An Experimental Study of Buckling and Post-Buckling of Laterally Constrained Rods

1995 ◽  
Vol 117 (2) ◽  
pp. 115-124 ◽  
Author(s):  
P. V. R. Suryanarayana ◽  
R. C. McCann
Keyword(s):  
Experimental Study ◽  
Horizontal Wells ◽  
Current Theory ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Experimental Apparatus ◽  
Compressive Loads ◽  
Weight On Bit ◽  
Post Buckling ◽  
Safe Load

The effects of friction and curvature on buckling, post-buckling, and unbuckling behavior of rods laterally constrained within an enclosure are studied experimentally. The experimental apparatus, measurement procedures, and uncertainty analysis are described. Results indicate that friction significantly delays the onset of buckling, and causes noticeable hysteresis in the post-buckling behavior. As a result, the unbuckling loads are always less than the corresponding buckling loads. The drag-related loss, which eventually leads to lock-up, is also measured and reported in this work. Friction is also a cause of post-buckling snapping and reversals in the direction of wrap of the helix. As expected, the effects of friction become less significant as the inclination decreases. It is shown that predictions of current theory agree with experimentally measured unbuckling rather than buckling loads. When friction is significant, current theory underestimates the compressive loads at which buckling occurs in straight or curved wellbores. Ignoring friction or curvature limits the estimated weight on bit well below the safe load that can be used in many drilling and completion operations in extended reach or horizontal wells. Moreover, the hysteresis effect of friction means that once buckling has occurred, the compressive loads must be reduced to values much below the buckling initiation loads to fully straighten the buckled pipe.

Effect of Matching Buckling Loads on Post-Buckling Behavior in Compliant Mechanisms

2021 ◽  
Author(s):  
A. Numić ◽  
T. W. A. Blad ◽  
F. van Keulen
Keyword(s):  
Compliant Mechanisms ◽  
Relative Length ◽  
Optimal Designs ◽  
Element Analysis ◽  
Buckling Loads ◽  
Actuation Force ◽  
Stepped Beam ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Novel Method

Abstract In this paper, a novel method for stiffness compensation in compliant mechanisms is investigated. This method involves tuning the ratio between the first two critical buckling loads. To this end, the relative length and width of flexures in two architectures, a stepped beam and parallel guidance, are adjusted. Using finite element analysis, it is shown that by maximizing this ratio, the actuation force for transversal deflection in post-buckling is reduced. These results were validated experimentally by identifying the optimal designs in a given space and capturing the force-deflection characteristics of these mechanisms.

Delamination Suppression in Sandwich Beams Using Translaminar Reinforcements

1999 ◽  
Author(s):  
Brian T. Wallace ◽  
Bhavani V. Sankar ◽  
Peter G. Ifju
Keyword(s):  
Axial Compression ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Thickness Direction ◽  
Compression Tests ◽  
Honeycomb Core ◽  
Element Analysis ◽  
Buckling Loads ◽  
Buckling Behavior ◽  
Post Buckling

Abstract The present study is concerned with translaminar reinforcement in a sandwich beam for preventing buckling of a delaminated face-sheet under axial compression. Graphite/epoxy pins are used as reinforcement in the thickness direction of sandwich beams consisting of graphite/epoxy face-sheets and a Aramid honeycomb core. Compression tests are performed to understand the effects of the diameter of the reinforcing pins and reinforcement spacing on the ultimate compressive strength of the delaminated beams. A finite element analysis is performed to understand the effects of translaminar reinforcement on the critical buckling loads and post-buckling behavior of the sandwich beam under axial compression.

The Buckling Behavior of Pipes and Its Influence on the Axial Force Transfer in Directional Wells

2000 ◽  
Vol 122 (3) ◽  
pp. 129-135 ◽  
Author(s):  
Ergun Kuru ◽  
Alexander Martinez ◽  
Stefan Miska ◽  
Weiyong Qiu
Keyword(s):  
Internal Pressure ◽  
Axial Force ◽  
Current Theory ◽  
Pipe Diameter ◽  
Computer Simulator ◽  
Buckling Behavior ◽  
Force Transfer ◽  
Post Buckling ◽  
Support Conditions ◽  
The University

An experimental setup was built at the University of Tulsa to study buckling and post-buckling behavior of pipes constrained in straight horizontal and curved wellbores. Experiments were conducted to investigate the axial force transfer with and without static internal pressure. Different stages of buckling phenomena and their relation to the axial force, the pipe diameter (1/4 and 3/8 in.) and the pipe end-support conditions have also been investigated. Experimental results have shown that the buckling load is a strong function of the pipe diameter and the pipe end-support conditions. Static internal pressure appears to have insignificant influence on the buckling behavior of pipes. A brief review of recently developed mathematical models to predict buckling behavior of pipes in inclined, curved, and horizontal sections of wellbore is also presented. Applications of the current theory are presented by using recently developed computer simulator. Results of the theoretical analysis have confirmed the versatility and effectiveness of computer simulator for better understanding and solving buckling related problems in the field. [S0195-0738(00)00903-1]

Onset and Post Buckling of Pipe-in-Pipe’s Helical Buckling Using Improved Energy Method

2018 ◽  
Author(s):  
Lixin Gong
Keyword(s):  
Potential Energy ◽  
Energy Method ◽  
Normal Force ◽  
Horizontal Wells ◽  
Energy Methods ◽  
Buckling Mode ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Helical Buckling ◽  
Remarkable Agreement

The purpose of this paper is to present theoretical solutions based on an improved energy method for predicting the helical buckling (HB) behavior of pipes in vertical, inclined, and horizontal wells. The energy method has been applied to solve the pipe-in-pipe’s (PIP) helical buckling behavior since Lubinski, et al [2] in the 1950’s. However, in the preceding studies, the energy methods are not yet completely correct because the pipe’s potential energy of the distributed contact normal force induced by the helical buckling was considered to be negligible. This deficiency caused improper deductive procedures. In this paper, the energy method is improved by adding the term of the potential energy of the distributed contact normal force. With this improvement, not only can the PIP’s critical helical buckling forces be successfully derived, but it also provides a deeper insight on the PIP’s helical buckling onset, as well as the post helical buckling behavior. For inclined and horizontal wells, equations are provided to determine the critical forces required to initiate the helical buckling mode for both “long” and “short” pipes. In addition, the post buckling behavior is also described, and a new concept of helical buckling zone (HBZ) for “short” pipes is introduced based on the force-pitch plots as an area in-between the helical buckling’s onset curve and the classical Lubinski curve. Finite element ABAQUS models have also been utilized to confirm the analysis using the improved energy method. And the ABAQUS results show remarkable agreement with the theoretical solutions.

The Effect of Wellbore Curvature on Tubular Buckling and Lockup

1995 ◽  
Vol 117 (3) ◽  
pp. 214-218 ◽  
Author(s):  
J. Wu ◽  
H. C. Juvkam-Wold
Keyword(s):  
Laboratory Experiments ◽  
Horizontal Wells ◽  
Buckling Load ◽  
Small Scale ◽  
Buckling Loads ◽  
Compressive Loads ◽  
Helical Buckling ◽  
Outer Curve

This paper studies tubular buckling in curved wellbores (such as the build section of horizontal wells) and its effect on tubular “lockup” in horizontal or extended-reach wells. New buckling load equations are derived to properly predict tubular sinusoidal and helical buckling in such wellbores. The results show that the buckling loads to initiate sinusoidal and helical buckling of tubulars in curved wellbores are usually much larger than those in straight wellbores. This is because the curved wellbore tends to hold the axially compressed tubular against the outer-curve side of the wellbore. The tubular becomes less easy to buckle until higher axial compressive loads are applied. Less tubular lockup risk is then predicted for tubulars in horizontal or extended-reach wells by using the new buckling load equations. The new buckling loads in curved wellbores agree with those in straight wellbores when wellbore curvature approaches zero. Small-scale laboratory experiments also confirmed these theoretically derived buckling loads.

On Post-Buckling Behavior of Edge Cracked Functionally Graded Beams Under Axial Loads

2015 ◽  
Vol 15 (04) ◽  
pp. 1450065 ◽  
Author(s):  
Şeref Doğuşcan Akbaş
Keyword(s):  
Nonlinear Problems ◽  
Functionally Graded ◽  
Element Approximation ◽  
Axial Loads ◽  
Buckling Behavior ◽  
Highly Nonlinear ◽  
Compressive Loads ◽  
Graded Material ◽  
Post Buckling ◽  
Fgm Beam

This paper presents the post-buckling analysis of an edge cracked cantilever beam composed of functionally graded material (FGM) subjected to axial compressive loads by using the total Lagrangian Timoshenko beam element approximation. Material properties of the beam change in the height direction according to the exponential distribution. The cracked beam is modeled as an assembly of two sub-beams connected through a massless elastic rotational spring. For beams subjected to compression loads, the load rise causes compressible forces and therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. The highly nonlinear problem considered herein is solved incrementally by using the finite element method in conjunction with the Newton–Raphson method, by which the full geometric nonlinearity is considered. There is no restriction on the magnitudes of deflections and rotations in contradistinction to the von Karman strain displacement relations of the beam. In the study, the effects of the location and depth of the crack, and different material distributions on the post-buckling behavior of the FGM beam are investigated in detail.

Buckling Behavior of Tire Breaker Structure

1983 ◽  
Vol 11 (1) ◽  
pp. 3-19
Author(s):  
T. Akasaka ◽  
S. Yamazaki ◽  
K. Asano
Keyword(s):  
Elastic Foundation ◽  
Elastic Moduli ◽  
Wave Length ◽  
Bending Moment ◽  
Experimental Results ◽  
Automobile Tire ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Steel Cord ◽  
Interlaminar Shear

Abstract The buckled wave length and the critical in-plane bending moment of laminated long composite strips of cord-reinforced rubber sheets on an elastic foundation is analyzed by Galerkin's method, with consideration of interlaminar shear deformation. An approximate formula for the wave length is given in terms of cord angle, elastic moduli of the constituent rubber and steel cord, and several structural dimensions. The calculated wave length for a 165SR13 automobile tire with steel breakers (belts) was very close to experimental results. An additional study was then conducted on the post-buckling behavior of a laminated biased composite beam on an elastic foundation. This beam is subjected to axial compression. The calculated relationship between the buckled wave rise and the compressive membrane force also agreed well with experimental results.

Appraisal of Allowable Loads by Simplified Rules

1986 ◽  
Vol 108 (2) ◽  
pp. 131-137
Author(s):  
D. Moulin
Keyword(s):  
Experimental Investigation ◽  
Plastic Region ◽  
Thin Structures ◽  
Geometric Imperfections ◽  
Buckling Behavior ◽  
Simplified Method ◽  
Post Buckling ◽  
Initial Geometric Imperfections ◽  
Fast Breeder Reactors ◽  
Breeder Reactors

This paper presents a simplified method to analyze the buckling of thin structures like those of Liquid Metal Fast Breeder Reactors (LMFBR). The method is very similar to those used for the buckling of beams and columns with initial geometric imperfections, buckling in the plastic region. Special attention is paid to the strain hardening of material involved and to possible unstable post-buckling behavior. The analytical method uses elastic calculations and diagrams that account for various initial geometric defects. An application of the method is given. A comparison is made with an experimental investigation concerning a representative LMFBR component.

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