The Experts below are selected from a list of 2328 Experts worldwide ranked by ideXlab platform
Qiang Zhang - One of the best experts on this subject based on the ideXlab platform.
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on the post buckling analysis of a circular column with cylindrical constraint under Concentrated Torque loading
Ocean Engineering, 2019Co-Authors: Qiang Zhang, Z M Xiao, Wei LiAbstract:Abstract With the hypotheses of small deformation and Bernoulli-Euler beam, a gap element is introduced to describe the contact between the circular column and the external cylinder. The dynamic relaxation method is used to calculate the static equilibrium of the twisted column constrained by the cylinder. The post-buckling modes of a torsional column in a cylinder are investigated for the deformation configurations of one-point, two-point, three-point, and point-line-point contact. It is found that the end constraint has an effect on the length of the two suspended sections of helical buckling mode, but has no effect on the length of the continuous contact section in the middle. The relations have been derived among critical Torque, post-buckling modes, lengths of each section, and loads (including shear, bending moment, and contact force). Finally, the torsional buckling has been investigated for sucker rods and drill pipes with lengths of 1 km. It is found that the helical buckling of multiple pitches occurs. The results of the current study provide theoretical guidance for the design of centralizer spacing in oil and gas engineering applications.
Wei Li - One of the best experts on this subject based on the ideXlab platform.
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on the post buckling analysis of a circular column with cylindrical constraint under Concentrated Torque loading
Ocean Engineering, 2019Co-Authors: Qiang Zhang, Z M Xiao, Wei LiAbstract:Abstract With the hypotheses of small deformation and Bernoulli-Euler beam, a gap element is introduced to describe the contact between the circular column and the external cylinder. The dynamic relaxation method is used to calculate the static equilibrium of the twisted column constrained by the cylinder. The post-buckling modes of a torsional column in a cylinder are investigated for the deformation configurations of one-point, two-point, three-point, and point-line-point contact. It is found that the end constraint has an effect on the length of the two suspended sections of helical buckling mode, but has no effect on the length of the continuous contact section in the middle. The relations have been derived among critical Torque, post-buckling modes, lengths of each section, and loads (including shear, bending moment, and contact force). Finally, the torsional buckling has been investigated for sucker rods and drill pipes with lengths of 1 km. It is found that the helical buckling of multiple pitches occurs. The results of the current study provide theoretical guidance for the design of centralizer spacing in oil and gas engineering applications.
V K Luk - One of the best experts on this subject based on the ideXlab platform.
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stress properties at the tip of a conical notch
International Journal of Solids and Structures, 1997Co-Authors: Leon M Keer, V K LukAbstract:The singular behavior of a three-dimensional conical notch under torsional or torsionless loading was analyzed using the Papkovich-Neuber displacement potential method. Based on the analysis of the Legendre polynomial with complex index λn (Thompson, T. R. and Little, R. W. (1970). End effects in a truncated semi-infinite cone, Quart. J. Mech. Appl. Math. 23, 185–196), transcendental equations to the stress order λn of a torsional or torsionless notch at the cone tip are given for various notch angles. Analytical solutions for stress distributions around the cone tip under a Concentrated Torque T, and around the line notch tip under an expansion source E, are derived using the Legendre polynomial expression. These solutions can be applied for the study of penetration or perforation, where a penetrator is simulated as a Concentrated force and as an expansion source. Curves of the first order eigenvalues show that there exist very weak singular stresses at the three-dimensional conical notch. According to the evidence observed in the conical notch experiment (Williams, M. L. (1966). Stress singular, adhesion, and fracture. In Proc. 5th Nat. Congress for Appl. Mech. pp. 451–464), when the base of a cone is loaded, fracture occurs along its side instead of at its tip. This observation suggests that there may exist a comparatively weak singularity at the cone tip.
Z M Xiao - One of the best experts on this subject based on the ideXlab platform.
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on the post buckling analysis of a circular column with cylindrical constraint under Concentrated Torque loading
Ocean Engineering, 2019Co-Authors: Qiang Zhang, Z M Xiao, Wei LiAbstract:Abstract With the hypotheses of small deformation and Bernoulli-Euler beam, a gap element is introduced to describe the contact between the circular column and the external cylinder. The dynamic relaxation method is used to calculate the static equilibrium of the twisted column constrained by the cylinder. The post-buckling modes of a torsional column in a cylinder are investigated for the deformation configurations of one-point, two-point, three-point, and point-line-point contact. It is found that the end constraint has an effect on the length of the two suspended sections of helical buckling mode, but has no effect on the length of the continuous contact section in the middle. The relations have been derived among critical Torque, post-buckling modes, lengths of each section, and loads (including shear, bending moment, and contact force). Finally, the torsional buckling has been investigated for sucker rods and drill pipes with lengths of 1 km. It is found that the helical buckling of multiple pitches occurs. The results of the current study provide theoretical guidance for the design of centralizer spacing in oil and gas engineering applications.
Xiaowu Zhu - One of the best experts on this subject based on the ideXlab platform.
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twisting statics of functionally graded nanotubes using eringen s nonlocal integral model
Composite Structures, 2017Co-Authors: Xiaowu ZhuAbstract:Abstract In this contribution, a nonlocal integral model is formulated to investigate the twisting static behaviors of through-radius functionally graded (FG) nanotubes based on Eringen’s nonlocal integral elasticity. In comparison to the widely-used nonlocal differential model in the literature, the nonlocal integral model developed herein is self-consistent and well-posed. Closed-form solutions of rotational angle are derived for both clamped–clamped and clamped-free FG nanotubes. It is shown that the nonlocal parameter has a stiffness-softening effect on both clamped–clamped and clamped-free tubes, and the scaling effect is more sensitive to the former than the latter. The serious unresolved paradox that the torsional angle of a clamped-free FG nanotube with a Concentrated Torque at free end, when being modeled using the nonlocal differential model, is found to be identical with the classical result can now be well resolved based on the developed nonlocal integral model. The illustrative examples show that the maximum torsional angle can be prescribed by tailoring the through-radius microstructures of the nanotubes, and the increment of the nonlocal parameter and the applied Torques can increase the torsional angle, while the increment of the effective shear rigidity can decrease the torsional angle.