2,063 research outputs found
Stress concentration factor parametric equations for tubular X and DT joints
No full textDuring the design stage, the peak stress is usually needed for estimating the fatigue life of offshore tubular welded joints by an S-N approach. However, for fracture mechanics calculations of remaining life, on cracked joints in service, information is required on the magnitude and distribution of the stress acting in the anticipated crack path, not just the peak stress at one location. Fatigue crack propagation rates are important to reliability-based inspection scheduling: hence the need for this information is becoming more pressing. Parametric equations are available for Y and T joints in terms of peak stress, stress distribution and bending-to-membrane ratio. However, for X and DT joints, there are no parametric equations for stress variation through the thickness and around the intersection. Even for stress concentration factor (SCF), so far there is no full set of parametric equations especially for single-brace loading. Thin-shell finite element analyses have been conducted for 330 X and DT joints typical of those used in offshore structures, subject to six modes of loading. The results from this work have been used to produce a new set of parametric equations as a function of non-dimensional joint geometric ratios α, β, γ, τ and θ by carrying out regression analysis. These equations can be used to predict SCFs at the crown toe, saddle, crown heel and hot-spot positions for each mode of loading, for both chord and brace, as well as the angular location of the hot-spot stress site around the intersection. This set of SCF parametric equations has been assessed by comparing the predicted values with results from steel and acrylic model tests and also with the predictions from existing parametric formulae given in the literature. The degree of bending data, and stress distribution data, will be reported in other publications
Prediction of degree of bending in tubular X and DT joints
No full textAnalysis of the large scale fatigue testing results of offshore welded tubular joints showed that the fatigue life is not dependent on the hot spot stress alone, but is also significantly influenced by the through thickness stress distribution which can be characterised by degree of bending (DoB). Accurate prediction of DoB data in tubular joints is crucial for improving the accuracy of fatigue life prediction using stress-life (S-N) curve and particularly for predicting fatigue crack growth using the fracture mechanics method. However, there is no set of DoB parametric equations available for tubular X and DT joints. For this reason, comprehensive thin shell finite element (FE) analyses were carried out for 330 tubular X and DT joints typical of those used in offshore structures, under six different modes of loading. The results of these FE analyses were used to derive a set of parametric equations to predict the DoBs at the critical positions on both brace and chord toes in tubular X and DT-joints under each mode of loading. • 1999 Elsevier Science Ltd. All rights reserved
Prediction of stress distributions along the intersection of tubular Y and T-joints
No full textSeveral sets of stress parametric equations have been derived for fatigue strength assessment of tubular Y and T-joints. Among them, the Hellier, Connolly and Dover (HCD) set is the only one which can provide the whole two dimensional (2D) stress information. However, the HCD characteristic stress distribution equations were derived from the limited number of typical finite element (FE) results and thus may not be able to capture the effects of all joint geometric parameters. As part of a large study including X and DT-joints, comprehensive thin shell FE analyses were carried out for 330 different tubular Y and T-joints and the whole FE result database was used to derive a new set of equations as a function of joint geometric parameters. These equations can be used to predict stress distributions along the intersection and also provide an alternative method for the calculation of the hot spot stress concentration factor (SCF). Furthermore, an improved methodology has been suggested for assessment of stress parametric equations
Parametric equations to predict stress distributions along the intersection of tubular X and DT-joints
No full textAccurate information on stress distributions along the intersection is required for fatigue strength assessment of tubular joints. However, there is no parametric equation currently available in the open literature to predict this information for tubular X and DT-joints. Systematic thin shell finite element (FE) analyses have been conducted for 330 different tubular X and DT-joints, typical of those used in offshore structures, subjected to six different modes of loading. A novel two dimensional regression methodology was developed to curve-fit all of the FE results from this work. A set of parametric equations was derived to predict the stress distributions along both chord and brace toes in tubular X and DT-joints under each mode of loading. These equations were assessed by comparing the predictions with available experimental data. Validation results show that they can be used to predict stress concentration factor (SCF) distributions along the intersection but also provide an alternative method for calculation of hot spot SCF
The production of imperatorin from angelica dahurica var Formosana by cell suspension culture
No full textBai-Zhi (Angelica dahurica) is a valuable medicinal plant used as source of curatives for headache and skin disease in China. The purpose of this study was to establish cell suspension culture as alternative source of imperatorin, the major active ingredient of the species. The formulation of MS basic salts, modified by increasing the phosphate concentration to 2 mM and using an ammonium to nitrate ratio of 2:1, provided the best imperatorin production. Glucose was a better carbon source than sucrose and fructose. The addition of 0.5-1 mg/l of BA to the culture medium increased imperatorin yield, whereas auxins produced only negative effects. Supplementing the medium with 20g/l of the adsorbent Amberlite XAD-7 increased imperatorin yield 140-fold
Report of change of status and address, W.D., A.G.O. form no. 641, Minoru Frank Saito
No full textA copy of a "report of change of status and address, W.D., A.G.O. form" submitted to War Department by Minoru Frank Saito. He added his sister Joyce Teruko Saito as his dependent. Due to lack of her birth certificate, he was not able to include her as his dependent when he applied for it
Application for dependency benefits (servicemen's dependents allowance act of 1942), W.D., A.G.O. Form no. 625., Minoru Frank Saito
No full textAn applicant's copy of an "application for dependency benefits (servicemen's dependents allowance act of 1942), W.D., A.G.O. Form no. 625" form submitted to War Department by Minoru Frank Saito. His mother, Kiku Saito, who has been incarcerated in the Granada camp, is listed as his dependent
America's other Muslims: Imam W.D. Mohammed, Islamic reform, and the making of American Islam Black diasporic worlds./ Muhammad Fraser-Rahim.
No full textIncludes bibliographical references (pages 111-125) and index.Fraser-Rahim spotlights the emergence of an American school of Islamic thought, which was created and established by the son of the former Nation of Islam leader. W.D. Mohammed rejected his father's teachings and embraced normative Islam on his own terms while balancing classical Islam and his lived experience of Islam in the diaspora.Intro -- Contents -- Acknowledgments -- Preface -- Introduction -- 1. African American Islam in context -- 2. Taffakur ("to think, ponder, reflect"): Islam in West Africa and Islamic revivalism -- 3. Africanizing Dixie: the enslaved African Muslim experience and the Black American Islamic continuum -- 4. Imam W.D. Mohammed, the patron saint of American Islam: personality, intellectual teachings, and reformation -- 5. Walking with Brother Imam: the community of W.D. Mohammed as a counterweight to extremism -- Conclusion -- Glossary of terms -- Bibliography -- Index -- About the author.1 online resource (148 pages
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