Showing papers by "Eduardo N. Dvorkin published in 2006"

On the modelling of complex 3D bulk metal forming processes via the pseudo‐concentrations technique. Application to the simulation of the Mannesmann piercing process

Abstract: The modelling of complex 3D metal forming processes using the flow formulation, implemented via the pseudo-concentrations technique, requires the development of robust computational strategies for dealing with the velocity and pseudo-concentration boundary conditions in the zone where the blank–tools contact is developed. A new algorithm, designed to fulfil those requirements, is presented in this paper. The Mannesmann piercing process is a metal forming operation used in industry for manufacturing metal seamless pipes. The results of the Mannesmann process finite element simulation are particularly dependent on the accuracy and stability of the algorithm used to describe the contact boundary conditions between the forming tools and the blank. The validation of the finite element model is performed by comparing the numerical predictions obtained using the new algorithm with the results of industrial tests. Copyright © 2005 John Wiley & Sons, Ltd.

Collapse Arrestors for Deepwater Pipelines: Finite Element Models and Experimental Validations for Different Cross-Over Mechanisms

Abstract: Using finite element models it is possible to determine the cross-over external pressure of different pipeline arrestor designs. In this paper these finite element models are discussed and validated by comparing their results with experimental determinations. The flipping and flattening cross-over mechanisms are considered in the experimental validation of the numerical models.Copyright © 2006 by ASME

Deepwater Pipelines: Reliability of Finite Element Models in the Prediction of Collapse and Collapse Propagation Loads

Abstract: In the design of pipelines it is of utmost importance to use validated numerical tools, usually finite element models, to reliably determine the structural limit loads. Also for steel pipes manufacturers it is very important, for establishing the set-up of their production processes, to be able to analyze using validated finite element models the effect that different manufacturing imperfections have on the pipe limit loads (e.g. “ovalization” of the external diameter, eccentricity, residual stresses, etc.). For deepwater pipelines the most relevant limit states that need to be analyzed are the collapse and collapse propagation under different combinations of external pressure and bending. In the second section of this paper we discuss the finite element models that we developed to predict the collapse and collapse propagation of seamless steel pipes under external pressure and bending. The validation of these models was performed comparing the numerical results with experimental results obtained at CFER (Edmonton, Canada) [1] and at our lab for the pre-collapse and post-collapse regimes. In deepwater pipelines, in order to prevent the propagation of collapse failures through the pipeline length, buckle arrestors are used. In the third section of this paper we review the finite element models that we developed to predict buckle arrestors cross-over external pressures. The validation of these models was performed comparing the numerical results with experimental ones obtained at our lab for different ratios [arrestor thickness/pipe thickness] corresponding to either the flattening or flipping cross-over mechanisms [2]. Finally in the fourth section of this paper the validated finite element models are used to perform parametric analyses that provide useful data for pipeline engineers on the effect of different geometrical parameters on crossover pressure.Copyright © 2006 by ASME