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.

Shell Element Formulation Based Finite Element Modeling, Analysis and Experimental Validation of Incremental Sheet Forming Process

2015 ◽  
Author(s):  
Govind N. Sahu ◽  
Sumit Saxena ◽  
Prashant K. Jain ◽  
J. J. Roy ◽  
M. K. Samal ◽  
...  
Keyword(s):  
Finite Element ◽  
Thickness Distribution ◽  
Shell Element ◽  
Time Profile ◽  
Experimental Results ◽  
Computational Time ◽  
Element Formulation ◽  
Forming Process ◽  
Element Analysis ◽  
Shell Elements

This paper presents the effect of shell element formulations on the response parameters of incremental sheet metal forming process. In this work, computational time, profile prediction and thickness distribution are investigated by both finite element analysis and experimentally. The experimental results show that the thickness distribution is in good agreement with the results obtained with Belytschko-Tsay (BT) and Improved Flanagan-Belytschko (IFB) shell element formulations. These two shell element formulations do trade-off between computational time and accuracy. For more accurate results, the BT shell element formulation is better and for less computational time with good results, the IFB shell element is preferable. Finally, BT shell element formulation has been chosen for FE Analysis of ISF process in HyperWorks, since the results of thickness distribution and profile prediction is in better agreement with the experimental results as well as the computational time is less among the shell elements.

A FINITE ELEMENT PLATE FORMULATION FOR THE ACOUSTICAL INVESTIGATION OF THIN AIR LAYERS

2013 ◽  
Vol 21 (04) ◽  
pp. 1350014 ◽  
Author(s):  
PING RONG ◽  
OTTO VON ESTORFF ◽  
LORIS NAGLER ◽  
MARTIN SCHANZ
Keyword(s):  
Finite Element ◽  
Power Series ◽  
Transmission Loss ◽  
Fluid Layer ◽  
Single Layer ◽  
Shell Element ◽  
Thin Plates ◽  
Element Analysis ◽  
Shell Elements ◽  
Double Wall

Double wall systems consisting of thin plates separated by an air gap are common light-weighted wall structures with high transmission loss. Generally, these plate-like structures are modeled in a finite element analysis with shell elements and volume elements for the air (fluid) layer. An alternative approach is presented in this paper, using shell elements for the air layer as well. First, the element stiffness matrix is obtained by removing the thickness dependence of the variational form of the Helmholtz equation by use of a power series. Second, the coupling between the acoustical shell element and the elastic structure is described. To verify the new shell element, a simple double wall system is considered. Comparing the predicted sound field with the results from a commercial FE software (with a single layer of volume elements) a very good agreement is observed. At the same time, employing the new elements with a third-order power series (4 DOFs per node), the calculation time is reduced.

scholarly journals Topology optimization of a novel fuselage structure in the conceptual design phase

2018 ◽  
Vol 90 (9) ◽  
pp. 1385-1393
Author(s):  
Dianzi Liu ◽  
Chuanwei Zhang ◽  
Z. Wan ◽  
Z. Du
Keyword(s):  
Topology Optimization ◽  
Optimization Technique ◽  
Design Tool ◽  
Computational Time ◽  
Element Analysis ◽  
Content Type ◽  
Shell Elements ◽  
Upper And Lower Extremities ◽  
German Aerospace ◽  
Comparison Of The Results

Purpose In recent years, innovative aircraft designs have been investigated by researchers to address the environmental and economic issues for the purpose of green aviation. To keep air transport competitive and safe, it is necessary to maximize design efficiencies of the aircrafts in terms of weight and cost. The purpose of this paper is to focus on the research which has led to the development of a novel lattice fuselage design of a forward-swept wing aircraft in the conceptual phase by topology optimization technique. Design/methodology/approach In this paper, the fuselage structure is modelled with two different types of elements – 1D beam and 2D shell – for the validation purpose. Then, the finite element analysis coupled with topology optimization is performed to determine the structural layouts indicating the efficient distributed reinforcements. Following that, the optimal fuselage designs are obtained by comparison of the results of 1D and 2D models. Findings The topological results reveal the need for horizontal stiffeners to be concentrated near the upper and lower extremities of the fuselage cross section and a lattice pattern of criss-cross stiffeners should be well-placed along the sides of the fuselage and near the regions of window locations. The slight influence of windows on the optimal reinforcement layout is observed. To form clear criss-cross stiffeners, modelling the fuselage with 1D beam elements is suggested, whereas the less computational time is required for the optimization of the fuselage modelled using 2D shell elements. Originality/value The authors propose a novel lattice fuselage design in use of topology optimization technique as a powerful design tool. Two types of structural elements are examined to obtain the clear reinforcement detailing, which is also in agreement with the design of the DLR (German Aerospace Center) demonstrator. The optimal lattice layout of the stiffeners is distinctive to the conventional semi-monocoque fuselage design and this definitely provides valuable insights into the more efficient utilization of composite materials for novel aircraft designs.

Quick Aeromechanical Assessment of Turbine Blades Based on Shell Element Based Models

2014 ◽  
Author(s):  
Suryarghya Chakrabarti ◽  
Letian Wang ◽  
K. M. K. Genghis Khan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequencies ◽  
Turbine Blades ◽  
Computation Time ◽  
Shell Element ◽  
Element Model ◽  
Shell Elements ◽  
Barrier Coating ◽  
Order Of Magnitude

A fast finite element model based tool has been developed to calculate the natural frequencies of fundamental modes of cooled gas turbine bladed disk assemblies during conceptual design. The tool uses shell elements to model the airfoil, shank, and disk, and achieves order of magnitude reduction in computation time allowing exploration of a wide design space at the preliminary design stages. The analysis includes prestress effects due to centrifugal loading and approximate temperature loading on the parts. Sensitivity studies are performed to understand the relative impact of design features such as airfoil internal geometry, bond coat, and thermal barrier coating on the system natural frequencies. Critical features are selected which need to be modeled to get an accurate natural frequency estimate. The results obtained are shown to be within 5% of the frequencies obtained from a full-fidelity finite element model. A case study performed on seven blade designs illustrates the use of this tool for quick aeromechanical assessment of a large number of designs.

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.

Compressive Response of Thermoplastic Composites by Layered Shell Elements

1992 ◽  
Author(s):  
Hassan Mahfuz ◽  
Cynthia R. Ingram ◽  
Shaik Jeelani
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shell Element ◽  
Material Behavior ◽  
Thermoplastic Composites ◽  
Shear Stresses ◽  
Layered Shell ◽  
Element Analysis ◽  
Shell Elements ◽  
Compressive Response

Abstract Thick Laminates of thermoplastic Composites (APC-2) are modeled with isoparametric layered shell elements to predict the responses of the laminate at various temperatures under compressive loading. A large displacement finite element analysis is performed by considering the geometric non-linearities in the composite structure. Multiple load steps with linear material behavior are used to model the load-displacement characteristics found in a previous experimental study. A detailed description of the layered shell element along with its formulations is presented to highlight the limitations and scope of this element in composite structural analysis. Compressive response in respect of displacements, normal stresses, shear stresses and interlaminar shear stresses under three different temperatures is presented. Laminate response along its length as well as through the thickness is also presented to analyze and understand the failure mechanisms under such loading. Experimental data from a previous study are compared with the current result to validate the finite element analysis.

Potentials of Pulse Magnetic Forming and Joining

2014 ◽  
Vol 907 ◽  
pp. 349-364 ◽  
Author(s):  
Eckart Uhlmann ◽  
Lukas Prasol ◽  
Alexander Ziefle
Keyword(s):  
Magnesium Alloys ◽  
Metal Forming ◽  
High Speed ◽  
Weld Zone ◽  
Basic Research ◽  
Magnetic Pulse ◽  
Magnetic Pulse Welding ◽  
High Speed Forming ◽  
Pulse Welding ◽  
Welding Processes

Magnetic pulse production methods such as forming, joining or separating demonstrate innovative high-speed processes. Such processes can be realized using a capacitor and an appropriate tool coil for forming and welding processes. The process strain rates, which can amount to 20,000 s-1, increase the formability of metallic materials significantly. Magnesium and aluminium alloys find a wider application in the automotive industry due to their light weight potential. Through the low density of these materials, the vehicle weight can be reduced considerably. Due to the hexagonal lattice of magnesium alloys industry-relevant deformation in metal forming processes can only be achieved in hot forming processes. The high-speed forming allows a significant increase of deformability of this alloy. The use of dissimilar metals in an assembly requires the development of innovative joining methods. Apart from being used form and force closure the magnetic pulse welding and adhesive bonding material with different partners is possible. Currently at the Institute for Machine Tools and Factory Management (IWF), TU Berlin, various research topics in the field of pulsed magnetic are investigated. The magnetic pulse sheet metal forming of magnesium alloys at room temperature is investigated in a basic research project. A defined demarcation of high-speed forming with respect to the quasi-static deformation is done by means of hardness measurements in the deformation zone. For this purpose a suitable experimental setup with different matrices is constructed. The experimental results of the pulse magnetic deformation are iteratively compared with simulation results. The aim is to develop a new material model which gives a precise prediction about the high-speed process. In the field of magnetic pulse welding, both basic research and industry-related research projects conducted at the IWF. The process requires an adapted tool coil geometry that meets the requirements of the weld geometry. Different coil geometries and weld geometries and possible applications are presented by way of example, the welding quality is quantified by means of different analytical methods. The material microstructure in the weld zone, characterized by light and scanning electron microscopy shows the typical features of a shock welded joint, as also observed in explosive welding.

Mixed-dimensional coupling modeling for laser forming process

2014 ◽  
Vol 228 (16) ◽  
pp. 2950-2959
Author(s):  
Hong Shen ◽  
Jun Hu ◽  
Zhenqiang Yao
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Thermomechanical Analysis ◽  
Coupling Method ◽  
Computational Time ◽  
Laser Forming ◽  
Forming Process ◽  
Shell Elements

Efficient laser forming modeling for industrial application is still in the developing stage and many researchers are in the process of modifying it. Conventional three-dimensional finite element models are still expensive on computational time. In this paper, a finite element model adopting a shell-solid coupling technique is developed for the thermomechanical analysis of laser forming process. In the shell-solid coupling method, an additional shell element plane is utilized to transfer heat flux and displacement from the solid elements to the shell elements. The effects of the additional interface shell element thickness on temperature distribution and final distortion are investigated. The presented shell-solid coupling method is evaluated by the results of three-dimensional simulations and experimental data.

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