Lower-Bound Assessment of Creep Buckling Strength

1983 ◽  
Vol 105 (3) ◽  
pp. 216-221
Author(s):  
D. L. Marriot

A method is developed for predicting the creep buckling behavior of complex pressurized components from the results of ambient, short-term buckling tests on geometrically similar components. The method has been tested against experimental data on boss-loaded spherical shells and shows reasonable accuracy of prediction of the buckling load after a given period of time. Application to the design analysis of a component for a boiler is described. An analysis of the approximations made in developing the method is included. It is shown that a lower bound on buckling strength at a given time is obtained.

1976 ◽  
Vol 43 (3) ◽  
pp. 450-454 ◽  
Author(s):  
Norman Jones

The creep buckling behavior of a complete spherical shell which is subjected to a uniform external pressure is investigated using a perturbation method of analysis. The spherical shell has an arbitrary initial imperfect shape and is made from a material which creeps according to the generalized Norton’s law. It turns out that the critical mode number of the deformed profile is identical to that obtained previously by various authors for the linear elastic instability of complete spherical shells. It also appears that the resistance to creep buckling of complete spherical shells is greater than the resistance of a long cylindrical shell having the same R/h ratio and material properties.


2020 ◽  
Vol 833 ◽  
pp. 223-227
Author(s):  
Mohd Shahrom Ismail ◽  
O. Ifayefunmi ◽  
Siti Hajar Sheikh Md Fadzullah

This paper aims to examine the influence of ring stiffener reinforcement on the buckling behavior of cone-cylinder intersection subjected to external pressure. Three different stiffener locations were analyzed; they are (i) cone-cylinder intersection, (ii) cone mid-section, and (iii) cylinder mid-section. Internal and external stiffeners are used in the study. Buckling strength of the stiffened cone-cylinder intersections were obtained with the aid of FE analyses for all the cases above. Cone-cylinder intersections are modelled as elastic-perfectly plastic of Hiduminium alloy (HE-15). Validations of the present results with the published experimental data were presented. Result indicates that the introduction of stiffener reinforcement in externally pressurized cone-cylinder intersections seemed to be desirable in a preliminary design process, thus promotes a stronger shell to resist buckling.


1992 ◽  
Vol 26 (5-6) ◽  
pp. 1355-1363 ◽  
Author(s):  
C-W. Kim ◽  
H. Spanjers ◽  
A. Klapwijk

An on-line respiration meter is presented to monitor three types of respiration rates of activated sludge and to calculate effluent and influent short term biochemical oxygen demand (BODst) in the continuous activated sludge process. This work is to verify if the calculated BODst is reliable and the assumptions made in the course of developing the proposed procedure were acceptable. A mathematical model and a dynamic simulation program are written for an activated sludge model plant along with the respiration meter based on mass balances of BODst and DO. The simulation results show that the three types of respiration rate reach steady state within 15 minutes under reasonable operating conditions. As long as the respiration rate reaches steady state the proposed procedure calculates the respiration rate that is equal to the simulated. Under constant and dynamic BODst loading, the proposed procedure is capable of calculating the effluent and influent BODst with reasonable accuracy.


2015 ◽  
Vol 370 (1681) ◽  
pp. 20140267 ◽  
Author(s):  
Paul J. Ferraro ◽  
Merlin M. Hanauer

To develop effective protected area policies, scholars and practitioners must better understand the mechanisms through which protected areas affect social and environmental outcomes. With strong evidence about mechanisms, the key elements of success can be strengthened, and the key elements of failure can be eliminated or repaired. Unfortunately, empirical evidence about these mechanisms is limited, and little guidance for quantifying them exists. This essay assesses what mechanisms have been hypothesized, what empirical evidence exists for their relative contributions and what advances have been made in the past decade for estimating mechanism causal effects from non-experimental data. The essay concludes with a proposed agenda for building an evidence base about protected area mechanisms.


2016 ◽  
Vol 25 (12) ◽  
pp. 1650101 ◽  
Author(s):  
Luis Augusto Trevisan

In the present work, the effects of the nonextensivity are considered in a model to obtain the polarized structure function for the proton and neutron, including the strange contribution for each one. Any type of symmetry is made in consequence of the experimental data involved.


2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Jian-Guo Gong ◽  
Lei Yu ◽  
Feng Wang ◽  
Fu-Zhen Xuan

The effect of welding residual stress on the buckling behavior of storage tanks subjected to the harmonic settlement was simulated using the shell-to-solid coupling method. In the numerical model of tanks coupled with the welding residual stress, the welding joint and its adjacent zone were modeled using the solid submodel and the zone far away from the welding joint was built by the shell submodel. Effects of welding parameters (e.g., welding velocities and welding passes) on the buckling behavior of tanks were analyzed systematically. Results indicate that the buckling strength of tanks is enhanced due to the welding residual stress. Comparatively, a slow welding velocity presents a more remarkable strengthening effect than the fast welding velocity due to a larger axial residual stress produced at the welding joint. Nevertheless, no significant difference between the double-side welding and the one-side welding for buckling strength enhancement is observed for the cases studied. This indicates that the current design method causes a conservative design without considering the welding residual stress.


2014 ◽  
Vol 104 (10) ◽  
pp. 3154-3185 ◽  
Author(s):  
Eric T. Swanson ◽  
John C. Williams

According to standard macroeconomic models, the zero lower bound greatly reduces the effectiveness of monetary policy and increases the efficacy of fiscal policy. However, private-sector decisions depend on the entire path of expected future short-term interest rates, not just the current short-term rate. Put differently, longer-term yields matter. We show how to measure the zero bound's effects on yields of any maturity. Indeed, 1- and 2-year Treasury yields were surprisingly unconstrained throughout 2008 to 2010, suggesting that monetary and fiscal policy were about as effective as usual during this period. Only beginning in late 2011 did these yields become more constrained. (JEL E43, E52, E62)


Author(s):  
Gabriela Alor-Saavedra ◽  
Francisco Alejandro Alaffita-Hernández ◽  
Beatris Adriana Escobedo-Trujillo ◽  
Oscar Fernando Silva-Aguilar

This work makes a comparative study of two methods to determine deflection in steel beams: (a) Theoretical and (b) Finite element. For method (a) the solution of the differential equation associated with the modeling of the deflection of a beam is found, while for method (b) a simulation is made in Solidworks. Both methods are compared with experimental data in order to analyze which of the methods presents less uncertainty and show the usefulness of the theoretical part in the modeling of physical systems.


2017 ◽  
Author(s):  
Jason T. Wright ◽  
Michael P. Oman-Reagan

We discuss how visions for the futures of humanity in space and SETI are intertwined, and are shaped by prior work in the fields and by science fiction. This appears in the language used in the fields, and in the sometimes implicit assumptions made in discussions of them. We give examples from articulations of the so-called Fermi Paradox, discussions of the settlement of the Solar System (in the near future) and the Galaxy (in the far future), and METI. We argue that science fiction, especially the campy variety, is a significant contributor to the ‘giggle factor’ that hinders serious discussion and funding for SETI and Solar System settlement projects. We argue that humanity's long-term future in space will be shaped by our short-term visions for who goes there and how. Because of the way they entered the fields, we recommend avoiding the term ‘colony’ and its cognates when discussing the settlement of space, as well as other terms with similar pedigrees. We offer examples of science fiction and other writing that broaden and challenge our visions of human futures in space and SETI. In an appendix, we use an analogy with the well-funded and relatively uncontroversial searches for the dark matter particle to argue that SETI's lack of funding in the national science portfolio is primarily a problem of perception, not inherent merit.Also on arXiv: https://arxiv.org/abs/1708.05318Please cite this version:Wright, Jason T., and Michael P. Oman-Reagan. “Visions of Human Futures in Space and SETI.” International Journal of Astrobiology, 2017, 1–12. doi:10.1017/S1473550417000222.


2014 ◽  
Vol 7 (1) ◽  
pp. 115-122
Author(s):  
Jodi M. Smith ◽  
Vikas R. Dharnidharka

Significant progress has been made in pediatric kidney transplantation. Advances in immunosuppression have dramatically decreased rates of acute rejection leading to improved short term graft survival but similar improvements in long term graft survival remain elusive. Changes in allocation policy provide the pediatric population with timely access to transplant but there remains concern about the impact of less HLA matching and a decrease in living donors. This report presents data from North America on these successes and the ongoing challenges that face the pediatric transplant community.


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