is longer than that in simulated BWR and PWR primary environments. In high temperature water, domestic F316Ti has almost the same low cycle corrosion fatigue performance as F316 (made in Japan). All of the fatigue data are scattered within ASME best-fit curve and ASME design fatigue curve. In high strain range, there is no significant difference of the CF performance for F316Ti in both of BWR and PWR primary environments. With the decrease of strain amplitude, the difference appears gradually. The data is located at the short life side of the fatigue data in simulated BWR primary environment. Titanium is distributed uniformly in F316Ti manufactured in Fushun Steel Factory. Ni, Cr, Mo in this material are located at the high side of the alloy chemical composition range. So, F316Ti has a better CF property in high temperature water

  15. Creep fatigue design of FBR components

    International Nuclear Information System (INIS)

    Bhoje, S.B.; Chellapandi, P.

    1997-01-01

    This paper deals with the characteristic features of Fast Breeder Reactor (FBR) with reference to creep fatigue, current creep fatigue design approach in compliance with RCCMR (1987) design code, material data, effects of weldments and neutron irradiation, material constitutive models employed, structural analysis and further R and D required for achieving maturity in creep fatigue design of FBR components. For the analysis reported in this paper, material constitutive models developed based on ORNIb (Oak Ridge National Laboratory) and Chaboche viscoplastic theories are employed to demonstrate the potential of FBR components for higher plant temperatures and/or longer life. The results are presented for the studies carried out towards life prediction of Prototype Fast Breeder Reactor (PFBR) components. (author). 24 refs, 8 figs, 5 tabs

  16. A life evaluation under creep-fatigue-environment interaction of Ni-base wrought alloys

    International Nuclear Information System (INIS)

    Hattori, Hiroshi; Kitagawa, Masaki; Ohtomo, Akira; Itoh, Mitsuyoshi

    1986-01-01

    In order to determine a failure criteria under cyclic loading and affective environment for HTGR systems, a series of strain controlled low-cycle fatigue tests were carried out at HTGR maximum gas temperatures in air, in vacuum and in HTGR helium environments on two nickel-base wrought alloys, namely Inconel 617 and Hastelloy XR. This paper first describes the creep-fatigue-environment properties of these alloys followed by a proposal of an evaluation method of creep-fatigue-environment interaction based on the experimental data to define the more reasonable design criteria, which is a modification of the linear damage summation rule. Second, the creep-fatigue properties of Hastelloy XR at 900 deg C and the result evaluated by this proposed method are shown. This criterion is successfully applied to the life prediction at 900 deg C. In addition, the creep-fatigue properties of Hastelloy XR-II are discussed. (author)

  17. Probabilistic Fatigue Design of Composite Material for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2011-01-01

    In the present paper a probabilistic design approach to fatigue design of wind turbine blades is presented. The physical uncertainty on the fatigue strength for composite material is estimated using public available fatigue tests. Further, the model uncertainty on Miner rule for damage accumulation...

  18. Maternal fatigue and its relationship to the caregiving environment.

    Science.gov (United States)

    White, Carmel Parker; White, Mark B; Fox, Melissa A

    2009-12-01

    For women with an autoimmune illness, fatigue can be a debilitating symptom that impacts many aspects of their life. There is scant research on maternal fatigue and its impact on the caregiving environment for either well women or women with chronic illnesses. The objective of this study was to examine the role maternal fatigue played in the caregiving environment, specifically in the mother's experience of the daily hassles of parenting, the discipline style she employed, and how she monitored her child's whereabouts. Two-hundred sixty-two mothers participated in this study: 103 mothers with multiple sclerosis (MS), 68 mothers with rheumatoid arthritis (RA), and a comparison group of 91 well mothers. Mothers completed questionnaires assessing their self-reported levels of fatigue, depression, quality and quantity of sleep, parenting daily hassles, discipline styles, and monitoring. After sleep, depression, and number of children were controlled for, fatigue explained additional variance in predicting monitoring for all three groups of mothers. Fatigue was also a significant predictor of parenting daily hassles for both well mothers and mothers with RA, but not for mothers with MS. For mothers with MS, it was the covariates (i.e., the number of children in the family and sleep quality and quantity) that were predictive of parenting daily hassles. Several explanations for mothers with MS not being as influenced by fatigue are discussed.

  19. Fatigue strength degradation of metals in corrosive environments

    Science.gov (United States)

    Adasooriya, N. D.; Hemmingsen, T.; Pavlou, D.

    2017-12-01

    Structures exposed to aggressive environmental conditions are often subjected to time-dependent loss of coating and loss of material due to corrosion; this causes reduction in the cross-sectional properties of the members, increased surface roughness, surface irregularities and corrosion pits, and degradation of material strengths. These effects have been identified and simulated in different research studies. However, time and corrosive media dependent fatigue strength curves for materials have not been discussed in the design or assessment guidelines for structures. This paper attempts to review the corrosion degradation process and available approaches/models used to determine the fatigue strength of corroded materials and to interpolate corrosion deterioration data. High cycle fatigue and full range fatigue life formulae for fatigue strength of corroded materials are proposed. The above formulae depend on the endurance limit of corroded material, in addition to the stress-life fatigue curve parameters of the uncorroded material. The endurance limit of corroded material can either be determined by a limited number of tests in the very high-cycle fatigue region or predicted by an analytical approach. Comparison with experimentally measured corrosion fatigue behavior of several materials is provided and discussed.

  20. Incorporating the effects of environment in fatigue evaluations

    International Nuclear Information System (INIS)

    Huettner, C.; Dittmar, S.

    2003-01-01

    There are national and international activities for assessing the influence of the environment on fatigue of austenitic and ferritic components. On the basis of the results obtained, specifications for nuclear and conventional power plants are re-evaluated with a view to their accuracy in taking account of the influence of the environment in German nuclear power stations. In particular, KTA 3201.2 and KTA 3211.2 are gone into. The draft KTA 3211.2 contains qualitative specifications for taking account of the environment. Especially in the USA, methods were developed which take account of the environment in fatigue analyses as a function of several different influencing parameters. These methods are presented, and it is discussed inhowfar they should be taken into consideration in fatigue analyses according to KTA specifications. (orig.) [de

  1. Fatigue Life of Stainless Steel in PWR Environments with Strain Holding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taesoon; Kim, Kyuhyung [KHNP CRI, Daejeon (Korea, Republic of); Seo, Myeonggyu; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    Many components and structures of nuclear power plants are exposed to the water chemistry conditions during the operation. Recently, as design life of nuclear power plant is expanded over 60 years, the environmentally assisted fatigue (EAF) due to these water chemistry conditions has been considered as one of the important damage mechanisms of the safety class 1 components. Therefore, many studies to evaluate the effect of light water reactor (LWR) coolant environments on fatigue life of materials have been conducted. Many EAF test results including Argonne National Laboratory’s consistently indicated the substantial reduction of fatigue life in the light water reactor environments. However, there is a discrepancy between laboratory test data and plant operating experience regarding the effects of environment on fatigue: while laboratory test data suggest huge accumulation of fatigue damage, very limited experience of cracking caused by the low cycle fatigue in light water reactor. These hold-time effect tests are preformed to characterize the effects of strain holding on the fatigue life of austenitic stainless steels in PWR environments in comparison with the existing fixed strain rate results. Low cycle fatigue life tests were conducted for the type 316 stainless steel in 310℃ air and PWR environments with triangular strain. In agreement with the previous reports, the LCF life was reduced in PWR environments. Also for the slower strain rate, the reduction of LCF life was greater than the faster strain rate. The LCF test conditions for the hold-time effects were determined by the references and consideration of actual plant transient. To simulate the heat-up and cooldown transient, sub-peak strain holding during the down-hill of strain amplitude was chosen instead of peak strain holding which used in the previous researches.

  2. Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Dominguez, Sergio Marquez; Sørensen, John Dalsgaard

    2012-01-01

    Consequences of failure of offshore wind turbines (OWTs) are in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration...

  3. Visualization Design Environment

    Energy Technology Data Exchange (ETDEWEB)

    Pomplun, A.R.; Templet, G.J.; Jortner, J.N.; Friesen, J.A.; Schwegel, J.; Hughes, K.R.

    1999-02-01

    Improvements in the performance and capabilities of computer software and hardware system, combined with advances in Internet technologies, have spurred innovative developments in the area of modeling, simulation and visualization. These developments combine to make it possible to create an environment where engineers can design, prototype, analyze, and visualize components in virtual space, saving the time and expenses incurred during numerous design and prototyping iterations. The Visualization Design Centers located at Sandia National Laboratories are facilities built specifically to promote the ''design by team'' concept. This report focuses on designing, developing and deploying this environment by detailing the design of the facility, software infrastructure and hardware systems that comprise this new visualization design environment and describes case studies that document successful application of this environment.

  4. Designing Creative Learning Environments

    Directory of Open Access Journals (Sweden)

    Thomas Cochrane

    2015-05-01

    Full Text Available Designing creative learning environments involves not only facilitating student creativity, but also modeling creative pedagogical practice. In this paper we explore the implementation of a framework for designing creative learning environments using mobile social media as a catalyst for redefining both lecturer pedagogical practice, as well as redesigning the curriculum around student generated m-portfolios.

  5. Impact of Fatigue in Rheumatic Diseases in the Work Environment: A Qualitative Study.

    LENUS (Irish Health Repository)

    Connolly, Deirdre

    2015-10-28

    Fatigue is a symptom of arthritis that causes difficulty at work. An improved understanding of this symptom could assist its management in the work environment. The aim of this study was to explore people with rheumatic diseases\\' experiences of fatigue in work. A qualitative descriptive design was used with semi-structured interviews and a constant comparative method of data analysis. There were 18 participants, the majority of them female with Rheumatoid Arthritis (RA) and working full-time. Three themes were identified: "Impact of fatigue on work performance" with cognition, mood and physical abilities being the main difficulties reported. In the second theme "Disclosure at Work" participants discussed disclosing their disease to employers but reported a lack of understanding of fatigue from colleagues. The final theme "work-based fatigue management strategies" included cognitive strategies and energy management techniques, which were mainly self-taught. In this study, fatigue was reported to impact on many areas of work performance with limited understanding from colleagues and employers. Interventions from health professionals to assist with development of work-related self-management skills are required to assist with symptom management in the work place. Such interventions should include education to employers and colleagues on the nature of fatigue in Rheumatic diseases.

  6. Impact of Fatigue in Rheumatic Diseases in the Work Environment: A Qualitative Study

    Directory of Open Access Journals (Sweden)

    Deirdre Connolly

    2015-10-01

    Full Text Available Fatigue is a symptom of arthritis that causes difficulty at work. An improved understanding of this symptom could assist its management in the work environment. The aim of this study was to explore people with rheumatic diseases’ experiences of fatigue in work. A qualitative descriptive design was used with semi-structured interviews and a constant comparative method of data analysis. There were 18 participants, the majority of them female with Rheumatoid Arthritis (RA and working full-time. Three themes were identified: “Impact of fatigue on work performance” with cognition, mood and physical abilities being the main difficulties reported. In the second theme “Disclosure at Work” participants discussed disclosing their disease to employers but reported a lack of understanding of fatigue from colleagues. The final theme “work-based fatigue management strategies” included cognitive strategies and energy management techniques, which were mainly self-taught. In this study, fatigue was reported to impact on many areas of work performance with limited understanding from colleagues and employers. Interventions from health professionals to assist with development of work-related self-management skills are required to assist with symptom management in the work place. Such interventions should include education to employers and colleagues on the nature of fatigue in Rheumatic diseases.

  7. Fatigue properties of Zircaloy-2 in a PWR water environment

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    The continuing trend of operation of light water reactors is towards power cycling as a means of operating the systems more efficiently. Depending upon the reactor design and mode of power cycling this could lead to significant fatigue usage in Zircaloy structural components. In order to design against the possibility of gross yielding or fast fracture of such components as a result of this it is obviously necessary to be able to predict conservatively the fatigue properties of Zircaloy under the reactor operating conditions

  8. Fatigue Reliability and Calibration of Fatigue Design Factors for Offshore Wind Turbines

    Directory of Open Access Journals (Sweden)

    Sergio Márquez-Domínguez

    2012-06-01

    Full Text Available Consequences of failure of offshore wind turbines (OWTs is in general lower than consequences of failure of, e.g., oil & gas platforms. It is reasonable that lower fatigue design factors can be applied for fatigue design of OWTs when compared to other fixed offshore structures. Calibration of appropriate partial safety factors/Fatigue Design Factors (FDF for steel substructures for OWTs is the scope of this paper. A reliability-based approach is used and a probabilistic model has been developed, where design and limit state equations are established for fatigue failure. The strength and load uncertainties are described by stochastic variables. SN and fracture mechanics approaches are considered for to model the fatigue life. Further, both linear and bi-linear SN-curves are formulated and various approximations are investigated. The acceptable reliability level for fatigue failure of OWTs is discussed and results are presented for calibrated optimal fatigue design factors. Further, the influence of inspections is considered in order to extend and maintain a given target safety level.

  9. The hold-time effects on the low cycle fatigue behaviors of 316 SS in PWR primary environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Junho; Hong, Jong-Dae; Seo, Myung-Gyu; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    The effects of the environments on fatigue life of the structural materials used in nuclear power plants (NPPs) were known to be significant according to the extensive test results. Accordingly, the fatigue analysis procedures and the design fatigue curves were proposed in the ASME Code. However, the implication that the existing ASME design fatigue curves did not sufficiently reflect the effect of the operation conditions of nuclear power plants emerged as an issue to be resolved. One of possible reasons to explain the discrepancy is that the laboratory test conditions do not represent the actual plant transients. Therefore, it is necessary to clarify the effects of light water environments on fatigue life while considering more plant-relevant transient conditions such as hold-time. For this reason, this study will focus on the fatigue life of type 316 stainless steel (SS) in the pressurized water reactor (PWR) environments while incorporating the hold-time during the low cycle fatigue (LCF) test in simulated PWR environments. The objective of this study is to characterize the effects of hold-time on the fatigue life of austenitic stainless steels in PWR environments in comparison with the existing fixed strain rate results. Low cycle fatigue life tests were conducted for the type 316 SS in 310 .deg. C air and simulated PWR environments. To simulate the heat-up and cool-down transient, sub-peak strain holding during the down-hill of strain amplitude was chosen. Currently, LCF tests with 60 seconds holding are in progress. The 0.4, 0.04%/s strain rate condition test results are presented in this study, which shows somewhat longer fatigue life.

  10. The hold-time effects on the low cycle fatigue behaviors of 316 SS in PWR primary environment

    International Nuclear Information System (INIS)

    Lee, Junho; Hong, Jong-Dae; Seo, Myung-Gyu; Jang, Changheui

    2015-01-01

    The effects of the environments on fatigue life of the structural materials used in nuclear power plants (NPPs) were known to be significant according to the extensive test results. Accordingly, the fatigue analysis procedures and the design fatigue curves were proposed in the ASME Code. However, the implication that the existing ASME design fatigue curves did not sufficiently reflect the effect of the operation conditions of nuclear power plants emerged as an issue to be resolved. One of possible reasons to explain the discrepancy is that the laboratory test conditions do not represent the actual plant transients. Therefore, it is necessary to clarify the effects of light water environments on fatigue life while considering more plant-relevant transient conditions such as hold-time. For this reason, this study will focus on the fatigue life of type 316 stainless steel (SS) in the pressurized water reactor (PWR) environments while incorporating the hold-time during the low cycle fatigue (LCF) test in simulated PWR environments. The objective of this study is to characterize the effects of hold-time on the fatigue life of austenitic stainless steels in PWR environments in comparison with the existing fixed strain rate results. Low cycle fatigue life tests were conducted for the type 316 SS in 310 .deg. C air and simulated PWR environments. To simulate the heat-up and cool-down transient, sub-peak strain holding during the down-hill of strain amplitude was chosen. Currently, LCF tests with 60 seconds holding are in progress. The 0.4, 0.04%/s strain rate condition test results are presented in this study, which shows somewhat longer fatigue life

  11. Physical and Model Uncertainty for Fatigue Design of Composite Material

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    The main aim of the present report is to establish stochastic models for the uncertainties related to fatigue design of composite materials. The uncertainties considered are the physical uncertainty related to the static and fatigue strength and the model uncertainty related to Miners rule...

  12. Review of the margins for ASME code fatigue design curve - effects of surface roughness and material variability

    International Nuclear Information System (INIS)

    Chopra, O. K.; Shack, W. J.

    2003-01-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. The Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ((var e psilon)-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of the existing fatigue (var e psilon)-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue (var e psilon)-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for ASME Code fatigue design curves is presented

  13. Review of the margins for ASME code fatigue design curve - effects of surface roughness and material variability.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Shack, W. J.; Energy Technology

    2003-10-03

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. The Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of the existing fatigue {var_epsilon}-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for ASME Code fatigue design curves is presented.

  14. Partial Safety Factors for Fatigue Design of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2010-01-01

    In the present paper calibration of partial safety factors for fatigue design of wind turbine blades is considered. The stochastic models for the physical uncertainties on the material properties are based on constant amplitude fatigue tests and the uncertainty on Miners rule for linear damage...... accumulation is determined from variable amplitude fatigue tests with the Wisper and Wisperx spectra. The statistical uncertainty for the assessment of the fatigue loads is also investigated. The partial safety factors are calibrated for design load case 1.2 in IEC 61400-1. The fatigue loads are determined...... from rainflow-counting of simulated time series for a 5MW reference wind turbine [1]. A possible influence of a complex stress state in the blade is not taken into account and only longitudinal stresses are considered....

  15. Fatigue life response of ASME SA 106-B steel in pressurized water reactor environments

    Energy Technology Data Exchange (ETDEWEB)

    Terrell, J B [Materials Engineering Associates, Inc., Lanham, MD (USA)

    1989-01-01

    Fatigue strain-life tests were conducted on ASMESA 106-B piping steel base metal and weld metal specimens in 288{sup 0}C (550{sup 0}F) pressurized water reactor (PWR) environments as a function of strain amplitude, strain ratio, notch acuity, and cyclic frequency. Notched base metal specimens tested at 0.017 Hz in 0.001 part per million (ppm) dissolved oxygen environments nearly completely used up the margins of safety of 2 on stress and 20 on cycles incorporated into the ASMA Section III design curve for carbon steels. Tests conducted with smooth base metal and weld metal specimens at 1.0 Hz showed virtually no degradation in cycles to failure when compared to 288{sup 0}C air test results. In all cases, however, the effect of temperature alone reduced the margin of safety offered by the design curve in the low cycle regime for the test specimens. Comparison between the fatigue life results of smooth and notched specimens suggests that fatigue crack initiation is not significantly affected by 0.001 ppm dissolved oxygen, and that most of the observed degradation may be attributed to crack growth acceleration. These results suggest that the ASMA Section III methodology should be reviewed, taking into account the PWR environment variables which degrade the fatigue life of pressure-retaining components. (author).

  16. Fatigue life response of ASME SA 106-B steel in pressurized water reactor environments

    International Nuclear Information System (INIS)

    Terrell, J.B.

    1989-01-01

    Fatigue strain-life tests were conducted on ASMESA 106-B piping steel base metal and weld metal specimens in 288 0 C (550 0 F) pressurized water reactor (PWR) environments as a function of strain amplitude, strain ratio, notch acuity, and cyclic frequency. Notched base metal specimens tested at 0.017 Hz in 0.001 part per million (ppm) dissolved oxygen environments nearly completely used up the margins of safety of 2 on stress and 20 on cycles incorporated into the ASMA Section III design curve for carbon steels. Tests conducted with smooth base metal and weld metal specimens at 1.0 Hz showed virtually no degradation in cycles to failure when compared to 288 0 C air test results. In all cases, however, the effect of temperature alone reduced the margin of safety offered by the design curve in the low cycle regime for the test specimens. Comparison between the fatigue life results of smooth and notched specimens suggests that fatigue crack initiation is not significantly affected by 0.001 ppm dissolved oxygen, and that most of the observed degradation may be attributed to crack growth acceleration. These results suggest that the ASMA Section III methodology should be reviewed, taking into account the PWR environment variables which degrade the fatigue life of pressure-retaining components. (author)

  17. Design Optimization and Fatigue Analysis of Laser Stake Welded Connections

    National Research Council Canada - National Science Library

    Singh, Anshuman; Vel, Senthil S; Caccese, Vincent

    2008-01-01

    This report summanzes research on the design and fatigue analysis of laser-stake welded connections performed at the University of Maine from January 2006 to December 2007 for the Structural Response...

  18. Recommendations for fatigue design of welded joints and components

    CERN Document Server

    Hobbacher, A F

    2016-01-01

    This book provides a basis for the design and analysis of welded components that are subjected to fluctuating forces, to avoid failure by fatigue. It is also a valuable resource for those on boards or commissions who are establishing fatigue design codes. For maximum benefit, readers should already have a working knowledge of the basics of fatigue and fracture mechanics. The purpose of designing a structure taking into consideration the limit state for fatigue damage is to ensure that the performance is satisfactory during the design life and that the survival probability is acceptable. The latter is achieved by the use of appropriate partial safety factors. This document has been prepared as the result of an initiative by Commissions XIII and XV of the International Institute of Welding (IIW).

  19. Fatigue and rutting strain analysis of flexible pavements designed ...

    African Journals Online (AJOL)

    ELO

    The study was carried out with the layered elastic analysis software EVERSTRESS. Key words: Layered elastic analysis, fatigue, rutting, strains, design, flexible pavement, CBR. ..... Numerical Computational Stresses and Strains in Multi-Layer ...

  20. Fatigue Performance of SFPSC under Hot-Wet Environments and Cyclic Bending Loads

    Directory of Open Access Journals (Sweden)

    Shanshan Luo

    2018-01-01

    Full Text Available A new structural material named “steel fiber polymer structural concrete (SFPSC” with features of both high strength and high toughness was developed by this research group and applied to the bridge superstructures in the hot-wet environments. In order to investigate the fatigue performance and durability of SFPSC under hot-wet environments, the environment and fatigue load uncoupling method and the coupling action of environment and fatigue load were used or developed. Three-point bending fatigue experiments with uncoupling action of environments and cyclic loads were carried out for SFPSC specimens which were pretreated under hot-wet environments, and the experiments with the coupling action of environments and cyclic loads for SFPSC specimens were carried out under hot-wet environments. Then, the effects of hot-wet environments and the experimental methods on the fatigue mechanism of SFPSC material were discussed, and the environmental fatigue equations of SFPSC material under coupling and uncoupling action of hot-wet environments and cyclic bending loads were established. The research results show that the fatigue limits of SFPSC under the coupling action of the environments and cyclic loads were lower about 15%. The proposed fatigue equations could be used to estimate the fatigue lives and fatigue limits of SFPSC material.

  1. Designing Fatigue Warning Systems: The perspective of professional drivers.

    Science.gov (United States)

    Meng, Fanxing; Li, Shuling; Cao, Lingzhi; Peng, Qijia; Li, Musen; Wang, Chunhui; Zhang, Wei

    2016-03-01

    Professional drivers have been characterized as experiencing heavy fatigue resulting from long driving time in their daily work. This study aimed to explore the potential demand of Fatigue Warning Systems (FWSs) among professional drivers as a means of reducing the danger of fatigue driving and to examine their opinions regarding the design of FWSs. Six focus groups with 35 participants and a questionnaire survey with 600 respondents were conducted among Chinese truck and taxi drivers to collect qualitative and quantitative data concerning the current situation of fatigue driving and opinions regarding the design of FWSs. The results revealed that both truck and taxi drivers had a positive attitude toward FWSs, and they hoped this system could not only monitor and warn them regarding their fatigue but also somewhat relieve their fatigue before they could stop and rest. As for warning signals, participants preferred auditory warnings, as opposed to visual, vibrotactile or electric stimuli. Interestingly, it was proposed that verbal warnings involving the information regarding consequences of fatigue driving or the wishes of drivers' family members would be more effective. Additionally, different warning patterns, including graded, single and continuous warnings, were discussed in the focus group. Finally, the participants proposed many other suggestions, as well as their concerns regarding FWSs, which will provide valuable information for companies who wish to develop FWSs for professional drivers. Copyright © 2015. Published by Elsevier Ltd.

  2. Fatigue

    Science.gov (United States)

    ... to help you find out what's causing your fatigue and recommend ways to relieve it. Fatigue itself is not a disease. Medical problems, treatments, and personal habits can add to fatigue. These include Taking certain medicines, such as antidepressants, ...

  3. The effects of heat treatment and environment on corrosion fatigue

    International Nuclear Information System (INIS)

    Ballinger, R.G.; Hwang, I.S.; Elliott, C.K.

    1993-05-01

    Alloy X-750 is a nickel-base alloy used extensively in Light Water Reactor (LWR) nuclear power systems due to its excellent corrosion resistance and high temperature strength. In spite of alloy X-750's exceptional high temperature properties, it has been found to be susceptible to environmentally assisted fatigue and stress corrosion cracking in relatively low temperature aqueous environments such as those that exist in LWR systems. In order to develop a better understanding of the role that microstructure plays in the fatigue behavior of alloy X-750, three thermal treatments were studied. The treatments used were as hot worked + : (1) 24 h at 885 degree C + 20 h at 704 degree C (AH), (2) lh at 982 degree C + 20 h at 704 degree C (BH), and (3) 1 h at 1093 degree C + 20 h at 704 degree C (HTH). Fatigue crack growth tests were conducted at frequencies of 0.1 and 10 Hz in the following aqueous environments: (1) high purity, air saturated water (8 ppM O 2 ) at 93 degree C and 288 degree C, (2) high purity, deoxygenated water (5 ppb O 2 ) at 93 degree C, and (3) simulated BWR water chemistry with hydrogen additions at 288 degree C. Crack growth rate data was collected at constant values of stress intensity factor range (ΔK). The results show that crack growth rates and morphology are a function of ΔK, frequency, thermal treatment and environment. Frequency effects were most significant for the AH material. Crack growth rates generally decrease, for a given value of ΔK, in the BH and HTH materials with the HTH material showing the lowest growth rate

  4. Proposed design procedure for transmission shafting under fatigue loading

    Science.gov (United States)

    Loewenthal, S. H.

    1978-01-01

    The B106 American National Standards Committee is currently preparing a new standard for the design of transmission shafting. A design procedure, proposed for use in the new standard, for computing the diameter of rotating solid steel shafts under combined cyclic bending and steady torsion is presented. The formula is based on an elliptical variation of endurance strength with torque exhibited by combined stress fatigue data. Fatigue factors are cited to correct specimen bending endurance strength data for use in the shaft formula. A design example illustrates how the method is to be applied.

  5. GLobal Integrated Design Environment

    Science.gov (United States)

    Kunkel, Matthew; McGuire, Melissa; Smith, David A.; Gefert, Leon P.

    2011-01-01

    The GLobal Integrated Design Environment (GLIDE) is a collaborative engineering application built to resolve the design session issues of real-time passing of data between multiple discipline experts in a collaborative environment. Utilizing Web protocols and multiple programming languages, GLIDE allows engineers to use the applications to which they are accustomed in this case, Excel to send and receive datasets via the Internet to a database-driven Web server. Traditionally, a collaborative design session consists of one or more engineers representing each discipline meeting together in a single location. The discipline leads exchange parameters and iterate through their respective processes to converge on an acceptable dataset. In cases in which the engineers are unable to meet, their parameters are passed via e-mail, telephone, facsimile, or even postal mail. The result of this slow process of data exchange would elongate a design session to weeks or even months. While the iterative process remains in place, software can now exchange parameters securely and efficiently, while at the same time allowing for much more information about a design session to be made available. GLIDE is written in a compilation of several programming languages, including REALbasic, PHP, and Microsoft Visual Basic. GLIDE client installers are available to download for both Microsoft Windows and Macintosh systems. The GLIDE client software is compatible with Microsoft Excel 2000 or later on Windows systems, and with Microsoft Excel X or later on Macintosh systems. GLIDE follows the Client-Server paradigm, transferring encrypted and compressed data via standard Web protocols. Currently, the engineers use Excel as a front end to the GLIDE Client, as many of their custom tools run in Excel.

  6. Fatigue design of steel and composite structures Eurocode 3 : design of steel structures, part 1-9 fatigue ; Eurocode 4 : design of composite steel and concrete structures

    CERN Document Server

    Nussbaumer, Alain; Davaine, Laurence

    2012-01-01

    This volume addresses the specific subject of fatigue, a subject not familiar to many engineers, but still relevant for proper and good design of numerous steel structures. It explains all issues related to the subject: Basis of fatigue design, reliability and various verification formats, determination of stresses and stress ranges, fatigue strength, application range and limitations. It contains detailed examples of applications of the concepts, computation methods and verifications.

  7. Fatigue cracking of alloy 600 in simulated steam generator crevice environment

    International Nuclear Information System (INIS)

    Ogundele, G.; Lepik, O.

    1998-01-01

    Investigations were carried out to generate fatigue life (S-N) and near-threshold fatigue crack propagation (da/dN) data to determine the environmental influence on fatigue behavior for Alloy 600 in air, deionized water and in simulated Bruce Nuclear Generating Station 'A' crevice environments under appropriate loading conditions. In the low cycle fatigue regime, the simulated crevice environment did not affect the fatigue life of Alloy 600 under the applied loading conditions. The near-threshold fatigue crack growth rates of Alloy 600 in the simulated crevice environment were significantly lower compared to either pure water or air environments and is believed to be the result of higher crack closure in the crevice environment. (author)

  8. A literature review and inventory of the effects of environment on the fatigue behavior of metals

    Science.gov (United States)

    Hudson, C. M.; Seward, S. K.

    1976-01-01

    The current state of knowledge of the effects of gas environments (at atmospheric pressure and below) on the fatigue behavior of metals is reviewed. Among the topics considered are the mechanisms proposed to explain the differences observed in the fatigue behavior of vacuum- and air-tested specimens, the effects of environment on the surface topography of fatigue cycled specimens, the effect of environment on the various phases of the fatigue phenomenon, the effect of prolonged exposure to vacuum on fatigue life, the variation of fatigue life with decreasing gas pressure, and gas evolution during fatigue cycling. Analysis of the findings of this review indicates that hydrogen embrittlement is primarily responsible for decreased fatigue resistance in humid environments, and that dislocations move more easily during tests in vacuum than during test in air. It was found that fatigue cracks generally initiated and propagated more rapidly in air than in vacuum. Prolonged exposure to vacuum does not adversely affect fatigue resistance. The variation of fatigue life with decreasing gas pressure is sometimes stepped and sometimes continuous.

  9. An intriguing design concept to enhance the pulsatile fatigue life of self-expanding stents.

    Science.gov (United States)

    Hsiao, Hao-Ming; Yin, Ming-Ting

    2014-02-01

    Intravascular stenting has emerged as the primary treatment for vascular diseases and has received great attention from the medical community since its introduction two decades ago. The endovascular self-expanding stent is used to treat peripheral artery diseases; however, once implanted, these stents suffer from various cyclic motions caused by pulsatile blood pressure and daily activities. Due to this challenging environment, fatigue performance has become a critical issue for stent design. In this paper, a simple yet intriguing concept of stent design aimed at enhancing pulsatile fatigue life is investigated. The concept of this design is to shift the highly concentrated stresses/strains away from the crown and re-distribute them along the stress-free bar arm by tapering its strut width. Finite element models were developed to evaluate the mechanical integrity and pulsatile fatigue resistance of the stent to various loading conditions. Results show that the fatigue safety factor jumped to 2.5-3.0 times that of the standard stent with constant strut width. This is astonishing considering that the stent profile and scaffolding were not compromised. The findings of this paper provide an excellent approach to the optimization of future stent design to greatly improve stent fatigue performance.

  10. Mechanism of fatigue crack initiation in austenitic stainless steels in light water reactor environments

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.; Muscara, J.

    2003-01-01

    This paper examines the mechanism of fatigue crack initiation in austenitic stainless steels (SSs) in light water reactor (LWR) coolant environments. The effects of key material and loading variables on the fatigue lives of wrought and cast austenitic SSs in air and LWR environments have been evaluated. The influence of reactor coolant environments on the formation and growth of fatigue cracks in polished smooth SS specimens is discussed. The results indicate that the fatigue lives of these steels are decreased primarily by the effects of the environment on the growth of cracks <200 μm and, to a lesser extent, on enhanced growth rates of longer cracks. The fracture morphology in the specimens has been characterized. Exploratory fatigue tests were conducted to study the effects of surface micropits or minor differences in the surface oxide on fatigue crack initiation. (author)

  11. Fatigue proofing: The role of protective behaviours in mediating fatigue-related risk in a defence aviation environment.

    Science.gov (United States)

    Dawson, Drew; Cleggett, Courtney; Thompson, Kirrilly; Thomas, Matthew J W

    2017-02-01

    In the military or emergency services, operational requirements and/or community expectations often preclude formal prescriptive working time arrangements as a practical means of reducing fatigue-related risk. In these environments, workers sometimes employ adaptive or protective behaviours informally to reduce the risk (i.e. likelihood or consequence) associated with a fatigue-related error. These informal behaviours enable employees to reduce risk while continuing to work while fatigued. In this study, we documented the use of informal protective behaviours in a group of defence aviation personnel including flight crews. Semi-structured interviews were conducted to determine whether and which protective behaviours were used to mitigate fatigue-related error. The 18 participants were from aviation-specific trades and included aircrew (pilots and air-crewman) and aviation maintenance personnel (aeronautical engineers and maintenance personnel). Participants identified 147 ways in which they and/or others act to reduce the likelihood or consequence of a fatigue-related error. These formed seven categories of fatigue-reduction strategies. The two most novel categories are discussed in this paper: task-related and behaviour-based strategies. Broadly speaking, these results indicate that fatigued military flight and maintenance crews use protective 'fatigue-proofing' behaviours to reduce the likelihood and/or consequence of fatigue-related error and were aware of the potential benefits. It is also important to note that these behaviours are not typically part of the formal safety management system. Rather, they have evolved spontaneously as part of the culture around protecting team performance under adverse operating conditions. When compared with previous similar studies, aviation personnel were more readily able to understand the idea of fatigue proofing than those from a fire-fighting background. These differences were thought to reflect different cultural

  12. Some new fatigue tests in high temperature water and liquid sodium environment

    International Nuclear Information System (INIS)

    Hattori, Takahiro; Yamauchi, Takayoshi; Kanasaki, Hiroshi; Kondo, Yoshiyuki; Endo, Tadayoshi.

    1987-01-01

    To evaluate the fatigue strength of structural materials for PWR or FBR plants, fatigue test data must be obtained in an environment of simulated primary and secondary water for PWR or of high temperature liquid sodium for FBR. Generally, such tests make it necessary to prepare expensive facilities, so when large amount of fatigue data are required, it is necessary to rationalize and simplify the fatigue tests while maintaining high accuracy. At the Takasago Research Development Center, efforts to rationalize facilities and maintain accuracy in fatigue tests have been made by developing new test methods and improving conventional techniques. This paper introduces a new method of low cycle fatigue test in high temperature water, techniques for automatic measurement of crack initiation and propagation in high temperature water environment and a multiple type fatigue testing machine for high temperature liquid sodium. (author)

  13. Creep-fatigue-environment interaction of 9Cr-1Mo-V-Nb steel

    International Nuclear Information System (INIS)

    Shibata, Hiroyuki; Ishikawa, Akiyoshi; Asada, Yasuhide

    1996-01-01

    An extension of the creep-fatigue damage model has been conducted in the present study. The original damage model has been developed to the predict the creep-fatigue life of 9Cr-1Mo-V-Nb steel (Modified 9Cr-1Mo steel) in a very high vacuum environment. The present study is to extend an applicability of the model to the creep-fatigue damage accumulation in the air environment. (orig.)

  14. The effect of creep-fatigue damage relationships upon HTGR heat exchanger design

    International Nuclear Information System (INIS)

    Kozina, M.M.; King, J.H.; Basol, M.

    1984-01-01

    Materials for heat exchangers in the high temperature gas-cooled reactor (HTGR) are subjected to cyclic loading, extending the necessity to design against fatigue failure into the temperature region where creep processes become significant. Therefore, the fatigue life must be considered in terms of creep-fatigue interaction. In addition, since HTGR heat exchangers are subjected to holds at constant strain levels or constant stress levels in high-temperature environments, the cyclic life is substantially reduced. Of major concern in the design and analysis of HTGR heat exchangers is the accounting for the interaction of creep and fatigue. The accounting is done in conformance to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Code Case N-47, which allows the use of the linear damage criterion for interaction of creep and fatigue. This method separates the damage incurred in the material into two parts: one due to fatigue and one due to creep. The summation of the creep-fatigue damage must be less than 1.0. Recent material test data have indicated that the assumption of creep and fatigue damage equals unity at failure may not always be valid for materials like Alloy 800H, which is used in the higher temperature sections of HTGR steam generators. Therefore, a more conservative creep-fatigue damage relationship was postulated for Alloy 800H. This more conservative bilinear damage relationship consists of a design locus drawn from D F =1.0, D C =0 to D F =0.1, D C =0.1 to D F =0, D C =1.0. D F is the fatigue damage and D C is the creep damage. A more conservative damage relationship for 2-1/4 Cr-1 Mo material consisted of including factors that degrade the fatigue curves. These revised relationships were used in a structural evaluation of the HTGR steam cycle/cogeneration (SC/C) steam generator design. The HTGR-SC/C steam generator, a once-through type, is comprised of an economizer-evaporator-superheater (ESS) helical bundle of 2-1/4 Cr-1

  15. Reliability Based Calibration of Fatigue Design Guidelines for Ship Structures

    DEFF Research Database (Denmark)

    Folsø, Rasmus; Otto, S.; Parmentier, G.

    2002-01-01

    A simple reliability based framework is applied to calibrate a new set of fatigue design guidelines. This new guideline considers two different approaches for the assessment of both loads, stresses and local stress raising effects, and partial safety factors must be given for any combination...

  16. Fatigue Design and Prevention in Movable Scaffolding Systems

    Directory of Open Access Journals (Sweden)

    Coelho Hugo

    2017-06-01

    Full Text Available The Movable Scaffolding System (MSS is a heavy construction equipment used for casting situ of concrete bridge decks. In the past decades, MSSs have become increasingly complex and industrialized, enlarging its span ranges, incorporating auxiliary elevation machinery and increasing productivity. The tendency nowadays is for strong reutilization and the notion of MSS as a disposable or temporary structure is somehow reductive. The main structure of MSSs may be potentially exposed to fatigue, usually characterized by low number of cycles with significant stress amplitude. Fatigue may be prevented through adequate design; judicious selection of materials; demanding quality control and implementation of robust inspection and maintenance plans.

  17. Fatigue Design and Prevention in Movable Scaffolding Systems

    Science.gov (United States)

    Coelho, Hugo; Torres, Alberto; Pacheco, Pedro; Moreira, Cristiano; Silva, Rute; Soares, José M.; Pinto, Dânia

    2017-06-01

    The Movable Scaffolding System (MSS) is a heavy construction equipment used for casting situ of concrete bridge decks. In the past decades, MSSs have become increasingly complex and industrialized, enlarging its span ranges, incorporating auxiliary elevation machinery and increasing productivity. The tendency nowadays is for strong reutilization and the notion of MSS as a disposable or temporary structure is somehow reductive. The main structure of MSSs may be potentially exposed to fatigue, usually characterized by low number of cycles with significant stress amplitude. Fatigue may be prevented through adequate design; judicious selection of materials; demanding quality control and implementation of robust inspection and maintenance plans.

  18. IFMIF - Design Study for in Situ Creep Fatigue Tests

    International Nuclear Information System (INIS)

    Gordeev, S.; Heinzel, V.; Simakov, St.; Stratmanns, E.; Vladimirov, P.; Moeslang, A.

    2006-01-01

    While the high flux volume (20-50 dpa/fpy) of the International Fusion Materials Irradiation Facility (IFMIF) is dedicated to the irradiation of ∼ 1100 qualified specimens that will be post irradiation examined after disassembling in dedicated Hot Cells, various in situ experiments are foreseen in the medium flux volume (1-20 dpa/fpy). Of specific importance for structural lifetime assessments of fusion power reactors are instrumented in situ creep-fatigue experiments, as they can simulate realistically a superposition of thermal fatigue or creep fatigue and irradiation with fusion relevant neutrons. Based on former experience with in situ fatigue tests under high energy light ion irradiation, a design study has been performed to evaluate the feasibility of in situ creep fatigue tests in the IFMIF medium flux position. The vertically arranged test module for such experiments consists basically of a frame similar to a universal testing machine, but equipped with three pulling rods, driven by independent step motors, instrumentation systems and specimen cooling systems. Therefore, three creep fatigue specimens may be tested at one time in this apparatus. Each specimen is a hollow tube with coolant flow in the specimen interior to maintain individual specimen temperatures. The recently established IFMIF global 3D geometry model was used together the latest McDeLicious code for the neutral and charged particle transport calculations. These comprehensive neutronics calculations have been performed with a fine special resolution of 0.25 cm 3 , showing among others that the specimens will be irradiated with a homogeneous damage rate of up to 13(∼ 9%) dpa/fpy and a fusion relevant damage to helium ratio of 10-12 appm He/dpa. In addition, damage and gas production rates as well as the heat deposition in structural parts of the test module have been calculated. Despite of the vertical gradients in the nuclear heating, CFD code calculations with STAR-CD revealed very

  19. Fatigue Resistant Design Criteria for MD SHA Cantilevered Mast Arm Signal Structure

    Science.gov (United States)

    2017-12-01

    The fatigue design of the mast arm structures and connections vary significantly based on the Category of Importance factor adopted and the load cases for fatigue design loads. Consideration should include the cost and size of the structures for both...

  20. Fatigue analysis of assembled marine floating platform for special purposes under complex water environments

    Science.gov (United States)

    Ma, Guang-ying; Yao, Yun-long

    2018-03-01

    In this paper, the fatigue lives of a new type of assembled marine floating platform for special purposes were studied. Firstly, by using ANSYS AQWA software, the hydrodynamic model of the platform was established. Secondly, the structural stresses under alternating change loads were calculated under complex water environments, such as wind, wave, current and ice. The minimum fatigue lives were obtained under different working conditions. The analysis results showed that the fatigue life of the platform structure can meet the requirements

  1. Effect of environment on fatigue failure of controlled memory wire nickel-titanium rotary instruments.

    Science.gov (United States)

    Shen, Ya; Qian, Wei; Abtin, Houman; Gao, Yuan; Haapasalo, Markus

    2012-03-01

    This study examined the fatigue behavior of 2 types of nickel-titanium (NiTi) instruments made from a novel controlled memory NiTi wire (CM wire) under various environment conditions. Three conventional superelastic NiTi instruments of ProFile (Dentsply Maillefer, Ballaigues, Switzerland), Typhoon (Clinician's Choice Dental Products, New Milford, CT), and DS-SS0250425NEYY (Clinician's Choice Dental Products) and 2 new CM wire instruments of Typhoon CM and DS-SS0250425NEYY CM were subjected to rotational bending at the curvature of 35° in air, deionized water, 17% EDTA, or deionized water after immersion in 6% sodium hypochlorite for 25 minutes, and the number of revolutions of fracture (N(f)) was recorded. The fracture surface of all fragments was examined by a scanning electron microscope. The crack-initiation sites and the percentage of dimple area to the whole fracture cross-section were noted. Two new CM Wire instruments yielded an improvement of >4 to 9 times in N(f) than conventional NiTi files with the same design under various environments (P Wire instruments was significantly longer in liquid media than in air (P wire had one crack origin. The values of the area fraction occupied by the dimple region were significantly smaller on CM NiTi instruments than in conventional NiTi instruments under various environments (P < .05). Within the limitations of this study, the type of NiTi metal alloy (CM files vs conventional superelastic NiTi files) influences the cyclic fatigue resistance under various environments. The fatigue life of CM instruments is longer in liquid media than in air. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  2. Computer based approach to fatigue analysis and design

    International Nuclear Information System (INIS)

    Comstock, T.R.; Bernard, T.; Nieb, J.

    1979-01-01

    An approach is presented which uses a mini-computer based system for data acquisition, analysis and graphic displays relative to fatigue life estimation and design. Procedures are developed for identifying an eliminating damaging events due to overall duty cycle, forced vibration and structural dynamic characteristics. Two case histories, weld failures in heavy vehicles and low cycle fan blade failures, are discussed to illustrate the overall approach. (orig.) 891 RW/orig. 892 RKD [de

  3. The design of brake fatigue testing system

    Directory of Open Access Journals (Sweden)

    Huang, Xiaoya

    2015-01-01

    Full Text Available Brake is used to reduce the operating speed of the machinery equipment or to make it stop. It is essential for vehicles, climbing machines and many fixed equipment in their safety work. Brake tester is an experimental apparatus to measure and analyse the braking performance. Based on the PLC technology and for the purpose of testing brake shoe friction material’s life, this paper designed a virtual brake test platform. In it, inverter were used to control the motor, so that it can load automatically and ensure brake drum constant speed output; what is more, closed loop control system were used to control the brake shoe, so that the cylinder pressure keeps stable in the process of dynamic braking.

  4. Future integrated design environments

    DEFF Research Database (Denmark)

    Christiansson, Per; Svidt, Kjeld; Sørensen, Kristian Birch

    2009-01-01

    and modeling of explicit and implicit end-user needs and requirements on both the building to be designed and the supporting design tools. The paper provides grounds to higher success rate in capture of explicit and implicit end user needs and requirements on functional performance in use and re...

  5. Development of a remote controlled fatigue testing apparatus at elevated temperature in controlled environment

    International Nuclear Information System (INIS)

    Ohmi, Masao; Mimura, Hideaki; Ishii, Toshimitsu

    1996-02-01

    The fatigue characteristics of reactor structural materials at high temperature are necessary to be evaluated for ensuring the safety of the High Temperature engineering Test Reactor (HTTR). Especially, the high temperature test data on safety research such as low cycle fatigue property and crack propagation property for reactor pressure vessel material are important for the development of the HTTR. Responding to these needs, a remote controlled type fatigue testing machine has been developed and installed in a hot cell of JMTR Hot Laboratory to get the fatigue data of irradiated materials. The machine was developed modifying a commercially available electro-hydraulic servo type fatigue testing machine to withstand radiation and be remotely operated, and mainly consists of a testing machine frame, environment chamber, extensometer, actuator and vacuum exhaust system. It has been confirmed that the machine has good performance to obtain low cycle fatigue data through many demonstration tests on unirradiated and irradiated specimens. (author)

  6. Designing Virtual Learning Environments

    DEFF Research Database (Denmark)

    Veirum, Niels Einar

    2003-01-01

    The main objective of this working paper is to present a conceptual model for media integrated communication in virtual learning environments. The model for media integrated communication is very simple and identifies the necessary building blocks for virtual place making in a synthesis of methods...

  7. The psychosocial work environment and fatigue in Danish ferry shipping

    DEFF Research Database (Denmark)

    Bøggild Dohrmann, Solveig

    and endangerment of occupational safety, and in ferry shipping employees’ fatigue can lead not only to poor individual health and wellbeing but also to accidents, which can potentially jeopardize passengers’ safety. Objective Due to the risk of fatigue in the ferry shipping industry – and a lack of prior research...... on this topic - the main aim of this Phd study was to investigate the link between fatigue and working environmental factors among ferry shipping employees. The investigation specifically focuses on the role of psychosocial factors, as there is a distinct lack of research on such determinants in a seafaring...... of two Danish ferry shipping companies. Methods A systematic review and quality assessment of the empirical evidence was conducted as an initial step to summarize and analyze what was known about fatigue-determining factors in seafaring, the results of which were published in article 1. Two further...

  8. Fatigue

    Science.gov (United States)

    ... sleep. Fatigue is a lack of energy and motivation. Drowsiness and apathy (a feeling of not caring ... Call your provider right away if you have any of the following: Confusion or dizziness Blurred vision Little or no urine, or recent ...

  9. Evaluation of creep-fatigue/ environment interaction in Ni-base wrought alloys for HTGR application

    International Nuclear Information System (INIS)

    Hattori, Hiroshi; Kitagawa, Masaki; Ohtomo, Akira

    1986-01-01

    High Temperature Gas-cooled Reactor (HTGR) systems should be designed based on the high temperature structural strength design procedures. On the development of design code, the determination of failure criteria under cyclic loading and severe environments is one of the most important items. By using the previous experimental data for Ni-base wrought alloys, Inconel 617 and Hastelloy XR, several evaluation methods for creep-fatigue interaction were examined for their capability to predict their cyclic loading behavior for HTGR application. At first, the strainrange partitioning method, the frequency modified damage function and the linear damage summation rule were discussed. However, these methods were not satisfactory with the above experimental results. Thus, in this paper, a new fracture criterion, which is a modification of the linear damage summation rule, is proposed based on the experimental data. In this criterion, fracture is considered to occur when the sum of the fatigue damage, which is the function of the applied cyclic strain magnitude, and the modified creep damage, which is the function of the applied cyclic stress magnitude (determined as time devided by cyclic creep rupture time reflecting difference of creep damages by tensile creep and compressive creep), reaches a constant value. This criterion was successfully applied to the life prediction of materials at HTGR temperatures. (author)

  10. Thermal-Acoustic Fatigue of a Multilayer Thermal Protection System in Combined Extreme Environments

    Directory of Open Access Journals (Sweden)

    Liu Liu

    2014-06-01

    Full Text Available In order to ensure integrity of thermal protection system (TPS structure for hypersonic vehicles exposed to severe operating environments, a study is undertaken to investigate the response and thermal-acoustic fatigue damage of a representative multilayer TPS structure under combined thermal and acoustic loads. An unsteady-state flight of a hypersonic vehicle is composed of a series of steady-state snapshots, and for each snapshot an acoustic load is imposed to a static steady-state TPS structure. A multistep thermal-acoustic fatigue damage intensity analysis procedure is given and consists of a heat transfer analysis, a nonlinear thermoelastic analysis, and a random response analysis under a combined loading environment and the fatigue damage intensity has been evaluated with two fatigue analysis techniques. The effects of thermally induced deterministic stress and nondeterministic dynamic stress due to the acoustic loading have been considered in the damage intensity estimation with a maximum stress fatigue model. The results show that the given thermal-acoustic fatigue intensity estimation procedure is a viable approach for life prediction of TPS structures under a typical mission cycle with combined loadings characterized by largely different time-scales. A discussion of the effects of the thermal load, the acoustic load, and fatigue analysis methodology on the fatigue damage intensity has been provided.

  11. Low cycle fatigue of Alloy 690 and welds in a simulated PWR primary water environment

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jongdae; Cho, Pyungyeon; Jang, Changheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Cho, Pyungyeon [Khalifa Univ., Abu Dhabi (United Arab Emirates); Kim, Tae Soon; Lee, Yong Sung [Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)

    2013-05-15

    In this study, environmental fatigue tests for these materials were performed and the new prediction model of fatigue life of Alloy 690 and weld in primary water condition was proposed. To evaluate the fatigue life of Alloy 690 and 52M in a PWR environment, low cycle fatigue tests were performed and revised fatigue life prediction models and environmental factor were proposed. With the revised Fen model for Alloy 690 and 52M, the reliability of the fatigue life prediction has been improved. The reduction of low cycle fatigue life of metallic materials in the primary coolant water environments has been the subject of debate between the utility and regulator since 1980s. It became the significant licensing problem since the issue of RG-1.207 by U. S. NRC. The statistical model for the environmental factor, Fen, specified in RG-1.207 was based on the extensive test results accumulated by the ANL and Japanese national program. Of the materials, the limited fatigue life data of Ni-Cr-Fe alloys were used to develop the Fen for the alloys. Furthermore, test data for Alloy 690 and its weld are limited. Considering that Alloy 690 will be extensively used in the new nuclear power plants, additional effort to validate or improve current Fen model is required.

  12. Low cycle fatigue of alloy 718 in cryogenic environment

    International Nuclear Information System (INIS)

    Vergara Aimone, J.

    1989-01-01

    A specially processed Ni-Fe base superalloy 718 has been selected as a structural material for a critical component in ALCATOR C-MOD, the new fusion experimental facility at the Massachusetts Institute of Technology. Draw bars made out of this material will be subjected to large alternating loads while operating at 77 0 K. Monotonic and cyclic mechanical properties were determined in order to evaluate the reactor's maintenance schedule with special emphasis in developing a Low Cycle Fatigue database for this special alloy. Improved monotonic properties over conventionally heat treated alloy 718 were observed. Partial hardening was observed at 77 0 K at 1% of the fatigue life, while softening was observed at room temperature, both relative to their respective monotonic stress strain curves. The fatigue curves were corrected for non-zero mean stress allowing satisfactory safety margin for the expected alternating stress. (author)

  13. Designing for the global environment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    This document contains papers which were presented at the symposium entitled Designing for the Global Environment. Session topics included policy and the implementation of energy efficient technologies. Individual papers were processed separately for the Department of Energy databases.

  14. Development of elevated temperature fatigue design information for type 316 stainless steel

    International Nuclear Information System (INIS)

    Jaske, C.E.; Mindlin, H.; Perrin, J.S.

    1975-01-01

    To develop material properties information for use in elevated-temperature fatigue design, an extensive study of the fatigue and stress-strain behaviour of Type 316 stainless steel was conducted at temperatures from 21 to 649 0 C. Fatigue life and cyclic stress-strain curves were developed. Creep-fatigue interaction was evaluated by conducting strain hold-time tests at 566 and 649 0 C. Hold periods at peak tensile strain produced a large reduction in cyclic life. It was found that both a linear damage rule and the strain-partitioning method could be used to assess cumulative creep and fatigue damage. Aging for 1000 h at test temperature before testing caused only small or no changes in continuous cycling fatigue resistance at 566 and 649 0 C and in tension hold-time fatigue resistance at 566 0 C. This aging produced a significant increase in tension hold-time fatigue resistance at 649 0 C. (author)

  15. Extreme Environment Damage Index and Accumulation Model for CMC Laminate Fatigue Life Prediction, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Materials Research & Design (MR&D) is proposing in the SBIR Phase II an effort to develop a tool for predicting the fatigue life of C/SiC composite...

  16. Effects of lithium environment on the fatigue properties of ferritic and austenitic steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Smith, D.L.

    1982-01-01

    Low-cycle fatigue data have been obtained on HT-9 alloy and Type 304 stainless steel at 755 K in a flowing lithium environment of controlled purity. The results show that the fatigue properties of these materials are strongly influenced by the concentration of nitrogen in lithium. For HT-9 alloy, the fatigue life in lithium containing 1000-1500 wppm nitrogen is a factor of 2 to 5 lower than that in lithium with 100-200 wppm nitrogen. The reduction in fatigue life in high-nitrogen lithium can be attributed to internal corrosive attack of the material. The specimens tested in high-nitrogen lithium show considerable surface corrosion, internal corrosive attack, secondary cracks, and partial intergranular fracture mode. This behavior is not observed in specimens tested either in low-nitrogen lithium or a sodium environment. (orig.)

  17. Fatigue Test Design: Scenarios for Biaxial Fatigue Testing of a 60-Meter Wind Turbine Blade

    Energy Technology Data Exchange (ETDEWEB)

    Post, Nathan [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-07-01

    Current practice in commercial certification of wind turbine blades is to perform separate flap and lead-lag fatigue tests. The National Renewable Energy Laboratory has been researching and evaluating biaxial fatigue testing techniques and demonstrating various options, typically on smaller-scale test articles at the National Wind Technology Center. This report evaluates some of these biaxial fatigue options in the context of application to a multimegawatt blade certification test program at the Wind Technology Testing Center in Charlestown, Massachusetts.

  18. Effects of environment on the low-cycle fatigue behavior of Type 304 stainless steel

    International Nuclear Information System (INIS)

    Maiya, P.S.; Burke, W.F.

    1979-12-01

    The low-cycle fatigue behavior of Type 304 stainless steel has been investigated at 593 0 C in a dynamic vacuum of better than 1.3 x 10 -6 Pa (10 -8 torr). The results concerning the effects of strain range, strain rate and tensile hold time on fatigue life are presented and compared with results of similar tests performed in air and sodium environments. Under continuous symmetrical cycling, fatigue life is significantly longer in vacuum than in air; in the low strain range regime, the effect of sodium on fatigue life appears to be similar to that of vacuum. Strain rate (or frequency) strongly influences fatigue life in both air and vacuum. In compressive hold-time tests, the effect of environment on life is similar to that in a continuous-cycling test. However, tensile hold times are nearly as damaging in vacuum as in air. Thus, at least for austenitic stainless steels, the influence of the environment of fatigue life appears to depend on the loading waveshape

  19. Fatigue strength degradation of metals in corrosive environments

    OpenAIRE

    Adasooriya, Mudiyan Nirosha Damayanthi; Hemmingsen, Tor; Pavlou, Dimitrios

    2017-01-01

    Structures exposed to aggressive environmental conditions are often subjected to time-dependent loss of coating and loss of material due to corrosion; this causes reduction in the cross-sectional properties of the members, increased surface roughness, surface irregularities and corrosion pits, and degradation of material strengths. These effects have been identified and simulated in different research studies. However, time and corrosive media dependent fatigue strength curves for materials h...

  20. Fatigue behavior of welded austenitic stainless steel in different environments

    Directory of Open Access Journals (Sweden)

    D.S. Yawas

    2014-01-01

    Full Text Available The fatigue behavior of welded austenitic stainless steel in 0.5 M hydrochloric acid and wet steam corrosive media has been investigated. The immersion time in the corrosive media was 30 days to simulate the effect on stainless steel structures/equipment in offshore and food processing applications and thereafter annealing heat treatment was carried out on the samples. The findings from the fatigue tests show that seawater specimens have a lower fatigue stress of 0.5 × 10−5 N/mm2 for the heat treated sample and 0.1 × 10−5 N/mm2 for the unheat-treated sample compared to the corresponding hydrochloric acid and steam samples. The post-welding heat treatment was found to increase the mechanical properties of the austenitic stainless steel especially tensile strength but it reduces the transformation and thermal stresses of the samples. These findings were further corroborated by the microstructural examination of the stainless steel specimen.

  1. Fatigue of carbon and low-alloy steels in LWR environments

    International Nuclear Information System (INIS)

    Chopra, O.K.; Michaud, W.F.; Shack, W.J.

    1994-01-01

    Fatigue tests have been conducted on A106-Gr B carbon steel and A533-Gr B low-alloy steel to evaluate the effects of an oxygenated-water environment on the fatigue life of these steels. For both steels, environmental effects are modest in PWR water at all strain rates. Fatigue data in oxygenated water confirm the strong dependence of fatigue life on dissolved oxygen (DO) and strain rate. The effect of strain rate on fatigue life saturates at some low value, e.g., between 0.0004 and 0.001%/s in oxygenated water with ∼0.8 ppm DO. The data suggest that the saturation value of strain rate may vary with DO and sulfur content of the steel. Although the cyclic stress-strain and cyclic-hardening behavior of carbon and low-alloy steels is distinctly different, the degradation of fatigue life of these two steels with comparable sulfur levels is similar. The carbon steel exhibits pronounced dynamic strain aging, whereas strain-aging effects are modest in the low-alloy steel. Environmental effects on nucleation of fatigue crack have also been investigated. The results suggest that the high-temperature oxygenated water has little or not effect on crack nucleation

  2. On the influence of the environment on modeling the fatigue crack growth process

    International Nuclear Information System (INIS)

    Mc Evily, A.J.

    1987-01-01

    The effect of the environment at room and elevated temperature were considered with respect to the influence exerted on the basic mechanical aspects of the fatigue crack growth process. An experimental assessment of this influence was obtained by conducting fatigue crack growth tests both in air and vacuum and the results of such experiments are given. Topics considered include crack closure, short crack growth in notched and unnotched specimens, Mode II crack growth, and the effects of oxidation at elevated temperatures. It is shown that the basic mechanisms of fatigue crack growth can be greatly altered by the presence of oxide films at the fatigue crack tip. Modeling the mechanical aspects of the crack growth process is by itself a challenging task. In addition, the environmental considerations adds to the complexity of the modeling process. (Author)

  3. RNEDE: Resilient Network Design Environment

    Energy Technology Data Exchange (ETDEWEB)

    Venkat Venkatasubramanian, Tanu Malik, Arun Giridh; Craig Rieger; Keith Daum; Miles McQueen

    2010-08-01

    Modern living is more and more dependent on the intricate web of critical infrastructure systems. The failure or damage of such systems can cause huge disruptions. Traditional design of this web of critical infrastructure systems was based on the principles of functionality and reliability. However, it is increasingly being realized that such design objectives are not sufficient. Threats, disruptions and faults often compromise the network, taking away the benefits of an efficient and reliable design. Thus, traditional network design parameters must be combined with self-healing mechanisms to obtain a resilient design of the network. In this paper, we present RNEDEa resilient network design environment that that not only optimizes the network for performance but tolerates fluctuations in its structure that result from external threats and disruptions. The environment evaluates a set of remedial actions to bring a compromised network to an optimal level of functionality. The environment includes a visualizer that enables the network administrator to be aware of the current state of the network and the suggested remedial actions at all times.

  4. Energy and environment design guide

    Energy Technology Data Exchange (ETDEWEB)

    Harman, K. [Royal Australian Institute of Architects, Canberra, ACT (Australia)

    1996-04-01

    The Royal Australian Institute of Architects (RAIA) released an Environment Policy for architects in September 1994 which forms part of the RAIA Code of Professional Conduct. Prior to releasing the policy, it was recognised that members needed information and education in the area of energy and environment in order to adopt and implement the guide. This document is a report on the scope, work programme and achievements of a project to provide an easy reference resource for architects and other building designers, and bring together a wide range of information and research. It includes the Environment Policy as an appendix. The project produced 24 notes entitled the `Environment Design Guide - energy/environment notes` covering a wide range of topics, and four newsletters. Feedback received from architects to date indicates that the development of the notes has had a positive effect on their knowledge of these issues, resulting in the making of informed design decisions. The topics covered by the notes are expected to expand in 1996 with the preparation of additional notes which provide information on products and sustainable construction.

  5. Environment, information divide and design

    International Nuclear Information System (INIS)

    Iwata, Shuichi

    2007-01-01

    Design of human environment is to be made with understanding human-human and human-environment relations and environmental behaviors of human beings, artifacts and natural things and overcoming their differences and contradictions. Information divide exists naturally due to various differences of human beings. Many problems in the area of nuclear energy seem to be derived from various differences and contradictions in central-local interests, between the particles concerned and unconcerned and also in human being-artifacts relations. In order to harmonize nuclear energy with the society, it is necessary to vanish differences and solve contradictions with redesigning environments of those problems in their context. Case studies are highly recommended with continuous efforts to develop more universal design methodology. Open access to information and data in science and technology is encouraged in the area of nuclear energy. (T. Tanaka)

  6. Fatigue-crack propagation response of two nickel-base alloys in a liquid sodium environment

    International Nuclear Information System (INIS)

    Mills, W.J.; James, L.A.

    1979-01-01

    The elevated temperature fatigue-crack propagation response of Inconel 600 and Inconel 718 was characterized within a linear-elastic fracture mechanics framework in air and low-oxygen liquid sodium environments. The crack growth rates of both nickel-base alloys tested in liquid sodium were found to be considerably lower than those obtained in air. This enhanced fatigue resistance in sodium was attributed to the very low oxygen content in the inert sodium environment. Electron fractographic examination of the Inconel 600 and Inconel 718 fatigue fracture surfaces revealed that operative crack growth mechanisms were dependent on the prevailing stress intensity level. Under low growth rate conditions, Inconel 600 and Inconel 718 fracture surfaces exhibited a faceted, crystallographic morphology in both air and sodium environments. In the higher growth rate regime, fatigue striations were observed; however, striations formed in sodium were rather ill-defined. These indistinct striations were attributed to the absence of oxygen in the liquid sodium environment. Striation spacing measurements were found to be in excellent agreement with macroscopic growth rates in both environments

  7. Creep-fatigue of High Temperature Materials for VHTR: Effect of Cyclic Loading and Environment

    Energy Technology Data Exchange (ETDEWEB)

    Celine Cabet; L. Carroll; R. Wright; R. Madland

    2011-05-01

    Alloy 617 is the one of the leading candidate materials for Intermediate Heat eXchangers (IHX) of a Very High Temperature Reactor (VHTR). System start-ups and shut-downs as well as power transients will produce low cycle fatigue (LCF) loadings of components. Furthermore, the anticipated IHX operating temperature, up to 950°C, is in the range of creep so that creep-fatigue interaction, which can significantly increase the fatigue crack growth, may be one of the primary IHX damage modes. To address the needs for Alloy 617 codification and licensing, a significant creep-fatigue testing program is underway at Idaho National Laboratory. Strain controlled LCF tests including hold times up to 1800s at maximum tensile strain were conducted at total strain range of 0.3% and 0.6% in air at 950°C. Creep-fatigue testing was also performed in a simulated VHTR impure helium coolant for selected experimental conditions. The creep-fatigue tests resulted in failure times up to 1000 hrs. Fatigue resistance was significantly decreased when a hold time was added at peak stress and when the total strain was increased. The fracture mode also changed from transgranular to intergranular with introduction of a tensile hold. Changes in the microstructure were methodically characterized. A combined effect of temperature, cyclic and static loading and environment was evidenced in the targeted operating conditions of the IHX. This paper This paper reviews the data previously published by Carroll and co-workers in references 10 and 11 focusing on the role of inelastic strain accumulation and of oxidation in the initiation and propagation of surface fatigue cracks.

  8. Comparison of the ASME Environmental Fatigue Design Curve with the Leax' Low Bound Model

    International Nuclear Information System (INIS)

    Jeong, Ill Seok; Kim, Wan Jae; Jun, Hyun Ik

    2010-01-01

    Environmental fatigue issue long time argued between industry and regulator. The issues of the debates are about environmental fatigue data only from experiment laboratories, no evidences in fields, and over conservatism. However, NRC issued the requirement to implement it to the construction design prior to industry practical design code. American Society of Mechanical Engineers (ASME) determined to issue non-mandatory code cases of environmental fatigue design. This paper evaluated the conservatism of the ASME proposed environmental fatigue design curve in comparison with the Leax' low bound approach model of environmental fatigue curve. A group of CF8M cast austenitic stainless steel (CASS) produced in KEPCO Research Center was introduced in the evaluation

  9. Modeling Creep-Fatigue-Environment Interactions in Steam Turbine Rotor Materials for Advanced Ultra-supercritical Coal Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen [General Electric Global Research, Niskayuna, NY (United States)

    2014-04-01

    The goal of this project is to model creep-fatigue-environment interactions in steam turbine rotor materials for advanced ultra-supercritical (A-USC) coal power Alloy 282 plants, to develop and demonstrate computational algorithms for alloy property predictions, and to determine and model key mechanisms that contribute to the damages caused by creep-fatigue-environment interactions.

  10. Corrosion fatigue crack growth of pressure vessel welds in PWR environment

    International Nuclear Information System (INIS)

    Bamford, W.H.; Ceschini, L.J.; Moon, D.M.

    1983-01-01

    The fatigue crack growth rate behavior of several pressure vessel steel welds in PWR environment is discussed. The behavior is compared with associated heat-affected zone behavior, and with comparable base metal results. The welds show different degrees of susceptibility to the environmental influence, and this is discussed in some detail, along with fractographic observations on the tested specimens

  11. Study on the Mechanical Properties of Stay Cable HDPE Sheathing Fatigue in Dynamic Bridge Environments

    Directory of Open Access Journals (Sweden)

    Danhui Dan

    2015-08-01

    Full Text Available As the main force-bearing component of a cable-stayed bridge, a durable stay cable is paramount to the safety and durability of the entire bridge. High-density polyethylene (HDPE sheathing is the main protective component of a stay cable and is the key to insuring cable durability. To address the issue of HDPE sheathing fracture on service, strain level data for in-service, HDPE bridge cable sheathing was used in this study as the basis for HDPE material aging and fatigue testing. A fatigue yield phenomenon with a yield platform on the hysteresis curve of the fatigue cycles is observed by the fatigue test. The parameters to describe this phenomenon are proposed and defined in this paper. A preliminary examination of the relationship between these parameters and the factors, such as the number of cycles, the strain amplitude, and strain rate, are presented. Based on the results obtained, it is suggested that the condition of fatigue yield of HDPE sheathing be defined as the fatigue durability limit state for the purposes of durability design, assessment, and protection of cable-stayed bridges.

  12. Guide to safe work : fatigue management : an employer's guide to designing and implementing a fatigue management program. 2 ed.

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-02-15

    The impacts of fatigue on workplace safety are now commonly recognized. Many employers now wish to include fatigue management as part of their overall health and safety programs. This guide to fatigue management was written to help companies in the petroleum industry design and implement effective fatigue management programs that reduce incidents and injuries among employees. The guide provided information about workplace fatigue and discussed fatigue management issues and strategies. It was suggested that workplace culture can play a significant role in managing fatigue by allowing fatigue factors to be quickly recognized and managed. Employers who wish to build fatigue management programs should involve all levels of employees, and should consider all workplace practices and procedures. Consideration must also be given to the development of employee competency in managing fatigue. The guide included step-by-step recommendations for implementing a fatigue management program. It was concluded that the benefits of fatigue management include reduced worker absence and turnover, as well as avoiding the costs of safety incidents. 1 tab., 1 fig.

  13. Device Design and Test of Fatigue Behaviour of Expansion Anchor Subjected to Tensile Loads

    Directory of Open Access Journals (Sweden)

    Zhang Jinfeng

    2016-01-01

    Full Text Available In order to study on the fatigue behaviour of expansion anchor (M16, grade 8.8 for overhead contact system in electrification railways, a set of safe, practical loading device is designed and a fatigue test campaign was carried out at structural laboratory of China Academy of Building Research on expansion anchor embedded in concrete block. The mobile frame of the loading device was designed well by finite-element simulation. According to some fatigue performance test of expansion anchor with different size and form, the device have been assessed experimentally its dependability. The results were found that no fatigue damage phenomenon occurred in all specimens after 2×106 cycles tensile fatigue test in this specific series. It shows that in the condition of medium level or slightly lower maximum stress limit and nominal stress range, expansion bolt has good fatigue resistance. The biggest relative displacement and the residual relative displacement after test (Δδ = δ2-δ1 was also strongly lower than the symbol of the fatigue test failure index of this specific series (0.5mm in the high cycle fatigue regime. The ultimate tension failures mode after fatigue tests in all tested samples take place in the concrete anchorage zone. The reduction range of the ultimate tensile strength properties of the anchorage system was not obvious, and the concrete was seen to be the weakest link of the system.

  14. Design rule for fatigue of welded joints in elevated-temperature nuclear components

    International Nuclear Information System (INIS)

    O'Connor, D.G.; Corum, J.M.

    1986-01-01

    Elevated-temperature weldment fatigue failures have occurred in several operating liquid-metal reactor plants. Yet, ASME Code Case N-47, which governs the design of such plants in the United States, does not currently address the Code Subgroup on Elevated Temperature Design recently proposed a fatigue strength reduction factor for austenitic and ferritic steel weldments. The factor is based on a variety of weld metal and weldment fatigue data generated in the United States, Europe, and Japan. This paper describes the factor and its bases, and it presents the results of confirmatory fatigue tests conducted at Oak Ridge National Laboratory on 316 stainless steel tubes with axial and circumferential welds of 16-8-2 filler metal. These test results confirm the suitability of the design factor, and they support the premise that the metallurgical notch effect produced by yield strength variations across a weldment is largely responsible for the observed elevated-temperature fatigue strength reduction

  15. Low cycle fatigue life of two nickel-base casting alloys in a hydrogen environment

    International Nuclear Information System (INIS)

    Cooper, R.A.

    1976-01-01

    Results of low cycle fatigue tests on alloy Mar-M-246 and Inconel 713 are presented. Based on the limited data, it was concluded that the Mar-M-246 material had a cyclic life in hydrogen that averaged three times higher than the alloy 713LC material for similar strain ranges. The hydrogen environment reduced life for both materials. The life reduction was more than an order of magnitude for the 713LC material. Porosity content of the cast specimens was as expected and was an important factor governing low cycle fatigue life

  16. Design for a better environment

    International Nuclear Information System (INIS)

    Khan, Z.A.

    2005-01-01

    The paper discusses part of an ongoing study initiated at the Pakistan Navy Engineering College in Karachi. The study originated from the author's belief that design in this country is influenced by 'factors' other than considerations based on scientific knowledge and logical thinking. The same may be true for selection of materials for a particular application. The key thrust of the work is to explore how plastics and associated products affect the environment and the economy of the country, and the problems these may create. It also explores the role of people, government and industry in this regard. The study was planned to consist of case studies from the automotive sector in Pakistan. It was decided that plastic components manufactured in Pakistan would be studied and engineers and designers involved in 'design' would be interviewed. This paper focuses on the application of conceptual design techniques to the problem of sustainable design of a product in the automotive industry. It also attempts to focus on the role of this industry in the implementation of concepts related to sustainable development in engineering design. (author)

  17. A survey of the French creep-fatigue design rules for LMFBR

    International Nuclear Information System (INIS)

    Tribout, J.; Cordier, G.; Moulin, D.

    1987-01-01

    The paper provides a survey of the creep-fatigue design rules for the LMFBR in France. These rules are the ones currently implemented in French component manufacturing. The background of each item is discussed and the trends for improvements currently investigated are described. The creep-fatigue rules apply to elastic analysis only. (orig.)

  18. Fatigue and corrosion of a Pd-based bulk metallic glass in various environments

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, L.Y. [East Los Angeles College, Monterey Park, CA 91754 (United States); Roberts, S.N. [Keck Laboratory of Materials Science, California Institute of Technology, Pasadena, CA 91125 (United States); Baca, N. [Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330 (United States); Wiest, A. [Naval Surface Warfare Center, Norco, CA (United States); Garrett, S.J. [Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330 (United States); Conner, R.D., E-mail: rdconner@csun.edu [Department of Manufacturing Systems Engineering and Management, California State University Northridge, 18111 Nordhoff St., Mail Code 8295, Northridge, CA 91330 (United States)

    2013-10-15

    Bulk metallic glasses (BMGs) possess attractive properties for biomedical applications, including high strength, hardness and corrosion resistance, and low elastic modulus. In this study, we conduct rotating beam fatigue tests on Pd{sub 43}Ni{sub 10}Cu{sub 27}P{sub 20} bulk metallic glass in air and Eagle's medium (EM) and measure the corrosive resistance of the alloy by submersion in acidic and basic electrolytes. Fatigue results are compared to those of commonly used biometals in EM. Rotating beam fatigue tests conducted in air and in Eagle's medium show no deterioration in fatigue properties in this potentially corrosive environment out to 10{sup 7} cycles. A specimen size effect is revealed when comparing fatigue results to those of a similar alloy of larger minimum dimensions. Corrosion tests show that the alloy is not affected by highly basic (NaOH) or saline (NaCl) solutions, nor in EM, and is affected by chlorinated acidic solutions (HCl) to a lesser extent than other commonly used biometals. Corrosion in HCl initiates with selective leaching of late transition metals, followed by dissolution of Pd. - Highlights: • Fatigue limit of 600 MPa with no deterioration when exposed to Eagle's medium. • Fatigue shows sample size effect. • Pd-based BMG is unaffected by saline or strong basic solutions. • Pd-based BMG is substantially more resistant to chlorinated acids than CoCrMo, 316 L Stainless, or Ti6Al4V alloys. • Corrosion shows selective leaching of late transition metals, followed by Pd and P.

  19. Intrinsic fatigue crack propagation in aluminum-lithium alloys - The effect of gaseous environments

    Science.gov (United States)

    Piascik, Robert S.; Gangloff, Richard P.

    1989-01-01

    Gaseous environmental effects on intrinsic fatigue crack growth are significant for the Al-Li-Cu alloy 2090, peak aged. For both moderate Delta K-low R and low Delta K-high R regimes, crack growth rates decrease according to the environment order: purified water vapor, moist air, helium and oxygen. Gaseous environmental effects are pronounced near threshold and are not closure dominated. Here, embrittlement by low levels of H2O (ppm) supports hydrogen embrittlement and suggests that molecular transport controlled cracking, established for high Delta K-low R, is modified near threshold. Localized crack tip reaction sites or high R crack opening shape may enable the strong, environmental effect at low levels of Delta K. Similar crack growth in He and O2 eliminates the contribution of surface films to fatigue damage in alloy 2090. While 2090 and 7075 exhibit similar environmental trends, the Al-Li-Cu alloy is more resistant to intrinsic corrosion fatigue crack growth.

  20. Predicting fatigue and psychophysiological test performance from speech for safety critical environments

    Directory of Open Access Journals (Sweden)

    Khan Richard Baykaner

    2015-08-01

    Full Text Available Automatic systems for estimating operator fatigue have application in safety-critical environments. A system which could estimate level of fatigue from speech would have application in domains where operators engage in regular verbal communication as part of their duties. Previous studies on the prediction of fatigue from speech have been limited because of their reliance on subjective ratings and because they lack comparison to other methods for assessing fatigue. In this paper we present an analysis of voice recordings and psychophysiological test scores collected from seven aerospace personnel during a training task in which they remained awake for 60 hours. We show that voice features and test scores are affected by both the total time spent awake and the time position within each subject’s circadian cycle. However, we show that time spent awake and time of day information are poor predictors of the test results; while voice features can give good predictions of the psychophysiological test scores and sleep latency. Mean absolute errors of prediction are possible within about 17.5% for sleep latency and 5-12% for test scores. We discuss the implications for the use of voice as a means to monitor the effects of fatigue on cognitive performance in practical applications.

  1. Collaborative design in virtual environments

    CERN Document Server

    Wang, Xiangyu

    2011-01-01

    Collaborative virtual environments (CVEs) are multi-user virtual realities which actively support communication and co-operation. This book offers a comprehensive reference volume to the state-of-the-art in the area of design studies in CVEs. It is an excellent mix of contributions from over 25 leading researcher/experts in multiple disciplines from academia and industry, providing up-to-date insight into the current research topics in this field as well as the latest technological advancements and the best working examples. Many of these results and ideas are also applicable to other areas su

  2. Fatigue Characterization of Fabricated Ship Details for Design.

    Science.gov (United States)

    1982-08-01

    than the ques- tion of brittle fracture. Such cracking has been found in the forepeak region, bottom amidships, at the bulwark at both ends of the...results of the laboratory studies are presented in the Appendices. 1.3 References 1.1 Vedeler, G. "To What Extent Do Brittle Fracture and Fatigue...Civil Engineering. Appre- ciation is extended to Mr. John R. Williams who prepared the weldments, to Mr. Glen Lafenhagen who assisted in the fatigue

  3. Prodeto, a computer code for probabilistic fatigue design

    Energy Technology Data Exchange (ETDEWEB)

    Braam, H [ECN-Solar and Wind Energy, Petten (Netherlands); Christensen, C J; Thoegersen, M L [Risoe National Lab., Roskilde (Denmark); Ronold, K O [Det Norske Veritas, Hoevik (Norway)

    1999-03-01

    A computer code for structural relibility analyses of wind turbine rotor blades subjected to fatigue loading is presented. With pre-processors that can transform measured and theoretically predicted load series to load range distributions by rain-flow counting and with a family of generic distribution models for parametric representation of these distribution this computer program is available for carying through probabilistic fatigue analyses of rotor blades. (au)

  4. Influence of dynamic sodium environment on the creep-fatigue behaviour of Modified 9Cr-1Mo ferritic-martensitic steel

    International Nuclear Information System (INIS)

    Kannan, R.; Ganesan, V.; Mariappan, K.; Sukumaran, G.; Sandhya, R.; Mathew, M.D.; Bhanu Sankara Rao, K.

    2011-01-01

    Highlights: → The effects of dynamic sodium on the CFI behaviour of Mod. 9Cr-1Mo steel has investigated. → The cyclic stress response of Mod. 9Cr-1Mo steel under flowing sodium environment is similar to that of air environment. → The creep-fatigue endurance of the alloy is found to decrease with introduction of hold time and with increase in the duration of hold time and the factor of life increase in sodium compared to air environment is reduced with increase in hold time. → In contrast to air environment, tensile holds were found to be more damaging than compression hold in sodium environment. → Design rules based on air environment can be safely applied for the components operating in sodium environment. - Abstract: The use of liquid sodium as a heat transfer medium for sodium-cooled fast reactors (SFRs) necessitates a clear understanding of the effects of dynamic sodium on low cycle fatigue (LCF), creep and creep-fatigue interaction (CFI) behaviour of reactor structural materials. Mod. 9Cr-1Mo ferritic steel is the material of current interest for the steam generator components of sodium cooled fast reactors. The steam generator has a design life of 30-40 years. The effects of dynamic sodium on the LCF and CFI behaviour of Mod. 9Cr-1Mo steel have been investigated at 823 and 873 K. The CFI life of the steel showed marginal increase under flowing sodium environment when compared to air environment. Hence, the design rules for creep-fatigue interaction based on air tests can be safely applied for components operating in sodium environment. This paper attempts to explain the observed LCF and CFI results based on the detailed metallography and fractography conducted on the failed samples.

  5. Prediction of Mean and Design Fatigue Lives of Self Compacting Concrete Beams in Flexure

    Science.gov (United States)

    Goel, S.; Singh, S. P.; Singh, P.; Kaushik, S. K.

    2012-02-01

    In this paper, result of an investigation conducted to study the flexural fatigue characteristics of self compacting concrete (SCC) beams in flexure are presented. An experimental programme was planned in which approximately 60 SCC beam specimens of size 100 × 100 × 500 mm were tested under flexural fatigue loading. Approximately 45 static flexural tests were also conducted to facilitate fatigue testing. The flexural fatigue and static flexural strength tests were conducted on a 100 kN servo-controlled actuator. The fatigue life data thus obtained have been used to establish the probability distributions of fatigue life of SCC using two-parameter Weibull distribution. The parameters of the Weibull distribution have been obtained by different methods of analysis. Using the distribution parameters, the mean and design fatigue lives of SCC have been estimated and compared with Normally vibrated concrete (NVC), the data for which have been taken from literature. It has been observed that SCC exhibits higher mean and design fatigue lives compared to NVC.

  6. Fatigue life determination by damage measuring in SAE 8620 specimens steel subjected to multiaxial experiments in neutral and corrosive environment

    International Nuclear Information System (INIS)

    Silva, Luiz L. da; Filho, Nelson do N.A.; Gomes, Paulo de T.V.; Rabello, Emerson G.; Mansur, Tanius R.

    2013-01-01

    Fatigue is the fail phenomenon of a material subjected to cyclic loads. This phenomenon affects any component under loads (forces, temperatures, etc.) that changes in time. When there is a combined load, originating multiaxial fatigue, which is the most of the real loads, worst is the situation. Before the component fail, the fatigue phenomenon produces damages to its material and this is a cumulative process that could not be reduced. In the continuum mechanic context, material damage is defined as a parameter that reduces the component resistance and this could cause its fail. The process of damage measuring by changes in electrical resistance is used in this work, and from experimental results of SAE 8620 steel specimens subjected to multiaxial fatigue in corrosive and neutral environment, the remaining specimen time life could be determined. Each specimen has its initial electrical resistance measured and after a certain number of fatigue cycles stopping points, its electrical resistance was measured again. In order to study multiaxial fatigue in specimens, a machine that induces simultaneously bending and torsional loads in the specimen was developed. Air at the temperature range of 18 deg C and 20 deg C was considered neutral environment. The corrosive environment was a NaCl solution with a concentration of 3,5% in weigh. The experimental results showed that the measuring fatigue damage using the changes in electrical resistance is efficient and that is possible to estimate the effect of a corrosive environment in the fatigue damage. (author)

  7. Fatigue criterion for the design of rotating shafts under combined stress

    Science.gov (United States)

    Loewenthal, S. H.

    1977-01-01

    A revised approach to the design of transmission shafting which considers the flexure fatigue characteristics of the shaft material under combined cyclic bending and static torsion stress is presented. A fatigue failure relation, corroborated by published combined stress test data, is presented which shows an elliptical variation of reversed bending endurance strength with static torsional stress. From this elliptical failure relations, a design formula for computing the diameter of rotating solid shafts under the most common condition of loading is developed.

  8. Effect of Environment on Fatigue Behavior of a Nicalon(TM)/Si-N-C Ceramic Matrix Composite

    Science.gov (United States)

    Kalluri, Sreeramesh; Ojard, Greg C.; Verrilli, Michael J.; Kiraly, Louis J. (Technical Monitor)

    2002-01-01

    The effect of environmental exposure on the fatigue life of Nicalon(TM) /Si-N-C composite was investigated in this study. Test specimens with arrays of 1.8 mm diameter holes and two different open areas, 25 and 35%, were machined. Three environmental conditions were studied: 1) continuous fatigue cycling in air, 2) fatigue cycling in air alternating with humidity exposure, and 3) fatigue cycling in air alternating with exposure to a salt-fog environment. All fatigue testing on specimens with holes was performed with a load ratio, R = 0.05, and at a temperature of 910 C. In general, fatigue lives were shortest for specimens subjected to salt-fog exposure and longest for specimens subjected to continuous fatigue cycling in air. The fatigue data generated on the specimens with holes were compared with fatigue data generated in air on specimens with no holes. Fatigue strength reduction factors for different environmental conditions and open areas investigated in the study were calculated for the Nicalon(TM) /Si-N-C composite.

  9. Corrosion fatigue of pressure vessel steels in PWR environments--influence of steel sulfur content

    International Nuclear Information System (INIS)

    Scott, P.M.; Druce, S.G.; Truswell, A.E.

    1984-01-01

    Large effects of simulated light water reactor environments at 288 C on fatigue crack growth in low alloy pressure vessel steels are observed only when specific mechanical, metallurgical, and electrochemical conditions are satisfied simultaneously. In this paper, the relative importance of three key variables--steel impurity content, water chemistry, and flow rate--and their interaction with loading rate or strain rate are examined. In particular, the results of a systematic examination of the influence of a steel's sulfur content are described

  10. Effect of pressurized water reactor environment on fatigue crack propagation, including hole times

    International Nuclear Information System (INIS)

    Bamford, W.H.

    1976-01-01

    Results are presented from an experimental program being conducted to investigate the effects of pressurized water reactor environment on the fatigue crack growth rate of pressure vessel steels. Tests were conducted on precracked WOL type specimens under load controlled conditions. The effects of R ratio, loading rates, and loading wave form are evaluated, and the results are compared for both forging and plate material, as well as weldments

  11. Load assumption for fatigue design of structures and components counting methods, safety aspects, practical application

    CERN Document Server

    Köhler, Michael; Pötter, Kurt; Zenner, Harald

    2017-01-01

    Understanding the fatigue behaviour of structural components under variable load amplitude is an essential prerequisite for safe and reliable light-weight design. For designing and dimensioning, the expected stress (load) is compared with the capacity to withstand loads (fatigue strength). In this process, the safety necessary for each particular application must be ensured. A prerequisite for ensuring the required fatigue strength is a reliable load assumption. The authors describe the transformation of the stress- and load-time functions which have been measured under operational conditions to spectra or matrices with the application of counting methods. The aspects which must be considered for ensuring a reliable load assumption for designing and dimensioning are discussed in detail. Furthermore, the theoretical background for estimating the fatigue life of structural components is explained, and the procedures are discussed for numerous applications in practice. One of the prime intentions of the authors ...

  12. Fatigue crack growth characteristics of the pressure vessel steel SA 508 Cl. 3 in various environments

    International Nuclear Information System (INIS)

    Lee, S. G.; Kim, I. S.; Park, Y. S.; Kim, J. W.; Park, C. Y.

    2001-01-01

    Fatigue tests in air and in room temperature water were performed to obtain comparable data and stable crack measuring conditions. In air environment, fatigue crack growth rate was increased with increasing temperature due to an increase in crack tip oxidation rate. In room temperature water, the fatigue crack growth rate was faster than in air and crack path varied on loading conditions. In simulated light water reactor (LWR) conditions, there was little environmental effect on the fatigue crack growth rate (FCGR) at low dissolved oxygen or at high loading frequency conditions. While the FCGR was enhanced at high oxygen condition, and the enhancement of crack growth rate increased as loading frequency decreased to a critical value. In fractography, environmentally assisted cracks, such as semi-cleavage and secondary intergranular crack, were found near sulfide inclusions only at high dissolved oxygen and low loading frequency condition. The high crack growth rate was related to environmentally assisted crack. These results indicated that environmentally assisted crack could be formed by the Electrochemical effect in specific loading condition

  13. Corrosion fatigue studies on F82H mod. martensitic steel in reducing water coolant environments

    Energy Technology Data Exchange (ETDEWEB)

    Maday, M F; Masci, A [ENEA, Casaccia (Italy). Centro Ricerche Energia

    1998-03-01

    Load-controlled low cycle fatigue tests have been carried out on F82H martensitic steel in 240degC oxygen-free water with and without dissolved hydrogen, in order to simulate realistic coolant boundary conditions to be approached in DEMO. It was found that water independently of its hydrogen content, determined the same fatigue life reduction compared to the base-line air results. Water cracks exhibited in their first propagation stages similar fracture morphologies which were completely missing on the air cracks, and were attributed to the action of an environment related component. Lowering frequency gave rise to an increase in F82H fatigue lifetimes without any change in cracking mode in air, and to fatigue life reduction by microvoid coalescence alone in water. The data were discussed in terms of (i) frequency dependent concurrent processes for crack initiation and (ii) frequency-dependent competitive mechanisms for crack propagation induced by cathodic hydrogen from F82H corrosion. (author)

  14. Interactive Environment Design in Smart City

    Science.gov (United States)

    Deng, DeXiang; Chen, LanSha; Zhou, Xi

    2017-08-01

    The interactive environment design of smart city is not just an interactive progress or interactive mode design, rather than generate an environment such as the “organic” life entity as human beings through interactive design, forming a smart environment with perception, memory, thinking, and reaction.

  15. Surface Studies of Ultra Strength Drilling Steel after Corrosion Fatigue in Simulated Sour Environment

    Energy Technology Data Exchange (ETDEWEB)

    M. Ziomek-Moroz; J.A. Hawk; R. Thodla; F. Gui

    2012-05-06

    The Unites States predicted 60% growth in energy demand by 2030 makes oil and natural gas primary target fuels for energy generation. The fact that the peak of oil production from shallow wells (< 5000 m) is about to be reached, thereby pushing the oil and natural gas industry into deeper wells. However, drilling to depths greater than 5000 m requires increasing the strength-to weight ratio of the drill pipe materials. Grade UD-165 is one of the ultra- high yield strength carbon steels developed for ultra deep drilling (UDD) activities. Drilling UDD wells exposes the drill pipes to Cl{sup -}, HCO{sub 3}{sup -}/CO{sub 3}{sup 2-}, and H{sub 2}S-containig corrosive environments (i.e., sour environments) at higher pressures and temperatures compared to those found in conventional wells. Because of the lack of synergism within the service environment, operational stresses can result in catastrophic brittle failures characteristic for environmentally assisted cracking (EAC). Approximately 75% of all drill string failures are caused by fatigue or corrosion fatigue. Since there is no literature data on the corrosion fatigue performance of UD-165 in sour environments, research was initiated to better clarify the fatigue crack growth (FCGR) behavior of this alloy in UDD environments. The FCGR behavior of ultra-strength carbon steel, grade UD-165, was investigated by monitoring crack growth rate in deaerated 5%NaCl solution buffered with NaHCO{sub 3}/Na{sub 2}CO{sub 3} and in contact with H{sub 2}S. The partial pressure of H{sub 2}S (p{sub H2S}) was 0.83 kPa and pH of the solution was adjusted by NaOH to 12. The fatigue experiments were performed at 20 and 85 C in an autoclave with surface investigations augmented by scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. In this study, research focused on surface analyses supported by the fatigue crack growth rate measurements. Fig. 1 shows an SEM micrograph of the crack that propagated from the

  16. Research on the Effects of Fatigue within the Corporate/Business Aircraft Environment

    Science.gov (United States)

    Neri, David F.; Rosekind, Mark R.; Co, Elizabeth L.; Gregory, Kevin B.; Miller, Donna L.

    1997-01-01

    In 1980, responding to a Congressional request, NASA Ames Research Center created a program to examine whether 'there is a safety problem of uncertain magnitude, due to transmeridian flying and a potential problem due to fatigue in association with various factors found in air transport operations.' The NASA Ames Fatigue/Jet Lag Program was created to collect systematic, scientific information on fatigue, sleep, circadian rhythms, and performance in flight operations. Three Program goals were established and continue to guide research efforts to: (1) determine the extent of fatigue, sleep loss, and circadian disruption in flight operations; (2) determine the impact of these factors on flight crew performance; (3) develop and evaluate countermeasures to mitigate the adverse effects of these factors and maximize flight crew performance and alertness. Since 1980, studies have been conducted in a variety of aviation environments, in controlled laboratory environments, as well as in a full-mission flight simulation. Early studies included investigations of short-haul, long-haul, and overnight cargo flight crews. In 1991, the name of the program was changed to the Fatigue Countermeasures Program to provide a greater emphasis on the development and evaluation of countermeasures. More recent work has examined the effects of planned cockpit rest as an operational countermeasure and provided analyses of the pertinent sleep/duty factors preceding an aviation accident at Guantanamo Bay, Cuba. The Short-Haul study examined the extent of sleep loss, circadian disruption, and fatigue engendered by flying commercial short-haul air transport operations (flight legs less than eight hours). This was one of the first field studies conducted by the NASA program and provided unique insight into the physiological and subjective effects of flying commercial short-haul operations. It demonstrated that a range of measures could be obtained in an operational environment without disturbing

  17. Probabilistic Calibration of Fatigue Design Factors for Offshore Wind Turbine Support Structures

    DEFF Research Database (Denmark)

    Ramirez, José Rangel; Sørensen, John Dalsgaard

    2010-01-01

    for the considered offshore wind turbines in such a way that the specific uncertainties for the fatigue life are accounted in a rational manner. Similar approaches have been used for offshore oil & gas sub-structures, but the required reliability level for offshore wind turbines is generally lower and the fatigue......This paper describes a reliability-based approach to determine fatigue design factors (FDF) for offshore wind turbine support structures made of steel. The FDF values are calibrated to a specific reliability level and linked to a specific inspection and maintenance (I&M) strategy used...

  18. Reliability based code calibration of fatigue design criteria of nuclear Class-1 piping

    International Nuclear Information System (INIS)

    Mishra, J.; Balasubramaniyan, V.; Chellapandi, P.

    2016-01-01

    Fatigue design of Class-l piping of NPP is carried out using Section-III of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel code. The fatigue design criteria of ASME are based on the concept of safety factor, which does not provide means for the management of uncertainties for consistently reliable and economical designs. In this regards, a work is taken up to estimate the implicit reliability level associated with fatigue design criteria of Class-l piping specified by ASME Section III, NB-3650. As ASME fatigue curve is not in the form of analytical expression, the reliability level of pipeline fittings and joints is evaluated using the mean fatigue curve developed by Argonne National Laboratory (ANL). The methodology employed for reliability evaluation is FORM, HORSM and MCS. The limit state function for fatigue damage is found to be sensitive to eight parameters, which are systematically modelled as stochastic variables during reliability estimation. In conclusion a number of important aspects related to reliability of various piping product and joints are discussed. A computational example illustrates the developed procedure for a typical pipeline. (author)

  19. Design optimization and fatigue testing of an electronically-driven mechanically-resonant cantilever spring mechanism

    International Nuclear Information System (INIS)

    Kheng, Lim Boon; Kean, Koay Loke; Gitano-Briggs, Horizon

    2010-01-01

    A light scanning device consisting of an electronically-driven mechanically-resonant cantilever spring-mirror system has been developed for innovative lighting applications. The repeated flexing of the cantilever spring during operation can lead to premature fatigue failure. A model was created to optimize the spring design. The optimized spring design can reduce stress by approximately one-third from the initial design. Fatigue testing showed that the optimized spring design can operate continuously for over 1 month without failure. Analysis of failures indicates surface cracks near the root of the spring are responsible for the failures.

  20. Designing aluminium friction stir welded joints against multiaxial fatigue

    Directory of Open Access Journals (Sweden)

    L. Susmel

    2016-07-01

    Full Text Available The present paper investigates the accuracy of the Modified Wöhler Curve Method (MWCM in estimating multiaxial fatigue strength of aluminium friction stir (FS welded joints. Having developed a bespoke joining technology, circumferentially FS welded tubular specimens of Al 6082-T6 were tested under proportional and non-proportional tension and torsion, the effect of non-zero mean stresses being also investigated. The validation exercise carried out using the experimental results have demonstrated that the MWCM applied in terms of nominal stresses, notch stresses, and also the Point Method is accurate in predicting the fatigue lifetime of the tested FS welded joints, with its use resulting in life estimates that fall within the uniaxial and torsional calibration scatter bands.

  1. Effect of the environment on a SG tube fatigue cracking at Fessenheim unit 2

    International Nuclear Information System (INIS)

    Duisabeau, L.; Fargeas, E.; Miloudi, S.; Leduc, A.; Hollner, S.; Thebault, Y.; Legras, L.; Mansour, C.

    2015-01-01

    In 2008, a primary-to-secondary leak was detected at TSP n8 level, on the tube R12C62 of Fessenheim unit 2 SG3. The leak was associated to a high cycle fatigue crack that was confirmed two years after, when the tube was pulled out for destructive examination. It revealed on the one hand a highly oxidized fracture surface and on the other hand, that the fatigue crack was initiated on small IGA (Intergranular Attack) piles located at the OD (Outside Diameter) surface of the alloy 600MA tube. In order to take into account a potential environmental effect on the fatigue limit of alloy 600MA in mechanical calculations implemented to establish the root cause failure analysis, several investigations were conducted to evaluate the environment at the tube/tubesheet interstice. To achieve this goal, a multi-scale analysis has been performed. It includes a global analysis of the corrosion damage of the SG, the SG chemistry monitoring, an evaluation of the pH in confined areas with MulteQ calculations based on hide out returns, as well as oxides characterization on the tube by Transmission Electronic Microscopy. All methods converge to a slightly neutral pH with pollutants such as copper, lead and sulfates leading to the conclusion that the fatigue limit of alloy 600MA has not been reduced by the chemical environment. All these chemical elements are known to affect in a certain extent the corrosion resistance of the alloy 600 in the secondary water. If all these pollutants can be detected during the global monitoring of the plant during operation or outage (blow down, hideout returns, feed water and sludge chemical analysis), transmission electronic microscopy offers a unique technique for better understanding how these pollutants may react in confined area, corroded area or free span oxides in the alloy 600 and thus for a better understanding of the corrosion mechanism of nickel based alloys in the secondary side

  2. Fatigue Design Evaluation of Railway Bogie with Full-Scale Fatigue Test

    Directory of Open Access Journals (Sweden)

    Jung-Won Seo

    2017-01-01

    Full Text Available The bogie frame of a railway is an important structural member for the support of vehicle loading. In general, more than 25 years’ durability is necessary. Much study has been carried out in experimental and theoretical domains on the prediction of the structural integrity of the bogie frame. The objective of this paper is to estimate the structural integrity of the bogie frame of an electric railcar. Strength analysis has been performed by finite element analysis. From this analysis, stress concentration areas were investigated. To evaluate the loading conditions, dynamic stress was measured by strain gauge. It has been found that the stress and strain due to the applied loads were multiaxial conditions according to the location of the strain gauge. Fatigue strength evaluations of the bogie frame were performed to investigate the effect of a multiaxial load through the employment of a critical plane approach.

  3. Towards the development of mechanistically based design rules for corrosion fatigue in ductile steels

    International Nuclear Information System (INIS)

    Johnson, R.; McMinn, A.; Tomkins, B.

    1980-08-01

    Design curves for nuclear pressure vessels and off-shore structures are based on air endurance curves that have had a safety factor applied to account for effects such as corrosive environments, frequency and mean stress. These are supported by a limited number of endurance tests on actual pressure vessels, and on welded joints under service conditions. These data-based rules are limited in their ability to cope with environmental effects and as the time dependencies of fatigue and corrosion processes are so different, no sound basis exists for the extrapolation of data to long component lifetimes. The crack-growth behaviour of materials used in nuclear pressure vessels and off-shore structures is examined with a view to determining how it may be used to re-assess the design curves. Even simple integration of crack-growth laws can be seen to be within reasonable agreement with present design curves; with improved methods of stress analysis, etc. this approach could potentially improve these curves. Mechanistic studies are also seen to offer a means of examining and assessing time-dependent process interactions and so, potentially, to form the basis of new guidelines. Finally the areas where further work would be needed to substantiate any changes in design curves are indicated. (author)

  4. Robust design and thermal fatigue life prediction of anisotropic conductive film flip chip package

    International Nuclear Information System (INIS)

    Nam, Hyun Wook

    2004-01-01

    The use of flip-chip technology has many advantages over other approaches for high-density electronic packaging. ACF(Anisotropic Conductive Film) is one of the major flip-chip technologies, which has short chip-to-chip interconnection length, high productivity, and miniaturization of package. In this study, thermal fatigue life of ACF bonding flip-chip package has been predicted. Elastic and thermal properties of ACF were measured by using DMA and TMA. Temperature dependent nonlinear bi-thermal analysis was conducted and the result was compared with Moire interferometer experiment. Calculated displacement field was well matched with experimental result. Thermal fatigue analysis was also conducted. The maximum shear strain occurs at the outmost located bump. Shear stress-strain curve was obtained to calculate fatigue life. Fatigue model for electronic adhesives was used to predict thermal fatigue life of ACF bonding flip-chip packaging. DOE (Design Of Experiment) technique was used to find important design factors. The results show that PCB CTE (Coefficient of Thermal Expansion) and elastic modulus of ACF material are important material parameters. And as important design parameters, chip width, bump pitch and bump width were chose. 2 nd DOE was conducted to obtain RSM equation for the choose 3 design parameter. The coefficient of determination (R 2 ) for the calculated RSM equation is 0.99934. Optimum design is conducted using the RSM equation. MMFD (Modified Method for Feasible Direction) algorithm is used to optimum design. The optimum value for chip width, bump pitch and bump width were 7.87mm, 430μm, and 78μm, respectively. Approximately, 1400 cycles have been expected under optimum conditions. Reliability analysis was conducted to find out guideline for control range of design parameter. Sigma value was calculated with changing standard deviation of design variable. To acquire 6 sigma level thermal fatigue reliability, the Std. Deviation of design parameter

  5. Experimental evaluation of torsional fatigue strength of welded bellows and application to design of fusion device

    International Nuclear Information System (INIS)

    Takatsu, Hideyuki; Yamamoto, Masahiro; Shimizu, Masatsugu; Suzuki, Kazuo; Sonobe, Tadashi; Hayashi, Yuzo; Mizuno, Gen-ichiro.

    1984-01-01

    Torsional fatigue strength of the welded bellows was evaluated experimentally, aiming the application to a port of a fusion device. The welded bellows revealed elastic torsional buckling and spiral distorsion even under a small angle of torsion. Twisting load never leads the welded bellows to fracture easily so far as the angle of torsion is not excessively large, and the welded bellows has the torsional fatigue strength much larger than that expected so far. Two formulae were proposed to evaluate the stress of the welded bellows under the forced angle of torsion; shearing stress evaluation formula in the case that torsional buckling does not occur and the axial bending stress evaluation formula in the case that torsional buckling occurs. And the results of the torsional fatigue experiments showed that the former is reasonably conservative and simulates the actual behavior of the welded bellows better than the latter in the high cycle fatigue region and vice versa in the low cycle fatigue region from the viewpoint of the mechanical design. The present evaluation method of the torsional fatigue strength was applied to the welded bellows for the port of the JT-60 vacuum vessel and its structural integrity was confirmed under the design load condition. (author)

  6. Design and management of sustainable built environments

    CERN Document Server

    2013-01-01

    Climate change is believed to be a great challenge to built environment professionals in design and management. An integrated approach in delivering a sustainable built environment is desired by the built environment professional institutions. The aim of this book is to provide an advanced understanding of the key subjects required for the design and management of modern built environments to meet carbon emission reduction targets. In Design and Management of Sustainable Built Environments, an international group of experts provide comprehensive and the most up-to-date knowledge, covering sustainable urban and building design, management and assessment. The best practice case studies of the implementation of sustainable technology and management from the BRE Innovation Park are included. Design and Management of Sustainable Built Environments will be of interest to urban and building designers, environmental engineers, and building performance assessors.  It will be particularly useful as a reference book ...

  7. Corrosion fatigue of pressure vessel steels in PWR environments--influence of steel sulfur content

    Energy Technology Data Exchange (ETDEWEB)

    Scott, P.M.; Druce, S.G.; Truswell, A.E.

    1984-07-01

    Large effects of simulated light water reactor environments at 288 C on fatigue crack growth in low alloy pressure vessel steels are observed only when specific mechanical, metallurgical, and electrochemical conditions are satisfied simultaneously. In this paper, the relative importance of three key variables--steel impurity content, water chemistry, and flow rate--and their interaction with loading rate or strain rate are examined. In particular, the results of a systematic examination of the influence of a steel's sulfur content are described.

  8. Rapid Mission Design for Dynamically Complex Environments

    Data.gov (United States)

    National Aeronautics and Space Administration — Designing trajectories in dynamically complex environments is very challenging and easily becomes an intractable problem. More complex planning implies potentially...

  9. Investigation of LWR environmental effect on fatigue lifetime of austenitic stainless steel component

    International Nuclear Information System (INIS)

    Kim, J. S.; Youm, H. K.; Jin, T. E.

    1999-01-01

    The fatigue lifetime of principal components in nuclear power plant is evaluated by using the design fatigue curves in ASME B and PV code during design process. However, it is inadequate to evaluate fatigue lifetime considering the LWR environmental effect by these design fatigue curves because these are presented only under atmosphere environment. Therefore, many studies are recently performed for the design fatigue curves considering LWR environmental effect and are presented that the design fatigue curves in ASME B and PV code can be non-conservative. In present paper, the limits and differences of the design fatigue curves considering environmental effect are presented. To investigate the change of fatigue lifetime according to each design fatigue curve, the CUFs for the pressurizer spray nozzle partly composed of austenitic stainless steel are calculated according to each one. Finally, if the evaluation result can not be satisfied with fatigue design requirement, the alternatives to reduce design cumulative usage factor are discussed. (author)

  10. The increase in fatigue crack growth rates observed for Zircaloy-4 in a PWR environment

    Science.gov (United States)

    Cockeram, B. V.; Kammenzind, B. F.

    2018-02-01

    Cyclic stresses produced during the operation of nuclear reactors can result in the extension of cracks by processes of fatigue. Although fatigue crack growth rate (FCGR) data for Zircaloy-4 in air are available, little testing has been performed in a PWR primary water environment. Test programs have been performed by Gee et al., in 1989 and Picker and Pickles in 1984 by the UK Atomic Energy Authority, and by Wisner et al., in 1994, that have shown an enhancement in FCGR for Zircaloy-2 and Zircaloy-4 in high-temperature water. In this work, FCGR testing is performed on Zircaloy-4 in a PWR environment in the hydrided and non-hydrided condition over a range of stress-intensity. Measurements of crack extension are performed using a direct current potential drop (DCPD) method. The cyclic rate in the PWR primary water environment is varied between 1 cycle per minute to 0.1 cycle per minute. Faster FCGR rates are observed in water in comparison to FCGR testing performed in air for the hydrided material. Hydrided and non-hydrided materials had similar FCGR values in air, but the non-hydrided material exhibited much lower rates of FCGR in a PWR primary water environment than for hydrided material. Hydrides are shown to exhibit an increased tendency for cracking or decohesion in a PWR primary water environment that results in an enhancement in FCGR values. The FCGR in the PWR primary water only increased slightly with decreasing cycle frequency in the range of 1 cycle per minute to 0.1 cycle per minute. Comparisons between the FCGR in water and air show the enhancement from the PWR environment is affected by the applied stress intensity.

  11. Creep-fatigue damage rules for advanced fast reactor design. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    1997-03-01

    The IAEA, following the recommendations of the International Working Group on Fast Reactors, convened a Technical Committee Meeting on Creep-Fatigue Damage Rules to be used in Fast Reactor Design. The objective of the meeting was to review developments in design rules for creep-fatigue conditions and to identify any areas in which further work would be desirable. The meeting was hosted by AEA Technology, Risley, and held in Manchester, United Kingdom, 11-13 June 1996. It was attended by experts from the European Commission, France, India, Japan, the Republic of Korea, the Russian Federation and the United Kingdom. Refs, figs, tabs

  12. A Design Framework for Personal Learning Environments

    NARCIS (Netherlands)

    Rahimi, E.

    2015-01-01

    The purpose of our research was to develop a PLE (personal learning environment) design framework for workplace settings. By doing such, the research has answered this research question, how should a technology-based personal learning environment be designed, aiming at supporting learners to gain

  13. Designing an adaptive salutogenic care environment

    OpenAIRE

    Dalton, Cathy; Harrison, Jim D.

    2011-01-01

    Humans are profoundly affected by the surroundings which they inhabit. Environmental psychologists have produced numerous credible theories describing optimal human environments, based on the concept of congruence or “fit” (1, 2). Lack of person/environment fit can lead to stress-related illness and lack of psychosocial well-being (3). Conversely, appropriately designed environments can promote wellness (4) or “salutogenesis” (5). Increasingly, research in the area of Evidence-Based Design, l...

  14. Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment

    International Nuclear Information System (INIS)

    Liaw, P.K.; Logsdon, W.A.; Begley, J.A.

    1989-01-01

    The fatigue crack growth rate (FCGR) properties of SA508 Cl 2a and SA533 Gr A Cl 2 pressure vessel steels and the corresponding automatic submerged arc weldments were developed in a high-temperature pressurized water (HPW) environment at 288 degrees C (550 degrees F) and 7.2 MPa (1044 psi) at load ratios of 0.20 and 0.50. The properties were generally conservative compared to American Society of Mechanical Engineers Section XI water environment reference curve. The growth rate of fatigue cracks in the base materials, however, was faster in the HPW environment than in a 288 degrees C (550 degrees F) base line air environment. The growth rate of fatigue cracks in the two submerged arc weldments was also accelerated in the HPW environment but to a lesser degree than that demonstrated by the base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials compared the weldments attributed to a different sulfide composition and morphology

  15. An overview of fatigue

    International Nuclear Information System (INIS)

    Mc Evily, A.J.

    1987-01-01

    Four topics are briefly discussed in this paper: fatigue crack initiation and growth in a nickel-base superalloy single crystal, the environment effect on near-threshold fatigue crack growth behaviour, the role of crack closure in load-interaction effects in fatigue crack growth, and the nature of creep-fatigue interactions, if any, during fatigue crack growth. (Author)

  16. In-air and pressurized water reactor environment fatigue experiments of 316 stainless steel to study the effect of environment on cyclic hardening

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov; Soppet, William K., E-mail: soppet@anl.gov; Majumdar, Saurindranath, E-mail: majumdar@anl.gov; Natesan, Krishnamurti, E-mail: natesan@anl.gov

    2016-05-15

    Argonne National Laboratory (ANL), under the sponsorship of Department of Energy's Light Water Reactor Sustainability (LWRS) program, is trying to develop a mechanistic approach for more accurate life estimation of LWR components. In this context, ANL has conducted many fatigue experiments under different test and environment conditions on type 316 stainless steel (316 SS) material which is widely used in the US reactors. Contrary to the conventional S ∼ N curve based empirical fatigue life estimation approach, the aim of the present DOE sponsored work is to develop an understanding of the material ageing issues more mechanistically (e.g. time dependent hardening and softening) under different test and environmental conditions. Better mechanistic understanding will help develop computer-based advanced modeling tools to better extrapolate stress-strain evolution of reactor components under multi-axial stress states and hence help predict their fatigue life more accurately. Mechanics-based modeling of fatigue such as by using finite element (FE) tools requires the time/cycle dependent material hardening properties. Presently such time-dependent material hardening properties are hardly available in fatigue modeling literature even under in-air conditions. Getting those material properties under PWR environment, are even harder. Through this work we made preliminary attempt to generate time/cycle dependent stress-strain data both under in-air and PWR water conditions for further study such as for possible development of material models and constitutive relations for FE model implementation. Although, there are open-ended possibility to further improve the discussed test methods and related material estimation techniques we anticipate that the data presented in this paper will help the metal fatigue research community particularly, the researchers who are dealing with mechanistic modeling of metal fatigue such as using FE tools. In this paper the fatigue

  17. Fatigue Crack Propagation Behavior of RC Beams Strengthened with CFRP under High Temperature and High Humidity Environment

    Directory of Open Access Journals (Sweden)

    Dongyang Li

    2017-01-01

    Full Text Available Numerical and experimental methods were applied to investigate fatigue crack propagation behavior of reinforced concrete (RC beams strengthened with a new type carbon fiber reinforced polymer (CFRP named as carbon fiber laminate (CFL subjected to hot-wet environment. J-integral of a central crack in the strengthened beam under three-point bending load was calculated by ABAQUS. In finite element model, simulation of CFL-concrete interface was based on the bilinear cohesive zone model under hot-wet environment and indoor atmosphere. And, then, fatigue crack propagation tests were carried out under high temperature and high humidity (50°C, 95% R · H environment pretreatment and indoor atmosphere (23°C, 78% R · H to obtain a-N curves and crack propagation rate, da/dN, of the strengthened beams. Paris-Erdogan formula was developed based on the numerical analysis and environmental fatigue tests.

  18. Thermal stress and creep fatigue limitations in first wall design

    International Nuclear Information System (INIS)

    Majumdar, S.; Misra, B.; Harkness, S.D.

    1977-01-01

    The thermal-hydraulic performance of a lithium cooled cylindrical first wall module has been analyzed as a function of the incident neutron wall loading. Three criteria were established for the purpose of defining the maximum wall loading allowable for modules constructed of Type 316 stainless steel and a vanadium alloy. Of the three, the maximum structural temperature criterion of 750 0 C for vanadium resulted in the limiting wall loading value of 7 MW/m 2 . The second criterion limited thermal stress levels to the yield strength of the alloy. This led to the lowest wall loading value for the Type 316 stainless steel wall (1.7 MW/m 2 ). The third criterion required that the creep-fatigue characteristics of the module allow a lifetime of 10 MW-yr/m 2 . At wall temperatures of 600 0 C, this lifetime could be achieved in a stainless steel module for wall loadings less than 3.2 MW/m 2 , while the same lifetime could be achieved for much higher wall loadings in a vanadium module

  19. Fatigue and fail-safe design features of the DC-10 airplane

    Science.gov (United States)

    Stone, M. E.

    1972-01-01

    The philosophy and methods used in the design of the DC-10 aircraft to assure structural reliability against cracks under repeated service loads are described in detail. The approach consists of three complementary parts: (1) the structure is designed to be fatigue resistant for a crack-free life of 60,000 flight hours; (2) inasmuch as small undetected cracks could develop from other sources, such as material flaws and manufacturing preloads, the structure also is designed to arrest and control cracks within a reasonable service-inspection interval; and (3) a meaningful service-inspection program has been defined on the basis of analysis and test experience from the design development program. This service-inspection program closes the loop to assure the structural integrity of the DC-10 airframe. Selected materials, fasteners, and structural arrangements are used to achieve these design features with minimum structural weight and with economy in manufacturing and maintenance. Extensive analyses and testing were performed to develop and verify the design. The basic design considerations for fatigue-resistant structure are illustrated in terms of material selection, design loads spectra, methods for accurate stress and fatigue damage analysis, and proven concepts for efficient detail design.

  20. Tuning Low Cycle Fatigue Properties of Cu-Be-Co-Ni Alloy by Precipitation Design

    Directory of Open Access Journals (Sweden)

    Yanchuan Tang

    2018-06-01

    Full Text Available As material for key parts applied in the aerospace field, the Cu-Be-Co-Ni alloy sustains cyclic plastic deformation in service, resulting in the low cycle fatigue (LCF failure. The LCF behaviors are closely related to the precipitation states of the alloy, but the specific relevance is still unknown. To provide reasonable regulation of the LCF properties for various service conditions, the effect of precipitation states on the LCF behaviors of the alloy was investigated. It is found that the alloy composed fully of non-shearable γ′ precipitates has higher fatigue crack initiation resistance, resulting in a longer fatigue life under LCF process with low total strain amplitude. The alloy with fine shearable γ′I precipitates presents higher fatigue crack propagation resistance, leading to a longer fatigue life under LCF process with high total strain amplitude. The cyclic stress response behavior of the alloy depends on the competition between the kinematic hardening and isotropic softening. The fine shearable γ′I precipitates retard the decrease of effective stress during cyclic loading, causing cyclic hardening of the alloy. The present work would help to design reasonable precipitation states of the alloy for various cyclic loading conditions to guarantee its safety in service.

  1. Uniaxial low cycle fatigue behavior for pre-corroded 16MND5 bainitic steel in simulated pressurized water reactor environment

    Science.gov (United States)

    Chen, Xu; Ren, Bin; Yu, Dunji; Xu, Bin; Zhang, Zhe; Chen, Gang

    2018-06-01

    The effects of uniaxial tension properties and low cycle fatigue behavior of 16MND5 bainitic steel cylinder pre-corroded in simulated pressurized water reactor (PWR) were investigated by fatigue at room temperature in air and immersion test system, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS). The experimental results indicated that the corrosion fatigue lives of 16MND5 specimen were significantly affected by the strain amplitude and simulated PWR environments. The compositions of corrosion products were complexly formed in simulated PWR environments. The porous corrosion surface of pre-corroded materials tended to generate pits as a result of promoting contact area to the fresh metal, which promoted crack initiation. For original materials, the fatigue cracks initiated at inclusions imbedded in the micro-cracks. Moreover, the simulated PWR environments degraded the mechanical properties and low cycle fatigue behavior of 16MND5 specimens remarkably. Pre-corrosion of 16MND5 specimen mainly affected the plastic term of the Coffin-Manson equation.

  2. Thermomechanical fatigue behavior of SiC/Ti-24Al-11Nb in air and argon environments

    Science.gov (United States)

    Bartolotta, Paul A.; Verrilli, Michael J.

    1992-01-01

    A series of tension-tension, load-controlled thermomechanical fatigue (TMF) tests were conducted on a titanium aluminide composite in both laboratory air and a flowing argon environment. Results from these tests show that the environment plays an increasingly important role as applied stress levels are decreased. Differences in damage mechanisms between the two environments were observed which corresponds to observed variations in TMF lives.

  3. Design for the Environment Products (Raw Data)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains a list of products that carry the Design for the Environment (DfE) label. This mark enables consumers to quickly identify and choose products...

  4. Design for the Environment Products (Online Search)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains a list of products that carry the Design for the Environment (DfE) label. This mark enables consumers to quickly identify and choose products...

  5. Review of ASME-NH Design Materials for Creep-Fatigue

    International Nuclear Information System (INIS)

    Koo, Gyeong Hoi; Kim, Jong Bum

    2010-01-01

    To review and recommend the candidate design materials for the Sodium-Cooled Fast Reactor, the material sensitivity evaluations by the comparison of design data between the ASME-NH materials were performed by using the SIE ASME-NH computer program implementing the material database of the ASME-NH. The design material data provided by the ASME-NH code are the elastic modulus and yield Strength, Time-Independent Allowable Stress Intensity value, time-dependent allowable stress intensity value, expected minimum stress-to rupture value, stress rupture Factors for weldment, isochronous stress-strain curves, and design fatigue curves. Among these, the data related with the creep-fatigue evaluation are investigated in this study

  6. Kunst & de mens in dementie : Designing Environment

    NARCIS (Netherlands)

    Coumans, Anke; Schuffelers, Ingrid; Polstra, Louis

    2016-01-01

    The research project Designing Environment conducts research into how a different mind-set can be brought about concerning people with dementia, by intervening in care processes, and from the perspective of the participating observer. The objective is to create an environment for people with

  7. The influence of low oxygen and contaminated sodium environments on the fatigue behavior of solution treated AISI 316 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, P [CEGB, BNL, Berkeley (United Kingdom)

    1977-07-01

    The influence of air and sodium environments on the fatigue properties of solution treated AISI 316 steel was studied by predictive methods and by conducting tests in air, in high temperature sodium, or following pre-exposure to sodium. The sodium environments studied included contaminated sodium or the products of sodium/water flames possibly typical of fast reactor fault conditions, and low oxygen sodium more appropriate to normal plant operation. Generally, fatigue properties were reduced by contaminated sodium or the products of sodium/water flames and improved by low oxygen sodium when compared with similar tests conducted in air. However, complex effects were observed with respect to crack initiation. The experimental results are discussed and generally follow trends predicted by physically based fatigue models. (author)

  8. Fatigue Crack Growth Behavior of 2099-T83 Extrusions in two Different Environments

    Science.gov (United States)

    Goma, Franck Armel Tchitembo; Larouche, Daniel; Bois-Brochu, Alexandre; Blais, Carls; Boselli, Julien; Brochu, Mathieu

    Aluminum-lithium alloy 2099-T83 is an advanced material with superior mechanical properties, as compared to traditional alloys used in structural applications, and has been selected for use in the latest generation of airplanes. While this alloy exhibits improved fatigue crack growth (FCG) performance over non-Li alloys, it is of interest to simulate the impact of fluctuating loads under variable temperature during airplane service, particularly in terms of the potential effects of material processing history. In the present paper, the FCG behavior in an Integrally Stiffened Panel (ISP) has been investigated both at room temperature and at 243 K. It has been shown that the resistance to crack growth in a cold environment was higher than in ambient laboratory air. Results of this investigation are discussed from the microfractographic point of view, with regard to the variation of the local extrusion aspect ratio, a parameter which correlates with both the crystallographic texture and the grain structure.

  9. Influence of Working Environment on Fatigue Life Time Duration for Runner Blades of Kaplan Turbines

    Directory of Open Access Journals (Sweden)

    Ana-Maria Budai

    2010-10-01

    Full Text Available The paper present an analytical analyzes refer to influence of working environment on life time duration in service of runner blades of Kaplan turbines. The study are made using only analytical method, the entry dates being obtained from measurements made in situ for a Kaplan turbine. To calculate the maximum number of stress cycles whereupon the runner blades work without any damage it was used an analytical relation known in specialized literatures under the name of Morrow’s relation. To estimate fatigue life time duration will be used a formula obtained from one of most common cumulative damage methodology taking in consideration the real exploitation conditions of a specified Kaplan turbine.

  10. Fatigue crack growth in ferritic steels as influence by elevated temperature and environment

    International Nuclear Information System (INIS)

    Nakamura, H.; Minakawa, K.; Murali, K.; Mc Evily, A.J.

    1987-01-01

    Fatigue crack growth studies have been carried out at room temperature and at 538 deg C in air as well as in vacuum in order to assess the influence of both temperature and environment on the growth process. The materials investigated were 2 1/4Cr-1Mo steel, a modified 9Cr-1Mo steel and a 9Cr-2Mo steel, as well as weldments of the 9Cr-2Mo steel. Crack opening levels were determined for all test conditions. The R-dependency of the crack growth rate could be accounted for by crack closure, both at room and elevated temperature. Closure in air at 538 deg C was due to oxidation, whereas at room temperature closure was due to microstructurally related roughness and the influence of oxygen. (Author)

  11. Shoulder girdle muscle activity and fatigue in traditional and improved design carpet weaving workstations.

    Science.gov (United States)

    Allahyari, Teimour; Mortazavi, Narges; Khalkhali, Hamid Reza; Sanjari, Mohammad Ali

    2016-01-01

    Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders. The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg's Category-Ratio scale (Borg CR-10). Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations. The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  12. Designing Learning Resources in Synchronous Learning Environments

    DEFF Research Database (Denmark)

    Christiansen, Rene B

    2015-01-01

    Computer-mediated Communication (CMC) and synchronous learning environments offer new solutions for teachers and students that transcend the singular one-way transmission of content knowledge from teacher to student. CMC makes it possible not only to teach computer mediated but also to design...... and create new learning resources targeted to a specific group of learners. This paper addresses the possibilities of designing learning resources within synchronous learning environments. The empirical basis is a cross-country study involving students and teachers in primary schools in three Nordic...... Countries (Denmark, Sweden and Norway). On the basis of these empirical studies a set of design examples is drawn with the purpose of showing how the design fulfills the dual purpose of functioning as a remote, synchronous learning environment and - using the learning materials used and recordings...

  13. Above-knee prosthesis design based on fatigue life using finite element method and design of experiment.

    Science.gov (United States)

    Phanphet, Suwattanarwong; Dechjarern, Surangsee; Jomjanyong, Sermkiat

    2017-05-01

    The main objective of this work is to improve the standard of the existing design of knee prosthesis developed by Thailand's Prostheses Foundation of Her Royal Highness The Princess Mother. The experimental structural tests, based on the ISO 10328, of the existing design showed that a few components failed due to fatigue under normal cyclic loading below the required number of cycles. The finite element (FE) simulations of structural tests on the knee prosthesis were carried out. Fatigue life predictions of knee component materials were modeled based on the Morrow's approach. The fatigue life prediction based on the FE model result was validated with the corresponding structural test and the results agreed well. The new designs of the failed components were studied using the design of experimental approach and finite element analysis of the ISO 10328 structural test of knee prostheses under two separated loading cases. Under ultimate loading, knee prosthesis peak von Mises stress must be less than the yield strength of knee component's material and the total knee deflection must be lower than 2.5mm. The fatigue life prediction of all knee components must be higher than 3,000,000 cycles under normal cyclic loading. The design parameters are the thickness of joint bars, the diameter of lower connector and the thickness of absorber-stopper. The optimized knee prosthesis design meeting all the requirements was recommended. Experimental ISO 10328 structural test of the fabricated knee prosthesis based on the optimized design confirmed the finite element prediction. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  14. Virtual environments for nuclear power plant design

    International Nuclear Information System (INIS)

    Brown-VanHoozer, S.A.; Singleterry, R.C. Jr.; King, R.W.

    1996-01-01

    In the design and operation of nuclear power plants, the visualization process inherent in virtual environments (VE) allows for abstract design concepts to be made concrete and simulated without using a physical mock-up. This helps reduce the time and effort required to design and understand the system, thus providing the design team with a less complicated arrangement. Also, the outcome of human interactions with the components and system can be minimized through various testing of scenarios in real-time without the threat of injury to the user or damage to the equipment. If implemented, this will lead to a minimal total design and construction effort for nuclear power plants (NPP)

  15. Creep and fatigue properties of Incoloy 800H in a high-temperature gas-cooled reactor (HTGR) helium environment

    International Nuclear Information System (INIS)

    Chow, J.G.Y.; Soo, P.; Epel, L.

    1978-01-01

    A mechanical test program to assess the effects of a simulated HTGR helium environment on the fatigue and creep properties of Incoloy 800H and other primary-circuit metals is described. The emphasis and the objectives of this work are directed toward obtaining information to assess the integrity and safety of an HTGR throughout its service life. The helium test environment selected for study contained 40 μ atm H 2 O, 200 μ atm H 2 , 40 μ atm CO, 10 μ atm CO 2 , and 20 μ atm CH 4 . It is believed that this ''wet'' environment simulates that which could exist in a steam-cycle HTGR containing some leaking steam-generator tubes. A recirculating helium loop operating at about 4 psi in which impurities can be maintained at a constant level, has been constructed to supply the desired environment for fatigue and creep testing

  16. Update and Improve Subsection NH - Alternative Simplified Creep-Fatigue Design Methods

    International Nuclear Information System (INIS)

    Asayama, Tai

    2009-01-01

    This report described the results of investigation on Task 10 of DOE/ASME Materials NGNP/Generation IV Project based on a contract between ASME Standards Technology, LLC (ASME ST-LLC) and Japan Atomic Energy Agency (JAEA). Task 10 is to Update and Improve Subsection NH -- Alternative Simplified Creep-Fatigue Design Methods. Five newly proposed promising creep-fatigue evaluation methods were investigated. Those are (1) modified ductility exhaustion method, (2) strain range separation method, (3) approach for pressure vessel application, (4) hybrid method of time fraction and ductility exhaustion, and (5) simplified model test approach. The outlines of those methods are presented first, and predictability of experimental results of these methods is demonstrated using the creep-fatigue data collected in previous Tasks 3 and 5. All the methods (except the simplified model test approach which is not ready for application) predicted experimental results fairly accurately. On the other hand, predicted creep-fatigue life in long-term regions showed considerable differences among the methodologies. These differences come from the concepts each method is based on. All the new methods investigated in this report have advantages over the currently employed time fraction rule and offer technical insights that should be thought much of in the improvement of creep-fatigue evaluation procedures. The main points of the modified ductility exhaustion method, the strain range separation method, the approach for pressure vessel application and the hybrid method can be reflected in the improvement of the current time fraction rule. The simplified mode test approach would offer a whole new advantage including robustness and simplicity which are definitely attractive but this approach is yet to be validated for implementation at this point. Therefore, this report recommends the following two steps as a course of improvement of NH based on newly proposed creep-fatigue evaluation

  17. Aeroelastic analysis of an offshore wind turbine: Design and Fatigue Performance of Large Utility-Scale Wind Turbine Blades

    OpenAIRE

    Fossum, Peter Kalsaas

    2012-01-01

    Aeroelastic design and fatigue analysis of large utility-scale wind turbine blades are performed. The applied fatigue model is based on established methods and is incorporated in an iterative numerical design tool for realistic wind turbine blades. All aerodynamic and structural design properties are available in literature. The software tool FAST is used for advanced aero-servo-elastic load calculations and stress-histories are calculated with elementary beam theory.According to wind energy ...

  18. Thermal Exposure and Environment Effects on Tension, Fracture and Fatigue of 5XXX Alloys Tested in Different Orientations

    Science.gov (United States)

    2017-12-27

    Thermal Exposure and Environment Effects on Tension, Fracture and Fatigue of 5XXX Alloys Tested in Different Orientations Sb. GRANT NUMBER ONR-N000 14...e.g.Hl31, HI 16, HI 28), thermal exposure conditions (i .e. time, temperature), and environment (e.g. dry air, humid air, solutions) on the... environmental cracking susceptibility at different load ing rates in both the S-T and L-T orientations. Experiments were conducted using slow strain rate

  19. A fracture mechanics approach for estimating fatigue crack initiation in carbon and low-alloy steels in LWR coolant environments

    International Nuclear Information System (INIS)

    Park, H. B.; Chopra, O. K.

    2000-01-01

    A fracture mechanics approach for elastic-plastic materials has been used to evaluate the effects of light water reactor (LWR) coolant environments on the fatigue lives of carbon and low-alloy steels. The fatigue life of such steel, defined as the number of cycles required to form an engineering-size crack, i.e., 3-mm deep, is considered to be composed of the growth of (a) microstructurally small cracks and (b) mechanically small cracks. The growth of the latter was characterized in terms of ΔJ and crack growth rate (da/dN) data in air and LWR environments; in water, the growth rates from long crack tests had to be decreased to match the rates from fatigue S-N data. The growth of microstructurally small cracks was expressed by a modified Hobson relationship in air and by a slip dissolution/oxidation model in water. The crack length for transition from a microstructurally small crack to a mechanically small crack was based on studies on small crack growth. The estimated fatigue S-N curves show good agreement with the experimental data for these steels in air and water environments. At low strain amplitudes, the predicted lives in water can be significantly lower than the experimental values

  20. Design of supply chain in fuzzy environment

    OpenAIRE

    Rao, Kandukuri Narayana; Subbaiah, Kambagowni Venkata; Singh, Ganja Veera Pratap

    2013-01-01

    Nowadays, customer expectations are increasing and organizations are prone to operate in an uncertain environment. Under this uncertain environment, the ultimate success of the firm depends on its ability to integrate business processes among supply chain partners. Supply chain management emphasizes cross-functional links to improve the competitive strategy of organizations. Now, companies are moving from decoupled decision processes towards more integrated design and control of their compone...

  1. Fatigue of DIN 1.4914 martensitic stainless steel in a hydrogen environment

    Science.gov (United States)

    Shakib, J. I.; Ullmaier, H.; Little, E. A.; Faulkner, R. G.; Schmilz, W.; Chung, T. E.

    1994-09-01

    Fatigue tests at room temperature in vacuum, air and hydrogen have been carried out on specimens of DIN 1.4914 martensitic stainless steel in load-controlled, push-pull type experiments. Fatigue lifetimes in hydrogen are significantly lower than in both vacuum and air and the degradation is enhanced by lowering the test frequency or introducing hold times into the tension half-cycle. Fractographic examinations reveal hydrogen embrittlement effects in the form of internal cracking between fatigue striations together with surface modifications, particularly at low stress amplitudes. It is suggested that gaseous hydrogen can influence both fatigue crack initiation and propagation events in martensitic steels.

  2. Enhancement of fatigue crack growth rates in pressure boundary materials due to light-water-reactor environments

    International Nuclear Information System (INIS)

    VanDerSluys, W.A.; Emanuelson, R.H.

    1988-01-01

    The high level of reliability required of the primary-coolant pressure boundary in a nuclear reactor system leads to a continuing interest in the interaction among the coolant, pressure boundary materials, and service loadings. One area of concern involves the possible enhancement of the growth rate of fatigue cracks due to the coolant. Advances have occurred recently toward a better understanding of the variables influencing the material/environment interactions and methods of addressing this interaction. Sulfur now appears to be one of the principal agents responsible for the observed enhancement of the fatigue crack growth rates in light-water-reactor (LWR) environments. This paper presents the results of investigations on the effect of sulfur in the steel, bulk water environment, and at the crack tip

  3. Comparison of cyclic fatigue resistance of three different rotary nickel-titanium instruments designed for retreatment.

    Science.gov (United States)

    Inan, Ugur; Aydin, Cumhur

    2012-01-01

    A number of rotary nickel-titanium (NiTi) systems have been developed to provide better, faster, and easier cleaning and shaping of the root canal system, and recently, rotary NiTi systems designed for root canal retreatment have been introduced. Because the main problem with the rotary NiTi files is fracture, the aim of this study was to compare the cyclic fatigue resistance of 3 different rotary NiTi systems designed for root canal retreatment. Total of 60 instruments of 3 different rotary NiTi systems designed for root canal retreatment were used in this study. Twenty R-Endo R3, 20 ProTaper D3, and 20 Mtwo R (Retreatment) 25.05 instruments were tested. Cyclic fatigue testing of instruments was performed by using a device that allowed the instruments to rotate freely inside an artificial canal. Each instrument was rotated until fracture occurred, and the number of cycles to fracture for each instrument was calculated. Representative samples were also evaluated under a scanning electron microscope to confirm the fracture was flexural. Data were analyzed by using 1-way analysis of variance test. R-Endo R3 instruments showed better cyclic fatigue resistance than ProTaper D3 and Mtwo R 25.05 instruments, and the difference was statistically significant (P instruments were more resistant to fatigue failure than ProTaper D3 and Mtwo R 25.05. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  4. An Experiential Exercise in Service Environment Design

    Science.gov (United States)

    Fowler, Kendra; Bridges, Eileen

    2012-01-01

    A new experiential exercise affords marketing students the opportunity to learn to design service environments. The exercise is appropriate for a variety of marketing courses and is especially beneficial in teaching services marketing because the proposed activity complements two other exercises widely used in this course. Service journal and…

  5. Low-cycle fatigue behavior of HT-9 alloy in a flowing-lithium environment

    International Nuclear Information System (INIS)

    Chopra, O.K.; Smith, D.L.

    1983-06-01

    Low-cycle fatigue data have been obtained on normalized/tempered or lithium-preexposed HT-9 alloy at 755 K in flowing lithium of controlled purity. The results show that the fatigue life of this material decreases with an increase in nitrogen content in lithium. A reduction in strain rate also decreases the fatigue life in high-nitrogen lithium. However, in the range from approx. 4 x 10 - 4 to 4 x 10 - 2 s - 1 , the strain rate has no effect on fatigue life in lithium containing <200 wppM nitrogen. The fatigue life of the HT-9 alloy in low-nitrogen lithium is significantly greater than the fatigue life of Fe-9Cr-1Mo steel or Type 403 martensitic steel in air. Furthermore, a 4.0-Ms preexposure to low-nitrogen lithium has no influence on fatigue life. The reduction in fatigue life in high-nitrogen lithium is attributed to internal corrosive attack of the material. The specimens tested in high-nitrogen lithium show internal corrosion along grain and martensitic lathe boundaries and intergranular fracture. This behavior is not observed in specimens tested in low-nitrogen lithium. Results for a constant-load corrosion test in flowing lithium are also presented

  6. Research for the design of visual fatigue based on the computer visual communication

    Science.gov (United States)

    Deng, Hu-Bin; Ding, Bao-min

    2013-03-01

    With the era of rapid development of computer networks. The role of network communication in the social, economic, political, become more and more important and suggested their special role. The computer network communicat ion through the modern media and byway of the visual communication effect the public of the emotional, spiritual, career and other aspects of the life. While its rapid growth also brought some problems, It is that their message across to the public, its design did not pass a relat ively perfect manifestation to express the informat ion. So this not only leads to convey the error message, but also to cause the physical and psychological fatigue for the audiences. It is said that the visual fatigue. In order to reduce the fatigue when people obtain the useful information in using computer. Let the audience in a short time to obtain the most useful informat ion, this article gave a detailed account of its causes, and propose effective solutions and, through the specific examples to explain it, also in the future computer design visual communicat ion applications development prospect.

  7. Evaluation of weldment creep and fatigue strength-reduction factors for elevated-temperature design

    International Nuclear Information System (INIS)

    Corum, J.M.

    1989-01-01

    New explicit weldment strength criteria in the form of creep and fatigue strength-reduction factors were recently introduced into the American Society of Mechanical Engineers Code Case N-47, which governs the design of elevated-temperature nuclear plants components in the United States. This paper provides some of the background and logic for these factors and their use, and it describes the results of a series of long-term, confirmatory, creep-rupture and fatigue tests of simple welded structures. The structures (welded plates and tubes) were made of 316 stainless steel base metal and 16-8-2 weld filler metal. Overall, the results provide further substantiation of the validity of the strength-reduction factor approach for ensuring adequate life in elevated-temperature nuclear component weldments. 16 refs., 7 figs

  8. Characterization of fatigue-corrosion phenomena for Zircaloy in iodine environment

    International Nuclear Information System (INIS)

    Schuster-Magallon, Isabelle

    1986-01-01

    In this research thesis, the acquisition of data related to crack propagation rates and to smooth specimen lifetime in corrosion-fatigue of zircaloy allowed the quantification of the influence of iodine with respect to material, to loading direction and to test frequency. A systematic fractographic examination of propagation and fatigue strength specimens allowed the fatigue-corrosion fracture scenario to be described. This scenario comprises pitting for a stress higher than a threshold stress, the development of an intergranular corrosion area limited by a threshold stress intensity factor overrun, and the propagation by fatigue-corrosion in steady regime. This propagation is an association of a quasi-cleavage which is typical of stress corrosion cracking, and a plastic deformation under fatigue. This combination leads to the sudden disappearance of cleavage, and to a ductile fracture [fr

  9. Software support environment design knowledge capture

    Science.gov (United States)

    Dollman, Tom

    1990-01-01

    The objective of this task is to assess the potential for using the software support environment (SSE) workstations and associated software for design knowledge capture (DKC) tasks. This assessment will include the identification of required capabilities for DKC and hardware/software modifications needed to support DKC. Several approaches to achieving this objective are discussed and interim results are provided: (1) research into the problem of knowledge engineering in a traditional computer-aided software engineering (CASE) environment, like the SSE; (2) research into the problem of applying SSE CASE tools to develop knowledge based systems; and (3) direct utilization of SSE workstations to support a DKC activity.

  10. Fatigue Life of High Performance Grout for Wind Turbine Grouted Connection in Wet or Dry Environment

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.; Westhof, Luc; Yde, Elo

    Grouted connections of monopile supported offshore wind turbine structures are subjected to loads leading to very high oscillating service stresses in the grout material. The fatigue capacity of a high performance cement based grout was tested by dynamic compressive loading of cylindrical specimens...... at varying levels of cyclic frequency and load. The fatigue tests were performed in two series: one with the specimens in air and one with the specimens submerged in water during the test. The fatigue life of the grout, in terms of the number of cycles to failure, was found to be significantly shorter when...... tested in water than when tested in air....

  11. Fatigue Life of High Performance Grout in Dry and Wet Environment for Wind Turbine Grouted Connections

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.

    2011-01-01

    The cementitious material in grouted connections of offshore monopile wind turbine structures is subjected to very high oscillating service stresses. The fatigue capacity of the grout therefore becomes essential to the performance and service life of the grouted connection. In the present work...... the fatigue life of a high performance cement based grout was tested by dynamic compressive loading of cylindrical specimens at varying levels of cyclic frequency and load. The fatigue tests were performed in two series, one with the specimens tested in air and one with the specimens submerged in water during...

  12. Creep-Fatigue Relationsihps in Electroactive Polymer Systems and Predicted Effects in an Actuator Design

    Science.gov (United States)

    Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac

    2009-01-01

    The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.

  13. DPL/Daedalus design environment (for VLSI)

    Energy Technology Data Exchange (ETDEWEB)

    Batali, J; Mayle, N; Shrobe, H; Sussman, G; Weise, D

    1981-01-01

    The DPL/Daedalus design environment is an interactive VLSI design system implemented at the MIT Artificial Intelligence Laboratory. The system consists of several components: a layout language called DPL (for design procedure language); an interactive graphics facility (Daedalus); and several special purpose design procedures for constructing complex artifacts such as PLAs and microprocessor data paths. Coordinating all of these is a generalized property list data base which contains both the data representing circuits and the procedures for constructing them. The authors first review the nature of the data base and then turn to DPL and Daedalus, the two most common ways of entering information into the data base. The next two sections review the specialized procedures for constructing PLAs and data paths; the final section describes a tool for hierarchical node extraction. 5 references.

  14. IEA Joint Action. Wind turbine fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B [ed.

    1996-09-01

    Fatigue research on wind turbine blade material has been an important issue over the years in many countries and in the E.U. As a result of the effort the knowledge on fatigue properties of fibre reinforced materials has been expanded enormously. Practical fatigue design properties are available for constant amplitude tests at ambient temperatures. A lack of knowledge can be shown in several other fields, such as variable amplitude and multi-axial testing and the influence of the environment and carbon fibres. Fatigue is seen as dominant for the blade design, improvements in both the load prediction and material fatigue properties should be strove for. In discussions with blade manufacturers and subsidy agencies (E.U. DGXII, NOVEM, ETSU, etc.) on the importance of continuous materials fatigue research the improvement in reliability should be stressed. (au)

  15. Design of supply chain in fuzzy environment

    Science.gov (United States)

    Rao, Kandukuri Narayana; Subbaiah, Kambagowni Venkata; Singh, Ganja Veera Pratap

    2013-05-01

    Nowadays, customer expectations are increasing and organizations are prone to operate in an uncertain environment. Under this uncertain environment, the ultimate success of the firm depends on its ability to integrate business processes among supply chain partners. Supply chain management emphasizes cross-functional links to improve the competitive strategy of organizations. Now, companies are moving from decoupled decision processes towards more integrated design and control of their components to achieve the strategic fit. In this paper, a new approach is developed to design a multi-echelon, multi-facility, and multi-product supply chain in fuzzy environment. In fuzzy environment, mixed integer programming problem is formulated through fuzzy goal programming in strategic level with supply chain cost and volume flexibility as fuzzy goals. These fuzzy goals are aggregated using minimum operator. In tactical level, continuous review policy for controlling raw material inventories in supplier echelon and controlling finished product inventories in plant as well as distribution center echelon is considered as fuzzy goals. A non-linear programming model is formulated through fuzzy goal programming using minimum operator in the tactical level. The proposed approach is illustrated with a numerical example.

  16. Influence of air and vacuum environment on fatigue behavior of Zr-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Wang, G.Y.; Liaw, P.K.; Yokoyama, Y.; Peter, W.H.; Yang, B.; Freels, M.; Buchanan, R.A.; Liu, C.T.; Brooks, C.R.

    2007-01-01

    High-cycle fatigue (HCF) experiments in air and vacuum at room temperature were conducted on zirconium (Zr)-based bulk-metallic glasses (BMGs): Zr 50 Cu 40 Al 10 , Zr 50 Cu 30 Al 10 Ni 10 , and Zr 50 Cu 37 Al 10 Pd 3 in atomic percent. The fatigue-endurance limit of Zr 50 Cu 37 Al 10 Pd 3 was found to be significantly greater than those of Zr 50 Cu 40 Al 10 and Zr 50 Cu 30 Al 10 Ni 10 , which indicates that the inclusions of Pd and the resulting nano structures improve the fatigue resistances of the Zr-based BMGs. The fatigue lives in vacuum and air were generally found to be comparable

  17. Reliability high cycle fatigue design of gas turbine blading system using probabilistic goodman diagram

    Energy Technology Data Exchange (ETDEWEB)

    Herman Shen, M.-H. [Ohio State Univ., Columbus, OH (United States). Dept. of Aerospace Engineering and Aviation; Nicholas, T. [MLLN, Wright-Patterson AFB, OH (United States). Air Force Research Lab.

    2001-07-01

    A framework for the probabilistic analysis of high cycle fatigue is developed. The framework will be useful to U.S. Air Force and aeroengine manufacturers in the design of high cycle fatigue in disk or compressor components fabricated from Ti-6Al-4V under a range of loading conditions that might be encountered during service. The main idea of the framework is to characterize vibratory stresses from random input variables due to uncertainties such as crack location, loading, material properties, and manufacturing variability. The characteristics of such vibratory stresses are portrayed graphically as histograms, or probability density function (PDF). The outcome of the probability measures associated with all the values of a random variable exceeding the material capability is achieved by a failure function g(X) defined by the difference between the vibratory stress and Goodman line or surface such that the probability of HCF failure is P{sub f} =P(g(X<0)). Design can then be based on a go-no go criterion based on an assumed risk. The framework can be used to facilitate the development of design tools for the prediction of inspection schedules and reliability in aeroengine components. Such tools could lead ultimately to improved life extension schemes in aging aircraft, and more reliable methods for the design and inspection of critical components. (orig.)

  18. Crime: impacts of urban design and environment

    Directory of Open Access Journals (Sweden)

    Paula Santana

    2013-07-01

    Full Text Available The criminal research has confirmed that there are clear patterns of crime, with concentrations in specific places at specific times. That is to say, incidence of crime are not distributed randomly; rather, there are certain areas in cities that are relatively small, but where crimes occur much more frequently than elsewhere (the so-called “hotspots”, making them highly vulnerable and predictable. Urban design and environment may play a part in the decision of whether or not to commit a crime; for example, the lack of natural vigilance, poor lighting and other variables mean that a small area may easily be transformed into a potential crime hotspot. The relationship between specific aspects of urban design and the formation of “hotspots” is present in the theory of “Crime Prevention through Environmental Design” (CPTED. This paper examines the relationship between the “hotspots” and the characteristics of the environment, in accordance with CPTED Index, in one city from the Lisbon Metropolitan Area (Amadora. The results highlight the need to reassess specific elements of urban design. This fact has drawn attention to the study of localities and urban design.

  19. The effect of initiation feature and environment on fatigue crack formation and early propagation in aluminum zinc magnesium copper

    Science.gov (United States)

    Burns, James T.

    The current research provides insight into fatigue crack formation and progression in the poorly understood size regime that bridges safe-life and damage tolerance approaches; particular attention is given to the influences of corrosion-induced degradation and time-cycle dependent loading environment effects. Quantitative analysis of crack formation life (Ni), microstructurally small crack (database. Results show that fatigue crack formation involves a complex interaction of elastic stress concentration, due to a 3-dimensional macro-pit, coupled with local micro-feature (and constituent) induced plastic strain concentration. Such interactions cause high Ni variability, but, from an engineering perspective, a broadly corroded surface should contain an extreme group of features driving Ni to ˜0. At low-applied stresses, Ni consumes a significant portion of total life, which is well predicted by coupling elastic-plastic FEA with empirical low-cycle fatigue life models. All pristine and corroded da/dN were uniquely correlated using complex continuum stress intensity (K) and crack opening solutions which account for the stress concentrating formation feature. Multiple crack growth regimes were observed, typical of environment enhanced fatigue in Al alloys. Such behavior is not captured by prominent mechanics-based small crack models. Furthermore, neither local closure nor slip-based models captured the order of magnitude variability in da/dN attributed to microstructure. Low temperature loading produces an order of magnitude increase in Ni, and even larger reduction in da/dN, due to elimination of H-enhanced cracking by reduced external water vapor pressure, lower crack tip reaction rate (to produce atomic-H), and slower H diffusion. Engineering level modeling approaches are validated using these high fidelity experimental results, informing next generation prognosis methods for realistic airframe environments.

  20. Design for the Environment Products (Raw Data)

    Science.gov (United States)

    This dataset contains a list of products that carry the Design for the Environment (DfE) label. This mark enables consumers to quickly identify and choose products that can help protect the environment and are safer for families. When you see the DfE logo on a product it means that the DfE scientific review team has screened each ingredient for potential human health and environmental effects and that-based on currently available information, EPA predictive models, and expert judgment-the product contains only those ingredients that pose the least concern among chemicals in their class. Product manufacturers who become DfE partners, and earn the right to display the DfE logo on recognized products, have invested heavily in research, development and reformulation to ensure that their ingredients and finished product line up on the green end of the health and environmental spectrum while maintaining or improving product performance. EPA's Design for the Environment Program (DfE) has allowed use of their logo on over 2500 products. These products are formulated from the safest possible ingredients and have reduced the use of chemicals of concern by hundreds of millions of pounds. A Spanish version of this dataset is available for download at http://www.epa.gov/dfe/pubs/products/list_of_labeled_products.html

  1. Design for the Environment Products (Online Search)

    Science.gov (United States)

    This dataset contains a list of products that carry the Design for the Environment (DfE) label. This mark enables consumers to quickly identify and choose products that can help protect the environment and are safer for families. When you see the DfE logo on a product it means that the DfE scientific review team has screened each ingredient for potential human health and environmental effects and that-based on currently available information, EPA predictive models, and expert judgment-the product contains only those ingredients that pose the least concern among chemicals in their class. Product manufacturers who become DfE partners, and earn the right to display the DfE logo on recognized products, have invested heavily in research, development and reformulation to ensure that their ingredients and finished product line up on the green end of the health and environmental spectrum while maintaining or improving product performance. EPA's Design for the Environment Program (DfE) has allowed use of their logo on over 2500 products. These products are formulated from the safest possible ingredients and have reduced the use of chemicals of concern by hundreds of millions of pounds.

  2. Fatigue in seafarers working in the offshore oil and gas re-supply industry: effects of safety climate, psychosocial work environment and shift arrangement.

    Science.gov (United States)

    Hystad, Sigurd W; Saus, Evelyn-Rose; Sætrevik, Bjørn; Eid, Jarle

    2013-01-01

    This study examined the influence of safety climate and psychosocial work environment on the reported fatigue of seafarers working in the offshore oil and gas re-supply industry (n = 402). We found that seafarers who reported high psychological demands and perceived the organisational-level safety climate negatively,reported significantly more mental fatigue, physical fatigue, and lack of energy. In addition, seafarers who reported having high levels of job control reported being significantly less mentally fatigued. We also found some combined effects of safety climate and shift arrangement. Organisational-level safety climate did not influence the levels of physical fatigue in seafarers working on the night shift. On the contrary, seafarers working during the days reported to be more physically fatigued when they perceived the organisational-level climate to be negative compared with the positive. The opposite effect was found for group-level safety climate: seafarers working during the nights reported to be more physically fatigued when they perceived the group-level climate to be negative compared with the positive. The results from this study point to the importance of taking into consideration aspects of the psychosocial work environment and safety climate,and their potential impact on fatigue and safety in the maritime organisations.

  3. Reduced softening of EUROFER 97 under thermo-mechanical and multiaxial fatigue loading and its impact on the design rules

    International Nuclear Information System (INIS)

    Aktaa, J.; Weick, M.; Petersen, C.

    2007-01-01

    Full text of publication follows: Toward test blanket module (TBM) in ITER and DEMO fusion power plants design rules for components built from EUROFER 97 get more and more in the midpoint of interest. One of the specific characteristic of EUROFER 97 as a ferritic-martensitic steel is its cyclic softening yielding to lower stresses under strain controlled fatigue loading and thus longer lifetimes. However our thermo-mechanical and multiaxial fatigue tests showed lifetimes remarkably lower than those expected on the base of isothermal uniaxial fatigue tests. Reduced cyclic softening observed in these experiments is believed as one of the reasons of the shorter fatigue lifetimes. When applying the design rules, derived for EUROFER 97 on the base of isothermal uniaxial data considering the recommendations in the ASME and RCC-MR code, to our thermo-mechanical and multiaxial fatigue tests for verification strong loss in their conservatism has been found. The lifetimes observed in a part of the multiaxial experiments are even lower than the design lifetimes supposed to be sufficiently conservative. To overcome this problem new design rules are proposed among others on the base of damage and lifetime prediction model developed lately for EUROFER 97. In this paper the experimental findings as well as the new design approaches will be presented and discussed. (authors)

  4. Designing powerplants for today's competitive environment

    International Nuclear Information System (INIS)

    Makansi, J.

    1994-01-01

    Deregulation continues to unfold. Certainty about what the impact will be is as scarce as new US powerplant development opportunities. But one thing industry observers seem clear on is that the priorities for powerplant design will shift as competitive forces are rolled out. Powerplants will have to be developed, designed, and operated as a bottom-line business, not as part of a regulated industry. Thus, the design must enable the facility to accomplish this goal. In the emerging fully competitive environment, that bottom line applies to both the kilowatt and the kilowatt-hour. The entrepreneurial and business skills and talents of the independent power producer (IPP) have mostly been brought to bear on capital costs and project development thus far, with electricity sold under long-term power-purchase agreements. If retail wheeling takes hold, future plants must also be designed to merchandise power to a variety of customers scattered around the grid. This article provides insight into how powerplant design will accommodate new priorities

  5. Design and simulation of Macro-Fiber composite based serrated microflap for wind turbine blade fatigue load reduction

    Science.gov (United States)

    Sun, Xiao; Dai, Qingli; Bilgen, Onur

    2018-05-01

    A Macro-Fiber Composite (MFC) based active serrated microflap is designed in this research for wind turbine blades. Its fatigue load reduction potential is evaluated in normal operating conditions. The force and displacement output of the MFC-based actuator are simulated using a bimorph beam model. The work done by the aerodynamic, centripetal and gravitational forces acting on the microflap were calculated to determine the required capacity of the MFC-based actuator. MFC-based actuators with a lever mechanical linkage are designed to achieve the required force and displacement to activate the microflap. A feedback control scheme is designed to control the microflap during operation. Through an aerodynamic-aeroelastic time marching simulation with the designed control scheme, the time responses of the wind turbine blades are obtained. The fatigue analysis shows that the serrated microflap can reduce the standard deviation of the blade root flapwise bending moment and the fatigue damage equivalent loads.

  6. Approaches to Integrated Building Design Environments

    DEFF Research Database (Denmark)

    Bagger-Petersen, Susanne C; Andersen, Tom

    1996-01-01

    This report discusses functional requirements and specification which needs to be defined and fulfilled to initiate development of an integrated building design environment. The purpose is to outline specifications for further discussion and development. The report documents the first phase...... in an ongoing project at the Technical University of Denmark. The overall project objective is to provide a theoretically well-founded prototype of an integrated IT-system which can serve as a device of feedback from practice and as a test-bed for the developed concept and architecture....

  7. Fatigue based design and analysis of wheel hub for Student formula car by Simulation Approach

    Science.gov (United States)

    Gowtham, V.; Ranganathan, A. S.; Satish, S.; Alexis, S. John; Siva kumar, S.

    2016-09-01

    In the existing design of Wheel hub used for Student formula cars, the brake discs cannot be removed easily since the disc is mounted in between the knuckle and hub. In case of bend or any other damage to the disc, the replacement of the disc becomes difficult. Further using OEM hub and knuckle that are used for commercial vehicles will result in increase of unsprung mass, which should be avoided in Student formula cars for improving the performance. In this design the above mentioned difficulties have been overcome by redesigning the hub in such a way that the brake disc could be removed easily by just removing the wheel and the caliper and also it will have reduced weight when compared to existing OEM hub. A CAD Model was developed based on the required fatigue life cycles. The forces acting on the hub were calculated and linear static structural analysis was performed on the wheel hub for three different materials using ANSYS Finite Element code V 16.2. The theoretical fatigue strength was compared with the stress obtained from the structural analysis for each material.

  8. Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO2 environment

    DEFF Research Database (Denmark)

    Rogowska, Magdalena; Gudme, J.; Rubin, A.

    2016-01-01

    situ measurements of Fe2+ and pH. Characterisation of the corrosion scales and crack formations was performed using microscopic and diffraction techniques. Fatigue results showed two times better fatigue life, at the stress ranges of 250 MPa, for samples tested in solutions containing the concentration...... of Fe2+ marginally above the solubility limit of FeCO3 compared to the samples tested in highly supersaturated solution of Fe2+. Results revealed that the impact of the alternating stresses on the corrosion behaviour of samples reduces with lowering the applied stresses. At the stress range of 100 MPa...

  9. Design Environment for Multifidelity and Multidisciplinary Components

    Science.gov (United States)

    Platt, Michael

    2014-01-01

    One of the greatest challenges when developing propulsion systems is predicting the interacting effects between the fluid loads, thermal loads, and structural deflection. The interactions between technical disciplines often are not fully analyzed, and the analysis in one discipline often uses a simplified representation of other disciplines as an input or boundary condition. For example, the fluid forces in an engine generate static and dynamic rotor deflection, but the forces themselves are dependent on the rotor position and its orbit. It is important to consider the interaction between the physical phenomena where the outcome of each analysis is heavily dependent on the inputs (e.g., changes in flow due to deflection, changes in deflection due to fluid forces). A rigid design process also lacks the flexibility to employ multiple levels of fidelity in the analysis of each of the components. This project developed and validated an innovative design environment that has the flexibility to simultaneously analyze multiple disciplines and multiple components with multiple levels of model fidelity. Using NASA's open-source multidisciplinary design analysis and optimization (OpenMDAO) framework, this multifaceted system will provide substantially superior capabilities to current design tools.

  10. Design of Linear Control System for Wind Turbine Blade Fatigue Testing

    DEFF Research Database (Denmark)

    Toft, Anders; Roe-Poulsen, Bjarke Nørskov; Christiansen, Rasmus

    2016-01-01

    This paper proposes a linear method for wind turbine blade fatigue testing at Siemens Wind Power. The setup consists of a blade, an actuator (motor and load mass) that acts on the blade with a sinusoidal moment, and a distribution of strain gauges to measure the blade flexure. Based...... difficult to control. To make a linear controller, a different approach has been chosen, namely making a controller which is not regulating on the input frequency, but on the input amplitude. A non-linear mechanical model for the blade and the motor has been constructed. This model has been simplified based...... on the desired output, namely the amplitude of the blade. Furthermore, the model has been linearised to make it suitable for linear analysis and control design methods.\\\\ The controller is designed based on a simplified and linearised model, and its gain parameter determined using pole placement. The model...

  11. The Identification of Fatigue Resistant and Fatigue Susceptible Individuals

    National Research Council Canada - National Science Library

    Harrison, Richard; Chaiken, Scott; Harville, Donald; Fischer, Joseph; Fisher, Dion; Whitmore, Jeff

    2008-01-01

    The present study was designed to target two specific areas regarding fatigue. The primary purpose was to begin investigations into possible genetic markers linked to fatigue resistance and fatigue susceptibility...

  12. Influence of salivary enzymes and alkaline pH environment on fatigue behavior of resin composites

    NARCIS (Netherlands)

    Mirmohammadi, H.; Kleverlaan, C.J.; Aboushelib, M.N.; Feilzer, A.J.

    2011-01-01

    Purpose: To evaluate the effect of enzymatic activity and alkaline medium on flexural strength and rotary fatigue resistance of direct and indirect resin composite restorative materials. Methods: Three direct resin composite materials Filtek Z100, Filtek Z250 and Filtek Silorane (3M ESPE), and two

  13. Effects of loading variables on fatigue-crack growth in liquid-metal environments

    CSIR Research Space (South Africa)

    Fernandes, PJL

    1995-10-01

    Full Text Available Liquid-metal-induced embrittlement (LMIE) refers to the loss of ductility in normally ductile metals and alloys when stressed while in contact with a liquid metal. In this study, the fatigue crack growth behaviour of brass in molten gallium...

  14. Examination of fatigue development in elite soccer in a hot environment: a multi-experimental approach

    DEFF Research Database (Denmark)

    Mohr, Magni; Mujika, I; Santisteban, J

    2010-01-01

    The study examines fatigue in elite soccer played in hot conditions. High-profile soccer players (n=20) were studied during match play at ~31 °C. Repeated sprint and jump performances were assessed in rested state and after a game and activity profile was examined. Additionally, heart rate (HR...

  15. The effect of aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels

    International Nuclear Information System (INIS)

    James, L.A.

    1996-01-01

    The effect of elevated temperature aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels is discussed in terms of the several parameters which influence such behavior. These parameters include water chemistry, impurities within the steels themselves, as well as factors such as the water flow rate, loading waveform and loading rates. Some of these parameters have similar effects upon both crack initiation and propagation, while others exhibit different effects in the two stages of cracking. In the case of environmentally-assisted crack (EAC) growth, the most important impurities within the steel are metallurgical sulfide inclusions which dissolve upon contact with the water. A ''critical'' concentration of sulfide ions at the crack tip can then induce environmentally-assisted cracking which proceeds at significantly increased crack growth rates over those observed in air. The occurrence, or non-occurrence, of EAC is governed by the mass-transport of sulfide ions to and from the crack-tip region, and the mass-transport is discussed in terms of diffusion, ion migration, and convection induced within the crack enclave. Examples are given of convective mass-transport within the crack enclave resulting from external free stream flow. The initiation of fatigue cracks in elevated temperature aqueous environments, as measured by the S-N fatigue lifetimes, is also strongly influenced by the parameters identified above. The influence of sulfide inclusions does not appear to be as strong on the crack initiation process as it is on crack propagation. The oxygen content of the environment appears to be the dominant factor, although loading frequency (strain rate) and temperature are also important factors

  16. On the constitutive law of environment assisted fatigue: The physical meaning of the Paris type equations. Pt. 1

    International Nuclear Information System (INIS)

    Krausz, K.; Wu Xijia; Krausz, A.S.; Lian Zhiwen

    1992-01-01

    Environment assisted fatigue crack growth is a complex of thermally activated processes. Accordingly, the framework for the expression of rational constitutive law is developed from fracture kinetics theory. The correlation of the constitutive law with the Paris equation is discussed and the empirical parameters in the Paris equation are expressed explicitly in terms of activation energy, stress intensity factor range, temperature, stress ratio, and other physically rigorous engineering quantities. The theory assures and facilitates, the rigorous quantitative evaluation of the effects of the microstructure: the constitutive law gives guidance to its measurement and expresses it in terms of energy-related quantities. (orig.) [de

  17. Application of a Monte Carlo procedure for probabilistic fatigue design of floating offshore wind turbines

    Directory of Open Access Journals (Sweden)

    K. Müller

    2018-03-01

    Full Text Available Fatigue load assessment of floating offshore wind turbines poses new challenges on the feasibility of numerical procedures. Due to the increased sensitivity of the considered system with respect to the environmental conditions from wind and ocean, the application of common procedures used for fixed-bottom structures results in either inaccurate simulation results or hard-to-quantify conservatism in the system design. Monte Carlo-based sampling procedures provide a more realistic approach to deal with the large variation in the environmental conditions, although basic randomization has shown slow convergence. Specialized sampling methods allow efficient coverage of the complete design space, resulting in faster convergence and hence a reduced number of required simulations. In this study, a quasi-random sampling approach based on Sobol sequences is applied to select representative events for the determination of the lifetime damage. This is calculated applying Monte Carlo integration, using subsets of a resulting total of 16 200 coupled time–domain simulations performed with the simulation code FAST. The considered system is the Danmarks Tekniske Universitet (DTU 10 MW reference turbine installed on the LIFES50+ OO-Star Wind Floater Semi 10 MW floating platform. Statistical properties of the considered environmental parameters (i.e., wind speed, wave height and wave period are determined based on the measurement data from the Gulf of Maine, USA. Convergence analyses show that it is sufficient to perform around 200 simulations in order to reach less than 10 % uncertainty of lifetime fatigue damage-equivalent loading. Complementary in-depth investigation is performed, focusing on the load sensitivity and the impact of outliers (i.e., values far away from the mean. Recommendations for the implementation of the proposed methodology in the design process are also provided.

  18. The effect of frequency and environment on the fatigue crack growth behaviour of SA508 Cl.III RPV steel

    International Nuclear Information System (INIS)

    Achilles, R.D.; Bulloch, J.H.

    1987-01-01

    This paper describes the effect of frequency and environment on the fatigue crack growth behaviour of SA508 Cl. III RPV steel. The study has shown that the effect of the Pressurised Water Reactor (PWR) environment is directly related to the frequency and the level of applied stress intensity of the test; these results further showed that the lower the frequency the greater the environmental effect, especially at low ΔK levels. No such frequency effect was observed in either the laboratory air or ultra-high purity argon environments. At a frequency of 0.1 Hz the PWR water test exhibited characteristic EAC growth, i.e. plateau growth behaviour. Fractographical examination of the fracture surface revealed that the fracture mode during plateau growth was intergranular failure. The experimental results are described and discussed in terms of the hydrogen assisted cracking mechanism. (author)

  19. Design and fabrication of a unique electromechanical machine for long-term fatigue testing

    International Nuclear Information System (INIS)

    Boling, K.W.

    1984-12-01

    An electromechanical machine has been designed and fabricated for performing long-term fatigue tests under conditions that simulate those in modern plants. The machine is now commercially available. Its advantages over current electrohydraulic machines are lower initial cost, minimum maintenance requirements, and greater reliability especially when performing long tests. The machine operates in closed-loop fashion by utilizing continuous feedback signals from the specimen extensometer or load cell, it is programmable for testing in strain or load control. The maximum ram rate is 0.056 mm/s (0.134 in./min), maximum ram travel is 102 mm (4 in.) and load capacity is +-44 (+-10 kips). Induction heating controls speciment temperatures to 1000 0 C

  20. Structural design significance of tension-tension fatigue data on composites

    Science.gov (United States)

    Grimes, G. C.

    1977-01-01

    Constant cycle tension-tension fatigue and related static tension data have been generated on six single composite material/orientation combinations and twenty-one hybrid composite material/orientation combinations. Anomalies are related to the temperature rise and stopped interval creep, whereas endurance limit stresses (runouts) are associated with static proportional limit values, when they occur, and internal damage. The significance of these room temperature-dry data on the design allowables and weight of aerodynamic structueres is discussed. Such structures are helicopter rotor blades and wing and horizontal stabilizer lower surfaces. Typical criteria for turning these data into preliminary allowables are shown, as are examples of such allowables developed from the data. These values are then compared to those that might be used if the structures were made of metal.

  1. Efficacy of Warm Showers on Postpartum Fatigue Among Vaginal-Birth Taiwanese Women: A Quasi-Experimental Design.

    Science.gov (United States)

    Hsieh, Ching-Hsing; Chen, Chien-Lan; Chung, Feng-Fang; Lin, Su-Ying

    2017-05-01

    Postpartum fatigue is one of the most common complaints among women following childbirth. As a postpartum ritual practice, Taiwanese women refrain from taking showers while "doing the month." However, warm showers are the systemic application of moist heat, and they maintain physical hygiene, stimulate blood circulation, mitigate discomfort, and provide relaxation. As Taiwanese society becomes increasingly receptive to scientific and contemporary health care practice, more and more women choose to take warm showers after childbirth. The purpose of this study was to evaluate the efficacy of warm showers on postpartum fatigue among vaginal-birth women in Taiwan. This was a two-group quasi-experimental design. Women took showers in warm water with temperatures ranging between 40 °C and 43 °C for approximately 20 minutes. Postpartum women's fatigue is measured using the 10-item Postpartum Fatigue Scale (PFS). The intervention effect was analyzed using a generalized estimating equation (GEE) model. The study population consisted of 358 vaginal-birth postpartum Taiwanese women aged 20-43 years. Postpartum women who took warm showers showed improvements from their pretest to posttest mean scores of postpartum fatigue compared to postpartum women who did not take warm showers. Warm showers helped to reduce postpartum fatigue among vaginal-birth women during the study period. Nurses have the unique opportunity to provide the intervention to Taiwanese women who have vaginal birth to help them relieve postpartum fatigue with warm showers while "doing the month" without the taboo of no-showering customary practices in the early postpartum period.

  2. New specimen design for studying the growth of small fatigue cracks with surface acoustic waves

    Science.gov (United States)

    London, Blair

    1985-08-01

    The study of small surface fatigue cracks in AISI 4140 quenched and tempered steel by a nondestructive surface acoustic wave technique is summarized. A novel cantilevered bending, plate-type fatigue specimen is described that is compatible with the acoustic method. Small cracks are initiated from a 25-μm deep surface pit produced by an electrospark machine. The importance of studying these cracks which closely approximate naturally occurring fatigue cracks is briefly discussed.

  3. Autonomous Mission Design in Extreme Orbit Environments

    Science.gov (United States)

    Surovik, David Allen

    An algorithm for autonomous online mission design at asteroids, comets, and small moons is developed to meet the novel challenges of their complex non-Keplerian orbit environments, which render traditional methods inapplicable. The core concept of abstract reachability analysis, in which a set of impulsive maneuvering options is mapped onto a space of high-level mission outcomes, is applied to enable goal-oriented decision-making with robustness to uncertainty. These nuanced analyses are efficiently computed by utilizing a heuristic-based adaptive sampling scheme that either maximizes an objective function for autonomous planning or resolves details of interest for preliminary analysis and general study. Illustrative examples reveal the chaotic nature of small body systems through the structure of various families of reachable orbits, such as those that facilitate close-range observation of targeted surface locations or achieve soft impact upon them. In order to fulfill extensive sets of observation tasks, the single-maneuver design method is implemented in a receding-horizon framework such that a complete mission is constructed on-the-fly one piece at a time. Long-term performance and convergence are assured by augmenting the objective function with a prospect heuristic, which approximates the likelihood that a reachable end-state will benefit the subsequent planning horizon. When state and model uncertainty produce larger trajectory deviations than were anticipated, the next control horizon is advanced to allow for corrective action -- a low-frequency form of feedback control. Through Monte Carlo analysis, the planning algorithm is ultimately demonstrated to produce mission profiles that vary drastically in their physical paths but nonetheless consistently complete all goals, suggesting a high degree of flexibility. It is further shown that the objective function can be tuned to preferentially minimize fuel cost or mission duration, as well as to optimize

  4. Introduction of Residual Stresses to Enhance Fatigue Performance in the Initial Design

    National Research Council Canada - National Science Library

    Prevey, Paul; Jayaraman, N; Ravindranath, Ravi

    2004-01-01

    .... Recently, laser shock processing (LSP) and low plasticity burnishing (LPB) have been shown to provide spectacular fatigue and damage tolerance improvement by introducing deep (through-thickness...

  5. Enhancement of fatigue crack growth rates in pressure boundary materials due to light-water-reactor environments

    International Nuclear Information System (INIS)

    Van Der Sluys, W.A.; Emanuelson, R.H.

    1987-01-01

    Sulfur now appears to be one of the principal agents responsible for the observed enhancement of the fatigue crack growth rates in light-water-reactor (LWR) environments. This paper presents the results of investigations on the effect of sulfur in the steel, in the bulk water environment, and at the crack tip. A time-based format of data presentation is used in this paper along with the conventional crack growth rate based on cycle format. The time-based format is a useful method of data presentation. When presented in the conventional format, an apparent substantial amount of scatter in the data is eliminated and the data fall within a relatively narrow scatter band. This model permits extrapolation from the frequency and ΔK regions where experiments were conducted into previously unexplored regions. (orig./GL)

  6. Fatigue behaviour of NiTi shape memory alloy scaffolds produced by SLM, a unit cell design comparison.

    Science.gov (United States)

    Speirs, M; Van Hooreweder, B; Van Humbeeck, J; Kruth, J-P

    2017-06-01

    Selective laser melting (SLM) is an additive manufacturing technique able to produce complex functional parts via successively melting layers of metal powder. This process grants the freedom to design highly complex scaffold components to allow bone ingrowth and aid mechanical anchorage. This paper investigates the compression fatigue behaviour of three different unit cells (octahedron, cellular gyroid and sheet gyroid) of SLM nitinol scaffolds. It was found that triply periodic minimal surfaces display superior static mechanical properties in comparison to conventional octahedron beam lattice structures at identical volume fractions. Fatigue resistance was also found to be highly geometry dependent due to the effects of AM processing techniques on the surface topography and notch sensitivity. Geometries minimising nodal points and the staircase effect displayed the greatest fatigue resistance when normalized to yield strength. Furthermore oxygen analysis showed a large oxygen uptake during SLM processing which must be altered to meet ASTM medical grade standards and may significantly reduce fatigue life. These achieved fatigue properties indicate that NiTi scaffolds produced via SLM can provide sufficient mechanical support over an implants lifetime within stress range values experienced in real life. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Disinhibiting neurons in the dorsomedial hypothalamus delays the onset of exertional fatigue and exhaustion in rats exercising in a warm environment.

    Science.gov (United States)

    Zaretsky, Dmitry V; Kline, Hannah; Zaretskaia, Maria V; Brown, Mary Beth; Durant, Pamela J; Alves, Nathan J; Rusyniak, Daniel E

    2018-06-15

    Stimulants cause hyperthermia, in part, by increasing heat generation through exercise. Stimulants also delay the onset of fatigue and exhaustion allowing animals to exercise longer. If used in a warm environment, this combination (increased exercise and decreased fatigue) can cause heat stroke. The dorsomedial hypothalamus (DMH) is involved in mediating locomotion from stimulants. Furthermore, inhibiting the DMH decreases locomotion and prevents hyperthermia in rats given stimulants in a warm environment. Whether the DMH is involved in mediating exercise-induced fatigue and exhaustion is not known. We hypothesized that disinhibiting neurons in the dorsomedial hypothalamus (DMH) would delay the onset of fatigue and exhaustion in animals exercising in a warm environment. To test this hypothesis, we used automated video tracking software to measure fatigue and exhaustion. In rats, using wearable mini-pumps, we demonstrated that disinhibiting the DMH, via bicuculline perfusion (5 µM), increased the duration of exercise in a warm environment as compared to control animals (25 ± 3 min vs 15 ± 2 min). Bicuculline-perfused animals also had higher temperatures at exhaustion (41.4 ± 0.2 °C vs 40.0 ± 0.4 °C). Disinhibiting neurons in the DMH also increased the time to fatigue. Our data show that the same region of the hypothalamus that is involved in mediating locomotion to stimulants, is also involved in controlling exhaustion and fatigue. These findings have implications for understanding the cause and treatment of stimulant-induced-hyperthermia. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Fatigue design of a mechanically biocompatible lattice for a proof-of-concept femoral stem.

    Science.gov (United States)

    Arabnejad Khanoki, Sajad; Pasini, Damiano

    2013-06-01

    A methodology is proposed to design a spatially periodic microarchitectured material for a two-dimensional femoral implant under walking gait conditions. The material is composed of a graded lattice with controlled property distribution that minimizes concurrently bone resorption and interface failure. The periodic microstructure of the material is designed for fatigue fracture caused by cyclic loadings on the hip joint as a result of walking. The bulk material of the lattice is Ti6AL4V and its microstructure is assumed free of defects. The Soderberg diagram is used for the fatigue design under multiaxial loadings. Two cell topologies, square and Kagome, are chosen to obtain optimized property gradients for a two-dimensional implant. Asymptotic homogenization (AH) theory is used to address the multiscale mechanics of the implant as well as to capture the stress and strain distribution at both the macro and the microscale. The microstress distribution found with AH is also compared with that obtained from a detailed finite element analysis. For the maximum value of the von Mises stress, we observe a deviation of 18.6% in unit cells close to the implant boundary, where the AH assumption of spatial periodicity of the fluctuating fields ceases to hold. In the second part of the paper, the metrics of bone resorption and interface shear stress are used to benchmark the graded cellular implant with existing prostheses made of fully dense titanium implant. The results show that the amount of initial postoperative bone loss for square and Kagome lattice implants decreases, respectively, by 53.8% and 58%. In addition, the maximum shear interface failure at the distal end is significantly reduced by about 79%. A set of proof-of-concepts of planar implants have been fabricated via Electron Beam Melting (EBM) to demonstrate the manufacturability of Ti6AL4V into graded lattices with alternative cell size. Optical microscopy has been used to measure the morphological parameters

  9. Effect of boron control of environment on corrosion and resistance to low-cycle corrosion fatigue in structural steels

    International Nuclear Information System (INIS)

    Babej, Yu.I.; Zhitkov, V.V.; Zvezdin, Yu.I.; Liskevich, I.Yu.; Nazarov, A.A.

    1982-01-01

    Tests of the specimens on total, contact and crevice corrosion, corrosion cracking and low-cycle fatigue are conducted for determination of corrosion and corrosion-fatigue characteristics in the 15Kh3NMFA, 10N3MFA, 10Kh16N4B, 05Kh13N6M2 structural steels, used in energetics. The environment is subjected to boron control and contacting with atmosphere for simulation of stop and operation modes of the facility. The experiments are carried out in the distilled water with 12g/l H 3 BO 3 and 10 mg/l Cl' at 25, 60, 100 deg C under contacting with atmosphere. It is established, that the pearlitic steels 15Kh3NMFA, 10N3MFA, as well as transition and martensitic 05Kh13N6M2 and 10Kh16N4B steels are highly stable to total, crevice and contact corrosion at the high parameters of aqueous boron-containing medium. Steel resistance to low-cycle fracture decreases slightly under the conditions similar to the operation ones, in the water with 12 g/l H 3 BO 3 . Durability of the pearlitic steels at the simulation of stop conditions decreases more noticeably, crack formation as a rule, initiating from corrosion spots

  10. Designing Environment for Teaching Internet of Things

    Science.gov (United States)

    Simic, Konstantin; Vujin, Vladimir; Labus, Aleksandra; Stepanic, Ðorde; Stevanovic, Mladen

    2014-01-01

    One of the new topics taught at technical universities is Internet of Things. In this paper, a workshop for organizing a lab in academic environment for the subject Internet of Things is described. The architecture of the platform, scenario and a description of components used for creating the environment for learning Internet of things are also…

  11. Treatment of fatigue with methylphenidate, modafinil and amantadine in multiple sclerosis (TRIUMPHANT-MS): Study design for a pragmatic, randomized, double-blind, crossover clinical trial.

    Science.gov (United States)

    Nourbakhsh, Bardia; Revirajan, Nisha; Waubant, Emmanuelle

    2018-01-01

    Fatigue is the most common symptom of multiple sclerosis (MS). Amantadine, modafinil and amphetamine-like stimulants are commonly used in clinical practice for treatment of fatigue; however, the evidence supporting their effectiveness is sparse and conflicting. To describe the design of a trial study funded by Patient-Centered Outcome Research Institute (PCORI) that will compare the efficacy of commonly used fatigue medications in patients with MS. The study is a randomized, placebo-controlled, crossover, four-sequence, four-period, double-blind, multicenter trial of three commonly used medications for the treatment of MS-related fatigue (amantadine, modafinil, methylphenidate) versus placebo in fatigued subjects with MS. Adult patients with MS, with an Expanded Disability Status Scale of MS-related fatigue. Clinicaltrials.gov registration number: NCT03185065. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. SCC and Corrosion Fatigue characterization of a Ti-6Al-4V alloy in a corrosive environment – experiments and numerical models

    Directory of Open Access Journals (Sweden)

    S. Baragetti

    2014-10-01

    Full Text Available In the present article, a review of the complete characterization in different aggressive media of a Ti-6Al-4V titanium alloy, performed by the Structural Mechanics Laboratory of the University of Bergamo, is presented. The light alloy has been investigated in terms of corrosion fatigue, by axial fatigue testing (R = 0.1 of smooth and notched flat dogbone specimens in laboratory air, 3.5% wt. NaCl–water mixture and methanol–water mixture at different concentrations. The first corrosive medium reproduced a marine environment, while the latter was used as a reference aggressive environment. Results showed that a certain corrosion fatigue resistance is found in a salt water medium, while the methanol environment caused a significant drop – from 23% to 55% in terms of limiting stress reduction – of the fatigue resistance of the Ti-6Al-4V alloy, even for a solution containing 5% of methanol. A Stress Corrosion Cracking (SCC experimental campaign at different methanol concentrations has been conducted over slightly notched dog-bone specimens (Kt = 1.18, to characterize the corrosion resistance of the alloy under quasi-static load conditions. Finally, crack propagation models have been implemented to predict the crack propagation rates for smooth specimens, by using Paris, Walker and Kato-Deng-Inoue-Takatsu propagation formulae. The different outcomes from the forecasting numerical models were compared with experimental results, proposing modeling procedures for the numerical simulation of fatigue behavior of a Ti-6Al-4V alloy.

  13. SI:FatiguePro 4 Advanced Approach for Fatigue Monitoring

    International Nuclear Information System (INIS)

    Evon, Keith; Gilman, Tim; Carney, Curt

    2012-01-01

    Many nuclear plants are making commitments to implement fatigue monitoring systems in support of license renewal. Current fatigue monitoring systems use the methodology of ASME Code Subarticle NB-3200, which is a design code intended to compute a bounding cumulative usage factor (CUF). The first generation of fatigue monitoring software utilized a simplified, single stress term assumption and classical stress cycle-counting methods that take order into account such as Rainflow or Ordered Overall Range counting. Recently, the NRC has indicated in Regulatory Issue Summary 2008-30 that any fatigue analyses in support of License Renewal should use ASME Code Section III methodologies considering all six stress components. In addition, fatigue calculations for the license renewal term are required to consider the effects of environment. The implementation of a six stress term NB-3200 fatigue calculation to a Boiling Water Reactor (BWR) feedwater nozzle, including environmental effects, is the topic of this paper. Differences in results between the advanced methodology and the simplified methodology are discussed. (author)

  14. Design Analysis and Thermo-Mechanical Fatigue of a Polyimide Composite for Combustion Chamber Support

    Science.gov (United States)

    Thesken, J. C.; Melis, M.; Shin, E.; Sutter, J.; Burke, Chris

    2004-01-01

    Polyimide composites are being evaluated for use in lightweight support structures designed to preserve the ideal flow geometry within thin shell combustion chambers of future space launch propulsion systems. Principles of lightweight design and innovative manufacturing techniques have yielded a sandwich structure with an outer face sheet of carbon fiber polyimide matrix composite. While the continuous carbon fiber enables laminated skin of high specific stiffness; the polyimide matrix materials ensure that the rigidity and durability is maintained at operation temperatures of 316 C. Significant weight savings over all metal support structures are expected. The protypical structure is the result of ongoing collaboration, between Boeing and NASA-GRC seeking to introduce polyimide composites to the harsh environmental and loads familiar to space launch propulsion systems. Design trade analyses were carried out using relevant closed form solutions, approximations for sandwich beams/panels and finite element analysis. Analyses confirm the significant thermal stresses exist when combining materials whose coefficients of thermal expansion (CTEs) differ by a factor of about 10 for materials such as a polymer composite and metallic structures. The ramifications on design and manufacturing alternatives are reviewed and discussed. Due to stringent durability and safety requirements, serious consideration is being given to the synergistic effects of temperature and mechanical loads. The candidate structure operates at 316 C, about 80% of the glass transition temperature T(sub g). Earlier thermomechanical fatigue (TMF) investigations of chopped fiber polyimide composites made this near to T(sub g), showed that cyclic temperature and stress promoted excessive creep damage and strain accumulation. Here it is important to verify that such response is limited in continuous fiber laminates.

  15. Condensation of long-term wave climates for the fatigue design of hydrodynamically sensitive offshore wind turbine support structures

    DEFF Research Database (Denmark)

    Passon, Patrik; Branner, Kim

    2016-01-01

    important for hydrodynamically sensitive structures since the applied met-ocean parameters have a non-linear influence on calculated fatigue design loads. The present article introduces a new wave lumping method for condensation of the wave climate. The novelty is predominantly based on refined equivalence......Cost-efficient and reliable fatigue designs of offshore wind turbine support structures require an adequate representation of the site-specific wind–wave joint distribution. Establishment of this wind–wave joint distribution for design load calculation purposes requires typically a correlation...... of the marginal wind and wave distribution. This is achieved by condensation of the site-specific wave climate in terms of wave period or wave height lumping, subsequently used as input for a correlation with the corresponding wind climate. The quality of this resulting wind–wave correlation is especially...

  16. Inhibition of salt precipitation, corrosion and corrosion fatigue of steel in neutral environments

    International Nuclear Information System (INIS)

    Mikhajlovskij, V.Ya.; Slobodyan, Z.V.; Soprunyuk, N.G.; Ivanov, A.M.

    1983-01-01

    Processes of salt precipitation, corrosion under dynamic and static conditions, are studied as well as corrosion fatigue of 20 and 40Kh steels in neutral aqueous media without and with the addition of compounds of several classes. The solution of calcium bicarbonate with the initial concentration [Ca(HCO 3 ) 2 ]=1.3 g/l and 3% NaCl solution in distilled water are used for investigation. The effectiveness index of salt precipitation inhibitor is determined by the change in the rate of calcium bicarbonate transformation into carbonate. The combination of results obtained permits to make the conclusion that tripolyphosphate and pyrophosphoric acid are rather perspective inhibitors of complex effect with low protective concentrations

  17. Separating the Influence of Environment from Stress Relaxation Effects on Dwell Fatigue Crack Growth

    Science.gov (United States)

    Telesman, Jack; Gabb, Tim; Ghosn, Louis J.

    2016-01-01

    Seven different microstructural variations of LSHR were produced by controlling the cooling rate and the subsequent aging and thermal exposure heat treatments. Through cyclic fatigue crack growth testing performed both in air and vacuum, it was established that four out of the seven LSHR heat treatments evaluated, possessed similar intrinsic environmental resistance to cyclic crack growth. For these four heat treatments, it was further shown that the large differences in dwell crack growth behavior which still persisted, were related to their measured stress relaxation behavior. The apparent differences in their dwell crack growth resistance were attributed to the inability of the standard linear elastic fracture mechanics (LEFM) stress intensity parameter to account for visco-plastic behavior. Crack tip stress relaxation controls the magnitude of the remaining local tensile stresses which are directly related to the measured dwell crack growth rates. It was hypothesized that the environmentally weakened grain boundary crack tip regions fail during the dwells when their strength is exceeded by the remaining local crack tip tensile stresses. It was shown that the classical creep crack growth mechanisms such as grain boundary sliding did not contribute to crack growth, but the local visco-plastic behavior still plays a very significant role by determining the crack tip tensile stress field which controls the dwell crack growth behavior. To account for the influence of the visco-plastic behavior on the crack tip stress field, an empirical modification to the LEFM stress intensity parameter, Kmax, was developed by incorporating into the formulation the remaining stress level concept as measured by simple stress relaxation tests. The newly proposed parameter, Ksrf, did an excellent job in correlating the dwell crack growth rates for the four heat treatments which were shown to have similar intrinsic environmental cyclic fatigue crack growth resistance.

  18. Supporting design reviews with pre-meeting virtual reality environments

    NARCIS (Netherlands)

    van den Berg, Marc Casper; Hartmann, Timo; de Graaf, Robin S.

    2017-01-01

    The purpose of this paper is to explore how design reviews can be supported with pre-meeting virtual reality environments. Previous research has not systematically investigated how virtual environments can be used to communicate the design intent (to clients) and to communicate feedback (to design

  19. Low cycle fatigue behavior of hot-bent 347 stainless steel in a simulated PWR water environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Ho; Seo, Myung Gyu; Jang, Chang Heui [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Hong, Jong Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Tae Soon [Central Research InstituteKorea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2016-11-15

    The effect of hot bending on the Low cycle fatigue (LCF) behavior of 347 SS was evaluated in Room temperature (RT) air and simulated Pressurized water reactor (PWR) water environments. The LCF life of 347 SS in PWR water was shorter than that in RT air for the as-received and hot-bent conditions. The LCF life of hot-bent 347 SS was relatively longer than that of the as-received condition in both RT air and PWR water. Microstructure analysis indicated development of dislocation structure near niobium carbide particles and increase in dislocation density for the hot-bent 347 SS. Such microstructure acted as barriers to dislocation movement during the LCF test, resulting in minimal hardening for the hot-bent 347 SS in RT air.

  20. Apparatus and method for fatigue testing of a material specimen in a high-pressure fluid environment

    Science.gov (United States)

    Wang, Jy-An; Feng, Zhili; Anovitz, Lawrence M; Liu, Kenneth C

    2013-06-04

    The invention provides fatigue testing of a material specimen while the specimen is disposed in a high pressure fluid environment. A specimen is placed between receivers in an end cap of a vessel and a piston that is moveable within the vessel. Pressurized fluid is provided to compression and tension chambers defined between the piston and the vessel. When the pressure in the compression chamber is greater than the pressure in the tension chamber, the specimen is subjected to a compression force. When the pressure in the tension chamber is greater than the pressure in the compression chamber, the specimen is subjected to a tension force. While the specimen is subjected to either force, it is also surrounded by the pressurized fluid in the tension chamber. In some examples, the specimen is surrounded by hydrogen.

  1. Some questions regarding the interaction of creep and fatigue

    International Nuclear Information System (INIS)

    James, L.A.

    1975-04-01

    Data are presented from fatigue-crack growth tests conducted on Type 304 S.S. in inert environments at elevated temperatures which show that the thermal-activation noted in similar tests run in air environments is not present in the inert environment. Similar observations from the literature are reviewed, including the observation that the time-dependency noted in tests conducted in elevated temperature air environments is also greatly suppressed in inert environments. These findings suggest that an interaction between the fatigue process and the corrosive air environments is responsible for the thermally activated time-dependent behavior often attributed to creep-fatigue interaction. Data are also presented which show that the fatigue-crack growth behavior of Type 304 S.S. subjected to significant creep damage prior to fatigue testing does not differ appreciably from the behavior of material not subjected to prior creep damage, again indicating minimal interaction between creep and fatigue. It is suggested that in the temperature range where pressure vessels and piping are generally designed to operate (i.e. below about one-half the absolute melting temperature of the alloy), the interaction between creep and fatigue is far less significant than once supposed, and that the major parameter interacting with the fatigue process is that of high-temperature corrosion. (39 references, 12 fig) (auth)

  2. Design of New Food Technology: Social Shaping of Working Environment

    DEFF Research Database (Denmark)

    Broberg, Ole

    2000-01-01

    A five-year design process of a continuous process wok has been studied with the aim of elucidating the conditions for integrating working environment aspects. The design process is seen as a network building activity and as a social shaping process of the artefact. A working environment log...... is suggested as a tool designers can use to integrate considerations of future operators' working environment....

  3. Fatigue assessment by the RCC-MR design rules: remarks on the elastic analysis

    International Nuclear Information System (INIS)

    Taleb, L.; Sidoroff, F.

    1999-01-01

    According to RCC--MR (French rules for mechanical engineering design of FBR), fatigue life assessment is based on the evaluation of the equivalent elastoplastic strain range resulting from a given cyclic loading. Two methods can be used according to whether an elastoplastic or an elastic structure analysis is performed. The elastic analysis is of course more attractive for it avoids a heavy iterative elastoplastic analysis and an expensive identification of the material behavior from mechanical tests. On the other hand it relies on some empirical extrapolation rules from the elastic to the real case. The purpose of the present paper is to draw attention to some limitations of this procedure. In particular attention will be focused on two points: 1, the classification of the applied stress into primary and secondary parts is essential and it is shown that the thermal stresses which are often considered as secondary may in some cases play a primary role; 2. the Neuber's rule which is used to evaluate the plastic strain from the elastic stress will be shown to be significantly wrong for some special configurations. This is in fact essentially related to situations where the elastic follow up effect is important. (authors)

  4. Avoiding thermal striping damage: Experimentally-based design procedures for high-cycle thermal fatigue

    International Nuclear Information System (INIS)

    Betts, C.; Judd, A.M.; Lewis, M.W.J.

    1994-01-01

    In the coolant circuits of a liquid metal cooled reactor (LMR), where there is turbulent mixing of coolant streams at different temperatures, there are temperature fluctuations in the fluid. If an item of the reactor structure is immersed in this fluid it will, because of the good heat transfer from the flowing liquid metal, experience surface temperature fluctuations which will induce dynamic surface strains. It is necessary to design the reactor so that these temperature fluctuations do not, over the life of the plant, cause damage. The purpose of this paper is to describe design procedures to prevent damage of this type. Two such procedures are given, one to prevent the initiation of defects in a nominally defect-free structure or to allow initiation only at the end of the component life, and the other to prevent significant growth of undetectable pre-existing defects of the order of 0.2 to 0.4 mm in depth. Experimental validation of these procedures is described, and the way they can be applied in practice is indicated. To set the scene the paper starts with a brief summary of cases in which damage of this type, or the need to avoid such damage, have had important effects on reactor operation. Structural damage caused by high-cycle thermal fatigue has had a significant adverse influence on the operation of LMRs on several occasions. It is necessary to eliminate the risk of such damage at the design stage. In the absence of detailed knowledge of the temperature history to which it will be subject, an LMR structure can be designed so that, if it is initially free of defects more than 0.1 mm deep, no such defects will be initiated by high-cycle fatigue. This can be done by ensuring that the maximum source temperature difference in the liquid metal is less than a limiting value, which depends on temperature. The limit is very low, however, and likely to be restrictive. This method, by virtue of its safety margin, takes into account pre-existing surface crack

  5. Multi-Disciplinary Multi-Fidelity Design Environment, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Phoenix Integration will develop a collaborative simulation and design environment that will seamlessly integrate the people, data, and tools required for analyzing...

  6. Fatigue Resistant Design Criteria for MD SHA Cantilevered Mast Arm Signal Structure : Research Summary

    Science.gov (United States)

    2017-12-01

    Over the past two decades, wind induced fatigue cracking of highway signs, luminaires, and traffic signal support structures have been increasingly reported all over the United States. While fatalities associated with these failures have been limited...

  7. Design as a way to develop a relevant urban environment ...

    African Journals Online (AJOL)

    Design as a way to develop a relevant urban environment. ... Futuristic ideas of young designers can become the first stage in solving these challenging tasks. ... the problems of a modern city: from space organization to leisure organization.

  8. Designing persuasive interactive environments : a hands-on workshop to explore interactivity and persuasion in design

    NARCIS (Netherlands)

    Rozendaal, Marco; Bekker, Tilde; Vermeeren, Arnold; Kanis, Marije; Aprile, Walter; van der Helm, Aadjan; Middendorf, Wouter

    2012-01-01

    Ambient Intelligent environments are interactive environments that sense human behaviour and can respond intelligently. This workshop explores how interactive environments can be designed with persuasive quality, influencing human experience and behaviour. The workshop follows a

  9. Architectural design and the collaborative research environment.

    Science.gov (United States)

    Goldstein, Roger N

    2006-10-20

    Given that science is a collaborative endeavor, architects are striving to design new research buildings that not only provide a more pleasant work space but also facilitate interactions among researchers.

  10. Analysis and Design of Complex Network Environments

    Science.gov (United States)

    2012-03-01

    and J. Lowe, “The myths and facts behind cyber security risks for industrial control systems ,” in the Proceedings of the VDE Kongress, VDE Congress...questions about 1) how to model them, 2) the design of experiments necessary to discover their structure (and thus adapt system inputs to optimize the...theoretical work that clarifies fundamental limitations of complex networks with network engineering and systems biology to implement specific designs and

  11. On the constitutive law of environment assisted fatigue: The physical meaning of the Paris type equations. Pt. 2

    International Nuclear Information System (INIS)

    Krausz, A.S.; Wu Xijia; Krausz, K.; Lian Zhiwen

    1992-01-01

    The physically based constitutive law of corrosion fatigue, derived in Part I from the principles of thermally activated processes and fracture kinetics, is applied for the representation of the crack growth rate over the whole stress intensity range. The behavior is expressed in terms of design and environmental factors and microstructural quantities. The constitutive law of fracture kinetics defines explicitly the effects of stress and temperature. Similarly, the role of the stress ratio R, the frequency and microstructure, follow rigorously. The influence of these factors on the crack growth rate and threshold behavior is discussed extensively. It is also demonstrated that fracture kinetics provides the framework for the detailed incorporation of corrosion chemical reaction and the associated diffusion processes. (orig.) [de

  12. Interval Solution for Nonlinear Programming of Maximizing the Fatigue Life of V-Belt under Polymorphic Uncertain Environment

    Directory of Open Access Journals (Sweden)

    Zhong Wan

    2013-01-01

    Full Text Available In accord with the practical engineering design conditions, a nonlinear programming model is constructed for maximizing the fatigue life of V-belt drive in which some polymorphic uncertainties are incorporated. For a given satisfaction level and a confidence level, an equivalent formulation of this uncertain optimization model is obtained where only interval parameters are involved. Based on the concepts of maximal and minimal range inequalities for describing interval inequality, the interval parameter model is decomposed into two standard nonlinear programming problems, and an algorithm, called two-step based sampling algorithm, is developed to find an interval optimal solution for the original problem. Case study is employed to demonstrate the validity and practicability of the constructed model and the algorithm.

  13. Reduction of fatigue loads on jacket substructure through blade design optimization for multimegawatt wind turbines at 50 m water depths

    DEFF Research Database (Denmark)

    NJOMO WANDJI, Wilfried; Pavese, Christian; Natarajan, Anand

    2016-01-01

    This paper addresses the reduction of the fore-aft damage equivalent moment at the tower base for multi-megawatt offshore wind turbines mounted on jacket type substructures at 50 m water depths. The study investigates blade design optimization of a reference 10 MW wind turbine under standard wind...... conditions of onshore sites. The blade geometry and structure is optimized to yield a design that minimizes tower base fatigue loads without significant loss of power production compared to that of the reference setup. The resulting blade design is then mounted on a turbine supported by a jacket and placed...

  14. Knowledge management in the engineering design environment

    Science.gov (United States)

    Briggs, Hugh C.

    2006-01-01

    The Aerospace and Defense industry is experiencing an increasing loss of knowledge through workforce reductions associated with business consolidation and retirement of senior personnel. Significant effort is being placed on process definition as part of ISO certification and, more recently, CMMI certification. The process knowledge in these efforts represents the simplest of engineering knowledge and many organizations are trying to get senior engineers to write more significant guidelines, best practices and design manuals. A new generation of design software, known as Product Lifecycle Management systems, has many mechanisms for capturing and deploying a wider variety of engineering knowledge than simple process definitions. These hold the promise of significant improvements through reuse of prior designs, codification of practices in workflows, and placement of detailed how-tos at the point of application.

  15. A Well Designed School Environment Facilitates Brain Learning.

    Science.gov (United States)

    Chan, Tak Cheung; Petrie, Garth

    2000-01-01

    Examines how school design facilitates learning by complementing how the brain learns. How the brain learns is discussed and how an artistic environment, spaciousness in the learning areas, color and lighting, and optimal thermal and acoustical environments aid student learning. School design suggestions conclude the article. (GR)

  16. Using IMPRINT to Guide Experimental Design with Simulated Task Environments

    Science.gov (United States)

    2015-06-18

    USING IMPRINT TO GUIDE EXPERIMENTAL DESIGN OF SIMULATED TASK ENVIRONMENTS THESIS Gregory...ENG-MS-15-J-052 USING IMPRINT TO GUIDE EXPERIMENTAL DESIGN WITH SIMULATED TASK ENVIRONMENTS THESIS Presented to the Faculty Department...Civilian, USAF June 2015 DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENG-MS-15-J-052 USING IMPRINT

  17. Design of energy markets and environment

    International Nuclear Information System (INIS)

    Birk Mortensen, J.; Olsen, O.J.; Skytte, K.

    1999-01-01

    The introduction of competition in electricity and gas markets has necessitated the creation of new markets, power pools and financial markets. Such markets are well known from other industries (e.g. oil) but have not been applied for the gas and electricity industries during the monopoly era. To which extent can market design applied elsewhere be transferred to gas and electricity and to which extent must they be modified? The interest in new market designs has recently been extended to environmentally goals, but existing policies to encourage them are considered inefficient and a burden for the state budget. This conference brings some of these subjects into focus. (au)

  18. Telemedicine Workplace Environments: Designing for Success

    OpenAIRE

    Elizabeth A. Krupinski

    2014-01-01

    When designing a facility for telemedicine, there are several things to consider from a human factors point of view, as well as from a practicality point of view. Although the future practice of telemedicine is likely to be more of a mobile-based practice and centered more in the home than it is now, it is still very important to consider ways to optimize the design of clinic-based telemedicine facilities. This is true on both ends of a consultation?where the patient is and where the consulta...

  19. Considerations for Designing Instructional Virtual Environments.

    Science.gov (United States)

    Dennen, Vanessa Paz; Branch, Robert C.

    Virtual reality is an immersive, interactive medium that manipulates the senses in order provide users with simulated experiences in computer-generated worlds. The visual design of virtual reality is an important issue, but literature has tended to stress the medium's instructional potential rather than setting forth a protocol for designing…

  20. Low cycle fatigue design data for India-specific reduced activation ferritic-martensitic (IN-RAFM) steel

    Energy Technology Data Exchange (ETDEWEB)

    Mariappan, K.; Shankar, Vani, E-mail: vani@igcar.gov.in; Sandhya, R.; Laha, K.

    2016-03-15

    Highlights: • Generation of first set of experimental data related to LCF performance of the commercial heat of IN-RAFM steel. • Analysis of cyclic behavior from the perspective of both design and material characteristics. • Various correction factors to account for various plastic strain accumulations, change in Poisson’s ratio and asymmetry of loadings. • Low cycle fatigue design parameters and correction factor values were comparable with P91 steel as reported in RCC-MR design code. - Abstract: The objective of the present paper is to provide first hand experimental data and analysis on the low cycle fatigue (LCF) performance of a commercial heat of Indian reduced activation ferritic-martensitic (IN-RAFM) steel. Since this material is not yet codified in RCC-MR, cyclic properties were generated for the design of the structural material of the Test Blanket Modules (TBM) made of RAFM steel. Hence, as a part of the material development program, LCF experiments were conducted on IN-RAFM steel obtained in the normalized and tempered condition. Total axial strain controlled experiments were performed in air by employing strain amplitudes ranging from ±0.25 to ±1.0% and at temperatures of 300, 673, 723, 823, and 873 K and a nominal strain rate, 3 × 10{sup −3} s{sup −1}. In the present work, various cyclic parameters that are useful for the design oriented fatigue analysis are derived as per the systematic procedure given in the RCC-MR design code. The physical significance of each design parameter such as elasto-plastic corrections based on Neuber analysis has been explained and correlated with the material behavior such as the cyclic softening nature of the RAFM steel.

  1. Investigation of the effect of vacuum environment on the fatigue and fracture behavior of 7075-T6.

    Science.gov (United States)

    Hudson, C. M.

    1972-01-01

    Axial-load fatigue-life, fatigue-crack propagation, and fracture-toughness experiments were conducted on sheet specimens made of 7075-T6 aluminum alloy. These experiments were conducted at air pressures ranging from 101 kN/sq m to 7 micronewtons/sq m to determine the effect of air pressure on fatigue behavior. Analysis of the results from the fatigue-life experiments indicated that for a given stress level, the lower the air pressure was the longer the fatigue life. At a pressure of 7 micronewtons/sq m, fatigue lives were 15 to 30 times longer than at 101 kN/sq m. Analysis of the results from the fatigue-crack-growth experiments indicates that at low values of stress-intensity range, the fatigue-crack-growth rates were approximately twice as high at atmospheric pressure as in vacuum. However, at higher values of stress-intensity range, the fatigue-crack-growth rates were nominally the same in vacuum and at atmospheric pressure.

  2. Effect of microstructure and environment on the crack growth behaviour on Inconel 718 alloy at 650/sup 0/C under fatigue, creep and combined loading

    Energy Technology Data Exchange (ETDEWEB)

    Pedron, J P; Pineau, A

    1982-11-01

    The crack growth properties of various microstructures developed in one heat of Inconel 718 alloy were investigated at 650/sup 0/C under air and vacuum environments. The microstructures included fine-grained material (ASTM grain sizes 6-8), coarse-grained material (ASTM grain sizes 3-4) and material of a necklace structure (ASTM grain sizes 3-4 and 8-10). The effect of grain boundary ..beta.. (Ni/sub 3/Nb) phase precipitation was also studied. Continuous fatigue, creep and creep-fatigue conditions were examined. For continuous fatigue the influence of frequency was investigated over the range between 5x10/sup -2/ and 20 Hz. For creep-fatigue conditions, hold times of 10 and 300 s were superimposed on a 5x10/sup -2/ Hz triangular wave shape signal. It was shown that the grain boundary microstructure had a very strong effect when the fatigue crack propagation behaviour was essentially time dependent. This effect is associated with the occurrence of brittle intergranular fracture and dramatic increases in crack growth rate. The microstructure had no effect under vacuum testing.

  3. Rate design in a competitive environment

    International Nuclear Information System (INIS)

    Wathen, J.M.

    1995-01-01

    Innovative rate designs used by several United States utilities to become more competitive, were presented. Considerations of retail wheeling and other services for increasing competitiveness were debated. The process for designing specialized rate programs was described, along with descriptions of special rate types, including economic development rates, load retention/anti-bypass rates, cogeneration/self-generation rates, distressed industry rates, load management rates and special situation rates. The existence of special provisions in state legislation allowing special rates to be offered was noted. Confidentiality and the need for a review process to ensure fairness of special agreements was discussed. The efficacy of using individual customer contracts to allow full recognition of the special characteristics and needs of individual customers and the effects of such contracts on the industry, were considered

  4. A Distributed Feature-based Environment for Collaborative Design

    Directory of Open Access Journals (Sweden)

    Wei-Dong Li

    2003-02-01

    Full Text Available This paper presents a client/server design environment based on 3D feature-based modelling and Java technologies to enable design information to be shared efficiently among members within a design team. In this environment, design tasks and clients are organised through working sessions generated and maintained by a collaborative server. The information from an individual design client during a design process is updated and broadcast to other clients in the same session through an event-driven and call-back mechanism. The downstream manufacturing analysis modules can be wrapped as agents and plugged into the open environment to support the design activities. At the server side, a feature-feature relationship is established and maintained to filter the varied information of a working part, so as to facilitate efficient information update during the design process.

  5. Creep-Fatigue Life Design with Various Stress and Temperature Conditions on the Basis of Lethargy Coefficient

    International Nuclear Information System (INIS)

    Park, Jung Eun; Yang, Sung Mo; Han, Jae Hee; Yu, Hyo Sun

    2011-01-01

    High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipment. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously

  6. Reconfiguring Course Design in Virtual Learning Environments

    DEFF Research Database (Denmark)

    Mullins, Michael; Zupancic, Tadeja

    2007-01-01

    for architectural students offers some innovative insights into experientially oriented educational interfaces. A comparative analysis of VIPA courses and project results are presented in the paper. Special attention in the discussion is devoted to the improvements of e-learning solutions in architecture......Although many administrators and educators are familiar with e-learning programs, learning management systems and portals, fewer may have experience with virtual distributed learning environments and their academic relevance. The blended learning experience of the VIPA e-learning project....... The criterion of the relation between the actual applicability of selected e-learning solutions and elements of collaborative educational interfaces with VR are taken into account. A system of e-learning applicability levels in program and course development and implementation of architectural tectonics...

  7. The temperature dependence and environmental enhancement mechanism of fatigue crack growth rates of A 351-CF8A cast stainless steel in LWR environment

    International Nuclear Information System (INIS)

    Cullen, W.H.; Haenninen, H.; Toerroenen, K.; Kemppainen, M.

    1984-01-01

    The fatigue crack growth rates for A 351-CF8A cast stainless steel were determined over a range of temperatures from 93 degC to 338 degC (200 degF to 640 degF). The waveform was 17 mHz sinusoidal and the load ratio was 0.2. The environment was borated and lithiated water with a dissolved oxygen content of approximately 1 ppb. The results show an easily measurable (factors of 2 to 8) increase in crack growth rates due to the environment. However, these rates are well within the known band of results for low-alloy pressure vessel and low-carbon piping steels in LWR environments. An extensive fractographic investigation shows fatigue fracture surfaces consisting of brittle morphology. This fracture morphology is similar to that of stress corrosion cracking of stainless steels, suggesting that there is a distinctive environmental assistance mechanism resulting in the increased crack growth rates. (author)

  8. Encoder designed to work in harsh environments

    Energy Technology Data Exchange (ETDEWEB)

    Toop, L.

    2007-05-15

    Dynapar has developed the Acuro AX71 absolute encoder for use on offshore or land-based oil rig operations. It provides feedback on the operation of automated systems such as draw works, racking systems, rotary tables and top drives. By ensuring that automated systems function properly, this encoder responds to a need by the oil and gas industry to keep workers safe and improve efficiency, particularly for operations in rugged situations. The encoder provides feedback from motor systems to controllers, giving information about position and speed of downhole drill bits. This newly developed encoder is better than commonly used incremental encoders which are not precise in strong electrical noise environments. Rather, the absolute encoder uses a different method of reporting to the controller. A digital signal is transmitted constantly as the device operates. It is less susceptible to noise issues. It is highly accurate, tolerant of noise and is not affected by power outages. However, the absolute encoder is generally more delicate in drilling applications with high ambient temperatures and shock levels. Dynapar addressed this issue by developing compact stainless steel housing that is useful for corrosion resistance in marine applications. The AX71 absolute encoder can withstand up to 100 G of mechanical shock and ambient temperatures of up to 60 degrees C. The encoder is ATEX certified without barriers, and offers the high resolution feedback of 4,000 counts of multiturn rotation and 16,000 counts of position. 1 fig.

  9. Human-centered environment design in intensive care unit

    OpenAIRE

    Li, Y.; Albayrak, A.; Goossens, R.H.M.; Xiao, D.; Jakimowicz, J.J.

    2013-01-01

    Because of high risk and instability of the patients in Intensive care unit(ICU), the design of ICU is very difficult. ICU design, auxiliary building design, lighting design, noise control and other aspects can also enhance its management. In this paper, we compare ICU design in China and Holland based on related standards. We also premeditate the indoor environment from planning perspective, analyze patients, their families, medical staff and space requirement to conduct research in ICU desi...

  10. Design of Fatigue Resistant Heusler-strengthened PdTi-based Shape Memory Alloys for Biomedical Applications

    Science.gov (United States)

    Frankel, Dana J.

    The development of non-surgical transcatheter aortic valve implantation (TAVI) techniques, which utilize collapsible artificial heart valves with shape memory alloy (SMA)-based frames, pushes performance requirements for biomedical SMAs beyond those for well-established vascular stent applications. Fatigue life for these devices must extend into the ultra-high cycle fatigue (UHCF) regime (>600M cycles) with zero probability of failure predicted at applied strain levels. High rates of Ni-hypersensitivity raise biocompatibility concerns, driving the development of low-Ni and Ni-free SMAs. This work focuses on the development of biocompatible, precipitation-strengthened, fatigue-resistant PdTi-based SMAs for biomedical applications. Functional and structural fatigue are both manifestations of cyclic instability resulting in accumulation of slip and eventual structural damage. While functional fatigue is easily experimentally evaluated, structural fatigue is more difficult to measure without the proper equipment. Therefore, in this work a theoretical approach using a model well validated in steels is utilized to investigate structural fatigue behavior in NiTi in the UHCF regime, while low cycle functional fatigue is evaluated in order to monitor the core phenomena of the cyclic instability. Results from fatigue simulations modeling crack nucleation at non-metallic inclusions in commercial NiTi underscore the importance of increasing yield strength for UHCF performance. Controlled precipitation of nanoscale, low-misfit, L21 Heusler aluminides can provide effective strengthening. Phase relations, precipitation kinetics, transformation temperature, transformation strain, cyclic stability, and mechanical properties are characterized in both Ni-free (Pd,Fe)(Ti,Al) and low-Ni high-strength "hybrid" (Pd,Ni)(Ti,Zr,Al) systems. Atom probe tomography is employed to measure phase compositions and particle sizes used to calibrate LSW models for coarsening kinetics and Gibbs

  11. Development and evaluation of an intervention aiming to reduce fatigue in airline pilots: design of a randomised controlled trial.

    Science.gov (United States)

    van Drongelen, Alwin; van der Beek, Allard J; Hlobil, Hynek; Smid, Tjabe; Boot, Cécile R L

    2013-08-26

    A considerable percentage of flight crew reports to be fatigued regularly. This is partly caused by irregular and long working hours and the crossing of time zones. It has been shown that persistent fatigue can lead to health problems, impaired performance during work, and a decreased work-private life balance. It is hypothesized that an intervention consisting of tailored advice regarding exposure to daylight, optimising sleep, physical activity, and nutrition will lead to a reduction of fatigue in airline pilots compared to a control group, which receives a minimal intervention with standard available information. The study population will consist of pilots of a large airline company. All pilots who posses a smartphone or tablet, and who are not on sick leave for more than four weeks at the moment of recruitment, will be eligible for participation.In a two-armed randomised controlled trial, participants will be allocated to an intervention group that will receive the tailored advice to optimise exposure to daylight, sleep, physical activity and nutrition, and a control group that will receive standard available information. The intervention will be applied using a smartphone application and a website, and will be tailored on flight- and participant-specific characteristics. The primary outcome of the study is perceived fatigue. Secondary outcomes are need for recovery, duration and quality of sleep, dietary and physical activity behaviours, work-private life balance, general health, and sickness absence. A process evaluation will be conducted as well. Outcomes will be measured at baseline and at three and six months after baseline. This paper describes the development of an intervention for airline pilots, consisting of tailored advice (on exposure to daylight and sleep-, physical activity, and nutrition) applied into a smartphone application. Further, the paper describes the design of the randomised controlled trial evaluating the effect of the intervention on

  12. Very high-cycle fatigue failure in micron-scale polycrystalline silicon films : Effects of environment and surface oxide thickness

    NARCIS (Netherlands)

    Alsem, D. H.; Boyce, B. L.; Stach, E. A.; De Hosson, J. Th. M.; Ritchie, R. O.

    2007-01-01

    Fatigue failure in micron-scale polycrystalline silicon structural films, a phenomenon that is not observed in bulk silicon, can severely impact the durability and reliability of microelectromechanical system devices. Despite several studies on the very high-cycle fatigue behavior of these films (up

  13. A DBR Framework for Designing Mobile Virtual Reality Learning Environments

    Science.gov (United States)

    Cochrane, Thomas Donald; Cook, Stuart; Aiello, Stephen; Christie, Duncan; Sinfield, David; Steagall, Marcus; Aguayo, Claudio

    2017-01-01

    This paper proposes a design based research (DBR) framework for designing mobile virtual reality learning environments. The application of the framework is illustrated by two design-based research projects that aim to develop more authentic educational experiences and learner-centred pedagogies in higher education. The projects highlight the first…

  14. Designing safer living environments support for local government

    CSIR Research Space (South Africa)

    Landman, K

    1999-06-01

    Full Text Available This paper addresses the built environment, the opportunities it presents for crime and the role city planners and urban designers have to play in the design of safer cities and towns. City planners and urban designers can play a role...

  15. Design of a Fatigue Detection System for High-Speed Trains Based on Driver Vigilance Using a Wireless Wearable EEG

    Directory of Open Access Journals (Sweden)

    Xiaoliang Zhang

    2017-03-01

    Full Text Available The vigilance of the driver is important for railway safety, despite not being included in the safety management system (SMS for high-speed train safety. In this paper, a novel fatigue detection system for high-speed train safety based on monitoring train driver vigilance using a wireless wearable electroencephalograph (EEG is presented. This system is designed to detect whether the driver is drowsiness. The proposed system consists of three main parts: (1 a wireless wearable EEG collection; (2 train driver vigilance detection; and (3 early warning device for train driver. In the first part, an 8-channel wireless wearable brain-computer interface (BCI device acquires the locomotive driver’s brain EEG signal comfortably under high-speed train-driving conditions. The recorded data are transmitted to a personal computer (PC via Bluetooth. In the second step, a support vector machine (SVM classification algorithm is implemented to determine the vigilance level using the Fast Fourier transform (FFT to extract the EEG power spectrum density (PSD. In addition, an early warning device begins to work if fatigue is detected. The simulation and test results demonstrate the feasibility of the proposed fatigue detection system for high-speed train safety.

  16. A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

    Directory of Open Access Journals (Sweden)

    Dylan Agius

    2018-01-01

    Full Text Available Ti-6Al-4V has been widely used in both the biomedical and aerospace industry, due to its high strength, corrosion resistance, high fracture toughness and light weight. Additive manufacturing (AM is an attractive method of Ti-6Al-4V parts’ fabrication, as it provides a low waste alternative for complex geometries. With continued progress being made in SLM technology, the influence of build layers, grain boundaries and defects can be combined to improve further the design process and allow the fabrication of components with improved static and fatigue strength in critical loading directions. To initiate this possibility, the mechanical properties, including monotonic, low and high cycle fatigue and fracture mechanical behaviour, of machined as-built SLM Ti-6Al-4V, have been critically reviewed in order to inform the research community. The corresponding crystallographic phases, defects and layer orientations have been analysed to determine the influence of these features on the mechanical behaviour. This review paper intends to enhance our understanding of how these features can be manipulated and utilised to improve the fatigue resistance of components fabricated from Ti-6Al-4V using the SLM technology.

  17. Unified approach for estimating the probabilistic design S-N curves of three commonly used fatigue stress-life models

    International Nuclear Information System (INIS)

    Zhao Yongxiang; Wang Jinnuo; Gao Qing

    2001-01-01

    A unified approach, referred to as general maximum likelihood method, is presented for estimating probabilistic design S-N curves and their confidence bounds of the three commonly used fatigue stress-life models, namely three parameter, Langer and Basquin. The curves are described by a general form of mean and standard deviation S-N curves of the logarithm of fatigue life. Different from existent methods, i.e., the conventional method and the classical maximum likelihood method,present approach considers the statistical characteristics of whole test data. The parameters of the mean curve is firstly estimated by least square method and then, the parameters of the standard deviation curve is evaluated by mathematical programming method to be agreement with the maximum likelihood principle. Fit effects of the curves are assessed by fitted relation coefficient, total fitted standard error and the confidence bounds. Application to the virtual stress amplitude-crack initiation life data of a nuclear engineering material, Chinese 1Cr18Ni9Ti stainless steel pipe-weld metal, has indicated the validity of the approach to the S-N data where both S and N show the character of random variable. Practices to the two states of S-N data of Chinese 45 carbon steel notched specimens (k t = 2.0) have indicated the validity of present approach to the test results obtained respectively from group fatigue test and from maximum likelihood fatigue test. At the practices, it was revealed that in general the fit is best for the three-parameter model,slightly inferior for the Langer relation and poor for the Basquin equation. Relative to the existent methods, present approach has better fit. In addition, the possible non-conservative predictions of the existent methods, which are resulted from the influence of local statistical characteristics of the data, are also overcome by present approach

  18. DEFACTO: A Design Environment for Adaptive Computing Technology

    National Research Council Canada - National Science Library

    Hall, Mary

    2003-01-01

    This report describes the activities of the DEFACTO project, a Design Environment for Adaptive Computing Technology funded under the DARPA Adaptive Computing Systems and Just-In-Time-Hardware programs...

  19. Designing an Interactive Multimedia Environment for Learning and Aiding Troubleshooting

    National Research Council Canada - National Science Library

    Kolodner, Janet

    1997-01-01

    .... However troubleshooting is a complex process both to learn and perform. This report examines the prospects for designing an interactive learning environment that helps users acquire and engage in effective troubleshooting...

  20. Understanding and Designing Military Organizations for a Complex Dynamic Environment

    National Research Council Canada - National Science Library

    Hicks, Christopher E

    2008-01-01

    .... The two theories will be used to describe the external environment and how it relates to DoD organizations, current DoD organizational structures, and transformational concepts related to organizational design...

  1. Designing user models in a virtual cave environment

    Energy Technology Data Exchange (ETDEWEB)

    Brown-VanHoozer, S. [Argonne National Lab., Idaho Falls, ID (United States); Hudson, R. [Argonne National Lab., IL (United States); Gokhale, N. [Madge Networks, San Jose, CA (United States)

    1995-12-31

    In this paper, the results of a first study into the use of virtual reality for human factor studies and design of simple and complex models of control systems, components, and processes are described. The objective was to design a model in a virtual environment that would reflect more characteristics of the user`s mental model of a system and fewer of the designer`s. The technology of a CAVE{trademark} virtual environment and the methodology of Neuro Linguistic Programming were employed in this study.

  2. Internet-centric collaborative design in a distributed environment

    International Nuclear Information System (INIS)

    Kim, Hyun; Kim, Hyoung Sun; Do, Nam Chul; Lee, Jae Yeol; Lee, Joo Haeng; Myong, Jae Hyong

    2001-01-01

    Recently, advanced information technologies including internet-related technology and distributed object technology have opened new possibilities for collaborative designs. In this paper, we discuss computer supports for collaborative design in a distributed environment. The proposed system is the internet-centric system composed of an engineering framework, collaborative virtual workspace and engineering service. It allows the distributed designers to more efficiently and collaboratively work their engineering tasks throughout the design process

  3. POTENTIAL USE OF VIRTUAL ENVIRONMENTS IN DESIGN EDUCATION

    OpenAIRE

    SAGUN, Aysu

    2011-01-01

    This paper explores the potential use of Virtual Environments (VE) in design education. Recently, the way the designers form their mental concepts, develop and test their design is enhanced with the new computer technologies. Computer generated VE has a great potential to be used in the design process and collaborative studies because they enable manipulation of simulated products as well as interaction of people with each other and the simulated space for communication and col...

  4. Standardization of green building technologies for environment design

    Directory of Open Access Journals (Sweden)

    Benuzh Andrey

    2016-01-01

    Full Text Available The article describes the structure and field of standardization ISO / TC 205 “Building environment design”, provides examples of green building technologies. The main purpose of the article is to show the interaction between international ISO / TC 205 “Building environment design” and created in Russia in 2016 the Technical Committee of Standardization № 366 “Green technology of the build environment and green innovative products”. Both of these technical committees promote green building technologies for environment design, thereby deal with the negative impact on the environment and the reasons of global warming. Instead of buildings that attempt to suppress and overcome nature, why not design buildings that integrate with the environment, on every possible level? The international standardization work which ISO/TC 205 “Building environment design” performs seeks, in addition to lowering trade barriers for engineering design, to promote and facilitate the design of high performance buildings: higher performing as economic assets for their owners, higher performing as buildings that provide amenable indoor environment for their occupants, and higher performing with respect to resource utilization and environmental impact.

  5. Design Rework Prediction in Concurrent Design Environment: Current Trends and Future Research Directions

    OpenAIRE

    Arundachawat, Panumas; Roy, Rajkumar; Al-Ashaab, Ahmed; Shehab, Essam

    2009-01-01

    Organised by: Cranfield University This paper aims to present state-of-the-art and formulate future research areas on design rework in concurrent design environment. Related literatures are analysed to extract the key factors which impact design rework. Design rework occurs due to changes from upstream design activities and/or by feedbacks from downstream design activities. Design rework is considered as negative iteration; therefore, value in design activities will be increase...

  6. Building a Case-Based Design Assistant for Workplace Environment Design

    NARCIS (Netherlands)

    Mallory-Hill, S.M.; Timmermans, H.J.P.

    1998-01-01

    This paper reports on the early stages of development of a case-based design tool. The purpose of this tool, called the Workplace Environment Design Advisor (WEDA), is to support architects in the conceptual design of workplace environments. The objective of this system is to provide electronic

  7. Flight crew fatigue management in a more flexible regulatory environment: an overview of the New Zealand aviation industry.

    Science.gov (United States)

    Signal, T Leigh; Ratieta, Denise; Gander, Philippa H

    2008-04-01

    Since 1995, air transport operators in New Zealand have been able to meet the flight and duty time (FDT) regulations by operating according to prescriptive FDT limits or by seeking approval to operate under a potentially more flexible company-specific FDT scheme. There has been no formal assessment of the impact of this increased flexibility on fatigue management processes. The aim of the present study was to determine the strategies and processes that commercial aircraft operators in New Zealand have in place for managing fatigue and whether these differed according to the type of FDT system under which organizations were operating. All air transport operators in New Zealand were sent questionnaires that were to be completed by an individual in a management role, a line pilot, and an individual in a rostering role. Questions were asked about the FDT system under which the organization operated, the strategies and processes in place for managing fatigue, and the consequences of the organization's approach to managing fatigue. One hundred and fifty-three responses were received from 88 organizations (55% of all air operators) and were representative of the structure of the New Zealand industry. Air operators were most likely to report that they monitored flight and duty times and pilot workload to manage fatigue (used by 90-99% and 70-90%, respectively), while educating rostering staff and reviewing the processes for managing fatigue were the least utilized strategies (used by 36-50% and 39-60%, respectively). Within the same organization, managers were more likely than line pilots to report the use of specific fatigue management strategies. There were no differences found between organizations operating under prescriptive regulations and those using a company-specific scheme on ratings of how well fatigue was managed, the number of fatigue management strategies employed, or the frequency of use of selected strategies. Across the industry as a whole, the provision

  8. Urban Environment Development based on Universal Design Principles

    Science.gov (United States)

    Harsritanto, Bangun Ir

    2018-02-01

    Universal Design is a design which facilitated full range of human diversity. By applying Universal design principles, urban environment can be more functional and more user-friendly for everyone. This study examined five urban streets of South Korea as a country experienced on developing various urban street designs based on universal design. This study aimed to examine and compare the South Korea cases using seven principles of universal design. The research methods of this study are literature study, case study, and site observation. The results of this study are: South Korea cases are good practices, urgency of implementing the direction into local regulations; and change of urban development paradigm.

  9. The combined effects of prior-corrosion and aggressive chemical environments on fatigue crack growth behavior in aluminum alloy 7075-T651

    Science.gov (United States)

    Mills, Thomas Brian

    1997-11-01

    Exfoliation corrosion is a potentially severe form of corrosion that frequently affects high-strength aluminum, particularly 2xxx- and 7xxx-series alloys. Exfoliation degrades components such as sheets, plates, and extrusions that have highly elongated grain structures. Few attempts have been made to investigate the effects of this form of corrosion on the fatigue performance of these materials, so a preliminary study was conducted to determine the effects of exfoliation corrosion on the fatigue response of quarter-inch 7075-T651 aluminum alloy plate. This was accomplished by subjecting aluminum panels to an ASTM standard corrosive solution known as EXCO then fatiguing the panels in corrosion fatigue environments of dry air, humid air, and artificial acid rain. Statistical analyses of the fatigue crack growth data suggest that prior-corrosion and corrosion fatigue are competing mechanisms that both have the potential of accelerating crack growth rates. In the dry air cases, exfoliation accelerated crack growth rates a maximum of 4.75 times over the uncorroded material at lower stress intensities such as 5 ksi surdinch. This accelerated behavior dropped off rapidly, however, and was nonexistent at higher stress intensities. Humid air increased crack velocities considerably as compared to the dry air uncorroded case, but the addition of exfoliation corrosion to the humid cases did not have a significant effect on crack growth behavior. On the other hand, specimens containing exfoliation corrosion and then exposed to artificial acid rain had significantly higher crack growth rates than their uncorroded counterparts. Finally, fractographic examinations of the specimens revealed evidence of lower energy, quasi-cleavage fracture persisting near to the exfoliated edge of specimens tested in the dry air, humid air, and artificial acid rain environments. The implications of this research are that prior-corrosion damage has the ability to significantly increase crack growth

  10. Designing presence for real locomotion in immersive virtual environments

    DEFF Research Database (Denmark)

    Turchet, Luca

    2015-01-01

    This paper describes a framework for designing systems for real locomotion in virtual environments (VEs) in order to achieve an intense sense of presence. The main outcome of the present research is a list of design features that the virtual reality technology should have in order to achieve...

  11. Synthetic Environments as visualization method for product design

    NARCIS (Netherlands)

    Meijer, F.; van den Broek, Egon; Schouten, Theo E.; Damgrave, Roy Gerhardus Johannes; Damgrave, Roy G.J.; de Ridder, Huib; Rogowitz, Bernice E.; Pappas, Thrasyvoulos N.

    2010-01-01

    In this paper, we explored the use of low fidelity Synthetic Environments (SE; i.e., a combination of simulation techniques) for product design. We explored the usefulness of low fidelity SE to make design problems explicit. In particular, we were interested in the influence of interactivity on user

  12. Project Selection in the Design Studio: Absence of Learning Environments

    Science.gov (United States)

    Basa, Inci

    2010-01-01

    Project selection is an essential matter of design teaching. Based on observations of a specific curriculum, the author claims that a wide repertoire of subjects including offices, restaurants, hotels, and other public places are used to prepare design students, but that schools and other "learning environments/ schools" are similarly…

  13. Designing Learning Environments to Teach Interactive Quantum Physics

    Science.gov (United States)

    Puente, Sonia M. Gomez; Swagten, Henk J. M.

    2012-01-01

    This study aims at describing and analysing systematically an interactive learning environment designed to teach Quantum Physics, a second-year physics course. The instructional design of Quantum Physics is a combination of interactive lectures (using audience response systems), tutorials and self-study in unit blocks, carried out with small…

  14. Designing Prediction Tasks in a Mathematics Software Environment

    Science.gov (United States)

    Brunström, Mats; Fahlgren, Maria

    2015-01-01

    There is a recognised need in mathematics teaching for new kinds of tasks which exploit the affordances provided by new technology. This paper focuses on the design of prediction tasks to foster student reasoning about exponential functions in a mathematics software environment. It draws on the first iteration of a design based research study…

  15. Designing learning environments to teach interactive Quantum Physics

    NARCIS (Netherlands)

    Gómez Puente, S.M.; Swagten, H.J.M.

    2012-01-01

    This study aims at describing and analysing systematically an interactive learning environment designed to teach Quantum Physics, a second-year physics course. The instructional design of Quantum Physics is a combination of interactive lectures (using audience response systems), tutorials and

  16. Computational predictive methods for fracture and fatigue

    Science.gov (United States)

    Cordes, J.; Chang, A. T.; Nelson, N.; Kim, Y.

    1994-09-01

    The damage-tolerant design philosophy as used by aircraft industries enables aircraft components and aircraft structures to operate safely with minor damage, small cracks, and flaws. Maintenance and inspection procedures insure that damages developed during service remain below design values. When damage is found, repairs or design modifications are implemented and flight is resumed. Design and redesign guidelines, such as military specifications MIL-A-83444, have successfully reduced the incidence of damage and cracks. However, fatigue cracks continue to appear in aircraft well before the design life has expired. The F16 airplane, for instance, developed small cracks in the engine mount, wing support, bulk heads, the fuselage upper skin, the fuel shelf joints, and along the upper wings. Some cracks were found after 600 hours of the 8000 hour design service life and design modifications were required. Tests on the F16 plane showed that the design loading conditions were close to the predicted loading conditions. Improvements to analytic methods for predicting fatigue crack growth adjacent to holes, when multiple damage sites are present, and in corrosive environments would result in more cost-effective designs, fewer repairs, and fewer redesigns. The overall objective of the research described in this paper is to develop, verify, and extend the computational efficiency of analysis procedures necessary for damage tolerant design. This paper describes an elastic/plastic fracture method and an associated fatigue analysis method for damage tolerant design. Both methods are unique in that material parameters such as fracture toughness, R-curve data, and fatigue constants are not required. The methods are implemented with a general-purpose finite element package. Several proof-of-concept examples are given. With further development, the methods could be extended for analysis of multi-site damage, creep-fatigue, and corrosion fatigue problems.

  17. Fatigue Reliability of Offshore Wind Turbine Systems

    DEFF Research Database (Denmark)

    Marquez-Dominguez, Sergio; Sørensen, John Dalsgaard

    2012-01-01

    of appropriate partial safety factors / fatigue design factors (FDF) for steel substructures of offshore wind turbines (OWTs). The fatigue life is modeled by the SN approach. Design and limit state equations are established based on the accumulated fatigue damage. The acceptable reliability level for optimal...... fatigue design of OWTs is discussed and results for reliability assessment of typical fatigue critical design of offshore steel support structures are presented....

  18. An in vitro investigation into retention strength and fatigue resistance of various designs of tooth/implant supported overdentures.

    Science.gov (United States)

    Fatalla, Abdalbseet A; Song, Ke; Du, Tianfeng; Cao, Yingguang

    2012-02-01

    Previously, the choice of prosthetic implant-retained overdentures has depended on data from previous studies about the retention-fatigue strength of the attachment system selected. Little or no data have been available on the correlation between the attachment system selected and the overdenture support configuration. The purpose of the present study was to evaluate the retention force and fatigue resistance of three attachment systems and four support designs of overdenture prosthesis. Four lower edentulous acrylic models were prepared and eight combinations of attachments groups were investigated in the study. These included: O-Rings with mini-dental implants (MDIs), Dalbo elliptic with Dalbo Rotex and fabricated flexible acrylic attachments with both MDI and Dalbo Rotex. The study was divided into four test groups: groups A and B, controls, and groups C and D, experimental groups. Control group A contained three overdenture supports: two free standing MDIs in the canine region and at the midline, and one simulated tooth root with Dalbo Rotex screwed in. Control group B contained four overdenture support foundations: two free standing MDIs in the right canine region and the first premolar region, and two simulated tooth roots with Dalbo Rotex screwed in at the same MDI position, but on the left side of the model. Experimental group C contained three overdenture support foundations: two free standing MDIs in the canine region and at the midline, and one simulated tooth root with MDI screwed in. Experimental group D contained four overdenture support foundations: two free standing MDIs in the right canine region and the first premolar region, and two simulated tooth roots with MDIs screwed in at the same MDI position, but on the left side of the model. Each group was further divided into two subgroups according to attachment type used. Five samples were prepared for each group. Retention force (N) values were recorded initially (0 cycles) and after 360, 720, 1440

  19. The Effects of Hot Bending on the Low Cycle Fatigue Behaviors of 347 SS in PWR Primary Environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho-Sub; Hong, Jong-Dae; Lee, Junho; Jang, Changheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-10-15

    Fatigue damage could be significant for some locations, especially the welds and bends where stress concentration is typically high. As a possible solution, a large radius hot-bending method has been suggested to eliminate some weld joints and all tight bends. However, for the hot-bending process which involves a high temperature thermal cycle, there is a concern about changes in mechanical properties including low cycle fatigue behaviors. In APR1400, Type 347 SS have been used as surge line pipes. Therefore, to verify the applicability of hot-bending on 347 SS surge line pipes, an environmental fatigue test program was initiated. In this paper, the preliminary results of the on-going test program are introduced. Also, the low cycle fatigue behaviors of 347 SS are compared with those of other grade of stainless steels. The effects of hot bending on the low cycle fatigue behavior of 347 SS were quantitatively evaluated. The fatigue life was compared with the estimated values per NUREG 6909 rev. 1. There are no distinct differences between NUREG 6909 and LCF tests. According to fractography and cross section analysis in progress, basically, the reduction of LCF life of 347 SS in PWR water was caused by operation of HIC mechanism. The cyclic stress responses shows that there is no secondary hardening in 330 .deg.C air and PWR water.

  20. Research and Application of Integration Design Environment Faced to CSCD

    Institute of Scientific and Technical Information of China (English)

    ZHAO Han; LI Yanfeng; DONG Yude

    2006-01-01

    Computer supported collaborative design(CSCD) technology has been applied extensively with intensive market competition. The key technologies and problems of CSCD are analyzed and a CSCD design frame faced to product design is established. Then a CSCD system faced to radar key components is founded with Pro/INTRALINK software and re-exploiting technology. Some key processes are also designed, such as database management, workflow programming, information communication, file release, conflict identification and safety management. These will provide a reference for constructing a cooperative design environment.

  1. Design research and the globalization of healthcare environments.

    Science.gov (United States)

    Shepley, Mardelle McCuskey; Song, Yilin

    2014-01-01

    Global healthcare practice has expanded in the past 20 years. At the same time the incorporation of research into the design process has gained prominence as a best practice among architects. The authors of this study investigated the status of design research in a variety of international settings. We intended to answer the question, "how pervasive is healthcare design research outside of the United States?" The authors reviewed the international literature on the design of healthcare facilities. More than 500 international studies and conference proceedings were incorporated in this literature review. A team of five research assistants searched multiple databases comparing approximately 16 keywords to geographic location. Some of those keywords included: evidence-based design, salutogenic design, design research, and healthcare environment. Additional articles were gathered by contacting prominent researchers and asking for their personal assessment of local health design research studies. While there are design researchers in most parts of the world, the majority of studies focus on the needs of populations in developed countries and generate guidelines that have significant cost and cultural implications that prohibit their implementation in developing countries. Additionally, the body of literature discussing the role of culture in healthcare environments is extremely limited. Design researchers must address the cultural implications of their studies. Additionally, we need to expand our research objectives to address healthcare design in countries that have not been previous considered. © 2014 Vendome Group, LLC.

  2. Using software interoperability to achieve a virtual design environment

    Science.gov (United States)

    Gregory, G. Groot; Koshel, R. John

    2005-09-01

    A variety of simulation tools, including optical design and analysis, have benefited by many years of evolution in software functionality and computing power, thus making the notion of virtual design environments a reality. To simulate the optical characteristics of a system, one needs to include optical performance, mechanical design and manufacturing aspects simultaneously. To date, no single software program offers a universal solution. One approach to achieve an integrated environment is to select tools that offer a high degree of interoperability. This allows the selection of the best tools for each aspect of the design working in concert to solve the problem. This paper discusses the issues of how to assemble a design environment and provides an example of a combination of tools for illumination design. We begin by offering a broad definition of interoperability from an optical analysis perspective. This definition includes aspects of file interchange formats, software communications protocols and customized applications. One example solution is proposed by combining SolidWorks1 for computer-aided design (CAD), TracePro2 for optical analysis and MATLAB3 as the mathematical engine for tolerance analysis. The resulting virtual tool will be applied to a lightpipe design task to illustrate how such a system can be used.

  3. Creating Learning Environment Connecting Engineering Design and 3D Printing

    Science.gov (United States)

    Pikkarainen, Ari; Salminen, Antti; Piili, Heidi

    Engineering education in modern days require continuous development in didactics, pedagogics and used practical methods. 3D printing provides excellent opportunity to connect different engineering areas into practice and produce learning by doing applications. The 3D-printing technology used in this study is FDM (Fused deposition modeling). FDM is the most used 3D-printing technology by commercial numbers at the moment and the qualities of the technology makes it popular especially in academic environments. For achieving the best result possible, students will incorporate the principles of DFAM (Design for additive manufacturing) into their engineering design studies together with 3D printing. This paper presents a plan for creating learning environment for mechanical engineering students combining the aspects of engineering design, 3D-CAD learning and AM (additive manufacturing). As a result, process charts for carrying out the 3D printing process from technological point of view and design process for AM from engineering design point of view were created. These charts are used in engineering design education. The learning environment is developed to work also as a platform for Bachelor theses, work-training environment for students, prototyping service centre for cooperation partners and source of information for mechanical engineering education in Lapland University of Applied Sciences.

  4. Ward design: creating a healing patient-environment.

    Science.gov (United States)

    Biley, F

    The drive for cost-effectiveness in hospital design over the decades has meant that minimal thought has been given to the effect of environments on patients' health. The author draws on research evidence to demonstrate how the appearance and ambience of patient areas can have profound effects on recovery patterns, and suggests that the creation of environments more conducive to healing need not incur heavy expense in time or money.

  5. Towards a Development Environment for Model Based Test Design

    OpenAIRE

    Jing, Han

    2008-01-01

    Within the UP IP I&V organization there is high focus on increasing the ability to predict product quality in a cost efficient way. Test automation has therefore been an important enabler for us. The IP test design environment is continuously evolving and the investigations will show which improvements that is most important to implement in short and long term. In Ericsson UP IP I&V, the test automation framework environments are severed to complete some process by automated method, f...

  6. Fatigue crack growth characteristics of a533 brade b glass i plate in an environment of high-temperature primary grade nuclear reactor water

    International Nuclear Information System (INIS)

    Mager, T.R.; Moon, D.M.; Landes, J.D.

    1976-01-01

    To characterize the effect of environment on crack growth rate properties of reactor pressure vessel materials, a program was initiated as part of the Heavy Section Steel Technology Program (HSST) to evaluate the effect of Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) primary grade coolant environments. The experiments included such variables as frequency, temperature and R ratio. This paper describes the investigation and presents the results of a fracture mechanics evaluation of the fatigue crack growth rate tests of A533 Grade B Class 1 steel plate material in an environment of primary reactor grade water at 550 0 F (288 0 C). A compliance crack growth monitoring technique was utilized to measure the crack growth. The compliance crack length monitor uses a linear variable differential transformer (LVDT) to measure the specimen front face displacement which is converted to crack length by the appropriate compliance calibration curve. The crack growth rate tests were conducted on constant load universal fatigue machines, under sinusoidal tension to tension loading conditions. Tests showed an increase in growth rates at a frequency of 1 cpm over previous results obtained at frequencies of 60 cpm and higher. This increase, the general character of the crack growth rate versus the $DELTA$K curve, and the results from fractographic studies, all indicated that stress corrosion cracking might have occurred for this material and environment. However, a specimen loaded statically in a PWR environment showed no static load crack growth. 13 refs

  7. The RHIC/AGS Online Model Environment: Design and Overview

    International Nuclear Information System (INIS)

    Satogata, T.; Brown, K.; Pilat, F.; Tafti Alai, A.; Tepikian, S.; Vanzeijtz

    1999-01-01

    An integrated online modeling environment is currently under development for use by AGS and RHIC physicists and commissioners. This environment combines the modeling efforts of both groups in a CDEV[1] client-server design, providing access to expected machine optics and physics parameters based on live and design machine settings. An abstract modeling interface has been designed as a set of adapters[2] around core computational modeling engines such as MAD and UAL/Teapot++[3]. This approach allows us to leverage existing survey, lattice, and magnet infrastructure, as well as easily incorporate new model engine developments. This paper describes the architecture of the RHIC/AGS modeling environment, including the application interface through CDEV and general tools for graphical interaction with the model using Tcl/Tk. Separate papers at this conference address the specifics of implementation and modeling experience for AGS and RHIC

  8. Design of Feedback in Interactive Multimedia Language Learning Environments

    Directory of Open Access Journals (Sweden)

    Vehbi Türel

    2012-01-01

    Full Text Available In interactive multimedia environments, different digital elements (i. e. video, audio, visuals, text, animations, graphics and glossary can be combined and delivered on the same digital computer screen (TDM 1997: 151, CCED 1987, Brett 1998: 81, Stenton 1998: 11, Mangiafico 1996: 46. This also enables effectively provision and presentation of feedback in pedagogically more efficient ways, which meets not only the requirement of different teaching and learning theories, but also the needs of language learners who vary in their learning-style preferences (Robinson 1991: 156, Peter 1994: 157f.. This study aims to bring out the pedagogical and design principles that might help us to more effectively design and customise feedback in interactive multimedia language learning environments. While so doing, some examples of thought out and customized computerised feedback from an interactive multimedia language learning environment, which were designed and created by the author of this study and were also used for language learning purposes, will be shown.

  9. Empirical studies of design software: Implications for software engineering environments

    Science.gov (United States)

    Krasner, Herb

    1988-01-01

    The empirical studies team of MCC's Design Process Group conducted three studies in 1986-87 in order to gather data on professionals designing software systems in a range of situations. The first study (the Lift Experiment) used thinking aloud protocols in a controlled laboratory setting to study the cognitive processes of individual designers. The second study (the Object Server Project) involved the observation, videotaping, and data collection of a design team of a medium-sized development project over several months in order to study team dynamics. The third study (the Field Study) involved interviews with the personnel from 19 large development projects in the MCC shareholders in order to study how the process of design is affected by organizationl and project behavior. The focus of this report will be on key observations of design process (at several levels) and their implications for the design of environments.

  10. Aerospace Systems Design in NASA's Collaborative Engineering Environment

    Science.gov (United States)

    Monell, Donald W.; Piland, William M.

    1999-01-01

    Past designs of complex aerospace systems involved an environment consisting of collocated design teams with project managers, technical discipline experts, and other experts (e.g. manufacturing and systems operations). These experts were generally qualified only on the basis of past design experience and typically had access to a limited set of integrated analysis tools. These environments provided less than desirable design fidelity, often lead to the inability of assessing critical programmatic and technical issues (e.g., cost risk, technical impacts), and generally derived a design that was not necessarily optimized across the entire system. The continually changing, modern aerospace industry demands systems design processes that involve the best talent available (no matter where it resides) and access to the best design and analysis tools. A solution to these demands involves a design environment referred to as collaborative engineering. The collaborative engineering environment evolving within the National Aeronautics and Space Administration (NASA) is a capability that enables the Agency's engineering infrastructure to interact and use the best state-of-the-art tools and data across organizational boundaries. Using collaborative engineering, the collocated team is replaced with an interactive team structure where the team members are geographically distributed and the best engineering talent can be applied to the design effort regardless of physical location. In addition, a more efficient, higher quality design product is delivered by bringing together the best engineering talent with more up-to-date design and analysis tools. These tools are focused on interactive, multidisciplinary design and analysis with emphasis on the complete life cycle of the system, and they include nontraditional, integrated tools for life cycle cost estimation and risk assessment. NASA has made substantial progress during the last two years in developing a collaborative

  11. Aerospace Systems Design in NASA's Collaborative Engineering Environment

    Science.gov (United States)

    Monell, Donald W.; Piland, William M.

    2000-07-01

    Past designs of complex aerospace systems involved an environment consisting of collocated design teams with project managers, technical discipline experts, and other experts (e.g., manufacturing and systems operations). These experts were generally qualified only on the basis of past design experience and typically had access to a limited set of integrated analysis tools. These environments provided less than desirable design fidelity, often led to the inability of assessing critical programmatic and technical issues (e.g., cost, risk, technical impacts), and generally derived a design that was not necessarily optimized across the entire system. The continually changing, modern aerospace industry demands systems design processes that involve the best talent available (no matter where it resides) and access to the best design and analysis tools. A solution to these demands involves a design environment referred to as collaborative engineering. The collaborative engineering environment evolving within the National Aeronautics and Space Administration (NASA) is a capability that enables the Agency's engineering infrastructure to interact and use the best state-of-the-art tools and data across organizational boundaries. Using collaborative engineering, the collocated team is replaced with an interactive team structure where the team members are geographically distributed and the best engineering talent can be applied to the design effort regardless of physical location. In addition, a more efficient, higher quality design product is delivered by bringing together the best engineering talent with more up-to-date design and analysis tools. These tools are focused on interactive, multidisciplinary design and analysis with emphasis on the complete life cycle of the system, and they include nontraditional, integrated tools for life cycle cost estimation and risk assessment. NASA has made substantial progress during the last two years in developing a collaborative

  12. In vitro fatigue tests and in silico finite element analysis of dental implants with different fixture/abutment joint types using computer-aided design models.

    Science.gov (United States)

    Yamaguchi, Satoshi; Yamanishi, Yasufumi; Machado, Lucas S; Matsumoto, Shuji; Tovar, Nick; Coelho, Paulo G; Thompson, Van P; Imazato, Satoshi

    2018-01-01

    The aim of this study was to evaluate fatigue resistance of dental fixtures with two different fixture-abutment connections by in vitro fatigue testing and in silico three-dimensional finite element analysis (3D FEA) using original computer-aided design (CAD) models. Dental implant fixtures with external connection (EX) or internal connection (IN) abutments were fabricated from original CAD models using grade IV titanium and step-stress accelerated life testing was performed. Fatigue cycles and loads were assessed by Weibull analysis, and fatigue cracking was observed by micro-computed tomography and a stereomicroscope with high dynamic range software. Using the same CAD models, displacement vectors of implant components were also analyzed by 3D FEA. Angles of the fractured line occurring at fixture platforms in vitro and of displacement vectors corresponding to the fractured line in silico were compared by two-way ANOVA. Fatigue testing showed significantly greater reliability for IN than EX (pimplant fixture platforms. FEA demonstrated that crack lines of both implant systems in vitro were observed in the same direction as displacement vectors of the implant fixtures in silico. In silico displacement vectors in the implant fixture are insightful for geometric development of dental implants to reduce complex interactions leading to fatigue failure. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  13. Design and Decorative Art in Shaping of Architectural Environment Image

    Science.gov (United States)

    Shabalina, N. M.

    2017-11-01

    The relevance of the topic is determined by the dynamic development of the promising branch, i.e. the architectural environment design, which requires, on the one hand, consideration of the morphology and typology of this art form, on the other hand, the specificity of the architectural environment artistic image. The intensive development of innovative computer technologies and materials in modern engineering, improvement of the information communications forms in their totality has led to the application of new methods in design and construction which, in their turn, have required the development of additional methods for content and context analysis in the integrated assessment of socially significant architectural environments. In the modern culture, correlative processes are steadily developing leading us to a new understanding of the interaction of architecture, decorative art and design. Their rapprochement at the morphological level has been noted which makes it possible to reveal a specific method of synthesis and similarity. The architecture of postmodern styles differs in its bionic form becoming an interactive part of the society and approaching its structural qualities with painting, sculpture, and design. In the modern world, these processes acquire multi-valued semantic nuances, expand the importance of associativity and dynamic processuality in the perception of environmental objects and demand the development of new approaches to the assessment of the architectural design environment. Within the framework of the universal paradigm of modern times the concept of the world develops as a set of systems that live according to the self-organization laws.

  14. An Experimental Investigation of the Effects of Vacuum Environment on the Fatigue Life, Fatigue-Crack-Growth Behavior, and Fracture Toughness of 7075-T6 Aluminum Alloy. Ph.D. Thesis - North Carolina State Univ.

    Science.gov (United States)

    Hudson, C. M.

    1972-01-01

    Axial load fatigue life, fatigue-crack propagation, and fracture toughness tests were conducted on 0.090-inch thick specimens made of 7075-T6 aluminum alloy. The fatigue life and fatigue-crack propagation experiments were conducted at a stress ratio of 0.02. Maximum stresses ranged from 33 to 60 ksi in the fatigue life experiments, and from 10 to 40 ksi in the fatigue-crack propagation experiments, and fatigue life experiments were conducted at gas pressures of 760, 0.5, 0.05, and 0.00000005 torr. Fatigue-crack-growth and fracture toughness experiments were conducted at gas pressures of 760 and 5 x 10 to the minus 8th power torr. Residual stress measurements were made on selected fatigue life specimens to determine the effect of such stresses on fatigue life. Analysis of the results from the fatigue life experiments indicated that fatigue life progressively increased as the gas pressure decreased. Analysis of the results from the fatigue-crack-growth experiments indicates that at low values of stress-intensity range, the fatigue crack growth rates were approximately twice as high in air as in vacuum. Fracture toughness data showed there was essentially no difference in the fracture toughness of 7075-T6 in vacuum and in air.

  15. Effects of fatigue and environment on residual strengths of center-cracked graphite/epoxy buffer strip panels

    Science.gov (United States)

    Bigelow, Catherine A.

    1989-01-01

    The effects of fatigue, moisture conditioning, and heating on the residual tension strengths of center-cracked graphite/epoxy buffer strip panels were evaluated using specimens made with T300/5208 graphite epoxy in a 16-ply quasi-isotropic layup, with two different buffer strip materials, Kevlar-49 or S-glass. It was found that, for panels subjected to fatigue loading, the residual strengths were not significantly affected by the fatigue loading, the number of repetitions of the loading spectrum, or the maximum strain level. The moisture conditioning reduced the residual strengths of the S-glass buffer strip panels by 10 to 15 percent below the ambient results, but increased the residual strengths of the Kevlar-49 buffer strip panels slightly. For both buffer strip materials, the heat increased the residual strengths of the buffer strip panels slightly over the ambient results.

  16. Influence of temperature, environment, and thermal aging on the continuous cycle fatigue behavior of Hastelloy X and Inconel 617

    International Nuclear Information System (INIS)

    Strizak, J.P.; Brinkman, C.R.; Booker, M.K.; Rittenhouse, P.L.

    1982-04-01

    Results are presented for strain-controlled fatigue and tensile tests for two nickel-base, solution-hardened reference structural alloys for use in several High-Temperature Gas-Cooled Reactor (HTGR) concepts. These alloys, Hastelloy X and Inconel 617, were tested from room temperature to 871 0 C in air and impure helium. Materials were tested in both the solution-annealed and the preaged conditios, in which aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are given between the strain-controlled fatigue lives of these and several other commonly used alloys, all tested at 538 0 C. An analysis is also presented of the continuous cycle fatigue data obtained from room temperature to 427 0 C for Hastelloy G, Hastelloy X, Hastelloy C-276, and Hastelloy C-4, an effort undertaken in support of ASME code development

  17. Health by Design: Interweaving Health Promotion into Environments and Settings

    Science.gov (United States)

    Springer, Andrew E.; Evans, Alexandra E.; Ortuño, Jaquelin; Salvo, Deborah; Varela Arévalo, Maria Teresa

    2017-01-01

    The important influence of the environmental context on health and health behavior—which includes place, settings, and the multiple environments within place and settings—has directed health promotion planners from a focus solely on changing individuals, toward a focus on harnessing and changing context for individual and community health promotion. Health promotion planning frameworks such as Intervention Mapping provide helpful guidance in addressing various facets of the environmental context in health intervention design, including the environmental factors that influence a given health condition or behavior, environmental agents that can influence a population’s health, and environmental change methods. In further exploring how to harness the environmental context for health promotion, we examine in this paper the concept of interweaving of health promotion into context, defined as weaving or blending together health promotion strategies, practices, programs, and policies to fit within, complement, and build from existing settings and environments. Health promotion interweaving stems from current perspectives in health intervention planning, improvement science and complex systems thinking by guiding practitioners from a conceptualization of context as a backdrop to intervention, to one that recognizes context as integral to the intervention design and to the potential to directly influence health outcomes. In exploring the general approach of health promotion interweaving, we examine selected theoretical and practice-based interweaving concepts in relation to four key environments (the policy environment, the information environment, the social/cultural/organizational environment, and the physical environment), followed by evidence-based and practice-based examples of health promotion interweaving from the literature. Interweaving of health promotion into context is a common practice for health planners in designing health promotion interventions, yet

  18. Squidy : a Zoomable Design Environment for Natural User Interfaces

    OpenAIRE

    König, Werner A.; Rädle, Roman; Reiterer, Harald

    2009-01-01

    We introduce the interaction library Squidy, which eases the design of natural user interfaces by unifying relevant frameworks and toolkits in a common library. Squidy provides a central design environment based on high-level visual data flow programming combined with zoomable user interface concepts. The user interface offers a Simple visual language and a collection of ready-to-use devices, filters and interaction techniques. The concept of semantic zooming enables nevertheless access to mo...

  19. Designing Interactive Storytelling: A Virtual Environment for Personal Experience Narratives

    OpenAIRE

    Ladeira , Ilda; Marsden , Gary; Green , Lesley

    2011-01-01

    Part 1: Long and Short Papers; International audience; We describe an ongoing collaboration with the District Six Museum, in Cape Town, aimed at designing a storytelling prototype for preserving personal experience narratives. We detail the design of an interactive virtual environment (VE) which was inspired by a three month ethnography of real-life oral storytelling. The VE places the user as an audience member in a virtual group listening to two storytelling agents capable of two forms of i...

  20. Living closer to the environment: Housing design concept

    Directory of Open Access Journals (Sweden)

    Kosorić Vesna

    2011-01-01

    Full Text Available The main idea of this design concept is to strengthen the relationship and understanding between a man - resident and his environment. Residents are separated from the outdoor environment by glazing, which enables constant observation of environment from nearly all points of indoor space, encouraging positive feelings towards external world and understanding of the fragility of biosphere. Care for the environment should become a part of a man's nature and way of living, and it is the people who are expected to become the driving force of positive global changes towards sustainable development. The semisphere-like single family house of 14m in diameter has a multifunctional, multi-layer 'active' facade envelope. The envelope ensures constant visual contact of residents with the whole surroundings, while still providing comfort. The living space of the house reflects natural shapes which are organic rather than rectangular. Such indoor space becomes a part of the environment, rather than being protected, distanced and isolated from it. The house is designed to use solar energy 'passively' by absorption through insulated glazed envelope and 'actively' by outer skin layer on the first floor, made of stripes of flat semi-transparent polycrystalline photovoltaic (PV panels. In addition to its constructive role, the concrete core of the house acts as thermal mass and enables absorption and accumulation of thermal energy. The developed housing concept is applicable in different urban-design units and sets.

  1. Fatigue-crack growth correlations for design and analysis of stainless steel components

    International Nuclear Information System (INIS)

    James, L.A.

    1981-10-01

    A relatively large collection of fatigue-crack growth results for annealed Types 304 and 316 stainless steels over a wide range of temperature was processed and analyzed in a consistent way. Only data that satisfied the criteria of ASTM E647-82 was retained and used in the statistical treatments that followed. Linear least-squares regression equations and 95% confidence intervals were fitted through the results for each material/temperature set. The regression results (and their associated limits of validity) provide useful equations for the analysis of structural components. Overlap (or the lack of overlap) of the confidence intervals was employed as a criterion as to whether the results for Types 304 and 316 should be separated into discrete sets, and on this basis it was concluded that the two alloys should be treated separately. 38 references, 16 figures, 1 table

  2. Knowledge management in an integrated design and engineering environment

    NARCIS (Netherlands)

    Reefman, R.J.B.; Van Nederveen, G.A.

    2012-01-01

    Organisations and / or disciplines in Building and Construction projects are usually working in their own design and engineering environments and using their own Building Information Models (BIM). The discipline models are merged into a project BIM which is mainly used to check for interferences or

  3. Ethics, Design and Planning of the Built Environment

    NARCIS (Netherlands)

    Basta, C.; Moroni, S.

    2013-01-01

    The book proposes a set of original contributions in research areas shared by planning theory, architectural research, design and ethical inquiry. The contributors gathered in 2010 at the Ethics of the Built Environment seminar organized by the editors at Delft University of Technology. Both

  4. Designing for social interaction in open-ended play environments

    NARCIS (Netherlands)

    de Valk, L.; Bekker, T.; Eggen, J.H.

    2015-01-01

    Interactive technology is becoming more strongly integrated in innovative play solutions. As play is often a social experience, understanding the dynamic social context in which such play takes place is an essential step in designing new interactive play environments. In this paper, we explore the

  5. Designing for Learning: Online Social Networks as a Classroom Environment

    Science.gov (United States)

    Casey, Gail; Evans, Terry

    2011-01-01

    This paper deploys notions of emergence, connections, and designs for learning to conceptualize high school students' interactions when using online social media as a learning environment. It makes links to chaos and complexity theories and to fractal patterns as it reports on a part of the first author's action research study, conducted while she…

  6. Designing a Virtual-Reality-Based, Gamelike Math Learning Environment

    Science.gov (United States)

    Xu, Xinhao; Ke, Fengfeng

    2016-01-01

    This exploratory study examined the design issues related to a virtual-reality-based, gamelike learning environment (VRGLE) developed via OpenSimulator, an open-source virtual reality server. The researchers collected qualitative data to examine the VRGLE's usability, playability, and content integration for math learning. They found it important…

  7. Liner shipping hub network design in a competitive environment

    DEFF Research Database (Denmark)

    Gelareh, Shahin; Nickel, Stefan; Pisinger, David

    2010-01-01

    A mixed integer programming formulation is proposed for hub-and-spoke network design in a competitive environment. It addresses the competition between a newcomer liner service provider and an existing dominating operator, both operating on hub-and-spoke networks. The newcomer company maximizes i...

  8. The Mystery Tour; Exploring the Designed Environment with Children.

    Science.gov (United States)

    Balaban, Richard C.; St. Clair, Alison Igo

    The Mystery Tour is a multi-sensory approach to the man-made environment. It is designed to acquaint children with historical significance of buildings and architecture and thus prepare them to participate in decisions concerning historical preservation. Developed through a grant from the national Endowment for the Arts, the Mystery Tour guides…

  9. Instructional Design Issues in a Distributed Collaborative Engineering Design (CED) Instructional Environment

    Science.gov (United States)

    Koszalka, Tiffany A.; Wu, Yiyan

    2010-01-01

    Changes in engineering practices have spawned changes in engineering education and prompted the use of distributed learning environments. A distributed collaborative engineering design (CED) course was designed to engage engineering students in learning about and solving engineering design problems. The CED incorporated an advanced interactive…

  10. Design of wireless communication systems for nuclear power plant environments

    International Nuclear Information System (INIS)

    Kadri, A.

    2007-01-01

    The problem of low-SNR (Signal-to-Noise ratio) digital communication system design in man-made electromagnetic environment within a nuclear power plant is addressed. A canonical structure of the low-SNR receiver is derived and analyzed for its bit error rate performance. The parameters that affect the error rate performance are identified and illustrated. Several well-known digital modulations are considered. It is shown that the receiver structure is dependent on the first-order probability density function of the noise environment. Thus, we offer comments for its robust implementation and its effect on bit error rate performance. We model the EM environment within the nuclear power plant to be e - mixture model, the parameters of which can be estimated to fit the environment. (author)

  11. Influence of PbBi environment on the low-cycle fatigue behavior of SNS target container materials

    International Nuclear Information System (INIS)

    Kalkhof, D.; Grosse, M.

    2003-01-01

    The low-cycle fatigue (LCF) behavior of the stainless steel 316L and the 10.5Cr-steel Manet-II was investigated at 260 deg. C in air and in stagnant lead-bismuth (PbBi). At low-strain levels, the fatigue lives for 316L in PbBi and air were comparable. At total strain amplitudes of 0.50% and higher a weak influence of PbBi was observed. In contrast to 316L, the results of LCF tests for Manet-II in PbBi showed a significant reduction of lifetime for all applied strain amplitudes. In the worst case the cycle number to crack initiation was reduced by a factor of ∼7 compared with the comparable test in air. For the low-strain amplitude of 0.30%, fatigue tests conducted at a frequency of 0.1 Hz had shorter fatigue lives than at a frequency of 1.0 Hz. For Manet-II the crack propagation in PbBi was much faster than in air, and failure immediate followed the formation of the first macroscopic crack

  12. Executive control systems in the engineering design environment

    Science.gov (United States)

    Hurst, P. W.; Pratt, T. W.

    1985-01-01

    Executive Control Systems (ECSs) are software structures for the unification of various engineering design application programs into comprehensive systems with a central user interface (uniform access) method and a data management facility. Attention is presently given to the most significant determinations of a research program conducted for 24 ECSs, used in government and industry engineering design environments to integrate CAD/CAE applications programs. Characterizations are given for the systems' major architectural components and the alternative design approaches considered in their development. Attention is given to ECS development prospects in the areas of interdisciplinary usage, standardization, knowledge utilization, and computer science technology transfer.

  13. ELISA, a demonstrator environment for information systems architecture design

    Science.gov (United States)

    Panem, Chantal

    1994-01-01

    This paper describes an approach of reusability of software engineering technology in the area of ground space system design. System engineers have lots of needs similar to software developers: sharing of a common data base, capitalization of knowledge, definition of a common design process, communication between different technical domains. Moreover system designers need to simulate dynamically their system as early as possible. Software development environments, methods and tools now become operational and widely used. Their architecture is based on a unique object base, a set of common management services and they host a family of tools for each life cycle activity. In late '92, CNES decided to develop a demonstrative software environment supporting some system activities. The design of ground space data processing systems was chosen as the application domain. ELISA (Integrated Software Environment for Architectures Specification) was specified as a 'demonstrator', i.e. a sufficient basis for demonstrations, evaluation and future operational enhancements. A process with three phases was implemented: system requirements definition, design of system architectures models, and selection of physical architectures. Each phase is composed of several activities that can be performed in parallel, with the provision of Commercial Off the Shelves Tools. ELISA has been delivered to CNES in January 94, currently used for demonstrations and evaluations on real projects (e.g. SPOT4 Satellite Control Center). It is on the way of new evolutions.

  14. The role of environment design in an educational Multi-User Virtual Environment

    DEFF Research Database (Denmark)

    Papachristos, Nikiforos; Vrellis, Ioannis; Natsis, Antonios

    2014-01-01

    This paper presents empirical results from an exploratory study conducted in an authentic educational situation with preservice education students enrolled in an undergraduate course, which was partially taught in Second Life. The study investigated the effect of environment design on presence, l...... necessary for all students to become familiar with the virtual environment and possible time losses due to technical issues. This study could act as support to construct and test hypotheses regarding the role of educational setting design in teaching and learning in MUVEs....

  15. Kohonen mapping of the crack growth under fatigue loading conditions of stainless steels in BWR environments and of nickel alloys in PWR environments

    International Nuclear Information System (INIS)

    Urquidi-Macdonald, Mirna

    2008-01-01

    In this study, crack growth rate data under fatigue loading conditions generated by Argonne National Laboratories and published in 2006 were analyzed [O.K. Chopra, B. Alexandreanu, E.E. Gruber, R.S. Daum, W.J. Shack, Argonne National Laboratory, NUREG CR 6891-series ANL 04/20, Crack Growth Rates of Austenitic Stainless Steel Weld Heat Affected Zone in BWR Environments, January, 2006; B. Alexandreanu, O.K. Chopra, H.M. Chung, E.E. Gruber, W.K. Soppet, R.W. Strain, W.J. Shack, Environmentally Assisted Cracking in Light Water Reactors, vol. 34 in the NUREG/CR-4667 series annual report of Argonne National Laboratory program studies for Calendar (Annual Report 2003). Manuscript Completed: May 2005, Date Published: May 2006], and reported by DoE [B. Alexandreanu, O.K. Chopra, W.J. Shack, S. Crane, H.J. Gonzalez, NRC, Crack Growth Rates and Metallographic Examinations of Alloy 600 and Alloy 82/182 from Field Components and Laboratory Materials Tested in PWR Environments, NUREG/CR-6964, May 2008]. The data collected were measured on austenitic stainless steels in BWR (boiling water reactor) environments and on nickel alloys in PWR (pressurized water reactor) environments. The data collected contained information on material composition, temperature, conductivity of the environment, oxygen concentration, irradiated sample information, weld information, electrochemical potential, load ratio, rise time, hydrogen concentration, hold time, down time, maximum stress intensity factor (K max ), stress intensity range (ΔK max ), crack length, and crack growth rates (CGR). Each position on that Kohonen map is called a cell. A Kohonen map clusters vectors of information by 'similarities.' Vectors of information were formed using the metal composition, followed by the environmental conditions used in each experiments, and finally followed by the crack growth rate (CGR) measured when a sample of pre-cracked metal is set in an environment and the sample is cyclically loaded

  16. Fictional space in participatory design of engaging interactive environments

    DEFF Research Database (Denmark)

    Dindler, Christian

    2010-01-01

    practices of visitors and museum knowledge. The second and larger part of the contribution addresses the issue of shaping design inquiries. This part is summarized through the overarching notion of fictional space denoting a perspective on the creation of a design space where established norms...... spaces for museums and science centres. The dissertation is composed of seven research papers framed by a general overview that summarises the arguments made in the papers and outlines related work and research method. The contribution reflects a dual yet intertwined concern for understanding engagement...... in exhibition spaces and shaping design inquiries around the notion of engaging interactive environments. The first part of the contribution relates to conceptualising aspects of engagement in relation to interactive environments. The perspective of participatory engagement is presented as an overarching...

  17. DESIGN COORDINATION IN DISTRIBUTED ENVIRONMENTS USING VIRTUAL REALITY SYSTEMS

    Directory of Open Access Journals (Sweden)

    Rusdi HA

    2003-01-01

    Full Text Available This paper presents a research project, which investigates the use of virtual reality and computer communication technology to facilitate building design coordination in distributed environments. The emphasis of the system, called VR-based DEsign COordination (VRDECO is providing a communication tool that can be used by remote designers for settling ideas before they fully engage in concurrent engineering environments. VRDECO provides the necessary design tools, library of building elements and communication procedures, for designers from remote places to perform and coordinate their initial tasks. It has been implemented using available commercial software packages, and is used in designing a simple house. VRDECO facilitates the creation a preliminary design and simple communication with the client. There are, however, some difficulties in the development of the full version of VRDECO, i.e.: creating an adequate number of building elements, building specification database with a sufficient number of choices, and establishing a systematic rule to determine the parts of a building that are updateable.

  18. Fatigue crack growth threshold as a design criterion - statistical scatter and load ratio in the Kitagawa-Takahashi diagram

    International Nuclear Information System (INIS)

    Kolitsch, S.; Gänser, H.-P.; Maierhofer, J.; Pippan, R.

    2016-01-01

    Cracks in components reduce the endurable stress so that the endurance limit obtained from common smooth fatigue specimens cannot be used anymore as a design criterion. In such cases, the Kitagawa-Takahashi diagram can be used to predict the admissible stress range for infinite life, at a given crack length and stress range. This diagram is constructed for a single load ratio R. However, in typical mechanical engineering applications, the load ratio R varies widely due to the applied load spectra and residual stresses. In the present work an extended Kitagawa-Takahashi diagram accounting for crack length, crack extension and load ratio is constructed. To describe the threshold behaviour of short cracks, a master resistance curve valid for a wide range of steels is developed using a statistical approach. (paper)

  19. 3-D finite element stress analysis for fatigue design and evaluation: a parametric study of MOV(Motor Operated Valve)

    International Nuclear Information System (INIS)

    Kim, Hyeong Keun; Lee, Sang Min; Chang, Yoon Suk; Choi, Jae Boong; Kim, Young Jin; Kim, Yun Jae

    2004-01-01

    In this paper, a new procedure is proposed to accomplish the primary plus secondary stress(P+Q) at the 'structural element' instead of 'transition element'. For the P+Q evaluation, the calculated stresses by FEA are linearized along a stress classification line to extract the stress category, then the stress intensity is calculated to compare with the 3Sm limit. Also, in this paper, the 'design by analysis' criteria, adopted fundamental concepts and a new approach to calculate Ke factors are explained. The new procedure combined with 3-D FEA has been applied to motor operated valve in order to the over conservatism and the rack of margin. The evaluation results show a good applicability and can be utilized for fatigue life evaluation by using P+Q

  20. Designing equipment for use in gamma radiation environments

    International Nuclear Information System (INIS)

    Vandergriff, K.U.

    1990-05-01

    High levels of gamma radiation are known to cause degradation in a variety of materials and components. When designing systems to operate in a high radiation environment, special precautions and procedures should be followed. This report (1) outlines steps that should be followed in designing equipment and (2) explains the general effects of radiation on various engineering materials and components. Much information exists in the literature on radiation effects upon materials. However, very little information is available to give the designer a step-by-step process for designing systems that will be subject to high levels of gamma radiation, such as those found in a nuclear fuel reprocessing facility. In this report, many radiation effect references are relied upon to aid in the design of components and systems. 11 refs., 4 tabs

  1. Mixed-mode fatigue fracture of adhesive joints in harsh environments and nonlinear viscoelastic modeling of the adhesive

    Science.gov (United States)

    Arzoumanidis, Alexis Gerasimos

    A four point bend, mixed-mode, reinforced, cracked lap shear specimen experimentally simulated adhesive joints between load bearing composite parts in automotive components. The experiments accounted for fatigue, solvent and temperature effects on a swirled glass fiber composite adherend/urethane adhesive system. Crack length measurements based on compliance facilitated determination of da/dN curves. A digital image processing technique was also utilized to monitor crack growth from in situ images of the side of the specimen. Linear elastic fracture mechanics and finite elements were used to determine energy release rate and mode-mix as a function of crack length for this specimen. Experiments were conducted in air and in a salt water bath at 10, 26 and 90°C. Joints tested in the solvent were fully saturated. In air, both increasing and decreasing temperature relative to 26°C accelerated crack growth rates. In salt water, crack growth rates increased with increasing temperature. Threshold energy release rate is shown to be the most appropriate design criteria for joints of this system. In addition, path of the crack is discussed and fracture surfaces are examined on three length scales. Three linear viscoelastic properties were measured for the neat urethane adhesive. Dynamic tensile compliance (D*) was found using a novel extensometer and results were considerably more accurate and precise than standard DMTA testing. Dynamic shear compliance (J*) was determined using an Arcan specimen. Dynamic Poisson's ratio (nu*) was extracted from strain gage data analyzed to include gage reinforcement. Experiments spanned three frequency decades and isothermal data was shifted by time-temperature superposition to create master curves spanning thirty decades. Master curves were fit to time domain Prony series. Shear compliance inferred from D* and nu* compared well with measured J*, forming a basis for finding the complete time dependent material property matrix for this

  2. Kinetics of Accumulation of Damage in Surface Layers of Lithium-Containing Aluminum Alloys in Fatigue Tests with Rigid Loading Cycle and Corrosive Effect of Environment

    Science.gov (United States)

    Morozova, L. V.; Zhegina, I. P.; Grigorenko, V. B.; Fomina, M. A.

    2017-07-01

    High-resolution methods of metal physics research including electron, laser and optical microscopy are used to study the kinetics of the accumulation of slip lines and bands and the corrosion damage in the plastic zone of specimens of aluminum-lithium alloys 1441 and B-1469 in rigid-cycle fatigue tests under the joint action of applied stresses and corrosive environment. The strain parameters (the density of slip bands, the sizes of plastic zones near fracture, the surface roughness in singled-out zones) and the damage parameters (the sizes of pits and the pitting area) are evaluated.

  3. Intelligent Agents for Design and Synthesis Environments: My Summary

    Science.gov (United States)

    Norvig, Peter

    1999-01-01

    This presentation gives a summary of intelligent agents for design synthesis environments. We'll start with the conclusions, and work backwards to justify them. First, an important assumption is that agents (whatever they are) are good for software engineering. This is especially true for software that operates in an uncertain, changing environment. The "real world" of physical artifacts is like that: uncertain in what we can measure, changing in that things are always breaking down, and we must interact with non-software entities. The second point is that software engineering techniques can contribute to good design. There may have been a time when we wanted to build simple artifacts containing little or no software. But modern aircraft and spacecraft are complex, and rely on a great deal of software. So better software engineering leads to better designed artifacts, especially when we are designing a series of related artifacts and can amortize the costs of software development. The third point is that agents are especially useful for design tasks, above and beyond their general usefulness for software engineering, and the usefulness of software engineering to design.

  4. A combined wear-fatigue design methodology for fretting in the pressure armour layer of flexible marine risers

    OpenAIRE

    O'Halloran, S.M.; Shipway, P.H.; Connaire, A.D.; Leen, Sean B.; Harte, A.M.

    2017-01-01

    This paper presents a combined experimental and computational methodology for fretting wear-fatigue prediction of pressure armour wire in flexible marine risers. Fretting wear, friction and fatigue parameters of pressure armour material have been characterised experimentally. A combined fretting wear-fatigue finite element model has been developed using an adaptive meshing technique and the effect of bending-induced tangential slip has been characterised. It has been shown that a surface dama...

  5. Fracture mechanics of ceramics. Vol. 8. Microstructure, methods, design, and fatigue

    International Nuclear Information System (INIS)

    Bradt, R.C.; Evans, A.G.; Hasselman, D.P.H.; Lange, F.F.

    1986-01-01

    This paper presents information on the following topics: fracture mechanics and microstructures; non-lubricated sliding wear of Al 2 O 3 , PSZ and SiC; mixed-mode fracture of ceramics; some fracture properties of alumina-containing electrical porcelains; transformation toughening in the Al 2 O 3 -Cr 2 O 3 /ZrO 2 -HfO 2 system; strength toughness relationships for transformation toughened ceramics; tensile strength and notch sensitivity of Mg-PSZ; fracture mechanisms in lead zirconate titanate ceramics; loading-unloading techniques for determining fracture parameters of brittle materials utilizing four-point bend, chevron-notched specimens; application of the potential drop technique to the fracture mechanics of ceramics; ceramics-to-metal bonding from a fracture mechanics perspective; observed changes in fracture strength following laser irradiation and ion beam mixing of Ni overlayers on sintered alpha-SiC; crack growth in single-crystal silicon; a fracture mechanics and non-destructive evaluation investigation of the subcritical-fracture process in rock; slow crack growth in sintered silicon nitride; uniaxial tensile fatigue testing of sintered silicon carbide under cyclic temperature change; and effect of surface corrosion on glass fracture

  6. Adrenal Fatigue

    Science.gov (United States)

    ... Search Featured Resource New Mobile App DOWNLOAD Adrenal Fatigue October 2017 Download PDFs English Editors Irina Bancos, MD Additional Resources Mayo Clinic What is adrenal fatigue? The term “adrenal fatigue” has been used to ...

  7. Fatigue approach for addressing environmental effects in fatigue usage calculation

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelm, Paul; Rudolph, Juergen [AREVA GmbH, Erlangen (Germany); Steinmann, Paul [Erlangen-Nuremberg Univ., erlangen (Germany). Chair of Applied Mechanics

    2015-04-15

    Laboratory tests consider simple trapezoidal, triangle, and sinusoidal signals. However, actual plant components are characterized by complex loading patterns and periods of holds. Fatigue tests in water environment show, that the damage from a realistic strain variation or the presence of hold-times within cyclic loading results in an environmental reduction factor (Fen) only half that of a simple waveform. This study proposes a new fatigue approach for addressing environmental effects in fatigue usage calculation for class 1 boiler and pressure vessel reactor components. The currently accepted method of fatigue assessment has been used as a base model and all cycles, which have been comparable with realistic fatigue tests, have been excluded from the code-based fatigue calculation and evaluated directly with the test data. The results presented show that the engineering approach can successfully be integrated in the code-based fatigue assessment. The cumulative usage factor can be reduced considerably.

  8. Fatigue approach for addressing environmental effects in fatigue usage calculation

    International Nuclear Information System (INIS)

    Wilhelm, Paul; Rudolph, Juergen; Steinmann, Paul

    2015-01-01

    Laboratory tests consider simple trapezoidal, triangle, and sinusoidal signals. However, actual plant components are characterized by complex loading patterns and periods of holds. Fatigue tests in water environment show, that the damage from a realistic strain variation or the presence of hold-times within cyclic loading results in an environmental reduction factor (Fen) only half that of a simple waveform. This study proposes a new fatigue approach for addressing environmental effects in fatigue usage calculation for class 1 boiler and pressure vessel reactor components. The currently accepted method of fatigue assessment has been used as a base model and all cycles, which have been comparable with realistic fatigue tests, have been excluded from the code-based fatigue calculation and evaluated directly with the test data. The results presented show that the engineering approach can successfully be integrated in the code-based fatigue assessment. The cumulative usage factor can be reduced considerably.

  9. Conservatism implications of shock test tailoring for multiple design environments

    Science.gov (United States)

    Baca, Thomas J.; Bell, R. Glenn; Robbins, Susan A.

    1987-01-01

    A method for analyzing shock conservation in test specifications that have been tailored to qualify a structure for multiple design environments is discussed. Shock test conservation is qualified for shock response spectra, shock intensity spectra and ranked peak acceleration data in terms of an Index of Conservation (IOC) and an Overtest Factor (OTF). The multi-environment conservation analysis addresses the issue of both absolute and average conservation. The method is demonstrated in a case where four laboratory tests have been specified to qualify a component which must survive seven different field environments. Final judgment of the tailored test specification is shown to require an understanding of the predominant failure modes of the test item.

  10. The Virtual Environment for Reactor Applications (VERA): Design and architecture

    International Nuclear Information System (INIS)

    Turner, John A.; Clarno, Kevin; Sieger, Matt; Bartlett, Roscoe; Collins, Benjamin; Pawlowski, Roger; Schmidt, Rodney; Summers, Randall

    2016-01-01

    VERA, the Virtual Environment for Reactor Applications, is the system of physics capabilities being developed and deployed by the Consortium for Advanced Simulation of Light Water Reactors (CASL). CASL was established for the modeling and simulation of commercial nuclear reactors. VERA consists of integrating and interfacing software together with a suite of physics components adapted and/or refactored to simulate relevant physical phenomena in a coupled manner. VERA also includes the software development environment and computational infrastructure needed for these components to be effectively used. We describe the architecture of VERA from both software and numerical perspectives, along with the goals and constraints that drove major design decisions, and their implications. We explain why VERA is an environment rather than a framework or toolkit, why these distinctions are relevant (particularly for coupled physics applications), and provide an overview of results that demonstrate the use of VERA tools for a variety of challenging applications within the nuclear industry.

  11. The Virtual Environment for Reactor Applications (VERA): Design and architecture

    Energy Technology Data Exchange (ETDEWEB)

    Turner, John A., E-mail: turnerja@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Clarno, Kevin; Sieger, Matt; Bartlett, Roscoe; Collins, Benjamin [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Pawlowski, Roger; Schmidt, Rodney; Summers, Randall [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

    2016-12-01

    VERA, the Virtual Environment for Reactor Applications, is the system of physics capabilities being developed and deployed by the Consortium for Advanced Simulation of Light Water Reactors (CASL). CASL was established for the modeling and simulation of commercial nuclear reactors. VERA consists of integrating and interfacing software together with a suite of physics components adapted and/or refactored to simulate relevant physical phenomena in a coupled manner. VERA also includes the software development environment and computational infrastructure needed for these components to be effectively used. We describe the architecture of VERA from both software and numerical perspectives, along with the goals and constraints that drove major design decisions, and their implications. We explain why VERA is an environment rather than a framework or toolkit, why these distinctions are relevant (particularly for coupled physics applications), and provide an overview of results that demonstrate the use of VERA tools for a variety of challenging applications within the nuclear industry.

  12. Restorative Virtual Environment Design for Augmenting Nursing Home Rehabilitation

    DEFF Research Database (Denmark)

    Bruun-Pedersen, Jon Ram; Serafin, Stefania; Kofoed, Lise

    2016-01-01

    do, but more studies on content and design of proper custom designs for RVEs is necessary. This paper reviews the background for RVE design, describes four custom RVE designs for recreational VE exploration and presents user preferences among nursing home users concerning content and other pivotal......With increasing age, muscle strength decreases excessively rapidly if physical activity is not maintained. However, physical activity is increasingly difficult with age, due to balance, strength or coordination difficulties, arthritis, etc. Moreover, many nursing home residents become unable...... to experience natural surroundings. Augmenting a conventional biking exercise with a recreational virtual environment (RVE) has shown to serve as an intrinsic motivation contributor to exercise for nursing home residents. RVEs might be able to provide some of the health benefits that regular nature experiences...

  13. Effect of sodium environment on the creep-rupture and low-cycle fatigue behavior of austenitic stainless steels

    International Nuclear Information System (INIS)

    Natesan, K.; Chopra, D.K.; Zeman, G.J.; Smith, D.L.; Kassner, T.F.

    1977-01-01

    Austenitic stainless steels used for in-core structural components, piping, valves, and the intermediate heat exchanger in Liquid-Metal Fast-Breeder Reactors (LMFBRs) are subjected to sodium at elevated temperatures and to complex stress conditions. As a result, the materials can undergo compositional and microstructural changes as well as mechanical deformation by creep and cyclic fatigue processes. In the present paper, information is presented on the creep-rupture and low-cycle fatigue behavior of Types 304 and 316 stainless steel in the solution-annealed condition and after long-term exposure to flowing sodium. The nonmetallic impurity-element concentrations in the sodium were controlled at levels similar to those in EBR-II primary sodium. Strain-time relationships developed from the experimental creep data were used to generate isochronous stress-creep strain curves as functions of sodium-exposure time and temperature. The low-cycle fatigue data were used to obtain relationships between plastic strain range and cycles-to-failure based on the Coffin-Manson formalism and a damage-rate approach developed at ANL. An analysis of the cyclic stress-strain behavior of the materials showed that the strain-hardening rates for the sodium-exposed steels were larger than those for the annealed material. However, the sodium-exposed specimens showed significant softening, as evidenced by the lower stress at half the fatigue life. Microstructural information obtained from the different specimens suggests that crack initiation is more difficult in the long-term sodium-exposed specimens when compared with the solution-annealed material. Based on the expected carbon concentrations in LMFBR primary system sodium, moderate carburization of the austenitic stainless steels will not degrade the mechanical properties to a significant extent, and therefore, will not limit the performance of out-of-core components. (author)

  14. Requirements of Integrated Design Teams While Evaluating Advanced Energy Retrofit Design Options in Immersive Virtual Environments

    Directory of Open Access Journals (Sweden)

    Xue Yang

    2015-12-01

    Full Text Available One of the significant ways to save energy use in buildings is to implement advanced energy retrofits in existing buildings. Improving energy performance of buildings through advanced energy retrofitting requires a clear understanding of the cost and energy implications of design alternatives from various engineering disciplines when different retrofit options are considered. The communication of retrofit design alternatives and their energy implications is essential in the decision-making process, as it affects the final retrofit selections and hence the energy efficiency of the retrofitted buildings. The objective of the research presented here was to identify a generic list of information requirements that are needed to be shared and collectively analyzed by integrated design teams during advanced energy retrofit design review meetings held in immersive settings. While identifying such requirements, the authors used an immersive environment based iterative requirements elicitation approach. The technology was used as a means to better identify the information requirements of integrated design teams to be analyzed as a group. This paper provides findings on information requirements of integrated design teams when evaluating retrofit options in immersive virtual environments. The information requirements were identified through interactions with sixteen experts in design and energy modeling domain, and validated with another group of participants consisting of six design experts who were experienced in integrated design processes. Industry practitioners can use the findings in deciding on what information to share with integrated design team members during design review meetings that utilize immersive virtual environments.

  15. Healing gardens: design processes and realizations of beneficial environments

    Directory of Open Access Journals (Sweden)

    Clare Cooper Marcus

    2015-04-01

    Full Text Available Having defined the topic and its related management effects in the healthcare environment, this paper reports considerations of specific design processes, including evidence-based design, Integrated Healthcare Strategies, participatory practices and post occupancy evaluation. Landscape of Italian examples follows before a case study of three Californian healing gardens dedicated to cancer patients, linked to a survey of this category of users’ needs in such spaces. Conclusions report the reflection of practical implications deriving from studying North American examples, underlining the opportunity for audit and certification of therapeutic gardens, as well as the chance to export them outside health infrastructures for social needs.

  16. Liner Shipping Hub Network Design in a Competitive Environment

    DEFF Research Database (Denmark)

    Gelareh, Shahin; Nickel, Stefan; Pisinger, David

    A new mixed integer programming formulation is proposed for hub-and-spoke network design in a competitive environment. It addresses competition between a newcomer liner service provider and an alliance, both operating on hub-and-spoke networks. The newcomer company maximizes its market share...... — proportional to service time and transportation cost —by locating a predefined number of hubs at candidate ports and designing its network. While general-purpose solvers do not solve instances of even small size, an accelerated lagrangian method coupled with a primal heuristic obtains very good bounds. Our...

  17. Design of plant safety model in plant enterprise engineering environment

    International Nuclear Information System (INIS)

    Gabbar, Hossam A.; Suzuki, Kazuhiko; Shimada, Yukiyasu

    2001-01-01

    Plant enterprise engineering environment (PEEE) is an approach aiming to manage the plant through its lifecycle. In such environment, safety is considered as the common objective for all activities throughout the plant lifecycle. One approach to achieve plant safety is to embed safety aspects within each function and activity within such environment. One ideal way to enable safety aspects within each automated function is through modeling. This paper proposes a theoretical approach to design plant safety model as integrated with the plant lifecycle model within such environment. Object-oriented modeling approach is used to construct the plant safety model using OO CASE tool on the basis of unified modeling language (UML). Multiple views are defined for plant objects to express static, dynamic, and functional semantics of these objects. Process safety aspects are mapped to each model element and inherited from design to operation stage, as it is naturally embedded within plant's objects. By developing and realizing the plant safety model, safer plant operation can be achieved and plant safety can be assured

  18. GLobal Integrated Design Environment (GLIDE): A Concurrent Engineering Application

    Science.gov (United States)

    McGuire, Melissa L.; Kunkel, Matthew R.; Smith, David A.

    2010-01-01

    The GLobal Integrated Design Environment (GLIDE) is a client-server software application purpose-built to mitigate issues associated with real time data sharing in concurrent engineering environments and to facilitate discipline-to-discipline interaction between multiple engineers and researchers. GLIDE is implemented in multiple programming languages utilizing standardized web protocols to enable secure parameter data sharing between engineers and researchers across the Internet in closed and/or widely distributed working environments. A well defined, HyperText Transfer Protocol (HTTP) based Application Programming Interface (API) to the GLIDE client/server environment enables users to interact with GLIDE, and each other, within common and familiar tools. One such common tool, Microsoft Excel (Microsoft Corporation), paired with its add-in API for GLIDE, is discussed in this paper. The top-level examples given demonstrate how this interface improves the efficiency of the design process of a concurrent engineering study while reducing potential errors associated with manually sharing information between study participants.

  19. Design considerations for medical devices in the home environment.

    Science.gov (United States)

    Kaufman-Rivi, Diana; Collins-Mitchell, Janette; Jetley, Raoul

    2010-01-01

    Patient demographics, economic forces, and technological advancements contribute to the rise in home care services. Advanced medical devices and equipment originally designed for use by trained personnel in hospitals and clinics are increasingly migrating into the home. Unlike the clinical setting, the home is an uncontrolled environment with additional hazards. The compatibility of the device with the recipient's knowledge, abilities, lifestyle, and home environment plays a significant role in their therapy and rehabilitation. The advent of new device technologies such as wireless devices and interoperability of systems lends a new and complex perspective for medical device use in the home that must also be addressed. Adequately assessing and matching the patient and their caregiver with the appropriate device technology while considering the suitability of the home environment for device operation and maintenance is a challenge that relies on good human factors principles. There is a need to address these challenges in the growing home care sector In this article, the authors take a look at some important considerations and design issues for medical devices used in the home care environment.

  20. DICE: An Object Oriented Programming Environment for Cooperative Engineering Design

    Science.gov (United States)

    1989-03-20

    environment called PARMENIDES /FRULEKIT; PARMENIDES /FRULEKIT supports programming in frames and rules and was developed in LISP at Carnegie-Mellon...the domain of building design and construction. The Blackboard in DICEY-BUILDER is represented as frames in PARMENIDES , while the KMs are implemented... PARMENIDES fo rart omat format d a b C /envelope BLACKBOAR D machine to machine (’BLACKBOARD l m message f il transfer message p read •d message format J

  1. Collaborative virtual reality environments for computational science and design

    International Nuclear Information System (INIS)

    Papka, M. E.

    1998-01-01

    The authors are developing a networked, multi-user, virtual-reality-based collaborative environment coupled to one or more petaFLOPs computers, enabling the interactive simulation of 10 9 atom systems. The purpose of this work is to explore the requirements for this coupling. Through the design, development, and testing of such systems, they hope to gain knowledge that allows computational scientists to discover and analyze their results more quickly and in a more intuitive manner

  2. Corrosion fatigue of biomedical metallic alloys: mechanisms and mitigation.

    Science.gov (United States)

    Antunes, Renato Altobelli; de Oliveira, Mara Cristina Lopes

    2012-03-01

    Cyclic stresses are often related to the premature mechanical failure of metallic biomaterials. The complex interaction between fatigue and corrosion in the physiological environment has been subject of many investigations. In this context, microstructure, heat treatments, plastic deformation, surface finishing and coatings have decisive influence on the mechanisms of fatigue crack nucleation and growth. Furthermore, wear is frequently present and contributes to the process. However, despite all the effort at elucidating the mechanisms that govern corrosion fatigue of biomedical alloys, failures continue to occur. This work reviews the literature on corrosion-fatigue-related phenomena of Ti alloys, surgical stainless steels, Co-Cr-Mo and Mg alloys. The aim was to discuss the correlation between structural and surface aspects of these materials and the onset of fatigue in the highly saline environment of the human body. By understanding such correlation, mitigation of corrosion fatigue failure may be achieved in a reliable scientific-based manner. Different mitigation methods are also reviewed and discussed throughout the text. It is intended that the information condensed in this article should be a valuable tool in the development of increasingly successful designs against the corrosion fatigue of metallic implants. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Designing discovery learning environments: process analysis and implications for designing an information system

    NARCIS (Netherlands)

    Pieters, Julius Marie; Limbach, R.; de Jong, Anthonius J.M.

    2004-01-01

    A systematic analysis of the design process of authors of (simulation based) discovery learning environments was carried out. The analysis aimed at identifying the design activities of authors and categorising knowledge gaps that they experience. First, five existing studies were systematically

  4. COVE: a visual environment for ocean observatory design

    International Nuclear Information System (INIS)

    Grochow, K; Lazowska, E; Stoermer, M; Kelley, D; Delaney, J

    2008-01-01

    Physical, chemical, and biological ocean processes play a crucial role in determining Earth's environment. Unfortunately, our knowledge of these processes is limited because oceanography is carried out today largely the way it was a century ago: as expeditionary science, going to sea in ships and measuring a relatively small number of parameters (e.g., temperature, salinity, and pressure) as time and budget allow. The NSF Ocean Observatories Initiative is a US$330 million project that will help transform oceanography from a data-poor to a data-rich science. A cornerstone of this project is the deep water Regional Scale Nodes (RSN) that will be installed off the coasts of Washington and Oregon. The RSN will include 1500 km of fiber optic cable providing power and bandwidth to the seafloor and throughout the water column. Thousands of sensors will be deployed to stream data and imagery to shore, where they will be available in real time for ocean scientists and the public at large. The design of the RSN is a complex undertaking, requiring a combination of many different interactive tools and areas of visualization: geographic visualization to see the available seafloor bathymetry, scientific visualization to examine existing geospatially located datasets, layout tools to place the sensors, and collaborative tools to communicate across the team during the design. COVE, the Common Observatory Visualization Environment, is a visualization environment designed to meet all these needs. COVE has been built by computer scientists working closely with the engineering and scientific teams who will build and use the RSN. This paper discusses the data and activities of cabled observatory design, the design of COVE, and results from its use across the team

  5. In situ fatigue-crack-propagation experiment

    International Nuclear Information System (INIS)

    Ermi, A.M.; Chin, B.A.

    1981-01-01

    An in-reactor fatigue experiment was conducted in the Oak Ridge Research Reactor to determine the effects of dynamic irradiation on fatigue crack propagation. Eight 20% cold-worked 316 stainless steel specimens were precracked to various initial crack lengths, linked together to form a chain, and inserted into a specially designed in-reactor fatigue machine. Test conditions included a maximum temperature of 460 0 C, an environment of sodium, a frequency of 1 cycle/min, and a stress ratio of 0.10. Results indicated that (1) no effects of dynamic irradiation were observed for a fluence of 1.5 x 10 21 n/cm 2 (E > 0.1 MeV); and (2) crack growth rates in elevated temperature sodium were a factor of 3 to 4 lower than in room temperature air

  6. Evaluation of Standard Concepts Design of Library Interior Physical Environment

    Directory of Open Access Journals (Sweden)

    Debri Harindya Putri

    2018-01-01

    Full Text Available Currently the function of a room is not only used as a shelter, the function of the room itself to be increased as a refreshing or relaxation area for users to follow the development of creativity and technology in the field of design. The comfortable factor becomes the main factor that indicates a successful process of creating a space. No exception library. The nature of library seemed stiff because of its function as a place to read, now can be developed and made into more dynamic with the special design concepts or color patterns used. Libraries can be created a special concept that suits the characteristics of the users themselves. Most users of the library, especially in college libraries are teenagers. Naturally, teenagers like to gather with their friends and we have to facilitate this activity in our library design concept. In addition we can also determine the needs of users through research by questionnaire method. The answers of users can be mapped and drawn conclusions. To explore the research, the author reviewed some literature about library interior design and observed the library of Ma Chung University as a case study. The combined results of the method can be concluded and the discovery of ideal standards of physical environment. So, the library can be made as a comfortable reading environment so as to increased interest in reading behavior and the frequent visits of students in the library

  7. Thermal Insulating Concrete Wall Panel Design for Sustainable Built Environment

    Science.gov (United States)

    Zhou, Ao; Wong, Kwun-Wah

    2014-01-01

    Air-conditioning system plays a significant role in providing users a thermally comfortable indoor environment, which is a necessity in modern buildings. In order to save the vast energy consumed by air-conditioning system, the building envelopes in envelope-load dominated buildings should be well designed such that the unwanted heat gain and loss with environment can be minimized. In this paper, a new design of concrete wall panel that enhances thermal insulation of buildings by adding a gypsum layer inside concrete is presented. Experiments have been conducted for monitoring the temperature variation in both proposed sandwich wall panel and conventional concrete wall panel under a heat radiation source. For further understanding the thermal effect of such sandwich wall panel design from building scale, two three-story building models adopting different wall panel designs are constructed for evaluating the temperature distribution of entire buildings using finite element method. Both the experimental and simulation results have shown that the gypsum layer improves the thermal insulation performance by retarding the heat transfer across the building envelopes. PMID:25177718

  8. Multifunctional design of footwear for hot environment condition

    Science.gov (United States)

    Dragcevic, Z.; Vujasinovic, E.; Hursa Sajatovic, A.

    2017-10-01

    For some time design of a new product is not connected only with aesthetic, artistic appearance but moreover with functionality and engineering (from rightful selection of materials, construction, and technological concept to prototyping). One good example of this is design of multifunctional footwear as well as hiking footwear, footwear for soldiers, police officers, first responders etc. All mentioned kinds of footwear have lot of specific requirements to fulfil starting from maintaining and enhancing mobility to maximizing protection and eliminating or minimizing the risk for the wearer. Therefore, designing appropriate footwear represents a great challenge not only for designers but for engineers as well. Having that entire in mind few years ago, Faculty of Textile Technology University of Zagreb started the research with the aim to develop 21st century multifunctional footwear for e.g. military, police, first respondents or any special human forces for different weather environment. The paper presents how it was done in the case of boots for hot environment conditions

  9. Analysis of stiffness and fatigue resistance of cold recycled asphalt mixtures manufactured with foamed bitumen for their application to airfield pavement design

    Directory of Open Access Journals (Sweden)

    H. I. Lacalle-Jiménez

    2017-07-01

    Full Text Available Cold recycled bound materials (CRBMs provide an economic and environmental advantage for pavements since they decrease energy and raw material consumption. However, design methods for airfield pavements do not include key CRBM properties. In this paper an empirical-mechanistic method is used to study airfield pavement design with CRBM in order to develop design guidance. The aim of the paper is to obtain the inputs related to material properties needed for use in this method. For this purpose, CRBM containing reclaimed asphalt, with fly ash, cement and foamed bitumen as stabilising agents, was characterised. The methodology included indirect tensile stiffness modulus (ITSM and indirect tensile fatigue tests (ITFT in strain control mode. The inputs needed for a pavement design analysis with CRBM were then obtained. The results showed the importance of further study on CRBM fatigue to understand the behaviour of these mixes under cyclic loading.

  10. Development and evaluation of an intervention aiming to reduce fatigue in airline pilots: design of a randomised controlled trial

    NARCIS (Netherlands)

    van Drongelen, A.; van der Beek, A.J.; Hlobil, H.; Smid, T.; Boot, C.R.L.

    2013-01-01

    Background: A considerable percentage of flight crew reports to be fatigued regularly. This is partly caused by irregular and long working hours and the crossing of time zones. It has been shown that persistent fatigue can lead to health problems, impaired performance during work, and a decreased

  11. User-centered virtual environment design for virtual rehabilitation

    Directory of Open Access Journals (Sweden)

    Rizzo Albert A

    2010-02-01

    Full Text Available Abstract Background As physical and cognitive rehabilitation protocols utilizing virtual environments transition from single applications to comprehensive rehabilitation programs there is a need for a new design cycle methodology. Current human-computer interaction designs focus on usability without benchmarking technology within a user-in-the-loop design cycle. The field of virtual rehabilitation is unique in that determining the efficacy of this genre of computer-aided therapies requires prior knowledge of technology issues that may confound patient outcome measures. Benchmarking the technology (e.g., displays or data gloves using healthy controls may provide a means of characterizing the "normal" performance range of the virtual rehabilitation system. This standard not only allows therapists to select appropriate technology for use with their patient populations, it also allows them to account for technology limitations when assessing treatment efficacy. Methods An overview of the proposed user-centered design cycle is given. Comparisons of two optical see-through head-worn displays provide an example of benchmarking techniques. Benchmarks were obtained using a novel vision test capable of measuring a user's stereoacuity while wearing different types of head-worn displays. Results from healthy participants who performed both virtual and real-world versions of the stereoacuity test are discussed with respect to virtual rehabilitation design. Results The user-centered design cycle argues for benchmarking to precede virtual environment construction, especially for therapeutic applications. Results from real-world testing illustrate the general limitations in stereoacuity attained when viewing content using a head-worn display. Further, the stereoacuity vision benchmark test highlights differences in user performance when utilizing a similar style of head-worn display. These results support the need for including benchmarks as a means of better

  12. User-centered virtual environment design for virtual rehabilitation.

    Science.gov (United States)

    Fidopiastis, Cali M; Rizzo, Albert A; Rolland, Jannick P

    2010-02-19

    As physical and cognitive rehabilitation protocols utilizing virtual environments transition from single applications to comprehensive rehabilitation programs there is a need for a new design cycle methodology. Current human-computer interaction designs focus on usability without benchmarking technology within a user-in-the-loop design cycle. The field of virtual rehabilitation is unique in that determining the efficacy of this genre of computer-aided therapies requires prior knowledge of technology issues that may confound patient outcome measures. Benchmarking the technology (e.g., displays or data gloves) using healthy controls may provide a means of characterizing the "normal" performance range of the virtual rehabilitation system. This standard not only allows therapists to select appropriate technology for use with their patient populations, it also allows them to account for technology limitations when assessing treatment efficacy. An overview of the proposed user-centered design cycle is given. Comparisons of two optical see-through head-worn displays provide an example of benchmarking techniques. Benchmarks were obtained using a novel vision test capable of measuring a user's stereoacuity while wearing different types of head-worn displays. Results from healthy participants who performed both virtual and real-world versions of the stereoacuity test are discussed with respect to virtual rehabilitation design. The user-centered design cycle argues for benchmarking to precede virtual environment construction, especially for therapeutic applications. Results from real-world testing illustrate the general limitations in stereoacuity attained when viewing content using a head-worn display. Further, the stereoacuity vision benchmark test highlights differences in user performance when utilizing a similar style of head-worn display. These results support the need for including benchmarks as a means of better understanding user outcomes, especially for patient

  13. IFR fuel cycle process equipment design environment and objectives

    International Nuclear Information System (INIS)

    Rigg, R.H.

    1993-01-01

    Argonne National laboratory (ANL) is refurbishing the hot cell facility originally constructed with the EBR-II reactor. When refurbishment is complete, the facility win demonstrate the complete fuel cycle for current generation high burnup metallic fuel elements. These are sodium bonded, stainless steel clad fuel pins of U-Zr or U-Pu-Zr composition typical of the fuel type proposed for a future Integral Fast Reactor (IFR) design. To the extent possible, the process equipment is being built at full commercial scale, and the facility is being modified to incorporate current DOE facility design requirements and modem remote maintenance principles. The current regulatory and safety environment has affected the design of the fuel fabrication equipment, most of which will be described in greater detail in subsequent papers in this session

  14. A framework for designing and improving learning environments fostering creativity

    Directory of Open Access Journals (Sweden)

    Norio Ishii

    Full Text Available This paper proposes a framework for designing and improving learning environment for creativity in engineering. The framework consists of the following three components: instructional design based on knowledge from psychology, development of systems for supporting creative activities, and objective evaluation of learning results related to creativity. Based on that framework, we design and practice course based in the programation of a robot at a Japan University in the 2004 academic year. As a result, we confirm the following two advantages of our framework: learners' idea generation skills were improved and their meta-cognitive activities were also activated. In the 2005 academic year, we improve the course based on 2004 results. As a result, we confirm that the number of uploads of activity data from students have increased in the 2005 course, students' reflection sheets have become more detailed, and their volume of information have also increased.

  15. Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.

    2015-01-01

    Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

  16. Life prediction methodology for thermal-mechanical fatigue and elevated temperature creep design

    Science.gov (United States)

    Annigeri, Ravindra

    Nickel-based superalloys are used for hot section components of gas turbine engines. Life prediction techniques are necessary to assess service damage in superalloy components resulting from thermal-mechanical fatigue (TMF) and elevated temperature creep. A new TMF life model based on continuum damage mechanics has been developed and applied to IN 738 LC substrate material with and without coating. The model also characterizes TMF failure in bulk NiCoCrAlY overlay and NiAl aluminide coatings. The inputs to the TMF life model are mechanical strain range, hold time, peak cycle temperatures and maximum stress measured from the stabilized or mid-life hysteresis loops. A viscoplastic model is used to predict the stress-strain hysteresis loops. A flow rule used in the viscoplastic model characterizes the inelastic strain rate as a function of the applied stress and a set of three internal stress variables known as back stress, drag stress and limit stress. Test results show that the viscoplastic model can reasonably predict time-dependent stress-strain response of the coated material and stress relaxation during hold times. In addition to the TMF life prediction methodology, a model has been developed to characterize the uniaxial and multiaxial creep behavior. An effective stress defined as the applied stress minus the back stress is used to characterize the creep recovery and primary creep behavior. The back stress has terms representing strain hardening, dynamic recovery and thermal recovery. Whenever the back stress is greater than the applied stress, the model predicts a negative creep rate observed during multiple stress and multiple temperature cyclic tests. The model also predicted the rupture time and the remaining life that are important for life assessment. The model has been applied to IN 738 LC, Mar-M247, bulk NiCoCrAlY overlay coating and 316 austenitic stainless steel. The proposed model predicts creep response with a reasonable accuracy for wide range of

  17. Design of marine structures with improved safety for environment

    International Nuclear Information System (INIS)

    Klanac, Alan; Varsta, Petri

    2011-01-01

    The paper describes a method for design of marine structures with increased safety for environment, considering also the required investment costs as well as the aspects of risk distribution onto the maritime stakeholders. Practically, the paper seeks to answer what is the optimal amount that should be invested into certain safety measure for any given vessel. Due to the uneven distribution of risk, as well as the differing impact of costs emerging from safety improvements, stakeholders experience conflicting ranking of alternatives. To solve this multi-stakeholder decision-making problem, in which each stakeholder is a decision-maker, the method applies concepts of group decision-making theory, namely the Game Theory. The method fosters axiomatic definition of the optimum solution, arguing that the solution, or the final selected design, should satisfy the non-dominance, efficiency, and fairness. These three are thoroughly discussed in terms of structural design, especially the latter. Considering the coupling of environmental risk and structural design, the method also builds on the preference structure of four maritime stakeholders: yards, owners, oil receivers and the public, who either share the risks or directly influence structural design. Method is presented on a practical study of structural design of a tanker with a crashworthy side structure that is capable of reducing the risk of collision. The outcome of this study outlines a number of possibilities for successful improvement of tanker safety that can benefit, concurrently, all maritime stakeholders.

  18. The Nature of Fatigue in Chronic Fatigue Syndrome.

    Science.gov (United States)

    Olson, Karin; Zimka, Oksana; Stein, Eleanor

    2015-10-01

    In this article, we report the findings of our study on the nature of fatigue in patients diagnosed with chronic fatigue syndrome. Using ethnoscience as a design, we conducted a series of unstructured interviews and card sorts to learn more about how people with chronic fatigue syndrome describe fatigue. Participants (N = 14) described three distinct domains: tiredness, fatigue, and exhaustion. Most participants experienced tiredness prior to diagnosis, fatigue during daily life, and exhaustion after overexertion. We also discuss participants' ability to adapt to a variety of stressors and prevent shifts to exhaustion, and relate our findings to stress theory and other current research. Primary strategies that promoted adaptation to stressors included pacing and extended rest periods. These findings can aid health care professionals in detecting impending shifts between tiredness, fatigue, and exhaustion and in improving adaptive strategies, thereby improving quality of life. © The Author(s) 2015.

  19. Evaluation of conservatisms and environmental effects in ASME Code, Section III, Class 1 fatigue analysis

    International Nuclear Information System (INIS)

    Deardorff, A.F.; Smith, J.K.

    1994-08-01

    This report documents the results of a study regarding the conservatisms in ASME Code Section 3, Class 1 component fatigue evaluations and the effects of Light Water Reactor (LWR) water environments on fatigue margins. After review of numerous Class 1 stress reports, it is apparent that there is a substantial amount of conservatism present in many existing component fatigue evaluations. With little effort, existing evaluations could be modified to reduce the overall predicted fatigue usage. Areas of conservatism include design transients considerably more severe than those experienced during service, conservative grouping of transients, conservatisms that have been removed in later editions of Section 3, bounding heat transfer and stress analysis, and use of the ''elastic-plastic penalty factor'' (K 3 ). Environmental effects were evaluated for two typical components that experience severe transient thermal cycling during service, based on both design transients and actual plant data. For all reasonable values of actual operating parameters, environmental effects reduced predicted margins, but fatigue usage was still bounded by the ASME Section 3 fatigue design curves. It was concluded that the potential increase in predicted fatigue usage due to environmental effects should be more than offset by decreases in predicted fatigue usage if re-analysis were conducted to reduce the conservatisms that are present in existing component fatigue evaluations

  20. Design requirements for ubiquitous computing environments for healthcare professionals.

    Science.gov (United States)

    Bång, Magnus; Larsson, Anders; Eriksson, Henrik

    2004-01-01

    Ubiquitous computing environments can support clinical administrative routines in new ways. The aim of such computing approaches is to enhance routine physical work, thus it is important to identify specific design requirements. We studied healthcare professionals in an emergency room and developed the computer-augmented environment NOSTOS to support teamwork in that setting. NOSTOS uses digital pens and paper-based media as the primary input interface for data capture and as a means of controlling the system. NOSTOS also includes a digital desk, walk-up displays, and sensor technology that allow the system to track documents and activities in the workplace. We propose a set of requirements and discuss the value of tangible user interfaces for healthcare personnel. Our results suggest that the key requirements are flexibility in terms of system usage and seamless integration between digital and physical components. We also discuss how ubiquitous computing approaches like NOSTOS can be beneficial in the medical workplace.

  1. Design of the Resources and Environment Monitoring Website in Kashgar

    International Nuclear Information System (INIS)

    Huang, Z; Lin, Q Z; Wang, Q J

    2014-01-01

    Despite the development of the web geographical information system (web GIS), many useful spatial analysis functions are ignored in the system implementation. As Kashgar is rich in natural resources, it is of great significance to monitor the ample natural resource and environment situation in the region. Therefore, with multiple uses of spatial analysis, resources and environment monitoring website of Kashgar was built. Functions of water, vegetation, ice and snow extraction, task management, change assessment as well as thematic mapping and reports based on TM remote sensing images were implemented in the website. The design of the website was presented based on database management tier, the business logic tier and the top-level presentation tier. The vital operations of the website were introduced and the general performance was evaluated

  2. Islam and the healthcare environment: designing patient rooms.

    Science.gov (United States)

    Kopec, D A K; Han, Li

    2008-01-01

    Islam and the Muslim population are often the source of much misunderstanding and media-influenced misconceptions. Muslim patients who enter the healthcare environment are often weak and likely to experience feelings of vulnerability. Because of the complex and interwoven nature of culture and religion in a person's identity, it is important to consider patient belief systems and values when designing a patient's immediate environment. Through an exploration of literature related to culture and diversity and the beliefs and value system of the Muslim population, the authors were able to identify flexible design initiatives that could accommodate an array of cultural and spiritual practices. Islam and the Muslim population were chosen as the points of reference for this study because of the strong influence of the religion on the culture, and because of the many nuances that differ from the dominant culture within the United States. From these points of reference, a hypothetical design was developed for a patient room that considers differing notions of privacy, alternatives for cultural and religious practices, and ways to include symbolic meaning derived from attributes such as color.

  3. Fatigue in soccer

    DEFF Research Database (Denmark)

    Mohr, Magni; Krustrup, Peter; Bangsbo, Jens

    2005-01-01

    This review describes when fatigue may develop during soccer games and the potential physiological mechanisms that cause fatigue in soccer. According to time?-?motion analyses and performance measures during match-play, fatigue or reduced performance seems to occur at three different stages......, acidity or the breakdown of creatine phosphate. Instead, it may be related to disturbances in muscle ion homeostasis and an impaired excitation of the sarcolemma. Soccer players' ability to perform maximally is inhibited in the initial phase of the second half, which may be due to lower muscle...... concentrations in a considerable number of individual muscle fibres. In a hot and humid environment, dehydration and a reduced cerebral function may also contribute to the deterioration in performance. In conclusion, fatigue or impaired performance in soccer occurs during various phases in a game, and different...

  4. Preliminary design of high temperature ultrasonic transducers for liquid sodium environments

    Science.gov (United States)

    Prowant, M. S.; Dib, G.; Qiao, H.; Good, M. S.; Larche, M. R.; Sexton, S. S.; Ramuhalli, P.

    2018-04-01

    Advanced reactor concepts include fast reactors (including sodium-cooled fast reactors), gas-cooled reactors, and molten-salt reactors. Common to these concepts is a higher operating temperature (when compared to light-water-cooled reactors), and the proposed use of new alloys with which there is limited operational experience. Concerns about new degradation mechanisms, such as high-temperature creep and creep fatigue, that are not encountered in the light-water fleet and longer operating cycles between refueling intervals indicate the need for condition monitoring technology. Specific needs in this context include periodic in-service inspection technology for the detection and sizing of cracking, as well as technologies for continuous monitoring of components using in situ probes. This paper will discuss research on the development and evaluation of high temperature (>550°C; >1022°F) ultrasonic probes that can be used for continuous monitoring of components. The focus of this work is on probes that are compatible with a liquid sodium-cooled reactor environment, where the core outlet temperatures can reach 550°C (1022°F). Modeling to assess sensitivity of various sensor configurations and experimental evaluation have pointed to a preferred design and concept of operations for these probes. This paper will describe these studies and ongoing work to fabricate and fully evaluate survivability and sensor performance over extended periods at operational temperatures.

  5. Strategic implementation of design for environment at Embraer

    DEFF Research Database (Denmark)

    Pigosso, Daniela Cristina Antelmi; Grandi, Carlos M.; Rozenfeld, Henrique

    2013-01-01

    Design for Environment (or ecodesign) has become increasingly important in the aircraft industry. Embraer, one of the world’s leading aircraft manufacturers, is committed to improve the environmental performance of the developed aircrafts. The roadmap for the strategic implementation of Df......E at Embraer, developed based on the application of the Ecodesign Maturity Model (EcoM2), is presented and further discussed in this paper. The paper describes the main projects and activities carried out at the company so to develop robust processes for the development of products with a better environmental...

  6. Risk factors and visual fatigue of baggage X-ray security screeners: a structural equation modelling analysis.

    Science.gov (United States)

    Yu, Rui-Feng; Yang, Lin-Dong; Wu, Xin

    2017-05-01

    This study identified the risk factors influencing visual fatigue in baggage X-ray security screeners and estimated the strength of correlations between those factors and visual fatigue using structural equation modelling approach. Two hundred and five X-ray security screeners participated in a questionnaire survey. The result showed that satisfaction with the VDT's physical features and the work environment conditions were negatively correlated with the intensity of visual fatigue, whereas job stress and job burnout had direct positive influences. The path coefficient between the image quality of VDT and visual fatigue was not significant. The total effects of job burnout, job stress, the VDT's physical features and the work environment conditions on visual fatigue were 0.471, 0.469, -0.268 and -0.251 respectively. These findings indicated that both extrinsic factors relating to VDT and workplace environment and psychological factors including job burnout and job stress should be considered in the workplace design and work organisation of security screening tasks to reduce screeners' visual fatigue. Practitioner Summary: This study identified the risk factors influencing visual fatigue in baggage X-ray security screeners and estimated the strength of correlations between those factors and visual fatigue. The findings were of great importance to the workplace design and the work organisation of security screening tasks to reduce screeners' visual fatigue.

  7. The Design Space of Multi-Language Development Environments

    DEFF Research Database (Denmark)

    Pfeiffer, Rolf-Helge; Wasowski, Andrzej

    2014-01-01

    Non-trivial software systems integrate many artifacts expressed in multiple modeling and program- ming languages. However, even though these artifacts heavily depend on each other, existing development envi- ronments do not sufficiently support handling relations between artifacts in different...... languages. By means of a literature survey, tool prototyping and experiments we study the design space of multi-language development environments (MLDEs)—tools that consider the cross-language relations as first artifacts. We ask: what is the state of the art in the MLDE space? What are the design choices...... and challenges faced by tool builders? To what extent MLDEs are desired by users, and for what support features? Our main conclusions are that (a) cross-language re- lations are ubiquitous and troublesome in multi-language systems, (b) users highly appreciated cross-language sup- port mechanisms of MLDEs and (c...

  8. Superconducting magnets in high radiation environments: Design problems and solutions

    International Nuclear Information System (INIS)

    St Lorant, S.J.; Tillmann, E.

    1989-11-01

    As part of the Stanford Linear Collider Project, three high-field superconducting solenoid magnets are used to rotate the spin direction of a polarized electron beam. The magnets are installed in a high-radiation environment, where they will receive a dose of approximately 10 3 rad per hour, or 10 8 rad over their lifetimes. This level of radiation and the location in which the magnets are installed, some 10 meters below ground in contiguous tunnels, required careful selection of materials for the construction of the solenoids and their ancillary cryogenic equipment, as well as the development of compatible component designs. This paper describes the materials used and the design of the equipment appropriate for the application. Included are summaries of the physical and mechanical properties of the materials and how they behave when irradiated. 16 refs., 7 figs., 1 tab

  9. Designing learning environments to teach interactive Quantum Physics

    Science.gov (United States)

    Gómez Puente, Sonia M.; Swagten, Henk J. M.

    2012-10-01

    This study aims at describing and analysing systematically an interactive learning environment designed to teach Quantum Physics, a second-year physics course. The instructional design of Quantum Physics is a combination of interactive lectures (using audience response systems), tutorials and self-study in unit blocks, carried out with small groups. Individual formative feedback was introduced as a rapid assessment tool to provide an overview on progress and identify gaps by means of questioning students at three levels: conceptual; prior knowledge; homework exercises. The setup of Quantum Physics has been developed as a result of several loops of adjustments and improvements from a traditional-like type of teaching to an interactive classroom. Results of this particular instructional arrangement indicate significant gains in students' achievements in comparison with the traditional structure of this course, after recent optimisation steps such as the implementation of an individual feedback system.

  10. Design and Implementation of an Extensible Learner-Adaptive Environment

    Directory of Open Access Journals (Sweden)

    Kiyoshi Nakabayashi

    2010-09-01

    Full Text Available This paper describes the design and implementation of a flexible architecture that is capable of extending the functions of a learner-adaptive self-learning environment. A “courseware object”, which is a program module that is used to implement various educational functionalities, has been newly introduced to ensure both function extensibility as well as content reusability. A prototype system was designed and implemented to investigate the feasibility of the proposed architecture and to identify the core behavior and interaction schema of courseware objects. The results from this trial indicated that several learner-adaptive functionalities including the SCORM 2004 standard specifications will be able to be successfully implemented into the proposed architecture.

  11. Fatigue behavior of ULTIMETRTM alloy: Experiment and theoretical modeling

    Science.gov (United States)

    Jiang, Liang

    ULTIMETRTM alloy is a commercial Co-26Cr-9Ni (weight percent) superalloy, which possesses excellent resistance to both wear and corrosion. In order to extend the structural applications of this alloy and improve the fundamental understanding of the fatigue damage mechanisms, stress- and strain-controlled fatigue tests were performed at various temperatures and in different environments. The stress- and strain-life data were developed for the structural design and engineering applications of this material. Fractographic studies characterized the crack-initiation and propagation behavior of the alloy. Microstructure evolution during fatigue was revealed by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Specifically, it was found that the metastable face-centered-cubic structure of this alloy in the as-received condition could be transformed into a hexagonal-close-packed structure either under the action of plastic deformation at room temperature, or due to the aging and cyclic deformation at intermediate temperatures. This interesting observation constructed a sound basis for the alloy development. The dominant mechanisms, which control the fatigue behavior of ULTIMET alloy, were characterized. High-speed, high-resolution infrared (IR) thermography, as a non-contact, full-field, and nondestructive technique, was used to characterize the damage during fatigue. The temperature variations during each fatigue cycle, which were due to the thermal-elastic-plastic effect, were observed and related to stress-strain analyses. The temperature evolution during fatigue manifested the cumulative fatigue damage process. A constitutive model was developed to predict thermal and mechanical responses of ULTIMET alloy subjected to cyclic deformation. The predicted cyclic stress-strain responses and temperature variations were found to be in good agreement with the experimental results. In addition, a fatigue life prediction model was developed

  12. Knowledge Flow Rules of Modern Design under Distributed Resource Environment

    Directory of Open Access Journals (Sweden)

    Junning Li

    2013-01-01

    Full Text Available The process of modern design under the distributed resource environment is interpreted as the process of knowledge flow and integration. As the acquisition of new knowledge strongly depends on resources, knowledge flow can be influenced by technical, economic, and social relation factors, and so forth. In order to achieve greater efficiency of knowledge flow and make the product more competitive, the root causes of the above factors should be acquired first. In this paper, the authors attempt to reveal the nature of design knowledge flow from the perspectives of fluid dynamics and energy. The knowledge field effect and knowledge agglomeration effect are analyzed, respectively, in which the knowledge field effect model considering single task node and the single knowledge energy model in the knowledge flow are established, then the general expression of knowledge energy conservation with consideration of the kinetic energy and potential energy of knowledge is built. Then, the knowledge flow rules and their influential factors including complete transfer and incomplete transfer of design knowledge are studied. Finally, the coupling knowledge flows in the knowledge service platform for modern design are analyzed to certify the feasibility of the research work.

  13. Engineering design constraints of the lunar surface environment

    Science.gov (United States)

    Morrison, D. A.

    1992-01-01

    Living and working on the lunar surface will be difficult. Design of habitats, machines, tools, and operational scenarios in order to allow maximum flexibility in human activity will require paying attention to certain constraints imposed by conditions at the surface and the characteristics of lunar material. Primary design drivers for habitat, crew health and safety, and crew equipment are: ionizing radiation, the meteoroid flux, and the thermal environment. Secondary constraints for engineering derive from: the physical and chemical properties of lunar surface materials, rock distributions and regolith thicknesses, topography, electromagnetic properties, and seismicity. Protection from ionizing radiation is essential for crew health and safety. The total dose acquired by a crew member will be the sum of the dose acquired during EVA time (when shielding will be least) plus the dose acquired during time spent in the habitat (when shielding will be maximum). Minimizing the dose acquired in the habitat extends the time allowable for EVA's before a dose limit is reached. Habitat shielding is enabling, and higher precision in predicting secondary fluxes produced in shielding material would be desirable. Means for minimizing dose during a solar flare event while on extended EVA will be essential. Early warning of the onset of flare activity (at least a half-hour is feasible) will dictate the time available to take mitigating steps. Warning capability affects design of rovers (or rover tools) and site layout. Uncertainty in solar flare timing is a design constraint that points to the need for quickly accessible or constructible safe havens.

  14. A Study on Fatigue Design Automation of Plug- and Ring-type Gas-welded Joints of STS301L Taking Welded Residual Stress into Account

    International Nuclear Information System (INIS)

    Baek, Seung yeb; Yun, Ki Ho

    2010-01-01

    This paper presents a fatigue design method for plug- and ring-type gas-welded joints, which takes into account the effects of welding residual stress. To develop this method, we simulated the gas-welding process by performing nonlinear finite element analysis (FEA) To validate the FEA results, numerically calculated residual stresses in the gas welds were then compared with experimental results obtained by the hole-drilling method. To evaluate the fatigue strength of plug- and ring-type gas-welded joints influenced by welding residual stresses, the use of stress amplitude (σ a )R, which includes the welding residual stress in gas welds, is proposed (σ a )R on the basis of a modified Goodman equation that includes the residual stress effects. Using the stress amplitude (σ a )R at the hot spot point of gas weld, the relations obtained as the fatigue test results for plug and ring type gas welded joints having various dimensions and shapes were systematically rearranged to obtain the (σ a )R-N f relationship. It was found that more systematic and accurate evaluation of the fatigue strength of plug- and ring-type gas-welded joints can be achieved by using (σ a )R

  15. Environmental Assisted Fatigue Evaluation of Direct Vessel Injection Piping Considering Thermal Stratification

    International Nuclear Information System (INIS)

    Kim, Taesoon; Lee, Dohwan

    2016-01-01

    As the environmentally assisted fatigue (EAF) due to the primary water conditions is to be a critical issue, the fatigue evaluation for the components and pipes exposed to light water reactor coolant conditions has become increasingly important. Therefore, many studies to evaluate the fatigue life of the components and pipes in LWR coolant environments on fatigue life of materials have been conducted. Among many components and pipes of nuclear power plants, the direct vessel injection piping is known to one of the most vulnerable pipe systems because of thermal stratification occurred in that systems. Thermal stratification occurs because the density of water changes significantly with temperature. In this study, fatigue analysis for DVI piping using finite element analysis has been conducted and those results showed that the results met design conditions related with the environmental fatigue evaluation of safety class 1 pipes in nuclear power plants. Structural and fatigue integrity for the DVI piping system that thermal stratification occurred during the plant operation has conducted. First of all, thermal distribution of the piping system is calculated by computational fluid dynamic analysis to analyze the structural integrity of that piping system. And the fatigue life evaluation considering environmental effects was carried out. Our results showed that the DVI piping system had enough structural integrity and fatigue life during the design lifetime of 60 years

  16. Operator fatigue detection and countermeasure development

    Energy Technology Data Exchange (ETDEWEB)

    Daniel Bongers [CRC Mining (Australia)

    2009-05-15

    A prototype technology for measuring and reporting an individual's fatigue, with the intention that such a technology could be used to prevent fatigue-related injuries in the Australian coal mining industry is known as the Smart Cap system. It resembles a typical baseball cap yet contains sophisticated sensors capable of measuring EEG (brain waves) through hair, determining an individual's fatigue level and reporting that to an in-cab display. The first phase of developmentwas to develop the sensor capable of reading EEG without the need for conductive gel. Once this was proven, a more sophisticated circuit was developed that incorporated tuned filtering and digital signal processing allowing the brain wave data to be stored and communicated using Bluetooth wireless. The third and final phase was focussed on the embodiment of the sensor array into a baseball cap in order to allow long term use in a mining environment. Two field trials of the Smart Cap fatigue detection system took place at surface coal mining operations in central Queensland during 2008. 53 operators were involved in these trials for one or more shifts. Both day and night shifts were incorporated for operators of haul trucks, excavators, water trucks, dozers and graders. Infrared video footage of some operators was captured for comparison with the real-time EEG and fatigue information collected by the Smart Cap system. This footage allowed the calculation of the percentage of eye closure (PERCLOS) of eleven operators. Comparison of the PERCLOS measurements with operator fatigue levels shows good correlation in line with similar published research. The Smart Cap system performed according to its design parameters. We show that the sophisticated sensor array is capable of eliminating ambient electrical noise in the mine environment, and that the Bluetooth connectivity is secure in the event of intentional mismatching of equipment or close vehicle interactions.

  17. Development and evaluation of an intervention aiming to reduce fatigue in airline pilots: design of a randomised controlled trial

    OpenAIRE

    van Drongelen, Alwin; van der Beek, Allard J; Hlobil, Hynek; Smid, Tjabe; Boot, C?cile RL

    2013-01-01

    Background: A considerable percentage of flight crew reports to be fatigued regularly. This is partly caused by irregular and long working hours and the crossing of time zones. It has been shown that persistent fatigue can lead to health problems, impaired performance during work, and a decreased work-private life balance. It is hypothesized that an intervention consisting of tailored advice regarding exposure to daylight, optimising sleep, physical activity, and nutrition will lead to a redu...

  18. Alarm Fatigue vs User Expectations Regarding Context-Aware Alarm Handling in Hospital Environments Using CallMeSmart.

    Science.gov (United States)

    Solvoll, Terje; Arntsen, Harald; Hartvigsen, Gunnar

    2017-01-01

    Surveys and research show that mobile communication systems in hospital settings are old and cause frequent interruptions. In the quest to remedy this, an Android based communication system called CallMeSmart tries to encapsulate most of the frequent communication into one hand held device focusing on reducing interruptions and at the same time make the workday easier for healthcare workers. The objective of CallMeSmart is to use context-awareness techniques to automatically monitor the availability of physicians' and nurses', and use this information to prevent or route phone calls, text messages, pages and alarms that would otherwise compromise patient care. In this paper, we present the results from interviewing nurses on alarm fatigue and their expectations regarding context-aware alarm handling using CallMeSmart.

  19. Designing and Improving a Blended Synchronous Learning Environment: An Educational Design Research

    Science.gov (United States)

    Wang, Qiyun; Lang Quek, Choon; Hu, Xiaoyong

    2017-01-01

    In this study, a blended synchronous learning environment (BSLE) was created to support a group of graduate students when they were taking a course. Instruction was delivered to both face-to-face (F2F) and online students simultaneously. The purpose of this paper is to present how this BSLE was gradually designed, implemented, and improved by…

  20. Architectural Design and the Learning Environment: A Framework for School Design Research

    Science.gov (United States)

    Gislason, Neil

    2010-01-01

    This article develops a theoretical framework for studying how instructional space, teaching and learning are related in practice. It is argued that a school's physical design can contribute to the quality of the learning environment, but several non-architectural factors also determine how well a given facility serves as a setting for teaching…

  1. Designing Environments for Handicapped Children: A Design Guide and Case Study. First Edition.

    Science.gov (United States)

    Moore, Gary T.; And Others

    This guide addresses the planning and architectural design of play/learning environments for special needs children. The exceptional children discussed include those with most types of mild to severe handicaps and developmental disabilities. Specifically excluded from consideration are health impairments, severe psycho-emotional difficulties such…

  2. Interaction fatigue-creep-environment in an austenitic stainless steel Z2 CND 17-13 (Type 316 L) at 600 and 650 deg C. Microstructural evolution and damage

    International Nuclear Information System (INIS)

    Rezgui, B.

    1982-12-01

    The resistance of steel to continuous fatigue is directly related to its behaviour towards the surroundings (oxidation). This interaction considerably lowers resistance to crack initiation but has no effect on propagation, and rupture is transgranular. Conversely the influence of the environment is negligible under fatigue conditions with a hold time and rupture becomes intergranular whatever the surroudings. Cavities are created inside the material during the hold time and their interaction with each other and with cracks from the surface are the factors responsible for the degradation of fatigue properties. Transgranular rupture initiated in slip bands, which characterises damage by pure fatigue, is gradually replaced by intergranular rupture under fatigue with hold time. Meanwhile a new deformation mode appears: intergranular slip. The longer the hold time the stronger its effect, a tendency offset at high temperature. Hold time, temperature and deformation promote dynamic structural aging and restoration in the material. Since the mechanisms and kinetics of creep fatigue damage are different according to the deformation level and the hold time duration it would not be safe to extrapolate the results [fr

  3. Multiaxial Creep-Fatigue and Creep-Ratcheting Failures of Grade 91 and Haynes 230 Alloys Toward Addressing Design Issues of Gen IV Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Tasnim [North Carolina State Univ., Raleigh, NC (United States); Lissenden, Cliff [Penn State Univ., University Park, PA (United States); Carroll, Laura [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-04-01

    The proposed research will develop systematic sets of uniaxial and multiaxial experimental data at a very high temperature (850-950°C) for Alloy 617. The loading histories to be prescribed in the experiments will induce creep-fatigue and creep-ratcheting failure mechanisms. These experimental responses will be scrutinized in order to quantify the influences of temperature and creep on fatigue and ratcheting failures. A unified constitutive model (UCM) will be developed and validated against these experimental responses. The improved UCM will be incorporated into the widely used finite element commercial software packages ANSYS. The modified ANSYS will be validated so that it can be used for evaluating the very high temperature ASME-NH design-by-analysis methodology for Alloy 617 and thereby addressing the ASME-NH design code issues.

  4. Multiaxial Creep-Fatigue and Creep-Ratcheting Failures of Grade 91 and Haynes 230 Alloys Toward Addressing Design Issues of Gen IV Nuclear Power Plants

    International Nuclear Information System (INIS)

    Hassan, Tasnim; Lissenden, Cliff; Carroll, Laura

    2015-01-01

    The proposed research will develop systematic sets of uniaxial and multiaxial experimental data at a very high temperature (850-950°C) for Alloy 617. The loading histories to be prescribed in the experiments will induce creep-fatigue and creep-ratcheting failure mechanisms. These experimental responses will be scrutinized in order to quantify the influences of temperature and creep on fatigue and ratcheting failures. A unified constitutive model (UCM) will be developed and validated against these experimental responses. The improved UCM will be incorporated into the widely used finite element commercial software packages ANSYS. The modified ANSYS will be validated so that it can be used for evaluating the very high temperature ASME-NH design-by-analysis methodology for Alloy 617 and thereby addressing the ASME-NH design code issues.

  5. Preliminary results of effect of environment on the low cycle fatigue behaviour of type 316 stainless steel and 9% Cr ferritic steel

    International Nuclear Information System (INIS)

    Wood, D.S.; Slattery, G.F.; Wynn, J.; Connaughton, M.D.; Lambert, M.E.

    1976-06-01

    Strain controlled fatigue tests on Type 316 steel at 625 0 C and 9% Cr steel at 525 0 C have been performed in air and in helium containing 200 μ atm H 2 and 1 μ atm H 2 O. In rapid cycling the endurance of Type 316 steel in this helium mixture was found to be about five times longer than in air. When a hold time was introduced into the tension part of the cycle however the endurance in the two environments was found to be virtually identical. Fractomicrographic examinations have been performed which have helped to explain some of these findings which are attributed to differences in oxidation behaviour at the crack tip. In the case of the 90% Cr steel the endurance in the helium mixture was found to be only slightly better than in air. The implications of these results are considered in relation to thermal shock effects on sodium cooled fast reactor components. (author)

  6. The role of crack tip opening in corrosion fatigue for the ductile ferritic steel-water system

    International Nuclear Information System (INIS)

    Tomkins, B.

    1977-01-01

    Water vapour or a water environment can dramatically reduce the fatigue strength of structural alloys, including aluminium and steel, and this reduction can be often related to the effect of the environment on crack initiation. More recently, however, under certain circumstances, it has become clear that fatigue crack growth rates can also be increased. A limited examination of crack tip openings in ductile steels under corrosion fatigue conditions, indicates that it may be possible to develop more physically based design rules for components which operate in some aqueous environments (author)

  7. Fatigue of Chinese railway employees and its influential factors: Structural equation modelling.

    Science.gov (United States)

    Tsao, Liuxing; Chang, Jing; Ma, Liang

    2017-07-01

    Fatigue is an identifiable and preventable cause of accidents in transport operations. Regarding the railway sector, incident logs and simulation studies show that employee fatigue leads to lack of alertness, impaired performance, and occurrence of incidents. China has one of the largest rail systems in the world, and Chinese railway employees work under high fatigue risks; therefore, it is important to assess their fatigue level and find the major factors leading to fatigue. We designed a questionnaire that uses Multidimensional Fatigue Instrument (MFI-20), NASA-TLX and subjective rating of work overtime feelings to assess employee fatigue. The contribution of each influential factor of fatigue was analysed using structural equation modelling. In total, 297 employees from the rail maintenance department and 227 employees from the locomotive department returned valid responses. The average scores and standard deviations for the five subscales of MFI-20, namely General Fatigue, Physical Fatigue, Reduced Activity, Reduced Motivation, and Mental Fatigue, were 2.9 (0.8), 2.8 (0.8), 2.5 (0.8), 2.5 (0.7), and 2.4 (0.8) among the rail maintenance employees and 3.5 (0.8), 3.5 (0.7), 3.3 (0.7), 3.0 (0.6), and 3.1 (0.7), respectively, among the locomotive employees. The fatigue of the locomotive employees was influenced by feelings related to working overtime (standardized r = 0.22) and workload (standardized r = 0.27). The work overtime control and physical working environment significantly influenced subjective feelings (standardized r = -0.25 and 0.47, respectively), while improper work/rest rhythms and an adverse physical working environment significantly increased the workload (standardized r = 0.48 and 0.33, respectively). Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Development of an in situ fatigue sensor.

    Science.gov (United States)

    2011-01-01

    A prototype in situ fatigue sensor has been designed, constructed and evaluated experimentally for its ability to monitor the accumulation of fatigue damage in a cyclically loaded steel structure, e.g., highway bridge. The sensor consists of multiple...

  9. Ethics, design and planning of the built environment

    CERN Document Server

    Moroni, Stefano

    2013-01-01

    The book proposes a set of original contributions in research areas shared by planning theory, architectural research, design and ethical inquiry. The contributors gathered in 2010 at the Ethics of the Built Environment seminar organized by the editors at Delft University of Technology. Both prominent and emerging scholars presented their researches in the areas of aesthetics, technological risks, planning theory and architecture. The scope of the seminar was highlighting shared lines of ethical inquiry among the themes discussed, in order to identify perspectives of innovative interdisciplinary research. After the seminar all seminar participants have elaborated their proposed contributions. Some of the most prominent international authors in the field were subsequently invited to join in with this inquiry. Claudia Basta teaches "Network Infrastructures and Mobility" at Wageningen University. Between 2009 and 2011 she worked as Coordinator of the 3TU Centre of Excellence for Ethics and Technology of Delft Un...

  10. Design and Testing of Electronic Devices for Harsh Environments

    CERN Document Server

    Nico, Costantino

    This thesis reports an overview and the main results of the research activity carried out within the PhD programme in Information Engineering of the University of Pisa (2010-2012). The research activity has been focused on different fields, including Automotive and High Energy Physics experiments, according to a common denominator: the development of electroni c devices and systems operating in harsh environments. There are many applications that forc e the adoption of design methodologies and strategies focused on this type of envir onments: military, biom edical, automotive, industrial and space. The development of solutions fulfilling specific operational requirements, therefore represents an interesting field of research. The first research activity has been framed within the ATHENIS project, funded by the CORDIS Commission of the European Community, and aiming at the development of a System-on-Chip, a r egulator for alternators employed on vehicles, presenting both configurability an d t...

  11. New design environment for defect detection in web inspection systems

    Science.gov (United States)

    Hajimowlana, S. Hossain; Muscedere, Roberto; Jullien, Graham A.; Roberts, James W.

    1997-09-01

    One of the aims of industrial machine vision is to develop computer and electronic systems destined to replace human vision in the process of quality control of industrial production. In this paper we discuss the development of a new design environment developed for real-time defect detection using reconfigurable FPGA and DSP processor mounted inside a DALSA programmable CCD camera. The FPGA is directly connected to the video data-stream and outputs data to a low bandwidth output bus. The system is targeted for web inspection but has the potential for broader application areas. We describe and show test results of the prototype system board, mounted inside a DALSA camera and discuss some of the algorithms currently simulated and implemented for web inspection applications.

  12. Designing for Change: Interoperability in a scaling and adapting environment

    Science.gov (United States)

    Yarmey, L.

    2015-12-01

    The Earth Science cyberinfrastructure landscape is constantly changing. Technologies advance and technical implementations are refined or replaced. Data types, volumes, packaging, and use cases evolve. Scientific requirements emerge and mature. Standards shift while systems scale and adapt. In this complex and dynamic environment, interoperability remains a critical component of successful cyberinfrastructure. Through the resource- and priority-driven iterations on systems, interfaces, and content, questions fundamental to stable and useful Earth Science cyberinfrastructure arise. For instance, how are sociotechnical changes planned, tracked, and communicated? How should operational stability balance against 'new and shiny'? How can ongoing maintenance and mitigation of technical debt be managed in an often short-term resource environment? The Arctic Data Explorer is a metadata brokering application developed to enable discovery of international, interdisciplinary Arctic data across distributed repositories. Completely dependent on interoperable third party systems, the Arctic Data Explorer publicly launched in 2013 with an original 3000+ data records from four Arctic repositories. Since then the search has scaled to 25,000+ data records from thirteen repositories at the time of writing. In the final months of original project funding, priorities shift to lean operations with a strategic eye on the future. Here we present lessons learned from four years of Arctic Data Explorer design, development, communication, and maintenance work along with remaining questions and potential directions.

  13. Exascale Co-design for Modeling Materials in Extreme Environments

    Energy Technology Data Exchange (ETDEWEB)

    Germann, Timothy C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-08

    Computational materials science has provided great insight into the response of materials under extreme conditions that are difficult to probe experimentally. For example, shock-induced plasticity and phase transformation processes in single-crystal and nanocrystalline metals have been widely studied via large-scale molecular dynamics simulations, and many of these predictions are beginning to be tested at advanced 4th generation light sources such as the Advanced Photon Source (APS) and Linac Coherent Light Source (LCLS). I will describe our simulation predictions and their recent verification at LCLS, outstanding challenges in modeling the response of materials to extreme mechanical and radiation environments, and our efforts to tackle these as part of the multi-institutional, multi-disciplinary Exascale Co-design Center for Materials in Extreme Environments (ExMatEx). ExMatEx has initiated an early and deep collaboration between domain (computational materials) scientists, applied mathematicians, computer scientists, and hardware architects, in order to establish the relationships between algorithms, software stacks, and architectures needed to enable exascale-ready materials science application codes within the next decade. We anticipate that we will be able to exploit hierarchical, heterogeneous architectures to achieve more realistic large-scale simulations with adaptive physics refinement, and are using tractable application scale-bridging proxy application testbeds to assess new approaches and requirements. Such current scale-bridging strategies accumulate (or recompute) a distributed response database from fine-scale calculations, in a top-down rather than bottom-up multiscale approach.

  14. Designing for Learning: Online Social Networks as a Classroom Environment

    Directory of Open Access Journals (Sweden)

    Gail Casey

    2011-11-01

    Full Text Available This paper deploys notions of emergence, connections, and designs for learning to conceptualize high school students’ interactions when using online social media as a learning environment. It makes links to chaos and complexity theories and to fractal patterns as it reports on a part of the first author’s action research study, conducted while she was a teacher working in an Australian public high school and completing her PhD. The study investigates the use of a Ning online social network as a learning environment shared by seven classes, and it examines students’ reactions and online activity while using a range of social media and Web 2.0 tools.The authors use Graham Nuthall’s (2007 “lens on learning” to explore the social processes and culture of this shared online classroom. The paper uses his extensive body of research and analyses of classroom learning processes to conceptualize and analyze data throughout the action research cycle. It discusses the pedagogical implications that arise from the use of social media and, in so doing, challenges traditional models of teaching and learning.

  15. Seafarer fatigue

    DEFF Research Database (Denmark)

    Jepsen, Jørgen Riis; Zhao, Zhiwei; van Leeuwen, Wessel M. A.

    2015-01-01

    Background: The consequences of fatigue for the health and safety of seafarers has caused concern in the industry and among academics, and indicates the importance of further research into risk factors and preventive interventions at sea. This review gives an overview of the key issues relating...... to seafarer fatigue. Materials and methods: A literature study was conducted aiming to collect publications that address risk factors for fatigue, short-term and long-term consequences for health and safety, and options for fatigue mitigation at sea. Due to the limited number of publications that deals...... with seafarers, experiences from other populations sharing the same exposures (e.g. shift work) were also included when appropriate. Results: Work at sea involves multiple risk factors for fatigue, which in addition to acute effects (e.g., impaired cognition, accidents) contributes through autonomic, immunologic...

  16. The influence of hydrogen on the fatigue life of metallic leaf spring components in a vacuum environment

    NARCIS (Netherlands)

    Kouters, M.H.M.; Slot, H.M.; Zwieten, W. van; Veer, J. van der

    2014-01-01

    Hydrogen is used as a process gas in vacuum environments for semiconductor manufacturing equipment. If hydrogen dissolves in metallic components during operation it can result in hydrogen embrittlement. In order to assess if hydrogen embrittlement occurs in such a vacuum environment a special

  17. Environmentally assisted fatigue evaluation model of alloy 690 steam generator tube in high temperature water

    International Nuclear Information System (INIS)

    Tan Jibo; Wu Xinqiang; Han Enhou; Wang Xiang; Liu Xiaoqiang; Xu Xuelian

    2015-01-01

    Nickel-based alloy 690 has been widely used as steam generator tube in light water reactor (LWR) nuclear power plants, which may suffer from corrosion fatigue during long-term service. Many researches and operating experience indicated that the effect of LWR environment could significantly reduce the fatigue life of structural materials. However. such an environmental degradation effect was not fully addressed in the current ASME code design fatigue curves. Therefore, the Regulatory Guide 1.207 issued by US NRC required a new NPP have to incorporate the environment effects into fatigue analyses. In the last few decades, researchers in USA and Japan systematically investigated the corrosion fatigue behavior of nuclear-grade structural materials in LWR environment. Then, ANL model and JSME model were proposed, which incorporated environmental effects, including temperature, dissolved oxygen (DO) and strain rate for the nickel-based alloys. Due to lack of experiment data on domestic materials, there is no related environmental fatigue design model in China. In the present work, based on the corrosion fatigue tests of a kind of boat-shaped specimen in borated and lithiated high temperature water, the corrosion fatigue behavior and environmentally assisted cracking mechanism of domestic Alloy 690 steam generator tube have been investigate. An IMR model for the nickel-based alloy was proposed. The environmental fatigue life correction factor (F en ) was established, which addressed the environmental factors, including temperature, strain rate and dissolved oxygen. The method to evaluate environmental fatigue damage of structural materials in NPPs was proposed. (authors)

  18. The design of a study environment for acquiring academic and professional competence

    NARCIS (Netherlands)

    Kirschner, P.A.; Vilsteren, P. van

    Proposes a framework for the design of a learning environment which encourages the acquisition of academic and professional competence. Definition of knowledge, cognitive skill and competence; Acquisition of competence; Designing an environment for competence acquisition; Implementation of study

  19. Understanding Creative Design Processes by Integrating Sketching and CAD Modelling Design Environments: A Preliminary Protocol Result from Architectural Designers

    Directory of Open Access Journals (Sweden)

    Yi Teng Shih

    2015-11-01

    Full Text Available This paper presents the results of a preliminary protocol study of the cognitive behaviour of architectural designers during the design process. The aim is to better understand the similarities and differences in cognitive behaviour using Sequential Mixed Media (SMM and Alternative Mixed Media (AMM approaches, and how switching between media may impact on design processes. Two participants with at least one-year’s professional design experience and a Bachelor of Design degree, and competence in both sketching and computer-aid design (CAD modelling participated in the study. Video recordings of participants working on different projects were coded using the Function-Behaviour-Structure (FBS coding scheme. Participants were also interviewed and their explanations about their switching behaviours were categorised into three types: S→C, S/C↹R and C→S. Preliminary results indicate that switching between media may influence how designers identify problems and develop solutions. In particular, two design issues were identified.  These relate to the FBS coding scheme, where structure (S and behaviour derived from structure (Bs, change to documentation (D after switching from sketching to CAD modelling (S→C. These switches make it possible for designers to integrate both approaches into one design medium and facilitate their design processes in AMM design environments.

  20. Parameters Studies on Surface Initiated Rolling Contact Fatigue of Turnout Rails by Three-Level Unreplicated Saturated Factorial Design

    Directory of Open Access Journals (Sweden)

    Xiaochuan Ma

    2018-03-01

    Full Text Available Surface initiated rolling contact fatigue (RCF, mainly characterized by cracks and material stripping, is a common type of damage to turnout rails, which can not only shorten service life of turnout but also lead to poor running safety of vehicle. The rail surface initiated RCF of turnouts is caused by a long-term accumulation, the size and distribution of which are related to the dynamic parameters of the complicated vehicle-turnout system. In order to simulate the accumulation of rail damage, some random samples of dynamic parameters significantly influencing it should be input. Based on the three-level unreplicated saturated factorial design, according to the evaluation methods of H, P and B statistic values, six dynamic parameters that influence the rail surface initiated RCF in turnouts, namely running speed of vehicle, axle load, wheel-rail profiles, integral vertical track stiffness and wheel-rail friction coefficient, are obtained by selecting 13 dynamic parameters significantly influencing the dynamic vehicle-turnout interaction as the analysis factors, considering four dynamic response results, i.e., the normal wheel-rail contact force, longitudinal creep force, lateral creep force and wheel-rail contact patch area as the observed parameters. In addition, the rail surface initiated RCF behavior in turnouts under different wheel-rail creep conditions is analyzed, considering the relative motion of stock/switch rails. The results show that the rail surface initiated RCF is mainly caused by the tangential stress being high under small creep conditions, the normal and tangential stresses being high under large creep conditions, and the normal stress being high under pure spin creep conditions.

  1. Biaxial fatigue of metals the present understanding

    CERN Document Server

    Schijve, Jaap

    2016-01-01

    Problems of fatigue under multiaxial fatigue loads have been addressed in a very large number of research publications. The present publication is primarily a survey of biaxial fatigue under constant amplitude loading on metal specimens. It starts with the physical understanding of the fatigue phenomenon under biaxial fatigue loads. Various types of proportional and non-proportional biaxial fatigue loads and biaxial stress distributions in a material are specified. Attention is paid to the fatigue limit, crack nucleation, initial micro crack growth and subsequent macro-crack in different modes of crack growth. The interference between the upper and lower surfaces of a fatigue crack is discussed. Possibilities for predictions of biaxial fatigue properties are analysed with reference to the similarity concept. The significance of the present understanding for structural design problems is considered. The book is completed with a summary of major observations.

  2. Game Design Narrative for Learning: Appropriating Adventure Game Design Narrative Devices and Techniques for the Design of Interactive Learning Environments

    Science.gov (United States)

    Dickey, Michele D.

    2006-01-01

    The purpose of this conceptual analysis is to investigate how contemporary video and computer games might inform instructional design by looking at how narrative devices and techniques support problem solving within complex, multimodal environments. Specifically, this analysis presents a brief overview of game genres and the role of narrative in…

  3. Factors related to the design and implementation of an 'design for environment' process

    DEFF Research Database (Denmark)

    Skelton, Kristen; Knitl, Teresa

    2013-01-01

    In the last two decades, Siemens AG has systematically built up the topic of environmental protection within its core functions. The company is currently expanding its focus by including additional product and supply related environmental activities to enable strategic and inclusive decisions. Most...... recently, the Energy Sector of Siemens AG developed a Design for Environment (DfE) process based on ISO/TR 14062 to integrate environmental issues into product design and development. This paper briefly presents the DfE process and the feedback that was gathered from engineers as input to improve...

  4. Probabilistic Fatigue Damage Program (FATIG)

    Science.gov (United States)

    Michalopoulos, Constantine

    2012-01-01

    FATIG computes fatigue damage/fatigue life using the stress rms (root mean square) value, the total number of cycles, and S-N curve parameters. The damage is computed by the following methods: (a) traditional method using Miner s rule with stress cycles determined from a Rayleigh distribution up to 3*sigma; and (b) classical fatigue damage formula involving the Gamma function, which is derived from the integral version of Miner's rule. The integration is carried out over all stress amplitudes. This software solves the problem of probabilistic fatigue damage using the integral form of the Palmgren-Miner rule. The software computes fatigue life using an approach involving all stress amplitudes, up to N*sigma, as specified by the user. It can be used in the design of structural components subjected to random dynamic loading, or by any stress analyst with minimal training for fatigue life estimates of structural components.

  5. Review of Opinions of Math Teachers Concerning the Learning Environment That They Design

    Science.gov (United States)

    Aydin, Bünyamin; Yavuz, Ayse

    2016-01-01

    Design of appropriate learning environment has a significant importance in creation of aims of the math teaching. In the design of learning environments, teachers play a significant role. The aim of this study is determination of opinions of the math teachers concerning the learning environment that they design. In accordance with this aim, an…

  6. Fatigue test on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, van IJ.J.

    2005-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge

  7. The effect of notches and pits on corrosion fatigue strength

    Science.gov (United States)

    Tatner, Ian

    An investigation has been undertaken to examine the fatigue behaviour of two martensitic steels in air and aggressive environments. The steels studied are, 18% Ni marageing steel and FV520B, the later being a stainless steel turbine blade material and the former being a marageing steel that suffers general corrosion in mild environments. Both steels were heat treated to give similar tensile strength.The design and manufacture of an autoclave allowed push-pull fatigue tests to be conducted in aggressive environments at elevated temperatures.Corrosion potential was monitored using a three electrode cell and was controlled during testing. Base-line fatigue tests were conducted with a range of constant corrosion potentials, using both notched and plain FV520B specimens. In addition fatigue tests with pulsed corrosion potential were performed to asses the effect of transient corrosion conditions on the corrosion fatigue strength. The pulsed tests were designed to simulate service transients in the oxygen content and general chemical hostility in the condensing steam environment during start-up and shut down of the steam turbine.Post test examination of fractured samples was performed using Scanning Electron Microscopy (SEM) and optical microscope techniques. The fractography results were used to quantify microstructural and fracture features of the steels.A model based on the size and geometry of the initial corrosion pitting has been proposed to asses the fatigue life of FV520B in an aggressive environment.The effect of pitting on the corrosion fatigue strength of FV520B has been modelled using linear elastic fracture mechanics (LEFM) type approach. The model has shown a good correlation between predicted fatigue lives with experimental results.The results suggest that the fatigue life is governed by the mechanical stress concentrating effect of the pits rather than the electrochemical damage caused by the environment.Finite Element Analysis (FEA) of the notch allowed

  8. Design of molecular imprinted polymers compatible with aqueous environment.

    Science.gov (United States)

    Piletska, Elena V; Guerreiro, Antonio R; Romero-Guerra, Maria; Chianella, Iva; Turner, Anthony P F; Piletsky, Sergey A

    2008-01-21

    The main problem of poor water compatibility of molecularly imprinted polymers (MIPs) was addressed in examples describing design of synthetic receptors with high affinity for drugs of abuse. An extensive potentiometric titration of 10 popular functional monomers and corresponding imprinted and blank polymers was conducted in order to evaluate the subtleties of functional groups ionisation under aqueous conditions. It was found that polymers prepared using 2-trifluoromethacrylic acid (TFMAA) in combination with toluene as porogen possess superior properties which make them suitable for effective template recognition in water. The potential impact of phase separation during polymerisation on formation of high quality imprints has been discussed. Three drugs of abuse such as cocaine, deoxyephedrine and methadone were used as template models in polymer preparation for the practical validation of obtained results. The polymer testing showed that synthesized molecularly imprinted polymers have high affinity and selectivity for corresponding templates in aqueous environment, with imprinting factors of 2.6 for cocaine and 1.4 for methadone and deoxyephedrine. Corresponding blank polymers were unable to differentiate between analytes, suggesting that imprinting phenomenon was responsible for the recognition properties.

  9. Fatigue (PDQ)

    Science.gov (United States)

    ... Data Conducting Clinical Trials Statistical Tools and Data Terminology Resources NCI Data Catalog Cryo-EM NCI's Role ... Problems getting enough sleep. Being less active. Other medical conditions. Fatigue is common in people with advanced ...

  10. Fatigue monitoring desktop guide

    International Nuclear Information System (INIS)

    Woods, K.; Thomas, K.

    2012-01-01

    The development of a program for managing material aging (MMG) in the nuclear industry requires a new and different perspective. The classical method for MMG is cycle counting, which has been shown to have limited success. The classical method has been successful in satisfying the ductile condition per the America Society of Mechanical Engineers' (ASME) design criteria. However, the defined material failure mechanism has transformed from through-wall cracking and leakage (ASME) to crack initiation (NUREG-6909). This transformation is based on current industry experience with material degradation early in plant life and can be attributed to fabrication issues and environment concerns where cycle counting has been unsuccessful. This new perspective provides a different approach to cycle counting that incorporates all of the information about the material conditions. This approach goes beyond the consideration of a static analysis and includes a dynamic assessment of component health, which is required for operating plants. This health definition should consider fabrication, inspections, transient conditions and industry operating experience. In addition, this collection of information can be transparent to a broader audience that may not have a full understanding of the system design or the potential causes of early material degradation. This paper will present the key points that are needed for a successful fatigue monitoring desktop guide. (authors)

  11. Fatigue monitoring desktop guide

    Energy Technology Data Exchange (ETDEWEB)

    Woods, K. [InnoTech Engineering Solutions, LLC (United States); Thomas, K. [Nebraska Public Power District (United States)

    2012-07-01

    The development of a program for managing material aging (MMG) in the nuclear industry requires a new and different perspective. The classical method for MMG is cycle counting, which has been shown to have limited success. The classical method has been successful in satisfying the ductile condition per the America Society of Mechanical Engineers' (ASME) design criteria. However, the defined material failure mechanism has transformed from through-wall cracking and leakage (ASME) to crack initiation (NUREG-6909). This transformation is based on current industry experience with material degradation early in plant life and can be attributed to fabrication issues and environment concerns where cycle counting has been unsuccessful. This new perspective provides a different approach to cycle counting that incorporates all of the information about the material conditions. This approach goes beyond the consideration of a static analysis and includes a dynamic assessment of component health, which is required for operating plants. This health definition should consider fabrication, inspections, transient conditions and industry operating experience. In addition, this collection of information can be transparent to a broader audience that may not have a full understanding of the system design or the potential causes of early material degradation. This paper will present the key points that are needed for a successful fatigue monitoring desktop guide. (authors)

  12. Proof of fatigue strength of nuclear components part II: Numerical fatigue analysis for transient stratification loading considering environmental effects

    International Nuclear Information System (INIS)

    Krätschmer, D.; Roos, E.; Schuler, X.; Herter, K.-H.

    2012-01-01

    For the construction, design and operation of nuclear components and systems the appropriate technical codes and standards provide detailed analysis procedures which guarantee a reliable behaviour of the structural components throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. To consider effects of light water reactor coolant environments, new design curves included in report NUREG/CR-6909 for austenitic stainless steels and for low alloy steels have been presented. For the usage of these new design curves an environmental fatigue correction factor for incorporating environmental effects has to be calculated and used. The application of this environmental correction factor to a fatigue analysis of a nozzle with transient stratification loads, derived by in-service monitoring, has been performed. The results are used to compare with calculated usage factors, based on design curves without taking environmental effects particularly into account. - Highlights: ► We model an nozzle for fatigue analysis und mechanical and thermal loading conditions. ► A simplified as well as a general elastic–plastic fatigue analysis considering environmental effects is performed. ► The influence of different factors calculating the environmental factor F en are shown. ► The presented numerical evaluation methodology allows the consideration of all relevant parameters to assess lifetime.

  13. Design of a study on suboptimal cognitive acts in the diagnostic process, the effect on patient outcomes and the influence of workload, fatigue and experience of physician

    Directory of Open Access Journals (Sweden)

    van der Wal Gerrit

    2009-04-01

    Full Text Available Abstract Background Diagnostic error is an important error type since diagnostic adverse events are regularly judged as being preventable and the consequences are considered to be severe. Existing research often focuses on either diagnostic adverse events or on the errors in diagnostic reasoning. Whether and when an incorrect diagnostic process results in adverse outcomes has not been studied extensively. The present paper describes the design of a study that aims to study the relationship between a suboptimal diagnostic process and patient outcomes. In addition, the role of personal and circumstantial factors on the quality of the diagnostic process will be examined. Methods/Design The research questions were addressed using several data sources. First, the differential diagnosis was assessed concurrently to the diagnostic process. Second, the patient records of 248 patients suffering from shortness of breath were reviewed by expert internists in order to reveal suboptimal cognitive acts and (potential consequences for the patient. The suboptimal cognitive acts were discussed with the treating physicians and classified with the taxonomy of unsafe acts. Third, workload, fatigue and work experience were measured during the physicians work. Workload and fatigue were measured during the physicians shift using the NASA tlx questionnaire on a handheld computer. Physicians participating in the study also answered questions about their work experience. Discussion The design used in this study provides insight into the relationship between suboptimal cognitive acts in the diagnostic process and possible consequences for the patient. Suboptimal cognitive acts in the diagnostic process and its causes can be revealed. Additional measurements of workload, fatigue and experience allow examining the influence of these factors on the diagnostic process. In conclusion, the present design provides a method with which insights in weaknesses of the diagnostic

  14. Generic Reliability-Based Inspection Planning for Fatigue Sensitive Details

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Straub, Daniel; Faber, Michael Havbro

    2005-01-01

    of fatigue sensitive details in fixed offshore steel jacket platforms and FPSO ship structures. Inspection and maintenance activities are planned such that code based requirements to the safety of personnel and environment for the considered structure are fulfilled and at the same time such that the overall......The generic approach for planning of in-service NDT inspections is extended to cover the case where the fatigue load is modified during the design lifetime of the structure. Generic reliability-based inspection planning has been developed as a practical approach to perform inspection planning...... expected costs for design, inspections, repairs and failures are minimized. The method is based on the assumption of “no-finds” of cracks during inspections. Each fatigue sensitive detail is categorized according to their type of details (SN curves), FDF values, RSR values, inspection, repair and failure...

  15. On public space design for Chinese urban residential area based on integrated architectural physics environment evaluation

    Science.gov (United States)

    Dong, J. Y.; Cheng, W.; Ma, C. P.; Tan, Y. T.; Xin, L. S.

    2017-04-01

    The residential public space is an important part in designing the ecological residence, and a proper physics environment of public space is of greater significance to urban residence in China. Actually, the measure to apply computer aided design software into residential design can effectively avoid an inconformity of design intent with actual using condition, and a negative impact on users due to bad architectural physics environment of buildings, etc. The paper largely adopts a design method of analyzing architectural physics environment of residential public space. By analyzing and evaluating various physics environments, a suitability assessment is obtained for residential public space, thereby guiding the space design.

  16. A social sustainability approach to birth environment design

    DEFF Research Database (Denmark)

    Jangaard, Karin; Folmer, Mette Blicher

    RESEARCH PROCESS Measuring on welness, lifequality and experience of user involvement in all processes. DESIGN PROCESS Research and design thinking USERINVOLVEMENT Ownership of design solutions CARE MODEL / ORGANISATION Humanity, vison for care and tre......RESEARCH PROCESS Measuring on welness, lifequality and experience of user involvement in all processes. DESIGN PROCESS Research and design thinking USERINVOLVEMENT Ownership of design solutions CARE MODEL / ORGANISATION Humanity, vison for care and tre...

  17. Transition of a Three-Dimensional Unsteady Viscous Flow Analysis from a Research Environment to the Design Environment

    Science.gov (United States)

    Dorney, Suzanne; Dorney, Daniel J.; Huber, Frank; Sheffler, David A.; Turner, James E. (Technical Monitor)

    2001-01-01

    The advent of advanced computer architectures and parallel computing have led to a revolutionary change in the design process for turbomachinery components. Two- and three-dimensional steady-state computational flow procedures are now routinely used in the early stages of design. Unsteady flow analyses, however, are just beginning to be incorporated into design systems. This paper outlines the transition of a three-dimensional unsteady viscous flow analysis from the research environment into the design environment. The test case used to demonstrate the analysis is the full turbine system (high-pressure turbine, inter-turbine duct and low-pressure turbine) from an advanced turboprop engine.

  18. Experimental verification of different parameters influencing the fatigue S/N-curve

    International Nuclear Information System (INIS)

    Roos, E.; Maile, K.; Herter, K.-H.; Schuler, X.

    2005-01-01

    For the construction, design and operation of nuclear components the appropriate technical codes and standards provide detailed stress analysis procedures, material data and a design philosophy which guarantees a reliable behavior throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various (specified or measured) loading histories which are of mechanical and/or thermal origin and the geometric complexities of the components. In order to fully understand the background of the fatigue analysis included in the codes and standards as well as of the fatigue design curves used as a limiting criteria (to determine the fatigue life usage factor), it is important to understand the history, background as well as the methodologies which are important for the design engineers to get reliable results. The design rules according to the technical codes and standards provide for explicit consideration of cyclic operation, using design fatigue curves of allowable alternating loads (allowable stress or strain amplitudes) vs. number of loading cycles (S/N-curves), specific rules for assessing the cumulative fatigue damage (cumulative fatigue life usage factor) caused by different specified or monitored load cycles. The influence of different factors like welds, environment, surface finish, temperature, mean stress and size must be taken into consideration. In the paper parameters influencing the S/N-curves used within a fatigue analysis, like different type of material, the surface finish, the temperature, the difference between unwelded and welded areas, the strain rate as well as the influences of notches are verified on the basis of experimental results obtained by specimens testing in the LCF regime for high strain amplitudes. Thus safety margins relevant for the assessment of fatigue life depending on the different influencing parameters are

  19. A Computer Environment for Beginners' Learning of Sorting Algorithms: Design and Pilot Evaluation

    Science.gov (United States)

    Kordaki, M.; Miatidis, M.; Kapsampelis, G.

    2008-01-01

    This paper presents the design, features and pilot evaluation study of a web-based environment--the SORTING environment--for the learning of sorting algorithms by secondary level education students. The design of this environment is based on modeling methodology, taking into account modern constructivist and social theories of learning while at…

  20. A Framework for Designing Collaborative Learning Environments Using Mobile AR

    Science.gov (United States)

    Cochrane, Thomas; Narayan, Vickel; Antonczak, Laurent

    2016-01-01

    Smartphones provide a powerful platform for augmented reality (AR). Using a smartphone's camera together with the built in GPS, compass, gyroscope, and touch screen enables the real world environment to be overlaid with contextual digital information. The creation of mobile AR environments is relatively simple, with the development of mobile AR…

  1. Design semantics of connections in a smart home environment

    NARCIS (Netherlands)

    Vlist, van der B.J.J.; Niezen, G.; Hu, J.; Feijs, L.M.G.

    2011-01-01

    As the environments in which we live become more intelligent|through more computational power, embedded sensors and network connections between the devices that reside in the environment|there is a risk of leaving its users clueless about what is going on. User interaction changes from interaction

  2. An assessment of prospective memory retrieval in women with chronic fatigue syndrome using a virtual-reality environment: an initial study.

    Science.gov (United States)

    Attree, Elizabeth A; Dancey, Christine P; Pope, Alison L

    2009-08-01

    People with chronic fatigue syndrome (CFS) have increased rates of depression, anxiety, and illness intrusiveness; they may also suffer from cognitive problems such as retrospective memory (RM) deficits and concentration difficulties that can stem from diminished information-processing capability. We predicted that this diminished capacity may also lead to deficits in other cognitive functions, such as prospective memory (ProM). Event-, time-, and activity-based ProM was assessed in 11 women with CFS and 12 healthy women using a computer-generated virtual environment (VE). RM was assessed using a free-recall test, and subjective assessment of both ProM and RM was assessed by questionnaire. Groups were equivalent in age and measures of IQ. People with CFS performed slightly worse than healthy controls on both the event- and time-based ProM measures, although these were not statistically significant. However, the CFS group performed significantly worse than the healthy controls on both the free recall-task and on subjective assessment of both RM and ProM. Women with CFS do have some subtle decrements in memory, particularly RM. However, it is possible that the decrements found in the present sample would be greater in real life. Further studies utilizing both healthy controls and illness controls are now needed to ascertain how sensitive the VE measure is and to inform the development of tasks in the VE that place progressively increasing demands on working memory capacity.

  3. Near threshold fatigue testing

    Science.gov (United States)

    Freeman, D. C.; Strum, M. J.

    1993-01-01

    Measurement of the near-threshold fatigue crack growth rate (FCGR) behavior provides a basis for the design and evaluation of components subjected to high cycle fatigue. Typically, the near-threshold fatigue regime describes crack growth rates below approximately 10(exp -5) mm/cycle (4 x 10(exp -7) inch/cycle). One such evaluation was recently performed for the binary alloy U-6Nb. The procedures developed for this evaluation are described in detail to provide a general test method for near-threshold FCGR testing. In particular, techniques for high-resolution measurements of crack length performed in-situ through a direct current, potential drop (DCPD) apparatus, and a method which eliminates crack closure effects through the use of loading cycles with constant maximum stress intensity are described.

  4. Compassion Satisfaction and Compassion Fatigue Among Critical Care Nurses.

    Science.gov (United States)

    Sacco, Tara L; Ciurzynski, Susan M; Harvey, Megan Elizabeth; Ingersoll, Gail L

    2015-08-01

    Although critical care nurses gain satisfaction from providing compassionate care to patients and patients' families, the nurses are also at risk for fatigue. The balance between satisfaction and fatigue is considered professional quality of life. To establish the prevalence of compassion satisfaction and compassion fatigue in adult, pediatric, and neonatal critical care nurses and to describe potential contributing demographic, unit, and organizational characteristics. In a cross-sectional design, nurses were surveyed by using a demographic questionnaire and the Professional Quality of Life Scale to measure levels of compassion fatigue and compassion satisfaction. Nurses (n = 221) reported significant differences in compassion satisfaction and compassion fatigue on the basis of sex, age, educational level, unit, acuity, change in nursing management, and major systems change. Understanding the elements of professional quality of life can have a positive effect on work environment. The relationship between professional quality of life and the standards for a healthy work environment requires further investigation. Once this relationship is fully understood, interventions to improve this balance can be developed and tested. ©2015 American Association of Critical-Care Nurses.

  5. Multi-Disciplinary Multi-Fidelity Design Environment, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — To meet the design challenges of tomorrow, NASA and industry require advancements in the state-of-the-art for physics-based design and analysis frameworks. In...

  6. A Software Environment for the Design of Organizational Structures

    National Research Council Canada - National Science Library

    Shlapak, Yuriy; Luo, Jie; Levchuk, Georgiy M; Tu, Fang; Pattipati, Krishna R

    2000-01-01

    ...) building an organizational hierarchy. In addition, basic modules for dynamic adaptation of organizational strategies and structures in the face of changing mission environment and/or resources are being added...

  7. An intelligent simulation environment for control system design

    International Nuclear Information System (INIS)

    Robinson, J.T.

    1989-01-01

    The Oak Ridge National Laboratory is currently assisting in the development of advanced control systems for the next generation of nuclear power plants. This paper presents a prototype interactive and intelligent simulation environment being developed to support this effort. The environment combines tools from the field of Artificial Intelligence; in particular object-oriented programming, a LISP programming environment, and a direct manipulation user interface; with traditional numerical methods for simulating combined continuous/discrete processes. The resulting environment is highly interactive and easy to use. Models may be created and modified quickly through a window oriented direct manipulation interface. Models may be modified at any time, even as the simulation is running, and the results observed immediately via real-time graphics. 8 refs., 3 figs

  8. The Relationship Among Change Fatigue, Resilience, and Job Satisfaction of Hospital Staff Nurses.

    Science.gov (United States)

    Brown, Robin; Wey, Howard; Foland, Kay

    2018-03-08

    The purpose of this study was to examine relationships between change fatigue, resilience, and job satisfaction among novice and seasoned hospital staff nurses. Health care is typified by change. Frequent and vast changes in acute care hospitals can take a toll on nurses and cause change fatigue, which has been largely overlooked and under-researched. A descriptive correlational design was employed with 521 hospital staff nurses in one midwestern state. Participants completed three online surveys: (a) Change Fatigue Scale, (b) Connor-Davidson Resilience Scale, and (c) McCloskey/Mueller Satisfaction Scale. In a multiple regression model, job satisfaction had a statistically significant negative association with change fatigue (p job satisfaction among hospital nursing staff being negatively influenced by change fatigue and positively influenced by resilience, although reverse causal connections are also possible. Change fatigue may be increased by larger hospital size (number of beds), and resilience may be increased by higher educational level of hospital staff nurses. The study advanced the nursing knowledge on change fatigue, resilience, and job satisfaction of staff nurses working in acute care hospitals. Engaging in strategies aimed at preventing change fatigue in nursing staff can enhance workplace environments, job satisfaction, and retention of nurses. © 2018 Sigma Theta Tau International.

  9. Design of a randomized controlled trial of physical training and cancer (Phys-Can) - the impact of exercise intensity on cancer related fatigue, quality of life and disease outcome

    DEFF Research Database (Denmark)

    Berntsen, Sveinung; Aaronson, Neil K; Buffart, Laurien

    2017-01-01

    BACKGROUND: Cancer-related fatigue is a common problem in persons with cancer, influencing health-related quality of life and causing a considerable challenge to society. Current evidence supports the beneficial effects of physical exercise in reducing fatigue, but the results across studies...... are not consistent, especially in terms of exercise intensity. It is also unclear whether use of behaviour change techniques can further increase exercise adherence and maintain physical activity behaviour. This study will investigate whether exercise intensity affects fatigue and health related quality of life...... on exercise adherence. We will also investigate whether exercise intensity influences inflammatory markers and cytokines, and whether gene expressions following training serve as mediators for the effects of exercise on fatigue and health related quality of life. METHODS/DESIGN: Six hundred newly diagnosed...

  10. Sociotechnical design processes and working environment: The case of a continuous process wok

    DEFF Research Database (Denmark)

    Broberg, Ole

    2000-01-01

    A five-year design process of a continuous process wok has been studied with the aim of elucidating the conditions for integrating working environment aspects. The design process is seen as a network building activity and as a social shaping process of the artefact. A working environment log...... is suggested as a tool designers can use to integrate considerations of future operators' working environment....

  11. Hydrogen diffusion into fatigue cracks of aluminium alloy 6013 in a corrosive environment; Wasserstoffeinlagerung an Ermuedungsrissen der Aluminiumlegierung 6013 unter korrosiver Umgebung

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Christian Alexander

    2009-08-13

    The author attempted a time-resolved detection of raised hydrogen concentrations in the plastic deformation region of fatigue cracks in an aluminium test piece deformed by cyclic stress in a corrosive environment. Mechanical material parameters like the crack propagation velocity under cyclic stress change dramatically in a corrosive environment. This is assumed to be caused by hydrogen diffusion, but so far there is no method that reliably measures additional hydrogen from the corrosive environment. For this reason, a special analytical configuration was set up which makes use of the thermal desorption method. First, chips with a thickness of about 20 micrometers are sawed out of the test specimen in high-vacuum conditions. The chips fall into a hot melting vessel in a UHV chamber, where the hydrogen contained in the chips is released. The resulting pressure increase is recorded by a mass spectrometer. A hydrogen profile of the test specimen is obtained by assigning the chip position to the signal. For the corrosive medium in which the test specimen is immersed during crack initiation, i.e. NaCl solution, heavy water was used. This makes it possible to distinguish between the hydrogen contained in a piece of technical aluminium alloy (AA6013) and the deuterium diffusing in from the corrosive fluid. The deuterium is found exclusively in the test piece volume in the strongly plastically deformed region surrounding the fatigue crack. (orig.) [German] Das Ziel der vorliegenden Arbeit besteht im ortsaufgeloesten Nachweis einer erhoehten Wasserstoffkonzentration im plastisch deformierten Bereich von Ermuedungsrissen einer unter korrosiver Umgebung zyklisch verformten Aluminiumprobe. Mechanische Materialparameter wie z.B. die Rissausbreitungsgeschwindigkeit unter zyklischer Belastung aendern sich drastisch in korrosiver Umgebung. Als Ursache fuer dieses Verhalten wird eine Eindiffusion von Wasserstoff vermutet, jedoch gibt es bisher keine Messung die den zusaetzlichen

  12. Mitigation of Over-conservatism in Fatigue Analysis of the Pressurizer Surge Line

    International Nuclear Information System (INIS)

    Moon, Chan Kook; Lee, Jang Gon; Kim, Tae Soon; Han, Sung Bong

    2007-01-01

    The U.S. Nuclear Regulatory Commission (NRC) issued draft regulatory guide DG-1144 in July 2006, entitled 'Guidelines for Evaluating Fatigue Analysis Incorporating the Life Reduction of Metal Components Due to the Effects of the Light-Water Reactor Environment for New Reactors.' This draft guide demands to perform fatigue analysis in accordance with the draft NUREG/CR-6909 report (Effect on Fatigue Life of Reactor material for LWR Coolant Environments) for carbon and low-alloy steels, and austenitic stainless steel materials. In March 2007, NRC formally issued Reg. guide 1.207 which demands to perform fatigue analysis in accordance with the final NUREG/CR-6909 report. Reviewing these documents it is found that in case of austenitic stainless steel and Ni-Cr alloy the new design fatigue curve is much more severe than present curve and will increase the cumulative usage factor (CUF) 4 to 5 times of the present value. In particular, detailed analysis for pressurizer surge line which is made of stainless steel is needed and mitigation of over-conservatism included in present fatigue analysis procedures is absolutely required. In this study, thus, the mitigation method for over conservatism in the present fatigue analysis procedure for the pressurizer surge line is studied

  13. Areva fatigue concept. Fast fatigue evaluation, a new method for fatigue analysis

    International Nuclear Information System (INIS)

    Heinz, Benedikt; Bergholz, Steffen; Rudolph, Juergen

    2011-01-01

    Within the discussions on the long term operation (LTO) of nuclear power plants the ageing management is on the focus of that analysis. The knowledge of the operational thermal cyclic load data on components of the power plants and their evaluation in the fatigue analysis is a central concern. The changes in fatigue requirements (e.g. the consideration of environmentally assisted fatigue - EAF) recently discussed and LTO efforts are a strong motivation for the identification of margins in the existing fatigue analysis approaches. These margins should be considered within new approaches in order to obtain realistic (or more accurate) analysis results. Of course, these new analysis approaches have to be manageable and efficient. The Areva Fatigue Concept (AFC) offers the comprehensive conceptual basis for the consideration of fatigue on different levels and depths. The combination of data logging and automated fatigue evaluation are important modules of the AFC. Besides the established simplified stress based fatigue estimation Areva develops a further automated fatigue analysis method called Fast Fatigue Evaluation (FFE). This method comprises highly automated stress analyses at the fatigue relevant locations of the component. Hence, a component specific course of stress as a function of time is determined based on FAMOS or similar temperature measurement systems. The subsequent application of the rain flow cycle counting algorithm allows for the determination of the usage factor following the rules of the design code requirements. The new FFE approach constitutes a cycle counting method based on the real stresses in the component, and determined as result a rule-conformity cumulative usage factor. (orig.)

  14. Design of a Networked Learning Master Environment for Professionals

    DEFF Research Database (Denmark)

    Dirckinck-Holmfeld, Lone

    2010-01-01

    The paper is presenting the overall learning design of MIL (Master in ICT and Learning). The learning design is integrating a number of principles: 1. Principles of problem and project based learning 2. Networked learning / learning in communities of practice. The paper will discuss how these pri......The paper is presenting the overall learning design of MIL (Master in ICT and Learning). The learning design is integrating a number of principles: 1. Principles of problem and project based learning 2. Networked learning / learning in communities of practice. The paper will discuss how...

  15. QUICK - AN INTERACTIVE SOFTWARE ENVIRONMENT FOR ENGINEERING DESIGN

    Science.gov (United States)

    Schlaifer, R. S.

    1994-01-01

    QUICK provides the computer user with the facilities of a sophisticated desk calculator which can perform scalar, vector and matrix arithmetic, propagate conic orbits, determine planetary and satellite coordinates and perform other related astrodynamic calculations within a Fortran-like environment. QUICK is an interpreter, therefore eliminating the need to use a compiler or a linker to run QUICK code. QUICK capabilities include options for automated printing of results, the ability to submit operating system commands on some systems, and access to a plotting package (MASL)and a text editor without leaving QUICK. Mathematical and programming features of QUICK include the ability to handle arbitrary algebraic expressions, the capability to define user functions in terms of other functions, built-in constants such as pi, direct access to useful COMMON areas, matrix capabilities, extensive use of double precision calculations, and the ability to automatically load user functions from a standard library. The MASL (The Multi-mission Analysis Software Library) plotting package, included in the QUICK package, is a set of FORTRAN 77 compatible subroutines designed to facilitate the plotting of engineering data by allowing programmers to write plotting device independent applications. Its universality lies in the number of plotting devices it puts at the user's disposal. The MASL package of routines has proved very useful and easy to work with, yielding good plots for most new users on the first or second try. The functions provided include routines for creating histograms, "wire mesh" surface plots and contour plots as well as normal graphs with a large variety of axis types. The library has routines for plotting on cartesian, polar, log, mercator, cyclic, calendar, and stereographic axes, and for performing automatic or explicit scaling. The lengths of the axes of a plot are completely under the control of the program using the library. Programs written to use the MASL

  16. Variable amplitude fatigue, modelling and testing

    International Nuclear Information System (INIS)

    Svensson, Thomas.

    1993-01-01

    Problems related to metal fatigue modelling and testing are here treated in four different papers. In the first paper different views of the subject are summarised in a literature survey. In the second paper a new model for fatigue life is investigated. Experimental results are established which are promising for further development of the mode. In the third paper a method is presented that generates a stochastic process, suitable to fatigue testing. The process is designed in order to resemble certain fatigue related features in service life processes. In the fourth paper fatigue problems in transport vibrations are treated

  17. Teacher-Led Design of an Adaptive Learning Environment

    Science.gov (United States)

    Mavroudi, Anna; Hadzilacos, Thanasis; Kalles, Dimitris; Gregoriades, Andreas

    2016-01-01

    This paper discusses a requirements engineering process that exemplifies teacher-led design in the case of an envisioned system for adaptive learning. Such a design poses various challenges and still remains an open research issue in the field of adaptive learning. Starting from a scenario-based elicitation method, the whole process was highly…

  18. Designing a Programmatic Digital Learning Environment: Lessons from Prototyping

    Science.gov (United States)

    Gal, Diane; Lewis, Mark

    2018-01-01

    Promoted as a way to enhance learning and improve efficiencies, the steady rise of technology adoption across higher education has created both new opportunities and new challenges. Borrowing principles of design thinking and related user- or learner-centered design practices, this descriptive case study offers an example of how institutions of…

  19. Advantageous application of Synthetic Environments in product design

    NARCIS (Netherlands)

    Miedema, J.; van der Voort, Mascha C.; van Houten, Frederikus J.A.M.

    2009-01-01

    Despite the abundance of supporting tools and methods engineers have at their disposal nowadays, the early stages of design processes are still not extensively supported. Strikingly, the whole of design aids is characterized by mono-disciplinarity, scattered availability and the fact that the

  20. Application of mechatronic design approach in a reconfigurable manufacturing environment

    CSIR Research Space (South Africa)

    Xing, B

    2008-12-01

    Full Text Available manufacturing system (FMS) do not longer meet the requirement of modern manufacturing. DMS were designed for mass production, while FMS was designed for batch manufacturing. These systems cannot address mass customization. There is a need for greater, more...

  1. Early user involvement in designing intelligent products and environments

    NARCIS (Netherlands)

    Kuijt-Evers, L.; Steen, M.

    2008-01-01

    A literature review was conducted on user involvement in design. The focus of the review was on how researchers and designers attempt to cooperate with end-users, with the goal of making a better match with end-users’ needs and preferences. The main goal of the research was to get insight in which

  2. The Design of Immersive English Learning Environment Using Augmented Reality

    Science.gov (United States)

    Li, Kuo-Chen; Chen, Cheng-Ting; Cheng, Shein-Yung; Tsai, Chung-Wei

    2016-01-01

    The study uses augmented reality (AR) technology to integrate virtual objects into the real learning environment for language learning. The English AR classroom is constructed using the system prototyping method and evaluated by semi-structured in-depth interviews. According to the flow theory by Csikszenmihalyi in 1975 along with the immersive…

  3. Designs for Living and Learning: Transforming Early Childhood Environments.

    Science.gov (United States)

    Curtis, Deb; Carter, Margie

    While the early childhood field has formed standards to help in recognizing quality programs for children, practitioners seldom use values to guide in selection of materials or to help plan early childhood environments. This book draws on a variety of educational approaches, including Waldorf, Montessori, and Reggio Emilia, to outline hundreds of…

  4. Visual Environment for Designing Interactive Learning Scenarios with Augmented Reality

    Science.gov (United States)

    Mota, José Miguel; Ruiz-Rube, Iván; Dodero, Juan Manuel; Figueiredo, Mauro

    2016-01-01

    Augmented Reality (AR) technology allows the inclusion of virtual elements on a vision of actual physical environment for the creation of a mixed reality in real time. This kind of technology can be used in educational settings. However, the current AR authoring tools present several drawbacks, such as, the lack of a mechanism for tracking the…

  5. Design semantics of connections in a smart home environment

    NARCIS (Netherlands)

    Vlist, van der B.J.J.; Niezen, G.; Hu, J.; Feijs, L.M.G.; Chen, L.L.; Djajadiningrat, T.; Feijs, L.M.G.; Kyffin, S.; Steffen, D.; Young, B.

    2010-01-01

    As the environments in which we live become more intelligent— through more computational power, embedded sensors and network connections between the devices that reside in the environment—there is a risk of leaving its users clueless about what is going on. User interaction changes from interaction

  6. Designing a Social Environment for Human-Robot Cooperation.

    Science.gov (United States)

    Amram, Fred M.

    Noting that work is partly a social activity, and that workers' psychological and emotional needs influence their productivity, this paper explores avenues for improving human-robot cooperation and for enhancing worker satisfaction in the environment of flexible automation. The first section of the paper offers a brief overview of the…

  7. Pre-Service Teachers Designing Virtual World Learning Environments

    Science.gov (United States)

    Jacka, Lisa; Booth, Kate

    2012-01-01

    Integrating Information Technology Communications in the classroom has been an important part of pre-service teacher education for over a decade. The advent of virtual worlds provides the pre-service teacher with an opportunity to study teaching and learning in a highly immersive 3D computer-based environment. Virtual worlds also provide a place…

  8. A design approach to socially adaptive lighting environments

    NARCIS (Netherlands)

    Magielse, R.; Ross, P.R.

    2011-01-01

    Historically light has been a catalyst for social life to emerge. In recent years of lighting research the social effect of light has been underexposed. The environments we occupy on a daily basis are used for a wider variety of activities. Consequently, lighting conditions need to become sensitive

  9. A survey of the prevalence of fatigue, its precursors and individual coping mechanisms among U.S. manufacturing workers.

    Science.gov (United States)

    Lu, Lin; Megahed, Fadel M; Sesek, Richard F; Cavuoto, Lora A

    2017-11-01

    Advanced manufacturing has resulted in significant changes on the shop-floor, influencing work demands and the working environment. The corresponding safety-related effects, including fatigue, have not been captured on an industry-wide scale. This paper presents results of a survey of U.S. manufacturing workers for the: prevalence of fatigue, its root causes and significant factors, and adopted individual fatigue coping methods. The responses from 451 manufacturing employees were analyzed using descriptive data analysis, bivariate analysis and Market Basket Analysis. 57.9% of respondents indicated that they were somewhat fatigued during the past week. They reported the ankles/feet, lower back and eyes were frequently affected body parts and a lack of sleep, work stress and shift schedule were top selected root causes for fatigue. In order to respond to fatigue when it is present, respondents reported coping by drinking caffeinated drinks, stretching/doing exercises and talking with coworkers. Frequent combinations of fatigue causes and individual coping methods were identified. These results may inform the design of fatigue monitoring and mitigation strategies and future research related to fatigue development. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Research on the Design of Public Space Environment for Aging Society

    Science.gov (United States)

    Fang, Gu; Soo, Kim Chul

    2018-03-01

    This paper studies the living space environment suitable for the elderly, because the elderly and the disabled have become increasingly prominent social problems. Through the discussion of the humanistic environment design method of the elderly and the disabled, the paper puts forward a new environment design which has the traditional characteristics and adapts to the new society to care for the elderly (the disabled).By studying and analyzing the background of social aging, the theory of public space environment design and the needs of the elderly, it is pointed out that the design of public space environment in the aged society needs to be implemented in detail design. The number of elderly people in public space will increase, give full attention to the public space outdoor environment quality, for the elderly to provide a variety of environmental facilities have long-term significance.

  11. Creep-fatigue interaction at high temperature; Proceedings of the Symposium, 112th ASME Winter Annual Meeting, Atlanta, GA, Dec. 1-6, 1991

    Science.gov (United States)

    Haritos, George K.; Ochoa, O. O.

    Various papers on creep-fatigue interaction at high temperature are presented. Individual topics addressed include: analysis of elevated temperature fatigue crack growth mechanisms in Alloy 718, physically based microcrack propagation laws for creep-fatigue-environment interaction, in situ SEM observation of short fatigue crack growth in Waspaloy at 700 C under cyclic and dwell conditions, evolution of creep-fatigue life prediction models, TMF design considerations in turbine airfoils of advanced turbine engines. Also discussed are: high temperature fatigue life prediction computer code based on the total strain version of strainrange partitioning, atomic theory of thermodynamics of internal variables, geometrically nonlinear analysis of interlaminar stresses in unsymmetrically laminated plates subjected to uniform thermal loading, experimental investigation of creep crack tip deformation using moire interferometry. (For individual items see A93-31336 to A93-31344)

  12. Application of NUREG/CR-5999 interim fatigue curves to selected nuclear power plant components

    International Nuclear Information System (INIS)

    Ware, A.G.; Morton, D.K.; Nitzel, M.E.

    1995-03-01

    Recent test data indicate that the effects of the light water reactor (LWR) environment could significantly reduce the fatigue resistance of materials used in the reactor coolant pressure boundary components of operating nuclear power plants. Argonne National Laboratory has developed interim fatigue curves based on test data simulating LWR conditions, and published them in NUREG/CR-5999. In order to assess the significance of these interim fatigue curves, fatigue evaluations of a sample of the components in the reactor coolant pressure boundary of LWRs were performed. The sample consists of components from facilities designed by each of the four U.S. nuclear steam supply system vendors. For each facility, six locations were studied, including two locations on the reactor pressure vessel. In addition, there are older vintage plants where components of the reactor coolant pressure boundary were designed to codes that did not require an explicit fatigue analysis of the components. In order to assess the fatigue resistance of the older vintage plants, an evaluation was also conducted on selected components of three of these plants. This report discusses the insights gained from the application of the interim fatigue curves to components of seven operating nuclear power plants

  13. Application of environmentally-corrected fatigue curves to nuclear power plant components

    International Nuclear Information System (INIS)

    Ware, A.G.; Morton, D.K.; Nitzel, M.E.

    1996-01-01

    Recent test data indicate that the effects of the light water reactor (LWR) environment could significantly reduce the fatigue resistance of materials used in the reactor coolant pressure boundary components of operating nuclear power plants. Argonne National Laboratory has developed interim fatigue curves based on test data simulating LWR conditions, and published them in NUREG/CR-5999. In order to assess the significance of these interim fatigue curves, fatigue evaluations of a sample of the components in the reactor coolant pressure boundary of LWRs were performed. The sample consists of components from facilities designed by each of the four US nuclear steam supply system vendors. For each facility, six locations were studied including two locations on the reactor pressure vessel. In addition, there are older vintage plants where components of the reactor coolant pressure boundary were designed to codes that did not require an explicit fatigue analysis of the components. In order to assess the fatigue resistance of the older vintage plants, an evaluation was also conducted on selected components of three of these plants. This paper discusses the insights gained from the application of the interim fatigue curves to components of seven operating nuclear power plants

  14. Multiaxial fatigue criterion for 2-1/4 Cr-1 Mo steel for use in high-temperature structural design

    International Nuclear Information System (INIS)

    Blass, J.J.

    1990-01-01

    An improved multiaxial fatigue failure criterion is described that is based on a definition of equivalent inelastic strain range incorporating the shear and normal components of inelastic strain range on the planes of maximum inelastic shear strain range. Optimum values of certain parameters contained in the formulation were obtained by the method of least squares from the results of combined axial-torsional strain cycling test of 2--1/4 Cr-1 Mo steel conducted at 538 degrees C (1000 degrees F). The ability of this criterion to correlate the test results was compared with that of the Mises equivalent inelastic strain range criterion and was found to be superior. A procedure is described for calculating the required shear and normal components of strain range under general multiaxial strain cycling conditions. An improved definition of equivalent total strain range based on these considerations is directly applicable to the method of estimating fatigue damage in ASME Code Case N-47. 17 refs., 5 figs., 1 tab

  15. Computer Aided Design Tools for Extreme Environment Electronics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This project aims to provide Computer Aided Design (CAD) tools for radiation-tolerant, wide-temperature-range digital, analog, mixed-signal, and radio-frequency...

  16. Modelling the cybersecurity environment using morphological ontology design engineering

    CSIR Research Space (South Africa)

    Jansen van Vuuren, JC

    2015-03-01

    Full Text Available ). This methodology is based on the combination of three different research methods, i.e. design science, general morphological analysis, and ontology based representation. General morphological analysis offers a solution for extracting meaningful information from...

  17. Investigation of fatigue crack growth in SA508-2 in a 2880C PWR environment by a constant δK test method

    International Nuclear Information System (INIS)

    Van Der Sluys, W.A.; DeMiglio, D.S.

    1983-01-01

    Fatigue crack growth experiments using a constant δK test technique were conducted on three 50.8 mm thick compact fracture specimens of SA508-2 in a 288 0 C simulated PWR water environment. Alternating stress intensity factor (δK) values were investigated in the range 16.5 to 44 MPa√m at sinusoidal loading frequencies ranging from 10 to .017 Hz (1 cpm) and R ratios 0.03 to 0.72. For a given δK and frequency, δK was held constant to within 1%. A steady-state rate of crack growth per cycle of stress (da/dN) was determined for each test condition. Over a typical crack extension of 1.3 mm, the crack growth rate in many cases was a constant. As many as 14 separate experiments were conducted on a single specimen. There was no influence of prior loading history or crack length on the crack growth rate. It was found that the crack growth rate was controlled by the δK, frequency, and R ratio of the test. Large changes in the crack growth rate did not occur as the frequency of loading was decreased from >1 Hz to .017 Hz (1 cpm). As compared to high frequency results (>1 Hz) the crack growth rate increased slightly at 1 cpm for δK > 22 MPa√m and decreased slightly for δK < 22 MPa√m. At 1 cpm the R ratio was observed to influence the crack growth rate; however, the magnitude of this effect was not well-defined

  18. Using virtual worlds as collaborative environments for innovation and design

    DEFF Research Database (Denmark)

    Ehsani, Ehsan; Chase, Scott Curland

    2009-01-01

    In this paper we discuss observations and lessons learned in conducting architectural design projects in virtual worlds. By integrating a community of users in virtual worlds into a collaborative architectural design process, organisations can tap the community's creativity and intelligence throu....... Here we propose four modes of collaboration, based on the choices for degree of openness and governance structure, which are illustrated by four case studies....

  19. Integrated design optimization research and development in an industrial environment

    Science.gov (United States)

    Kumar, V.; German, Marjorie D.; Lee, S.-J.

    1989-01-01

    An overview is given of a design optimization project that is in progress at the GE Research and Development Center for the past few years. The objective of this project is to develop a methodology and a software system for design automation and optimization of structural/mechanical components and systems. The effort focuses on research and development issues and also on optimization applications that can be related to real-life industrial design problems. The overall technical approach is based on integration of numerical optimization techniques, finite element methods, CAE and software engineering, and artificial intelligence/expert systems (AI/ES) concepts. The role of each of these engineering technologies in the development of a unified design methodology is illustrated. A software system DESIGN-OPT has been developed for both size and shape optimization of structural components subjected to static as well as dynamic loadings. By integrating this software with an automatic mesh generator, a geometric modeler and an attribute specification computer code, a software module SHAPE-OPT has been developed for shape optimization. Details of these software packages together with their applications to some 2- and 3-dimensional design problems are described.

  20. Measuring Radionuclides in the environment: radiological quantities and sampling designs

    International Nuclear Information System (INIS)

    Voigt, G.

    1998-10-01

    One aim of the workshop was to support and provide an ICRU report committee (International Union of Radiation Units) with actual information on techniques, data and knowledge of modern radioecology when radionuclides are to be measured in the environment. It has been increasingly recognised that some studies in radioecology, especially those involving both field sampling and laboratory measurements, have not paid adequate attention to the problem of obtaining representative, unbiased samples. This can greatly affect the quality of scientific interpretation, and the ability to manage the environment. Further, as the discipline of radioecology has developed, it has seen a growth in the numbers of quantities and units used, some of which are ill-defined and which are non-standardised. (orig.)

  1. Multimodality and Design of Interactive Virtual Environments for Creative Collaboration

    DEFF Research Database (Denmark)

    Gürsimsek, Remzi Ates

    . The three-dimensional representation of space and the resources for non-verbal communication enable the users to interact with the digital content in more complex yet engaging ways. However, understanding the communicative resources in virtual spaces with the theoretical tools that are conventionally used...... perspective particularly emphasizes the role of audio-visual resources in co-creating representations for effective collaboration, and the socio-cultural factors in construction of meaningful virtual environments....

  2. A Virtual Environment for Resilient Infrastructure Modeling and Design

    Science.gov (United States)

    2015-09-01

    Security CI Critical Infrastructure CID Center for Infrastructure Defense CSV Comma Separated Value DAD Defender-Attacker-Defender DHS Department...responses to disruptive events (e.g., cascading failure behavior) in a context- rich , controlled environment for exercises, education, and training...The general attacker-defender (AD) and defender-attacker-defender ( DAD ) models for CI are defined in Brown et al. (2006). These models help

  3. Gerald: a general environment for radiation analysis and design

    International Nuclear Information System (INIS)

    Boyle, Ch.; Oliveira, P.I.E. de; Oliveira, C.R.E. de; Adams, M.L.; Galan, J.M.

    2005-01-01

    Full text of publication follows: This paper describes the status of the GERALD interactive workbench for the analysis of radiation transport problems. GERALD basically guides the user through the various steps that are necessary to solve a radiation transport problem, and is aimed at education, research and industry. The advantages of such workbench are many: quality assurance of problem setup, interaction of the user with problem solution, preservation of theory and legacy research codes, and rapid proto-typing and testing of new methods. The environment is of general applicability catering for analytical, deterministic and stochastic analysis of the radiation problem and is not tied to one specific solution method or code. However, GERALD is being developed as a portable, modular, open source framework which renders itself quite naturally to the coupling of existing computational tools through specifically developed plug-ins. By offering a common route for setting up, solving and analyzing radiation transport problems GERALD offers the possibility of methods intercomparison and validation. Such flexible radiation transport environment will also facilitate the coupling of radiation physics methods to other physical phenomena and their application to other areas of application such as medical physics and the environment. (authors)

  4. Internal Charging Design Environments for the Earths Radiation Belts

    Science.gov (United States)

    Minow, Joseph I.; Edwards, David L.

    2009-01-01

    Relativistic electrons in the Earth's radiation belts are a widely recognized threat to spacecraft because they penetrate lightly shielded vehicle hulls and deep into insulating materials where they accumulate to sufficient levels to produce electrostatic discharges. Strategies for evaluating the magnitude of the relativistic electron flux environment and its potential for producing ESD events are varied. Simple "rule of thumb" estimates such as the widely used 10(exp 10) e-/sq cm fluence within 10 hour threshold for the onset of pulsing in dielectric materials provide a quick estimate of when to expect charging issues. More sophisticated strategies based on models of the trapped electron flux within the Earth s magnetic field provide time dependent estimates of electron flux along spacecraft orbits and orbit integrate electron flux. Finally, measurements of electron flux can be used to demonstrate mean and extreme relativistic electron environments. This presentation will evaluate strategies used to specify energetic electron flux and fluence environments along spacecraft trajectories in the Earth s radiation belts.

  5. Fatigue failure of dental implants in simulated intraoral media.

    Science.gov (United States)

    Shemtov-Yona, K; Rittel, D

    2016-09-01

    Metallic dental implants are exposed to various intraoral environments and repetitive loads during service. Relatively few studies have systematically addressed the potential influence of the environment on the mechanical integrity of the implants, which is therefore the subject of this study. Four media (groups) were selected for room temperature testing, namely dry air, saliva substitute, same with 250ppm of fluoride, and saline solution (0.9%). Monolithic Ti-6Al-4V implants were loaded until fracture, using random spectrum loading. The study reveals that the only aggressive medium of all is the saline solution, as it shortens significantly the spectrum fatigue life of the implants. The quantitative scanning electron fractographic analysis indicates that all the tested implants grew fatigue cracks of similar lengths prior to catastrophic fracture. However, the average crack growth rate in the saline medium was found to largely exceed that in other media, suggesting a decreased fracture toughness. The notion of a characteristic timescale for environmental degradation was proposed to explain the results of our spectrum tests that blend randomly low and high cycle fatigue. Random spectrum fatigue testing is powerful technique to assess and compare the mechanical performance of dental implants for various designs and/or environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Learning Environments Designed According to Learning Styles and Its Effects on Mathematics Achievement

    Science.gov (United States)

    Özerem, Aysen; Akkoyunlu, Buket

    2015-01-01

    Problem Statement: While designing a learning environment it is vital to think about learner characteristics (learning styles, approaches, motivation, interests… etc.) in order to promote effective learning. The learning environment and learning process should be designed not to enable students to learn in the same manner and at the same level,…

  7. Medium-Based Design: Extending a Medium to Create an Exploratory Learning Environment

    Science.gov (United States)

    Rick, Jochen; Lamberty, K. K.

    2005-01-01

    This article introduces "medium-based" design -- an approach to creating "exploratory learning environments" using the method of "extending a medium". First, the characteristics of exploratory learning environments and medium-based design are described and grounded in related work. Particular attention is given to "extending a medium" --…

  8. Participatory design in the project of virtual learning environment of histology

    OpenAIRE

    Santa-Rosa, José Guilherme da Silva

    2012-01-01

    This present article describes a research on the development, under the approach of participatory design, a virtual teaching-learning of Histology in which students and teachers participated actively in all stages of development of the educational environment. We postulates that the development of virtual learning environment of Histology, through the Participatory Design approach, contributes to greater acceptance and use by students and that the adoption of virtual environment for teaching ...

  9. Fatigue assessments in operating nuclear power plants

    International Nuclear Information System (INIS)

    Gosselin, S.R.; Deardorff, A.F.; Peltola, D.W.

    1994-01-01

    In November 1991, the ASME Section XI Task Group on Operating Plant Fatigue Assessment was formed to develop criteria and evaluation methodology for evaluating the effects of cyclic operation in operating nuclear power plants. The objective was to develop guidelines for inclusion in Section XI that could be used by plant operators in evaluating fatigue concerns and their impact on serviceability. This paper discusses the work performed by the Task Group. It explores the concept of ''Fatigue Design Basis'' versus ''Fatigue Operating Basis'' by examining the roles of ASME Section III and ASME Section XI in the design and operation of the nuclear power plants. Guidelines are summarized that may help plant operators perform effective design transient cycle evaluations and optimize cycle counting and fatigue usage tracking. The alternative fatigue evaluation approach using flaw tolerance is also introduced

  10. Low cycle fatigue of irradiated LMFBR materials

    International Nuclear Information System (INIS)

    Blackburn, L.D.

    1976-01-01

    A review of low cycle fatigue data on irradiated LMFBR materials was conducted and extensive graphical representations of available data are presented. Representative postirradiation tensile properties of annealed 304 and 316 SS are selected and employed in several predictive methods to estimate irradiated material fatigue curves. Experimental fatigue data confirm the use of predictive methods for establishing conservative design curves over the range of service conditions relevant to such CRBRP components as core former, fixed radial shielding, core barrel, lower inlet module and upper internals structures. New experimental data on fatigue curves and creep-fatigue interaction in irradiated 20 percent cold worked (CW) 316 SS and Alloy 718 would support the design of removable radial shielding and upper internals in CRBRP. New experimental information on notched fatigue behavior and cyclic stress-strain curves of all these materials in the irradiated condition could provide significant design data

  11. Designing the online oral language learning environment SpeakApps

    NARCIS (Netherlands)

    Nic Giolla Mhichíl, Mairéad; Appel, Christine; Ó Ciardubháin, Colm; Jager, Sake; Prizel-Kania, Adriana

    2015-01-01

    Purpose – The purpose of this paper is to report on SpeakApps, a major collaborative computer-assisted language learning project, developed based on an open source techno-pedagogical solution to facilitate online oral language production and interaction. Design/methodology/approach – A mixed method

  12. Applications of American design codes for elevated temperature environment

    International Nuclear Information System (INIS)

    Severud, L.K.

    1980-03-01

    A brief summary of the ASME Code rules of Case N-47 is presented. An overview of the typical procedure used to demonstrate Code compliance is provided. Application experience and some examples of detailed inelastic analysis and simplified-approximate methods are given. Recent developments and future trends in design criteria and ASME Code rules are also presented

  13. Adaptive Collaboration Support Systems : Designing Collaboration Support for Dynamic Environments

    NARCIS (Netherlands)

    Janeiro, J.; Knoll, S.W.; Lukosch, S.G.; Kolfschoten, G.L.

    2012-01-01

    Today, engineering systems offer a variety of local and webbased applications to support collaboration by assisting groups in structuring activities, generating and sharing data, and improving group communication. To ensure the quality of collaboration, engineering system design needs to analyze and

  14. Designing immersion exhibits as border-crossing environments

    DEFF Research Database (Denmark)

    Mortensen, Marianne Foss

    2010-01-01

    be applied to achieve an understanding of the immersion exhibit form. The argument proceeds by demonstrating how the characteristics of immersion exhibits, and visitors to them, classify them as microcultures, and examining the implications of this for exhibit design using a hypothetical immersion exhibit...

  15. Designing ee-Learning Environments: Lessons from an Online Workshop

    Science.gov (United States)

    Godwin, Lindsey; Kaplan, Soren

    2008-01-01

    Based on their work leading three experiential, online workshops with over 180 participants from around the world, Lindsey Godwin and Soren Kaplan share reflections on designing and conducting successful ee-learning courses. The workshops sought to translate a popular face-to-face seminar in appreciative inquiry, an increasingly popular…

  16. Interactive tool that empowers structural understanding and enables FEM analysis in a parametric design environment

    DEFF Research Database (Denmark)

    Christensen, Jesper Thøger; Parigi, Dario; Kirkegaard, Poul Henning

    2014-01-01

    This paper introduces an interactive tool developed to integrate structural analysis in the architectural design environment from the early conceptual design stage. The tool improves exchange of data between the design environment of Rhino Grasshopper and the FEM analysis of Autodesk Robot...... Structural Analysis. Further the tool provides intuitive setup and visual aids in order to facilitate the process. Enabling students and professionals to quickly analyze and evaluate multiple design variations. The tool has been developed inside the Performance Aided Design course at the Master...... of Architecture and Design at Aalborg University...

  17. Prevalence of fatigue in patients with multiple sclerosis and its effect on the quality of life

    Science.gov (United States)

    Nagaraj, Karthik; Taly, Arun B.; Gupta, Anupam; Prasad, Chandrajit; Christopher, Rita

    2013-01-01

    Objective: This prospective study was carried out to observe the prevalence of fatigue in patients with multiple sclerosis (MS) and its effect on quality-of-life (QoL). Study Design and Setting: Prospective observational study in a University Tertiary Research Hospital in India. Patients and Methods: A total of 31 patients (25 females) with definite MS according to McDonald's criteria presented in out-patient/admitted in the Department of Neurology (between February 2010 and December 2011) were included in the study. Disease severity was evaluated using the Kurtzke's expanded disability status scale (EDSS). Fatigue was assessed using Krupp's fatigue severity scale (FSS). QoL was assessed by the World Health Organization QoL-BREF questionnaire. Results: The mean age of patients was 30.1 ± 9.1 years. The mean age at first symptom was 25.23 ± 6.4 years. The mean number of relapses was 4.7 ± 3.6 in the patients. The mean duration of illness was 4.9 ± 4.4 years. The mean EDSS score was 3.5 ± 2.2. Mean fatigue score was 38.7 ± 18.5 (cut-off value 36 in FSS). The prevalence of fatigue in patients with MS was 58.1% (18/31). MS patients with fatigue were significantly more impaired (P < 0.05) on all QoL domains (i.e., physical, psychosocial, social, and environment) than MS patients without fatigue. Conclusion: Prevalence of fatigue was found to be high in the MS patients in the study. All four domains of QoL were significantly more impaired in the group with fatigue than in those without fatigue. PMID:24250159

  18. Design Quality in the Context of Healthcare Environments: A Scoping Review.

    Science.gov (United States)

    Anåker, Anna; Heylighen, Ann; Nordin, Susanna; Elf, Marie

    2017-07-01

    We explored the concept of design quality in relation to healthcare environments. In addition, we present a taxonomy that illustrates the wide range of terms used in connection with design quality in healthcare. High-quality physical environments can promote health and well-being. Developments in healthcare technology and methodology put high demands on the design quality of care environments, coupled with increasing expectations and demands from patients and staff that care environments be person centered, welcoming, and accessible while also supporting privacy and security. In addition, there are demands that decisions about the design of healthcare architecture be based on the best available information from credible research and the evaluation of existing building projects. The basic principles of Arksey and O'Malley's model of scoping review design were used. Data were derived from literature searches in scientific databases. A total of 18 articles and books were found that referred to design quality in a healthcare context. Design quality of physical healthcare environments involves three different themes: (i) environmental sustainability and ecological values, (ii) social and cultural interactions and values, and (iii) resilience of the engineering and building construction. Design quality was clarified herein with a definition. Awareness of what is considered design quality in relation to healthcare architecture could help to design healthcare environments based on evidence. To operationalize the concept, its definition must be clear and explicit and able to meet the complex needs of the stakeholders in a healthcare context, including patients, staff, and significant others.

  19. On the Design of Virtual Reality Learning Environments in Engineering

    Directory of Open Access Journals (Sweden)

    Diego Vergara

    2017-06-01

    Full Text Available Currently, the use of virtual reality (VR is being widely applied in different fields, especially in computer science, engineering, and medicine. Concretely, the engineering applications based on VR cover approximately one half of the total number of VR resources (considering the research works published up to last year, 2016. In this paper, the capabilities of different computational software for designing VR applications in engineering education are discussed. As a result, a general flowchart is proposed as a guide for designing VR resources in any application. It is worth highlighting that, rather than this study being based on the applications used in the engineering field, the obtained results can be easily extrapolated to other knowledge areas without any loss of generality. This way, this paper can serve as a guide for creating a VR application.

  20. Handbook of virtual environments design, implementation, and applications

    CERN Document Server

    Hale, Kelly S

    2014-01-01

    This second edition of a bestseller presents systematic and extensive coverage of the primary areas of research and development within VE technology. It brings together a comprehensive set of contributed articles that address the principles required to define system requirements and design, build, evaluate, implement, and manage the effective use of VE applications. The contributors provide critical insights and principles associated with their given area of expertise to provide extensive scope and detail on VE technology.

  1. New economic initiatives are designed to protect the environment

    International Nuclear Information System (INIS)

    Fleet, B.; Fleet, N.S.

    1992-01-01

    The use of economic initiatives or economic instruments as an alternative to or as support for existing environmental legislation is reviewed. The most controversial area of economic incentives is the concept of creating a market in pollution rights. While emissions trading can enable economic growth in areas of high pollution, this approach is only marginally different than the traditional regulatory approach. Environmental economics is complex, with mixtures of private and public costs. Social costs include subsidies, waste treatment, landfill disposal costs, etc. More intangible social costs include public health costs and damage to the natural environment. Conventional economic approaches ignore most such social costs. Several European countries have started to develop a green gross national product (GNP) which sets out an alternative approach to the traditional measure of economic activity by subtracting a figure for harm to the environment from economic activity. This ambitious approach attempts to measure the costs of all toxic discharges along with the disappearance of plant and animal life and other environmental changes. A powerful new tool for the environmental manager is full cost accounting, which uses a long (10-20 y) window for projects, anticipates the impact of stricter discharge standards, and attempts to quantify a range of less tangible social costs elements, such as liability, improved environmental image, etc. Various strategies can be ranked on the basis of their future risk cost. The application of full cost accounting models, small business, computer models and expert systems, developing country debt-for-nature swaps, and environmental risk assessment are discussed. 12 refs

  2. Towards a unified fatigue life prediction method for marine structures

    CERN Document Server

    Cui, Weicheng; Wang, Fang

    2014-01-01

    In order to apply the damage tolerance design philosophy to design marine structures, accurate prediction of fatigue crack growth under service conditions is required. Now, more and more people have realized that only a fatigue life prediction method based on fatigue crack propagation (FCP) theory has the potential to explain various fatigue phenomena observed. In this book, the issues leading towards the development of a unified fatigue life prediction (UFLP) method based on FCP theory are addressed. Based on the philosophy of the UFLP method, the current inconsistency between fatigue design and inspection of marine structures could be resolved. This book presents the state-of-the-art and recent advances, including those by the authors, in fatigue studies. It is designed to lead the future directions and to provide a useful tool in many practical applications. It is intended to address to engineers, naval architects, research staff, professionals and graduates engaged in fatigue prevention design and survey ...

  3. Development of pedagogical design in technology-rich environments for language teaching and learning

    OpenAIRE

    Jalkanen, Juha

    2015-01-01

    This study explores the development of pedagogical design for language teaching and learning in increasingly technology-rich environments. More specifically, it focuses on the process of design, enactment and analysis of language and literacy pedagogies in technology-rich environments. Two substudies are reported in five articles, each of which approaches pedagogical design from a different perspective. The first substudy examined (a) what pedagogical choices language studen...

  4. Energy and environment in an architectural design application

    Energy Technology Data Exchange (ETDEWEB)

    Schiller, Silvia de; Evans, John Martin [Universidad de Buenos Aires, Facultad de Arquitectura, Diseno y Urbanismo, Buenos Aires (Argentina)

    1998-09-01

    Office buildings with important administrative functions can produce high energy demands for lighting, cooling and heating. However, appropriate architectural design can achieve significant energy savings and improve environmental conditions, without sacrificing architectural quality. Intense solar radiation and high temperature swings in dry continental climates favour deep plan offices, though natural daylight requires limited depth. This paper presents a case study of a large administrative complex project for the Justice Palace, Neuquen Province, in the cold windy sem-desert climate in the Northern Patagonia Region of Argentina, demonstrating the relevance of specialised advisory services in the architectural field. (Author)

  5. Effect of load ratio and saltwater corrosive environment on the initiation life of fatigue of 10Ni5CrMoV steel

    Science.gov (United States)

    Xie, Xing; Yi, Hong; Xu, Jian; Gen, Liming; Chen, Luyun

    2017-09-01

    Fatigue initiation life has been studied with 10CrNi5MoV steel for use in ocean engineering at different load ratios and in different environmental media. The microstructure and micro-topography have been observed and analyzed by means of SEM, EDS and EBSD. Our findings indicate that, the initiation life of 10Ni5CrMoV steel in seawater is shorter than that in air, and the difference in longevity is larger with the increasing of load ratio. Corrosion pits had a great influence on initial corrosion fatigue life.

  6. Feature Fatigue, IT Fashion and IT Consumerization - Is There a Relationship?

    Directory of Open Access Journals (Sweden)

    Luiz Antonio Slongo

    2015-12-01

    Full Text Available Based on the concepts of Feature Fatigue, IT Fashion and IT Consumerization, this paper aims to investigate the relationships between them answering two questions: (1 does the phenomenon of IT Fashion result in Feature Fatigue? (2 Will the concept of Feature Fatigue cause the same effect when looking from the point of view of the IT Consumerization in the corporate environment? The research addresses these questions through two techniques: a laddering and a survey. Albeit tenuously, the results provide evidence that consumption motivated by IT Fashion leads to Feature Fatigue. This study contributes to management research by attempting at the phenomenon described from a multidisciplinary perspective, also contributing to management practice, specifically for marketing managers trying to understand the experiences and expectations of consumers, and also for IT managers engaged in the design of governance policies regarding the use of personal devices by employees in this context.

  7. Designing ecological flows to gravely braided rivers in alpine environments

    Science.gov (United States)

    Egozi, R.; Ashmore, P.

    2009-04-01

    Designing ecological flows in gravelly braided streams requires estimating the channel forming discharge in order to maintain the braided reach physical (allocation of flow and bed load) and ecological (maintaining the habitat diversity) functions. At present, compared to single meander streams, there are fewer guiding principles for river practitioners that can be used to manage braided streams. Insight into braiding morphodynamics using braiding intensity indices allows estimation of channel forming discharge. We assess variation in braiding intensity by mapping the total number of channels (BIT) and the number of active (transporting bed load) channels (BIA) at different stages of typical diurnal melt-water hydrographs in a pro-glacial braided river, Sunwapta River, Canada. Results show that both BIA and BIT vary with flow stage but over a limited range of values. Furthermore, maximum BIT occurs below peak discharge. At this stage there is a balance between channel merging from inundation and occupation of new channels as the stage rises. This stage is the channel forming discharge because above this stage the existing braided pattern cannot discharge the volume of water without causing morphological changes (e.g., destruction of bifurcations, channel avulsion). Estimation of the channel forming discharge requires a set of braiding intensity measurements over a range of flow stages. The design of ecological flows must take into consideration flow regime characteristics rather than just the channel forming discharge magnitude.

  8. Proof of fatigue strength of ferritic and austenitic nuclear components

    Energy Technology Data Exchange (ETDEWEB)

    Roos, E.; Herter, K.H.; Schuler, X.; Weissenberg, T. [Materialpruefungsanstalt, Univ. Stuttgart (Germany)

    2009-07-01

    For the construction, design and operation of nuclear components and systems the appropriate technical codes and standards provide material data, detailed stress analysis procedures and a design philosophy which guarantees a reliable behaviour of the structural components throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. For the fatigue design curves used as limiting criteria the influence of different factors like e.g., environment, surface finish and temperature must be taken into consideration in an appropriate way. Fatigue tests were performed with low alloy steels as well as with Nb- and Ti-stabilized German austenitic stainless steels in air and simulated high temperature boiling water reactor environment. The experimental results are compared and valuated with the mean data curves in air as well as with mean data curves under high temperature water environment published in the international literature. (orig.)

  9. Development of a fatigue analysis software system

    International Nuclear Information System (INIS)

    Choi, B. I.; Lee, H. J.; Han, S. W.; Kim, J. Y.; Hwang, K. H.; Kang, J. Y.

    2001-01-01

    A general purpose fatigue analysis software to predict fatigue lives of mechanical components and structures was developed. This software has some characteristic features including functions of searching weak regions on the free surface in order to reduce computing time significantly, a database of fatigue properties for various materials, and an expert system which can assist any users to get more proper results. This software can be used in the environment consists of commercial finite element packages. Using the software developed fatigue analyses for a SAE keyhole specimen and an automobile knuckle were carried out. It was observed that the results were agree well with those from commercial packages

  10. Designing natural gesture interaction for archaeological data in immersive environments

    Directory of Open Access Journals (Sweden)

    Niccolò Albertini

    2017-05-01

    Full Text Available Archaeological data are heterogeneous, making it difficult to correlate and combine different types.  Datasheets  and pictures,  stratigraphic  data  and  3D  models,  time and  space  mixed  together: these are  only a few  of  the  categories  a researcher has to deal with. New technologies may be able to help in this process and trying to solve research related problems needs innovative solutions. In this paper, we describe the whole process for the design and development of a prototype application that uses an Immersive Virtual Reality system to acces archaeological excavation3Ddata through the Gesture Variation Follower (GVF algorithm. This makes it possible to recognise which gesture is being performed and how it is performed. Archaeologist shave participated actively in the design of the interface and the set of gestures used for triggering the different tasks. Interactive machine learning techniques have been used for the real time detection of the gestures. As a case  study  the  agora  of  Segesta  (Sicily,  Italy  has  been  selected.  Indeed,  due  to  the  complex architectural  features  and  the  still  ongoing  fieldwork  activities,  Segesta  represents  an  ideal  context  where  to  test  and develop a research approach integrating both traditional and more innovative tools and methods.

  11. Side Effects: Fatigue

    Science.gov (United States)

    Fatigue is a common side effect of many cancer treatments such as chemotherapy, radiation therapy, immunotherapy, and surgery. Anemia and pain can also cause fatigue. Learn about symptoms and way to manage fatigue.

  12. Fatigue behaviour and crack growth of ferritic steel under environmental conditions

    International Nuclear Information System (INIS)

    Herter, K.H.; Schuler, X.; Weissenberg, T.

    2012-01-01

    The assessment of fatigue and cyclic crack growth behaviour of safety relevant components is of importance for the ageing management with regard to safety and reliability. For cyclic stress evaluation different codes and standards provide fatigue analysis procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. For the fatigue design curves used as a limiting criteria the influence of different factors like e.g. environment, surface finish and temperature must be taken into consideration in an appropriate way. Fatigue tests were performed in the low cycle fatigue (LCF) und high cycle fatigue (HCF) regime with low alloy steels as well as with Nb- and Ti-stabilized German austenitic stainless steels in air and high temperature (HT) boiling water reactor environment to extend the state of knowledge of environmentally assisted fatigue (EAF) as it can occur in boiling water reactor (BWR) plants. Using the reactor pressure vessel (RPV) steel 22NiMoCr3-7 experimental data were developed to verify the influence of BWR coolant environment (high purity water as well as sulphate containing water with 90 ppb SO 4 at a test temperature of 240 C and an oxygen content of 400 ppb) on the fatigue life and to extend the basis for a reliable estimation of the remaining service life of reactor components. Corresponding experiments in air were performed to establish reference data to determine the environmental correction factor F en accounting for the environment. The experimental results are compared with international available mean data curves, the new design curves and on the basis of the environmental factor F en . Furthermore the behaviour of steel 22NiMoCr3-7 in oxygenated high temperature water under transient loading conditions was investigated with respect to crack initiation and cyclic crack growth. In this process the stress state of the specimen and the chemical composition of the high

  13. Teachers as Participatory Designers: Two Case Studies with Technology-Enhanced Learning Environments

    Science.gov (United States)

    Cober, Rebecca; Tan, Esther; Slotta, Jim; So, Hyo-Jeong; Könings, Karen D.

    2015-01-01

    Teachers are not typically involved as participatory designers in the design of technology-enhanced learning environments. As they have unique and valuable perspectives on the role of technology in education, it is of utmost importance to engage them in a participatory design process. Adopting a case study methodology, we aim to reveal in what…

  14. Instructional Designers' Media Selection Practices for Distributed Problem-Based Learning Environments

    Science.gov (United States)

    Fells, Stephanie

    2012-01-01

    The design of online or distributed problem-based learning (dPBL) is a nascent, complex design problem. Instructional designers are challenged to effectively unite the constructivist principles of problem-based learning (PBL) with appropriate media in order to create quality dPBL environments. While computer-mediated communication (CMC) tools and…

  15. Corrosion fatigue crack growth behaviour of low-alloy RPV steels at different temperatures and loading frequencies under BWR/NWC environment

    International Nuclear Information System (INIS)

    Ritter, S.; Seifert, H.P.

    2004-01-01

    The strain-induced corrosion cracking or low-frequency corrosion fatigue (LFCF) crack growth behaviour of different reactor pressure vessel (RPV) steels and of a RPV weld filler/weld heat-affected zone (HAZ) material were characterized under simulated transient boiling water reactor/normal water chemistry conditions by cyclic fatigue tests with pre-cracked fracture mechanics specimens. The experiments were performed in oxygenated high-temperature water at temperatures of either 288, 250, 200, or 150 deg. C. Modern high-temperature water loops, on-line crack growth monitoring (DCPD) and fractographic analysis by SEM were used to quantify the cracking response. Under low-flow and highly oxidising conditions (ECP > 0 mV SHE , O 2 = 0.4 ppm) the cycle-based LFCF crack growth rates (CGR) Δa/ΔN increased with decreasing loading frequency and increasing temperature with a maximum/plateau at/above 250 deg. C. Sustained environmentally-assisted crack growth could be maintained down to low frequencies of 10 -5 Hz. The LFCF CGR of low- and high-sulphur steels and of the weld filler/HAZ material were comparable over a wide range of loading conditions and conservatively covered by the 'high-sulphur line' of the General Electric-model. The 'ASME XI wet fatigue CGR curves' could be significantly exceeded in all materials by cyclic fatigue loading at low frequencies ( -2 Hz) at high and low load ratios R. (authors)

  16. Corrosion fatigue of high strength fastener materials in seawater

    Science.gov (United States)

    Tipton, D. G.

    1983-12-01

    Environmental effects which significantly reduce the fatigue life of metals are discussed. Corrosion fatigue is a major concern in the engineering application of high strength fasteners in marine environments. The corrosion fatigue failure of an AISI 41L4O high strength steel blade to hub attachment bolt at the MOD-OA 200 kW wind turbine generator was investigated. The reduction of fatigue strength of AISI 41L4O in marine environments and to obtain similar corrosion fatigue data for candidate replacement materials was studied. The AISI 4140, PH 13-8Mo stainless steel, alloy 718 and alloy MP-35N were tested in axial fatigue at a frequency of 20 Hz in dry air and natural seawater. The fatigue data are fitted by regression equations to allow determination of fatigue strength for a given number of cycles to failure.

  17. [Research Progress on the Interaction Effects and Its Neural Mechanisms between Physical Fatigue and Mental Fatigue].

    Science.gov (United States)

    Zhang, Lixin; Zhang, Chuncui; He, Feng; Zhao, Xin; Qi, Hongzhi; Wan, Baikun; Ming, Dong

    2015-10-01

    Fatigue is an exhaustion state caused by prolonged physical work and mental work, which can reduce working efficiency and even cause industrial accidents. Fatigue is a complex concept involving both physiological and psychological factors. Fatigue can cause a decline of concentration and work performance and induce chronic diseases. Prolonged fatigue may endanger life safety. In most of the scenarios, physical and mental workloads co-lead operator into fatigue state. Thus, it is very important to study the interaction influence and its neural mechanisms between physical and mental fatigues. This paper introduces recent progresses on the interaction effects and discusses some research challenges and future development directions. It is believed that mutual influence between physical fatigue and mental fatigue may occur in the central nervous system. Revealing the basal ganglia function and dopamine release may be important to explore the neural mechanisms between physical fatigue and mental fatigue. Future effort is to optimize fatigue models, to evaluate parameters and to explore the neural mechanisms so as to provide scientific basis and theoretical guidance for complex task designs and fatigue monitoring.

  18. Design for Environment as a Tool for the Development of a Sustainable Supply Chain

    CERN Document Server

    Bevilacqua, Maurizio; Giacchetta, Giancarlo

    2012-01-01

    Environmental Design is becoming an increasingly significant agenda for many manufacturing companies and yet there is no standard to their approaches, strategies or their levels of execution. Applying Design for Environment (DfE) methodologies to develop a more sustainable supply chain has formed procedures and techniques which allow designers to integrate these methods with environmental supply chain management. Design for Environment as a Tool for the Development of a Sustainable Supply Chain aims to define relevant target specifications for a product throughout its life cycle; from conception and design to the end of its operating life.  Be considering this new approach to the supply chain, environmental responsiveness can work in tandem with sounds business management. The usual focus on suppliers, manufacturers and customers is expanded in Design for Environment as a Tool for the Development of a Sustainable Supply Chain to include stakeholders such as government bodies and recycling companies. The infl...

  19. Construction Worker Fatigue Prediction Model Based on System Dynamic

    OpenAIRE

    Wahyu Adi Tri Joko; Ayu Ratnawinanda Lila

    2017-01-01

    Construction accident can be caused by internal and external factors such as worker fatigue and unsafe project environment. Tight schedule of construction project forcing construction worker to work overtime in long period. This situation leads to worker fatigue. This paper proposes a model to predict construction worker fatigue based on system dynamic (SD). System dynamic is used to represent correlation among internal and external factors and to simulate level of worker fatigue. To validate...

  20. The effects of fatigue on performance in simulated nursing work.

    Science.gov (United States)

    Barker, Linsey M; Nussbaum, Maury A

    2011-09-01

    Fatigue is associated with increased rates of medical errors and healthcare worker injuries, yet existing research in this sector has not considered multiple dimensions of fatigue simultaneously. This study evaluated hypothesised causal relationships between mental and physical fatigue and performance. High and low levels of mental and physical fatigue were induced in 16 participants during simulated nursing work tasks in a laboratory setting. Task-induced changes in fatigue dimensions were quantified using both subjective and objective measures, as were changes in performance on physical and mental tasks. Completing the simulated work tasks increased total fatigue, mental fatigue and physical fatigue in all experimental conditions. Higher physical fatigue adversely affected measures of physical and mental performance, whereas higher mental fatigue had a positive effect on one measure of mental performance. Overall, these results suggest causal effects between manipulated levels of mental and physical fatigue and task-induced changes in mental and physical performance. STATEMENT OF RELEVANCE: Nurse fatigue and performance has implications for patient and provider safety. Results from this study demonstrate the importance of a multidimensional view of fatigue in understanding the causal relationships between fatigue and performance. The findings can guide future work aimed at predicting fatigue-related performance decrements and designing interventions.