Buckling of Drill Pipe in an Inclined Hole

1964 ◽  
Vol 86 (2) ◽  
pp. 214-218 ◽  
Author(s):  
D. B. Bogy ◽  
P. R. Paslay
Keyword(s):  
Stability Analysis ◽  
Gravity Field ◽  
Lateral Displacement ◽  
Drill Pipe ◽  
Vertical Plane ◽  
Approximate Analysis ◽  
Simple Experiment ◽  
Inclined Plane ◽  
Stability Equation ◽  
Simply Supported

The buckling of drill pipe in the vertical plane for the case of an inclined hole is studied. This is accomplished by performing a stability analysis of a simply supported column lying in compression on a rigid inclined plane in the presence of a gravity field. The lateral displacement of the column is restricted to be perpendicular to the plane. According to the results of an approximate analysis it is found that the system becomes unstable under the above conditions only if the lateral variational displacements are finite. The derived stability equation is verified for a particular case by a simple experiment. The results of this analysis can be used to determine the “crookedness” of a hole which, under specified conditions, will induce instability.

Column Moment Demands from Orthogonal Beam Twisting

2018 ◽  
Vol 763 ◽  
pp. 259-269
Author(s):  
George Webb ◽  
Kanyakon Kosinanonth ◽  
Tushar Chaudhari ◽  
Saeid Alizadeh ◽  
Gregory A. MacRae
Keyword(s):  
Lateral Displacement ◽  
Frame Structure ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Element Analysis ◽  
Soft Storey ◽  
Simply Supported ◽  
Composite Frame ◽  
Explicit Consideration ◽  
Column Joint

Beam column joint subassemblies in steel moment frames often have simply-supported gravity beams framing into the joint in the perpendicular direction. When these subassemblies undergo lateral displacement, moments enter the column from the beams. Some of these moments are directly applied from the in-plane beam and slab stresses as they contact the column, and additional moments occur as the slab causes the perpendicular simply supported beams to twist. In most design codes around the world, no explicit consideration of these moments is performed even though they may increase the likelihood of column yielding and a soft-storey mechanism. This paper quantifies the magnitude of these perpendicular beam twisting moments in typical subassemblies using inelastic finite element analysis. It is shown that for beam-column-joint-slab subassemblies where the primary and secondary beams are fully welded to the column, the addition of slab effects significantly increases the total stiffness and strength of the composite frame structure. In addition to this, it is also shown the twisting moment demand of the secondary beams increased the frames strength by approximately 2% for an imposed drift of 5% for the subassembly investigated when no gap was provided between slab and the column. It was also shown the twisting moment demand of the secondary beams increased the frames strength by approximately 10% for a maximum imposed drift of 5% for the subassembly investigated when a gap was provided between the slab and the column.

Surface instability of imperfectly bonded multi-layered curved films under van der Waals forces

2017 ◽  
Vol 82 (5) ◽  
pp. 1088-1103
Author(s):  
Xu Wang ◽  
Peter Schiavone
Keyword(s):  
Cylindrical Shell ◽  
Stability Analysis ◽  
Analytical Solutions ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Imperfect Interface ◽  
Surface Instability ◽  
Simply Supported ◽  
Linear Spring ◽  
Interface Parameters

Abstract Using a linear stability analysis and the transfer matrix method, we investigate the surface instability of an imperfectly bonded multi-layered curved film interacting with a curved rigid contactor, another imperfectly bonded multi-layered curved film or an imperfectly bonded multi-layered simply-supported cylindrical shell in each case through the action of attractive van der Waals forces. The imperfect interface is modelled as a linear spring layer with vanishing thickness characterized by normal and tangential imperfect interface parameters. Detailed numerical results are presented to demonstrate the resulting analytical solutions.

Three-Dimensional Nonlinear Stability Analysis of Tangent Continuous Welded Rail Track Under Temperature and Mechanical Loads

1997 ◽  
Vol 1584 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Yulin Bao ◽  
Ernest J. Barenberg
Keyword(s):  
Stability Analysis ◽  
Lateral Displacement ◽  
Three Dimensional ◽  
Initial Slope ◽  
Lateral Loads ◽  
Rotational Stiffness ◽  
Geometric Imperfections ◽  
Mechanical Loads ◽  
Lateral Resistance ◽  
Continuous Welded Rail

Results from applications of the three-dimensional continuous welded rail (CWR) track model ILLIBUCKLE to a tangent CWR track with nonlinear resistance and lateral geometric imperfections are presented. Stability analysis is made of the tracks under temperature and mechanical loads by using temperature lateral-displacement curves. Tangent CWR track stability is highly sensitive not only to ballast lateral resistance and geometric imperfections of the the initial track but also to the vertical rotational stiffness in rail-pad fastener systems and vehicle lateral loads. It is concluded that not only the peak values but also the initial slope and the limit resistance in the ballast lateral-resistance curve obtained from a single-tie push test are important in evaluation of track stability. With regard to vertical rotational stiffness in a rail-pad fastener system, track stability is not significantly affected by the nonlinearities, but it is affected by the initial slope. Effects of the combination of mechanical and thermal loads on tangent track stability are presented. The reduction of ballast lateral resistance due to the uplift of rail tie under vehicle vertical loads as well as the magnitude of vehicle lateral loads significantly decrease track stability. A 1400-kg vehicle lateral load can buckle tangent CWR track under a rail-temperature increase as low as 56°C (100°F) under unfavorable conditions.

Effects of Initial Geometric Imperfections on Parametric Instability of Rectangular Plates

2001 ◽  
Author(s):  
Lyne St-Georges ◽  
G. L. Ostiguy
Keyword(s):  
Lateral Displacement ◽  
Plate Thickness ◽  
Parametric Instability ◽  
Experimental Tests ◽  
Rectangular Plates ◽  
Rational Analysis ◽  
Geometric Imperfections ◽  
Simply Supported ◽  
Geometrical Imperfections ◽  
Initial Geometric Imperfections

Abstract The authors present a rational analysis of the effect of initial geometric imperfections on the dynamic behaviour of rectangular plates activated by a parametric excitation. This subject has been extensively investigated theoretically in the past, but no experimental data seems to be complete enough to validate the theory. The main objective of this investigation is to fill this void by performing experimental tests on geometrically imperfect plates, and to highlight the geometric imperfection’s influence on resonance’s curves. The study is carried out for an isotropic, elastic, homogeneous, and thin rectangular plate. The plate under investigation is subjected to the action of an in-plane force uniformly distributed along two opposite edges, is initially stress free and simply supported. Theoretical calculation and experimental tests are performed. In the theoretical approach, a dynamic version of the Von Kármán non-linear theory is used to evaluate the lateral displacement of the plate. The test rig used in the experimentation simulates simply supported edges and can accept plates with different aspect ratio. The test plates are pre-formed with lateral deflection or geometrical imperfections, in a shape corresponding to various vibration modes. Comparison between experimental and theoretical results reveals good agreement and allows the determination of the theory’s limitations. The theory used correctly describes the behaviour of the plate when imperfection amplitude is inferior to the plate thickness.

scholarly journals Controlling Laminate Plate Elastic Behavior

10.14311/566 ◽  
2004 ◽  
Vol 44 (3) ◽  
Author(s):  
T. Mareš
Keyword(s):  
Fiber Orientation ◽  
Scalar Product ◽  
Lateral Displacement ◽  
Laminate Plate ◽  
Lateral Loading ◽  
Elastic Behavior ◽  
Central Plane ◽  
Simply Supported ◽  
Rectangular Laminate

This paper aims to express the relation of a measure of laminate plate stiffness with respect to the fiber orientation of its plies. The inverse of the scalar product of the lateral displacement of the central plane and lateral loading of the plate is the measure of laminate plate stiffness. In the case of a simply supported rectangular laminate plate this measure of stiffness is maximized, and the optimum orientation of its plies is searched.

Thermocapillary Fingering of a Gravity-Driven Self-Rewetting Fluid Film Flowing Down a Vertical Slippery Wall

2021 ◽  
Author(s):  
Chicheng Ma ◽  
Jianlin Liu
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Stability Analysis ◽  
Film Theory ◽  
Vertical Plane ◽  
Wall Slip ◽  
Fluid Film ◽  
Numerical Verification ◽  
Gravity Driven ◽  
Interfacial Temperature

Abstract The surface tension of a self-rewetting fluid (SRF) has a parabolic shape with the increase of temperature, implying potential applications in many industrial fields. In this paper, flow patterns and stability analysis are numerically performed for a gravity driven self-rewetting fluid film flowing down a heated vertical plane with wall slip. Using the thin film theory, the evolution equation for the interfacial thickness is derived. The discussion is given considering two cases in the review of the temperature difference between the interfacial temperature and the temperature corresponding to the minimum surface tension. The base state of the two-dimensional flow is firstly obtained and the influence of the Marangoni effect and slippery effect is analyzed. Then linear stability analysis and related numerical verification are displayed, showing good consistency with each other. For a low interfacial temperature, the Marangoni promotes the fingering instability and for a high interfacial temperature, the inverse Marangoni impedes the surface instability. The wall slip is found to influence the free surface in a complex way because it can either destabilize or stabilize the flow of the free surface.

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