Continuum Finite Element Methods to Establish Compressive Strain Limits for Offshore Pipelines in Ice Gouge Environments

2007 ◽  
Author(s):  
Ali Fatemi ◽  
Shawn Kenny ◽  
Farid Taheri
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Compressive Strain ◽  
Pipeline System ◽  
Operational Parameters ◽  
Offshore Pipelines ◽  
Geometric Imperfection ◽  
Mesh Density ◽  
Post Buckling ◽  
Element Type

In the design process for offshore pipelines in ice gouge environments, compressive strain limits provide a basis to assess pipeline mechanical integrity for design load events. A parametric study, using the continuum finite element methods, has been conducted to assess the global pipeline moment-curvature response for displacement-based loading conditions through the post-buckling regime. The purpose of this study was to investigate the accuracy and efficiency of some computational parameters in simulating the stability characteristics of thick pipes. For that, the study used a pipe that has been the subject of a comprehensive and extensive experimental investigation. In specific, the study selected the exact geometric, material, loadings, boundary conditions and operational parameters similar to the BPXA Northstar pipeline system. The numerical analysis examined the effect of element type, mesh density, internal pressure, axial load, end moment, and geometric imperfection mode on the predicted post-buckling response. The analysis demonstrated the importance of element type, mesh density and characteristics of initial geometric imperfections on the post-buckling response of a thick-walled pipeline subject to combine loads. In addition, element performance and solution efficiency was examined.

scholarly journals Trustworthiness in Modeling Unreinforced and Reinforced T-Joints with Finite Elements

2019 ◽  
Vol 24 (1) ◽  
pp. 27 ◽  
Author(s):  
Slimane Ouakka ◽  
Nicholas Fantuzzi
Keyword(s):  
Finite Element ◽  
Static Strength ◽  
Fe Model ◽  
Static Behavior ◽  
T Joints ◽  
Shell Elements ◽  
Mesh Density ◽  
Element Type ◽  
Material Discontinuities ◽  
Conclusion Section

As required by regulations, Finite Element Analyses (FEA) can be used to investigate the behavior of joints which might be complex to design due to the presence of geometrical and material discontinuities. The static behavior of such problems is mesh dependent, thus these results must be calibrated by using laboratory tests or reference data. Once the Finite Element (FE) model is correctly setup, the same settings can be used to study joints for which no reference is available. The present work analyzes the static strength of reinforced T-joints and sheds light on the following aspects: shell elements are a valid alternative to solid modeling; the best combination of element type and mesh density for several configurations is shown; the ultimate static strength of joints can be predicted, as well as when mechanical properties are roughly introduced for some FE topologies. The increase in strength of 12 unreinforced and reinforced (with collar or doubler plate) T-joints subjected to axial brace loading is studied. The present studies are compared with the literature and practical remarks are given in the conclusion section.

Buckling and Post-buckling Behaviour of Plates with Holes

1975 ◽  
Vol 26 (4) ◽  
pp. 281-296 ◽  
Author(s):  
D Ritchie ◽  
J Rhodes
Keyword(s):  
Experimental Investigation ◽  
Finite Element ◽  
Theoretical Analysis ◽  
Finite Element Methods ◽  
Experimental Investigations ◽  
Rectangular Plates ◽  
Simply Supported ◽  
Circular Holes ◽  
Post Buckling ◽  
Plate Width

SummaryThis paper gives details of theoretical and experimental investigations into the behaviour of simply-supported uniformly compressed square and rectangular plates with central circular holes. The theoretical analysis employs an approximate approach using a combination of Rayleigh-Ritz and finite-element methods. The experimental investigation consisted of a number of experiments on plates with hole diameters from one- to seven-tenths of the plate width. Agreement between experiment and theory is shown to be good at buckling. In the post-buckling range it is found that the theoretical analysis is reasonably accurate for small holes, but loses accuracy when dealing with large holes.

End Boundary Effects on Local Buckling Response of High Strength Linepipe

2010 ◽  
Author(s):  
Ali Fatemi ◽  
Shawn Kenny ◽  
Farid Taheri ◽  
Da-Ming Duan ◽  
Joe Zhou
Keyword(s):  
Finite Element ◽  
Yield Stress ◽  
Large Scale ◽  
Stress Ratio ◽  
Compressive Strain ◽  
Local Buckling ◽  
High Strength ◽  
End Effects ◽  
Industry Practice ◽  
Post Buckling

In this paper, the significance of the length to diameter ratio (L/D) on the local buckling response was evaluated using continuum finite element modelling procedures. A numerical model was developed, using the finite-element simulator ABAQUS/Standard, to predict the local buckling and post-buckling response of high strength pipelines subject to combined state of loading. The numerical procedures were calibrated using test data from large-scale experiments examining the local buckling of high strength linepipe. The numerical model’s response was consistent with the measured experimental response for predicting the local buckling behavior well into the post-yield range. A parametric study was conducted to examine the significance of the linepipe L/D ratio with respect to the yield stress to ultimate stress ratio (Y/T) and hoop yield stress to longitudinal yield stress ratio or anisotropy factor (R). As the models with high L/D ratio exhibit global Euler-type response, a numerical algorithm was developed to calculate the local section moment response for the FE analysis. The analysis conducted provides insight on the significance of end effects on the local buckling response. There are questions on the approach taken by current industry practice with respect to establishing compressive strain limits for local buckling when using shorter linepipe segment lengths. The results from this study suggest end effects require assessment and potential mitigation.

Koiter’s Reduction Finite Element Method for Nonlinear Stability Analysis of Thin-Walled Shells

2019 ◽  
Vol 17 (01) ◽  
pp. 1843004 ◽  
Author(s):  
Ke Liang ◽  
Qin Sun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Path Following ◽  
Nonlinear Prediction ◽  
Nonlinear Stability Analysis ◽  
Geometric Imperfection ◽  
Thin Walled Structures ◽  
Post Buckling ◽  
Thin Walled ◽  
Element Method

Thin-walled structures are widely used in aeronautical and aerospace engineering. Conical and cylindrical shells structures, under axial compression, are prone to failure by buckling and typically show a snap-back phenomenon in the end-shortening curve. Path-following technologies based on Newton-type methods have difficulties to trace reliably the snap-back response due to the extremely sharp turning angle near the limit point. In this paper, a Koiter’s reduction finite element method, termed the Koiter–Newton (KN) method, is presented to trace reliably the post-buckling path of cylinders and cones considering either linear buckling modes or dimples from lateral perturbation loads as geometric imperfection. A robust algorithm based on the bifurcation-detection technique is applied during the solution of the reduced order model to achieve a successful path-tracing. The numerical results presented reveal that the nonlinear prediction obtained from Koiter’s perturbation theory at the unloaded state of the structure is numerically accurate up to the buckling load and the initial post-buckling path.

Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

2013 ◽  
Vol 41 (2) ◽  
pp. 127-151
Author(s):  
Rudolf F. Bauer
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Finite Element Methods ◽  
Mathematical Analysis ◽  
Internal Stresses ◽  
Stress Concentrations ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
And Performance ◽  
Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

Finite element methods for internal flow calculations

1983 ◽  
Author(s):  
W. HABASHI ◽  
M. HAFEZ ◽  
P. KOTIUGA
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Internal Flow

Post-buckling inelastic analysis of thin-walled metal members using the Generalised Beam Theory

2019 ◽  
Author(s):  
Miguel Abambres ◽  
Dinar Camotim ◽  
Miguel Abambres
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Beam Theory ◽  
Flow Theory ◽  
Promising Alternative ◽  
Inelastic Analysis ◽  
Post Buckling ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalised Beam Theory

A 2nd order inelastic Generalised Beam Theory (GBT) formulation based on the J2 flow theory is proposed, being a promising alternative to the shell finite element method. Its application is illustrated for an I-section beam and a lipped-C column. GBT results were validated against ABAQUS, namely concerning equilibrium paths, deformed configurations, and displacement profiles. It was concluded that the GBT modal nature allows (i) precise results with only 22% of the number of dof required in ABAQUS, as well as (ii) the understanding (by means of modal participation diagrams) of the behavioral mechanics in any elastoplastic stage of member deformation .

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