891 research outputs found
New Linear and Quadratic Piezoelectric Solid-Shell Finite Elements
No full textInternational audienceThe modeling of piezoelectric structures has been the subject of active research in recent decades (Tzou et al., 1994; Benjeddou et al., 1997; Klinkel and Wagner, 2006). However, advanced finite element technologies that are capable of efficiently modeling multilayer structures with high geometric contrast are still lacking. In this work, we propose piezoelectric extensions to recently developed solid-shell elements (Abed-Meraim and Combescure, 2009; Trinh et al., 2011; Abed-Meraim et al., 2013). For this purpose, we performed an electromechanical coupling, which consists in adding an electrical degree of freedom to each node of these elements. To increase efficiency, these elements are provided with a special direction, designated as the thickness, along which the integration points are located, while adopting a reduced integration rule in the other directions. To assess the performance of the proposed piezoelectric solid-shell elements, a variety of benchmark problems, both in static and vibration analysis, have been conducted on multilayer structures ranging from simple beams to more complex structures involving geometric nonlinearities. Compared to traditional finite elements with the same kinematics, the evaluation results allow emphasizing the higher performance of the newly developed solid-shell concept
Limit-point buckling analyses using solid, shell and solid–shell elements
No full textIn this paper, the recently-developed solid-shell element SHB8PS is used for the analysis of a representative set of popular limit-point buckling benchmark problems. For this purpose, the element has been implemented in Abaqus/Standard finite element software and the modified Riks method was employed as an efficient path-following strategy. For the. benchmark problems tested, the new element shows better performance compared to solid elements and often performs as well as state-of-the-art shell elements. In contrast to shell elements, it allows for the accurate prescription of boundary conditions as applied to the actual edges of the structure.Agence Nationale de la Recherche, France (ANR-005-RNMP-007
New Linear and Quadratic Piezoelectric Solid-Shell Finite Elements
No full textThe modeling of piezoelectric structures has been the subject of active research in recent decades (Tzou et al., 1994; Benjeddou et al., 1997; Klinkel and Wagner, 2006). However, advanced finite element technologies that are capable of efficiently modeling multilayer structures with high geometric contrast are still lacking. In this work, we propose piezoelectric extensions to recently developed solid-shell elements (Abed-Meraim and Combescure, 2009; Trinh et al., 2011; Abed-Meraim et al., 2013). For this purpose, we performed an electromechanical coupling, which consists in adding an electrical degree of freedom to each node of these elements. To increase efficiency, these elements are provided with a special direction, designated as the thickness, along which the integration points are located, while adopting a reduced integration rule in the other directions. To assess the performance of the proposed piezoelectric solid-shell elements, a variety of benchmark problems, both in static and vibration analysis, have been conducted on multilayer structures ranging from simple beams to more complex structures involving geometric nonlinearities. Compared to traditional finite elements with the same kinematics, the evaluation results allow emphasizing the higher performance of the newly developed solid-shell concept
Advances in Shell Finite Elements
No full textIASS-IACM 2008 Session: Advances in Shell Finite Elements --
Session Organizer: Christopher EARLS (Cornell University) --
Keynote Lecture:
"Stressing thermo-mechanical analysis of FGM shells" by
J.N. REDDY (Texas A & M), Roman A. ARCINIEGA (ABAQUS) --
"An investigation of the isogeometric approach from the viewpoint of finite element technology" by
Ralph ECHTER, Manfred BISCHOFF (University of Stuttgart) --
"Locking-free formulation for the stabilized enhanced strain solid-shell element (SHB8PS): Geometrically non-linear applications" by
Farid ABED-MERAIM (LPMM), Alain COMBESCURE (LaMCoS) --
"New prismatic solid-shell element: Assumed strain formulation and evaluation of benchmark problems" by
Vuong-Dieu TRINH, Farid ABED-MERAIM (LPMM), Alain COMBESCURE (LaMCoS) --
"Evolution of the new rotation-free finite element shell triangle using accurate geometrical data" by
Pere-Andreu UBACH, Eugenio ONATE (CIMNE, UPC) --
"New curvature formulation of the SFE rotation-free shell element" by
Sylvain COUEDO, Laetitia DUIGOU, Gerard RIO (LIMATB, UBS) --
"Largest geometrically exact nonlinear thin beam, plate & shell elements and c-type FEM" by
Debabrata RAY (Institute for Dynamic Response, Inc.) --
"A new shell element for elasto-plastic finite strain analysis: Application to the collapse and post-collapse analysis of marine pipelines" by
Rita TOSCANO (University of Buenos Aires), Eduardo DVORKIN (SIM&TEC) --
"A finite element analysis of axially crushed corrugated frusta" by
Mahmoud M. A. YOUNES (M.T.C. Cairo
Omar Abed: 2025 Irma Black Award Gold Medal Acceptance Speech
No full textAuthor Omar Abed gives an acceptance speech for The Book That Almost Rhymed, illustrated by Hatem Aly (Dial Books for Young Readers)https://educate.bankstreet.edu/irma_black_awards/1015/thumbnail.jp
Application of the continuum shell finite element SHB8PS to sheet forming simulation using an extended large strain anisotropic elastic–plastic formulation
No full texthttp://link.springer.com/article/10.1007%2Fs00419-012-0620-xThis paper proposes an extension of the SHB8PS solid–shell finite element to large strain anisotropic elasto-plasticity, with application to several non-linear benchmark tests including sheet metal forming simulations. This hexahedral linear element has an arbitrary number of integration points distributed along a single line, defining the "thickness" direction; and to control the hourglass modes inherent to this reduced integration, a physical stabilization technique is used. In addition, the assumed strain method is adopted for the elimination of locking. The implementation of the element in Abaqus/Standard via the UEL user subroutine has been assessed through a variety of benchmark problems involving geometric non-linearities, anisotropic plasticity, large deformation and contact. Initially designed for the efficient simulation of elastic–plastic thin structures, the SHB8PS exhibits interesting potentialities for sheet metal forming applications – both in terms of efficiency and accuracy. The element shows good performance on the selected tests, including springback and earing predictions for Numisheet benchmark problems
New quadratic solid-shell elements and their evaluation on popular benchmark problems
No full textInternational audienceIn recent years, considerable effort has been devoted to the development of 3D finite elements able to model thin structures (Cho et al., 1998; Sze and Yao, 2000; Abed-Meraim and Combescure, 2002; Vu-Quoc and Tan, 2003; Chen and Wu, 2004). To this end, coupling solid and shell formulations proved to be an interesting strategy, providing continuum finite element models that can be efficiently used for structural applications. In the present work, two solid-shell elements are formulated (a 20-node and a 15-node element) based on a purely three-dimensional approach. The advantages of these elements are shown through the analysis of various structural problems. Note that their main advantage is to allow complex structural shapes to be simulated without classical problems of connecting zones meshed with different element types. These solid-shell elements have a special direction called the “thickness”, along which a set of integration points are located. Reduced integration is also used to prevent some locking phenomena and to increase computational efficiency. Focus will be placed here on linear benchmark problems, where it is shown that these solid-shell elements perform much better than their counterparts, conventional solid elements
Investigation of advanced strain-path dependent material models for sheet metal forming simulations
No full textSheet metal forming processes often involve complex loading sequences. To improve the prediction of some undesirable phenomena, such as springback, physical behavior models should be considered. This paper investigates springback behavior predicted by advanced elastoplastic hardening models which combine isotropic and kinematic hardening and take strain-path changes into account. A dislocation-based microstructural hardening model formulated from physical observations and the more classical cyclic model of Chaboche have been considered in this work. Numerical implementation was carried out in the ABAQUS software using a return mapping algorithm with a combined backward Euler and semi-analytical integration scheme of the constitutive equations. The capability of each model to reproduce transient hardening phenomena at abrupt strain-path changes has been shown via simulations of sequential rheological tests. A springback analysis of strip drawing tests was performed in order to emphasize the impact of several influential parameters, namely: process, numerical and behavior parameters. The effect of the two hardening models with respect to the process parameters has been specifically highlighted
New quadratic solid-shell elements and their evaluation on popular benchmark problems
No full textInternational audienceIn recent years, considerable effort has been devoted to the development of 3D finite elements able to model thin structures (Cho et al., 1998; Sze and Yao, 2000; Abed-Meraim and Combescure, 2002; Vu-Quoc and Tan, 2003; Chen and Wu, 2004). To this end, coupling solid and shell formulations proved to be an interesting strategy, providing continuum finite element models that can be efficiently used for structural applications. In the present work, two solid-shell elements are formulated (a 20-node and a 15-node element) based on a purely three-dimensional approach. The advantages of these elements are shown through the analysis of various structural problems. Note that their main advantage is to allow complex structural shapes to be simulated without classical problems of connecting zones meshed with different element types. These solid-shell elements have a special direction called the “thickness”, along which a set of integration points are located. Reduced integration is also used to prevent some locking phenomena and to increase computational efficiency. Focus will be placed here on linear benchmark problems, where it is shown that these solid-shell elements perform much better than their counterparts, conventional solid elements
Numerical Study of Localization Failure in Structural Steel Under Impact Loading
No full textA Master of Science thesis in Civil Engineering submitted by Fadi Makarem entitled, "Numerical Study of Localization Failure in Structural Steel under Impact Loading," October 2011. Thesis advisor is Dr. Farid Abed and thesis is available in both soft and hard copies.High quality steels are used as a skeleton supporting many infrastructure constructions like, for example, skyscrapers, arenas, stadiums, bridges and others. The likelihood that these structures could be severely damaged by postulated accidental extreme loading has been increased recently. Such loading may come about due to impact, blast or fluid jet impingement etc., and is usually of high intensity but short duration. Since most steel structures are capable of absorbing a considerable amount of energy beyond the elastic range, analysis has to extend into the inelastic range in order to avoid excessively pessimistic assessments. This research presents a consistent methodology for the assessment of nonlinear behavior of structural steel under low and high velocity impacts. Three high strength low alloy steels were considered in this study; HSLA-65, DH-36 and HY- 100. Four well-known constitutive models for viscoplastic deformation of metals, i.e., Johnson-Cook (JC), Zerilli-Armstrong (ZA), Rusinek-Klepaczko (RK), and Voyiadjis-Abed (VA), were investigated and compared with reference to existing experimental data. The VA constitutive model was chosen among the others as it exhibited dominant performance in describing the thermoplastic deformation of ferrite steel at a wide range of temperatures and strain rates. The VA model was then integrated and implemented into the commercial finite elements code ABAQUS/Explicit via user material subroutine coded as VUMAT. Finite elements simulation of the formation of shear localizations in a cylindrical hat-shaped specimen was conducted for two ferrite steel alloys, HSLA-65 and DH-36, subjected to certain range of velocity impact. The effect of the VA microstructure based material parameters on the initiation and propagation of shear localization was also investigated. Several conclusions related to the width of the shear bands considering various velocities and temperatures were thoroughly discussed. Finally, a preliminarily study on localization failure in axially preloaded columns made of high strength steel HY-100 (lowest yield stress = 100 ksi) subjected to transverse impact is presented. The effect of impact velocity, impactor mass, impact location and preloading condition on the behavior and failure modes of the steel columns is investigated in an attempt to develop appropriate design calculation methods for steel columns under such loading conditions.College of EngineeringDepartment of Civil EngineeringMaster of Science in Civil Engineering (MSCE
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