Results 181 to 190 of about 9,704 (210)
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Buckling transition in long α-helices
The Journal of Chemical Physics, 2014The treatment of bending and buckling of stiff biopolymer filaments by the popular worm-like chain model does not provide adequate understanding of these processes at the microscopic level. Thus, we have used the atomistic molecular-dynamic simulations and the Amber03 force field to examine the compression buckling of α-helix (AH) filaments at room ...
Peter, Palenčár, Tomáš, Bleha
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Prediction of Helical / Sinusoidal Buckling
SPE/IADC Asia Pacific Drilling Technology, 1996Abstract A set of equations for helical and sinusoidal buckling under an ideal condition, where weight and frictional effects are not considered have been derived based on experimental and FEA data. An experimental method was developed canceling out frictional effects and FEA was carried out independently on both ...
H. Hishida +3 more
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Helical Buckling of Pipes in Extended Reach and Horizontal Wells—Part 1: Preventing Helical Buckling
Journal of Energy Resources Technology, 1993Abstract This paper studies the helical buckling of pipes (drillstring and tubing) in extended reach and horizontal wells, theoretically and experimentally, resulting in new equations to correctly predict and effectively prevent the helical buckling of pipes in such wells.
J. Wu, H. C. Juvkam-Wold, R. Lu
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SPE Drilling Engineering, 1988
Summary A new solution to helical buckling is presented yielding real helical shapes of buckled pipes with a varying helix pitch. This solution has been developed with the beam/column equation. The change in length and the bending stress can be computed from the helical-buckling solution. In addition, a new equation for tool clearance in
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Summary A new solution to helical buckling is presented yielding real helical shapes of buckled pipes with a varying helix pitch. This solution has been developed with the beam/column equation. The change in length and the bending stress can be computed from the helical-buckling solution. In addition, a new equation for tool clearance in
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On the buckling of helical compression springs
International Journal of Mechanical Sciences, 1992zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Becker, L. E., Cleghorn, W. L.
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New Concepts for Helical Buckling
SPE Drilling Engineering, 1988Summary An approximate analytic solution for the helical buckling of tubing with weight has been determined. This solution has good accuracy except near the neutral point. The solution used by Lubinski to solve the helical-buckling problem is shown to be a special case of this new analytic solution. It is generally accepted that Lubinski'
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Interactions between Torque and Helical Buckling in Drilling
SPE Annual Technical Conference and Exhibition, 1995Abstract The effects of torque on helical buckling are a concern in coiled tubing drilling. These effects are also important in conventional drilling of long horizontal wells. This paper presents theoretical models for the effects of torque on helical buckling, normal contact force, and pitch of helix in the curved well ...
X. He, G.W. Halsey, A. Kyllingstad
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Numerical Analysis of Helical Buckling
Proceedings of SPE Deep Drilling and Production Symposium, 1986Abstract The equilibrium equations for a helically buckled tubing with weight are solved by an approximate method that produces a generalized form of Lubinski's force-pitch relationship. This new solution provides a method for evaluating the range of application of Lubinski's results.
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Helical Buckling of Tubing Sealed in Packers
Journal of Petroleum Technology, 1962Abstract Most gas wells and flowing oil wells are completed and treated through a string of tubing and a packer. Changes in temperature and in pressure inside or outside the tubing will:if free motion of the tubing inside the packer is permitted, increase or decrease the length of the tubing; orif free motion is ...
Arthur Lubinski, W.S. Althouse
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New Analytic Solutions for Pipe Helical Buckling Problems
Proceedings of International Oil and Gas Conference and Exhibition in China, 2010Abstract There are some numerical solutions(4,5) for pipe buckling problems in vertical and horizontal wells, but, we need exact analytic solutions for precise analysis of pipe buckling problems. The first analytic solution for pipe buckling in a vertical well was presented by Lubinski and Woods in 1962(2).
M. Teymoorishamasbi +3 more
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