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Segen F. Estefen

Bio: Segen F. Estefen is an academic researcher from Federal University of Rio de Janeiro. The author has contributed to research in topics: Subsea & Welding. The author has an hindex of 22, co-authored 143 publications receiving 1745 citations.


Papers
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TL;DR: In this article, the reliability of pipelines with corrosion defects subjected to internal pressure using the first-order reliability method (FORM) is defined based on the results of a series of small-scale experiments and three-dimensional nonlinear finite element analysis of the burst pressure of intact and corroded pipelines.

228 citations

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TL;DR: In this paper, the effect of external corrosion defects was studied via a series of small-scale experiments and through a nonlinear numerical model based on the finite element method, which was used to determine the burst pressure as a function of material and geometric parameters of different pipes and defects.

201 citations

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TL;DR: A literature review on failure events experienced by the industry concerning pipelines, risers, and umbilical cables, describing their causes, consequences, and severity is presented in this article, where the main failure modes reported are due to mechanical damage, corrosion, construction defect, natural hazards and fatigue.

104 citations

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TL;DR: In this paper, a sequentially coupled thermo-mechanical finite element model that considers temperature-dependent material properties, high temperature effects and a moving volumetric heat source was used to investigate the effect of welding sequence on the residual stresses and distortions in T-joint welds.

95 citations

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TL;DR: In this paper, a methodology for the geometrical optimization of wave energy converters (WEC) based on statistical analysis methods and the hydrodynamics of the system in the frequency domain is presented.

90 citations


Cited by
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1,604 citations

Journal ArticleDOI
TL;DR: In this paper, the authors classify different residual stresses measurement methods and provide an overview of some of the recent advances in this area to help researchers on selecting their techniques depending on their application and the availabilities of those techniques.

633 citations

01 Jan 2001
TL;DR: In this paper, a model for the axisymmetric growth and coalescence of small internal voids in elastoplastic solids is proposed and assessed using void cell computations.
Abstract: A model for the axisymmetric growth and coalescence of small internal voids in elastoplastic solids is proposed and assessed using void cell computations. Two contributions existing in the literature have been integrated into the enhanced model. The first is the model of Gologanu-Leblond-Devaux, extending the Gurson model to void shape effects. The second is the approach of Thomason for the onset of void coalescence. Each of these has been extended heuristically to account for strain hardening. In addition, a micromechanically-based simple constitutive model for the void coalescence stage is proposed to supplement the criterion for the onset of coalescence. The fully enhanced Gurson model depends on the flow properties of the material and the dimensional ratios of the void-cell representative volume element. Phenomenological parameters such as critical porosities are not employed in the enhanced model. It incorporates the effect of void shape, relative void spacing, strain hardening, and porosity. The effect of the relative void spacing on void coalescence, which has not yet been carefully addressed in the literature. has received special attention. Using cell model computations, accurate predictions through final fracture have been obtained for a wide range of porosity, void spacing, initial void shape, strain hardening, and stress triaxiality. These predictions have been used to assess the enhanced model. (C) 2000 Elsevier Science Ltd. All rights reserved.

519 citations

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TL;DR: In this article, the rapidly developing state-of-the-art of fiber-reinforced geopolymer composites is discussed, focusing on material and geometrical properties of construction fibers, and underlying mechanisms on fiber-binder interaction at fresh and hardened states.
Abstract: There is a burgeoning interest in the development of geopolymers as sustainable construction materials and incombustible inorganic polymers. However, geopolymers show quasi-brittle behavior. To overcome this weakness, hundreds of research have been focused on development, characterization, and implementation of fiber-reinforced geopolymers for a wide range of applications. This paper discusses the rapidly developing state-of-the-art of fiber-reinforced geopolymer composites, focusing on material and geometrical properties of construction fibers, and underlying mechanisms on fiber-binder interaction at fresh and hardened states, mechanical properties, toughening mechanisms, thermal characteristics, and environmental durability. It is intended to build a strong conceptual and technical background for what is currently understood on fiber-reinforced geopolymers by tying the subject together with knowns for other similar cementitious composites rather than a historical report of literature.

289 citations

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TL;DR: In this paper, a wave energy has been shown to have some favorable variability properties (a perennial issue with many renewables, especially wind), especially when combined with wind energy, and wave energy can be used to fulfill future increasing energy needs.
Abstract: With the recent sharp increases in the price of oil, issues of security of supply, and pressure to honor greenhouse gas emission limits (e.g., the Kyoto protocol), much attention has turned to renewable energy sources to fulfill future increasing energy needs. Wind energy, now a mature technology, has had considerable proliferation, with other sources, such as biomass, solar, and tidal, enjoying somewhat less deployment. Waves provide previously untapped energy potential, and wave energy has been shown to have some favorable variability properties (a perennial issue with many renewables, especially wind), especially when combined with wind energy [1].

284 citations