scholarly journals Modeling of thin sheet forming processes by combining solid-shell finite element with isotropic elastoviscoplastic model. Application to magnetic pulse forming processes

2021 ◽  
Author(s):  
Mohamed Mahmoud ◽  
François Bay ◽  
Daniel Pino Mũnoz
Keyword(s):  
Sheet Metal ◽  
Thin Sheet ◽  
Magnetic Pulse ◽  
Solid Shell ◽  
Forming Process ◽  
Thin Structures ◽  
Shell Elements ◽  
Tetrahedral Element ◽  
Magnetic Pulse Forming ◽  
Assumed Strain

Sheet metal alloys are used in many industries to save material, reduce weight and improve the overall performance of products. For the last decades, many types of elements have been developed to resolve the locking problems encountered in the simulation of thin structures. Among these approaches, a family of assumed-strain solid-shell elements has proved to be very efficient and attractive in simulating thin 3D structures with various constitutive models. Furthermore, these elements are able to account for anisotropic behavior of thin structures since isotropic yield functions cannot capture the real physics of some forming processes. In this work, von Mises isotropic yield criterion with Johnson-cook hardening model are combined with a linear prismatic solid-shell element to simulate sheet metal forming processes. A new element assembly technique has been developed to permit the assembly of prismatic elements in a tetrahedral element-based software. This technique splits the prism into multiple tetrahedral elements in such a way that all the cross-terms are accounted for. Furthermore, a tetrahedral based partitioning code has been modified to account for the new prismatic element shape without changing the core structure of the code. More accurate results were obtained using low number of solid-shell elements compared to its counterpart tetrahedral element (MINI element). This reduction in the number of elements accelerated the simulation, especially in the coupled magnetic-structure simulation used for magnetic pulse forming process. The proposed element and criteria are implemented into FORGE (in-house code developed at CEMEF) for simulating magnetic pulse forming process.

scholarly journals Efficient Solid–Shell Finite Elements for Quasi-Static and Dynamic Analyses and their Application to Sheet Metal Forming Simulation

2015 ◽  
Vol 651-653 ◽  
pp. 344-349 ◽  
Author(s):  
Peng Wang ◽  
Hocine Chalal ◽  
Farid Abed-Meraim
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Large Strain ◽  
Solid Shell ◽  
Forming Process ◽  
Thin Structures ◽  
Shell Elements ◽  
Assumed Strain ◽  
Dynamic Analyses

Thin structures are commonly designed and employed in engineering industries to save material, reduce weight and improve the overall performance of products. The finite element (FE) simulation of such thin structural components has become a powerful and useful tool in this field. For the last few decades, much attention and effort have been paid to establish accurate and efficient FE. In this regard, the solid–shell concept proved to be very attractive due to its multiple advantages. Several treatments are additionally applied to the formulation of solid–shell elements to avoid all locking phenomena and to guarantee the accuracy and efficiency during the simulation of thin structures. The current contribution presents a family of prismatic and hexahedral assumed-strain based solid–shell elements, in which an arbitrary number of integration points are distributed along the thickness direction. Both linear and quadratic formulations of the solid–shell family elements are implemented into ABAQUS static/implicit and dynamic/explicit software to model thin 3D problems with only a single layer through the thickness. Two popular benchmark tests are first conducted, in both static and dynamic analyses, for validation purposes. Then, attention is focused on a complex sheet metal forming process involving large strain, plasticity and contact.

APPLICATION OF FORMING LIMIT CRITERIA BASED ON PLASTIC INSTABILITY CONDITION TO METAL FORMING PROCESS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5680-5685
Author(s):  
SEONG-CHAN HEO ◽  
TAE-WAN KU ◽  
JEONG KIM ◽  
BEOM-SOO KANG ◽  
WOO-JIN SONG
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Thin Sheet ◽  
Plastic Instability ◽  
Theoretical Background ◽  
Forming Limit ◽  
Preliminary Evaluation ◽  
Forming Process ◽  
Element Analysis

Metal forming processes such as hydroforming and sheet metal forming using tubular material and thin sheet metal have been widely used in lots of industrial fields for manufacturing of various parts that could be equipped with mechanical products. However, it is not easy to design sequential processes properly because there are various design variables that affect formability of the parts. Therefore preliminary evaluation of formability for the given process should be carried out to minimize time consumption and development cost. With the advances in finite element analysis technique over the decades, the formability evaluation using numerical simulation has been conducted in view of strain distribution and final shape. In this paper, the application of forming limit criteria is carried out for the tube hydroforming and sheet metal forming processes using theoretical background based on plastic instability conditions. Consequently, it is confirmed that the local necking and diffuse necking criteria of sheet are suitable for formability evaluation of both hydroforming and sheet metal forming processes.

Magnetic Pulse Forming of Thin-Aluminum Sheet Using Bar-Forming Coil

2011 ◽  
Vol 337 ◽  
pp. 621-624 ◽  
Author(s):  
Ji Yeon Shim ◽  
Ill Soo Kim ◽  
Dong Hwan Park ◽  
Bong Yong Kang
Keyword(s):  
Intelligent System ◽  
Analysis Data ◽  
Aluminum Sheet ◽  
Design Parameters ◽  
Fe Model ◽  
Magnetic Pulse ◽  
Forming Process ◽  
Thin Aluminum ◽  
Magnetic Pulse Forming ◽  
Measured Strain

Generally a MPF(Magnetic pulse forming) process refers to the high velocity and high strain rate deformation of a low-ductility materials driven by electromagnetic forces that are generated by the rapid discharge current through the forming coil. The goal of this study was to investigate the main design parameter in MPF. To achieve the above objectives, An intelligent system which consisted of thin 5053 aluminum sheet and bar forming coil was employed for the experiment. The measured strain data have been analyzed using the developed electromagnetic FE-model. The analysis data showed that the uniform electromagnetic force is one of most important design parameters in MPF process.

The Simulation of Robot Based Incremental Sheet Metal Forming by Means of a New Solid-Shell Finite Element Technology and a Finite Elastoplastic Model with Combined Hardening

2011 ◽  
Vol 473 ◽  
pp. 875-880 ◽  
Author(s):  
Yalin Kiliclar ◽  
Roman Laurischkat ◽  
Stefanie Reese ◽  
Horst Meier
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Kinematic Hardening ◽  
Industrial Robots ◽  
Solid Shell ◽  
Forming Process ◽  
Incremental Sheet Metal Forming ◽  
Shell Finite Element

The principle of robot based incremental sheet metal forming is based on flexible shaping by means of a freely programmable path-synchronous movement of two tools, which are operated by two industrial robots. The final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the geometry’s contour in lateral direction. The main problem during the forming process is the influence on the dimensional accuracy resulting from the compliance of the involved machine structures and the springback effects of the workpiece. The project aims to predict these deviations caused by resiliences and to carry out a compensative path planning based on this prediction. Therefore a planning tool is implemented which compensates the robot’s compliance and the springback effects of the sheet metal. Finite element analysis using a material model developed at the Institute of Applied Mechanics (IFAM) [1] has been used for the simulation of the forming process. The finite strain constitutive model combines nonlinear kinematic and isotropic hardening and is derived in a thermodynamical setting. It is based on the multiplicative split of the deformation gradient in the context of hyperelasticity. The kinematic hardening component represents a continuum extension of the classical rheological model of Armstrong–Frederick kinematic hardening which is widely adopted as capable of representing the above metal hardening effects. The major problem of low-order finite elements used to simulate thin sheet structures, such as used for the experiments, is locking, a non-physical stiffening effect. Recent research focuses on the large deformation version of a new eight-node solid-shell finite element based on reduced integration with hourglass stabilization. In the solid-shell formulation developed at IFAM ([2], [3]) the enhanced assumed strain (EAS) concept as well as the assumed natural strain (ANS) concept are implemented to circumvent locking. These tools are very important to obtain a good correlation between experiment and simulation.

Determination of High Strain-Rate Behavior of Metals: Applications to Magnetic Pulse Forming and Electrohydraulic Forming

2014 ◽  
Vol 611-612 ◽  
pp. 643-649 ◽  
Author(s):  
Anne Claire Jeanson ◽  
Gilles Avrillaud ◽  
Gilles Mazars ◽  
Jean Paul Cuq-Lelandais ◽  
Francois Bay ◽  
...  
Keyword(s):  
Strain Rate ◽  
Tensile Tests ◽  
Expansion Velocity ◽  
Magnetic Pulse ◽  
Constitutive Behaviour ◽  
Forming Process ◽  
Electrohydraulic Forming ◽  
Workpiece Material ◽  
Magnetic Pulse Forming ◽  
Static Conditions

The design of processes like magnetic pulse forming and electrohydraulic forming involves multiphysical couplings that require numerical simulation, and knowledge on dynamic behaviour of metals. The forming process is completed in about 100 μs, so that the workpiece material deforms at strain-rates between 100 and 10 000 s-1. In this range, the mechanical behaviour can be significantly different than that in quasi-static conditions. It is often noticed that the strength and the formability are higher. The main goal of this study is to use an electromagnetically driven test on tubes or sheets to identify the constitutive behaviour of the workpiece material. In the case of tube, an industrial helix coil is used as inductor. Simulations with the code LS-Dyna® permit to find a configuration where the tube deforms homogeneously enough to allow axisymmetric modelling of the setup. The coil current is measured and used as an input for the simulations. The radial expansion velocity is measured with a Photon Doppler Velocimeter. The parameter identification is lead with the optimization software LS-Opt®. LS-Dyna axisymmetric simulations are launched which different set of parameters for the constitutive behaviour, until the computed expansion velocity fits the experimental velocity. The optimization algorithm couples a gradient method and a global method to avoid local minima. Numerical studies show that for the Johnson-Cook constitutive model, two or three experiments at different energies are required to identify the expected parameters. The method is applied to Al1050 tubes, as received and annealed. The parameters for the Johnson-Cook and Zerilli-Armstrong models are identified. The dynamic constitutive behaviour is compared to that measured on quasi-static tensile tests, and exhibits a strong sensitivity to strain-rate. The final strains are also significantly higher at high velocity, which is one of the major advantages of this kind of processes.

scholarly journals An Efficient Computational Model for Magnetic Pulse Forming of Thin Structures

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7645
Author(s):  
Mohamed Mahmoud ◽  
François Bay ◽  
Daniel Pino Muñoz
Keyword(s):  
High Speed ◽  
Computation Time ◽  
Shell Element ◽  
Computational Time ◽  
Magnetic Pulse ◽  
Element Analysis ◽  
Shell Elements ◽  
Novel Approach ◽  
Magnetic Pulse Forming ◽  
High Speed Forming

Electromagnetic forming (EMF) is one of the most popular high-speed forming processes for sheet metals. However, modeling this process in 3D often requires huge computational time since it deals with a strongly coupled multi-physics problem. The numerical tools that are capable of modeling this process rely either on shell elements-based approaches or on full 3D elements-based approaches. The former leads to reduced computational time at the expense of the accuracy, while the latter favors accuracy over computation time. Herein, a novel approach was developed to reduce CPU time while maintaining reasonable accuracy through building upon a 3D finite element analysis toolbox which was developed in CEMEF. This toolbox was used to solve magnetic pulse forming (MPF) of thin sheets. The problem was simulated under different conditions and the results were analyzed in-depth. Innovative techniques, such as developing a termination criterion and using adaptive re-meshing, were devised to overcome the encountered problems. Moreover, a solid shell element was implemented and tested for thin structure problems and its applicability was verified. The results of this element type were comparable to the results of the standard tetrahedral MINI element but with reduced simulation time.

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