Application of the continuum shell finite element SHB8PS to sheet forming simulation using an extended large strain anisotropic elastic–plastic formulation

http://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

Evaluation of a new solid-shell finite element on the simulation of sheet metal forming processes

In this paper, the performance of the solid-shell finite element SHB8PS is assessed in the context of sheet metal forming simulation using anisotropic elastic-plastic behavior models. This finite element technology has been implemented into the commercial implicit finite element code Abaqus/Standard via the UEL subroutine. It consists of an eight-node three-dimensional hexahedron with reduced integration, provided with an arbitrary number of integration points along the thickness direction. The use of an in-plane reduced integration scheme prevents some locking phenomena, resulting in a computationally efficient formulation when compared to conventional 3D solid elements. Another interesting feature lies in the possibility of increasing the number of through-thickness integration points within a single element layer, which enables an accurate description of various phenomena in sheet forming simulations. A general elastic-plastic model has been adopted in the constitutive modeling for sheet forming applications with plastic anisotropy. As an illustrative example, the performance of the element is shown in the earing prediction of a cylindrical cup drawing process.ANR Formef & Région Lorrain

On the implementation of the continuum shell finite element SHB8PS and application to sheet forming simulation

In this contribution, the formulation of the SHB8PS continuum shell finite element is extended to anisotropic elastic-plastic behavior models with combined isotropic-kinematic hardening at large deformations. The resulting element is then implemented into the commercial implicit finite element code Abaqus/Standard via the UEL subroutine. The SHB8PS element is an eight-node, three-dimensional brick with displacements as the only degrees of freedom and a preferential direction called the thickness. A reduced integration scheme is adopted using an arbitrary number of integration points along the thickness direction and only one integration point in the other directions. The hourglass modes due to this reduced integration are controlled using a physical stabilization technique together with an assumed strain method for the elimination of locking. Therefore, the element can be used to model thin structures while providing an accurate description of the various through-thickness phenomena. Its performance is assessed through several applications involving different types of non-linearities: geometric, material and that induced by contact. Particular attention is given to springback prediction for a NUMISHEET benchmark problem.ANR Formef & Région Lorrain

On the implementation of the continuum shell finite element SHB8PS and application to sheet forming simulation

In this contribution, the formulation of the SHB8PS continuum shell finite element is extended to anisotropic elastic-plastic behavior models with combined isotropic-kinematic hardening at large deformations. The resulting element is then implemented into the commercial implicit finite element code Abaqus/Standard via the UEL subroutine. The SHB8PS element is an eight-node, three-dimensional brick with displacements as the only degrees of freedom and a preferential direction called the thickness. A reduced integration scheme is adopted using an arbitrary number of integration points along the thickness direction and only one integration point in the other directions. The hourglass modes due to this reduced integration are controlled using a physical stabilization technique together with an assumed strain method for the elimination of locking. Therefore, the element can be used to model thin structures while providing an accurate description of the various through-thickness phenomena. Its performance is assessed through several applications involving different types of non-linearities: geometric, material and that induced by contact. Particular attention is given to springback prediction for a NUMISHEET benchmark problem.ANR Formef & Région Lorrain

Elastic-plastic analyses using the solid-shell finite element SHB8PS and evaluation on sheet forming applications

In this contribution, the formulation of the SHB8PS continuum shell finite element is extended to anisotropic elastic-plastic behavior models with combined isotropic-kinematic hardening at large deformations. The resulting element is then implemented into the commercial implicit finite element code Abaqus/Standard via the UEL subroutine. The SHB8PS element is an eight-node, three-dimensional brick with displacements as the only degrees of freedom and a preferential direction called the thickness. A reduced integration scheme is adopted using an arbitrary number of integration points along the thickness direction and only one integration point in the other directions. The hourglass modes due to this reduced integration are controlled using a physical stabilization technique together with an assumed strain method for the elimination of locking. Therefore, the element can be used to model thin structures while providing an accurate description of the various throughthickness phenomena. Its performance is assessed through several applications involving different types of non-linearities: geometric, material and that induced by contact. Particular attention is given to springback prediction for a Numisheet benchmark problem.Projet ANR FORMEF & Région Lorrain

Elastic-plastic analyses using the solid-shell finite element SHB8PS and evaluation on sheet forming applications

In this contribution, the formulation of the SHB8PS continuum shell finite element is extended to anisotropic elastic-plastic behavior models with combined isotropic-kinematic hardening at large deformations. The resulting element is then implemented into the commercial implicit finite element code Abaqus/Standard via the UEL subroutine. The SHB8PS element is an eight-node, three-dimensional brick with displacements as the only degrees of freedom and a preferential direction called the thickness. A reduced integration scheme is adopted using an arbitrary number of integration points along the thickness direction and only one integration point in the other directions. The hourglass modes due to this reduced integration are controlled using a physical stabilization technique together with an assumed strain method for the elimination of locking. Therefore, the element can be used to model thin structures while providing an accurate description of the various throughthickness phenomena. Its performance is assessed through several applications involving different types of non-linearities: geometric, material and that induced by contact. Particular attention is given to springback prediction for a Numisheet benchmark problem.Projet ANR FORMEF & Région Lorrain

Evaluation of a new solid-shell finite element on the simulation of sheet metal forming processes

In this paper, the performance of the solid-shell finite element SHB8PS is assessed in the context of sheet metal forming simulation using anisotropic elastic-plastic behavior models. This finite element technology has been implemented into the commercial implicit finite element code Abaqus/Standard via the UEL subroutine. It consists of an eight-node three-dimensional hexahedron with reduced integration, provided with an arbitrary number of integration points along the thickness direction. The use of an in-plane reduced integration scheme prevents some locking phenomena, resulting in a computationally efficient formulation when compared to conventional 3D solid elements. Another interesting feature lies in the possibility of increasing the number of through-thickness integration points within a single element layer, which enables an accurate description of various phenomena in sheet forming simulations. A general elastic-plastic model has been adopted in the constitutive modeling for sheet forming applications with plastic anisotropy. As an illustrative example, the performance of the element is shown in the earing prediction of a cylindrical cup drawing process.ANR Formef & Région Lorrain

Identification de la loi de comportement cristallin du Zirconium à partir de la réponse locale et globale d'un polycristal

International audienceThe aim of this study is the identification of the parameters of the crystalline behavior law of Zirconium by minimizing a global cost function which is the sum of two cost functions. The first function represents the difference between the experimental macroscopic stress-strain curve and the one coming from a crystalline finite element calculation realized on a RVE. The second cost function represents the difference between the experimental strain fields by digital image correlation technique of deformed micro-grids, and those simulated on a real microstructure characterized by EBSD.Le but de ce travail est l'identification des paramètres de la loi de comportement cristallin du Zirconium grade 702 en minimisant une fonction coût globale qui représente la somme pondérée de deux fonctions coût. La première fonction représente l'écart entre la courbe σ-ε expérimentale macroscopique et celle provenant d'un calcul EF polycristallin réalisé sur un VER. La deuxième fonction coût représente l'écart entre les champs de déformations expérimentaux mesurés par corrélation d'images de microgrilles, et ceux simulés sur une microstructure réelle caractérisée par EBSD

Modeling of the cyclic behavior of elastic-viscoplastic composites by the additive tangent Mori-Tanaka approach and validation by finite element calculations

International audienceThis work deals with the prediction of the macroscopic behavior of two-phase composites, based on the Mori-Tanaka scheme combined with an additive/sequential interaction rule and tangent linearization of viscoplastic response. Cyclic tension compression loadings are considered to further validate the approach. The composite is made of spherical inclusions dispersed in a matrix. Both materials have an elastic-viscoplastic behavior. In a second part, finite element calculations are performed using ABAQUS/STANDARD software in order to validate the proposed homogenization technique. A representative volume element is analyzed with 30 randomly distributed inclusions. Comparisons between the additive tangent Mod-Tanaka scheme and finite element calculations are made for different volume fractions of inclusions, different contrasts in elastic and viscous properties and different strain rates and strain amplitudes. These comparisons demonstrate the efficiency of the proposed homogenization scheme. The effect of isotropization of the viscoplastic tangent stiffness is also investigated. It is concluded that quality of predictions does not benefit from such simplification, contrary to the known result for elastic-plastic case

Reliability of thermally stressed rigid-flex printed circuit boards for High Density Interconnect applications

International audienceThe thermal fatigue of vias in rigid-flex printed circuit boards (PCB) is considered in the paper. Dedicated printed circuit boards have been designed with different geometrical configurations (plating thickness, drilled hole diameter and PCB thickness). The PCB is made of hundreds of vias or holes which are wired by copper path to create a daisy chain. The PCB is subject to cyclic thermal loading (-55 degrees C, +125 degrees C). Electrical connectivity is recorded during tests. Cross sectioning is performed finally to characterize the loss of electrical connectivity. Fracture of plated copper, due to the thermal expansion mismatch between constituents, is shown to be responsible for the failure of the PCB. In addition to environmental tests, finite element model is developed to analyze the deformation of PCBs during thermal cycling. Areas of strain concentration determined by Finite Element Analysis (FEA) are consistent with locations where cracks were observed in experiments. In addition, the numerical estimation of the plastic strain increment per cycle enables the prediction of the fatigue life. The results confirm that for rigid flex boards, the fatigue life of vias increases with higher plating thickness, larger drilled hole size and lower PCB thickness. Numerical results are shown to be in good agreement with experiments