Mesh sensitivity analysis on implicit and explicit method for rolling simulation

2018 ◽  
Vol 9 (4) ◽  
pp. 465-474 ◽  
Author(s):  
Evangelos Gavalas ◽  
Ioannis Pressas ◽  
Spyros Papaefthymiou
Keyword(s):  
Finite Element ◽  
Computational Efficiency ◽  
Rolling Process ◽  
Material Behavior ◽  
Implicit Method ◽  
Explicit Method ◽  
Explicit Integration ◽  
Content Type ◽  
Integration Schemes ◽  
Implicit And Explicit

Purpose The purpose of this paper is to compare the performance of implicit and explicit integration schemes for simulating the metal rolling process using commercial software packages ANSYS™ and LS-DYNA™. Design/methodology/approach For the industrial application of finite element method, the time discretization is one of the most important factors that determine the stability and efficiency of the analysis. An iterative approach, which is unconditionally stable in linear analyses, is the obvious choice for a quasi-static problem such as metal rolling. However, this approach may be challenging in achieving convergence with non-linear material behavior and complicated contact conditions. Therefore, a non-iterative method is usually adopted, in order to achieve computational accuracy through very small time steps. Models using both methods were constructed and compared for computational efficiency. Findings The results indicate that the explicit method yields higher levels of efficiency compared to the implicit method as model complexity increases. Furthermore, the implicit method displayed instabilities and numerical difficulties in certain load conditions further disfavoring the solver’s performance. Originality/value Comparison of the implicit and explicit procedures for time stepping was applied in 3D finite element analysis of the plate rolling process in order to evaluate and quantify the computational efficiency.

Finite-element modeling of partially prestressed concrete beams with unbonded tendon under monotonic loadings

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Pandimani ◽  
Markandeya Raju Ponnada ◽  
Yesuratnam Geddada
Keyword(s):  
Finite Element ◽  
Prestressed Concrete ◽  
Nonlinear Response ◽  
Concrete Beams ◽  
Fe Analysis ◽  
Material Behavior ◽  
Fe Model ◽  
Ansys Software ◽  
Content Type ◽  
Prestressing Tendon

Purpose The partially prestressed concrete beam with unbonded tendon is still an active field of research because of the difficulty in analyzing and understanding its behavior. The finite-element (FE) simulation of such beams using numerical software is very scarce in the literature and therefore this study is taken to demonstrate the modeling aspects of unbonded partially prestressed concrete (UPPSC) beams. This study aims to present the three-dimensional (3-D) nonlinear FE simulations of UPPSC beams subjected to monotonic static loadings using the numerical analysis package ANSYS. Design/methodology/approach The sensitivity study is carried out with three different mesh densities to obtain the optimum elements that reflect on the load–deflection behavior of numerical models, and the model with optimum element density is used further to model all the UPPSC beams in this study. Three half-symmetry FE model is constructed in ANSYS parametric design language domain with proper boundary conditions at the symmetry plane and support to achieve the same response as that of the full-scale experimental beam available in the literature. The linear and nonlinear material behavior of prestressing tendon and conventional steel reinforcements, concrete and anchorage and loading plates are modeled using link180, solid65 and solid185 elements, respectively. The Newton–Raphson iteration method is used to solve the nonlinear solution of the FE models. Findings The evolution of concrete cracking at critical loadings, yielding of nonprestressed steel reinforcements, stress increment in the prestressing tendon, stresses in concrete elements and the complete load–deflection behavior of the UPPSC beams are well predicted by the proposed FE model. The maximum discrepancy of ultimate moments and deflections of the validated FE models exhibit 13% and −5%, respectively, in comparison with the experimental results. Practical implications The FE analysis of UPPSC beams is done using ANSYS software, which is a versatile tool in contrast to the experimental testing to study the stress increments in the unbonded tendons and assess the complete nonlinear response of partially prestressed concrete beams. The validated numerical model and the techniques presented in this study can be readily used to explore the parametric analysis of UPPSC beams. Originality/value The developed model is capable of predicting the strength and nonlinear behavior of UPPSC beams with reasonable accuracy. The load–deflection plot captured by the FE model is corroborated with the experimental data existing in the literature and the FE results exhibit good agreement against the experimentally tested beams, which expresses the practicability of using FE analysis for the nonlinear response of UPPSC beams using ANSYS software.

Formulation of local numerical methods in linear elasticity

2020 ◽  
Vol 16 (5) ◽  
pp. 853-886
Author(s):  
Tiago Oliveira ◽  
Wilber Vélez ◽  
Artur Portela
Keyword(s):  
Finite Element ◽  
Numerical Methods ◽  
Linear Elasticity ◽  
Computational Efficiency ◽  
Simple Algorithm ◽  
Benchmark Problems ◽  
Local Form ◽  
Local Domain ◽  
Perfect Agreement ◽  
Content Type

PurposeThis paper is concerned with new formulations of local meshfree and finite element numerical methods, for the solution of two-dimensional problems in linear elasticity.Design/methodology/approachIn the local domain, assigned to each node of a discretization, the work theorem establishes an energy relationship between a statically admissible stress field and an independent kinematically admissible strain field. This relationship, derived as a weighted residual weak form, is expressed as an integral local form. Based on the independence of the stress and strain fields, this local form of the work theorem is kinematically formulated with a simple rigid-body displacement to be applied by local meshfree and finite element numerical methods. The main feature of this paper is the use of a linearly integrated local form that implements a quite simple algorithm with no further integration required.FindingsThe reduced integration, performed by this linearly integrated formulation, plays a key role in the behavior of local numerical methods, since it implies a reduction of the nodal stiffness which, in turn, leads to an increase of the solution accuracy and, which is most important, presents no instabilities, unlike nodal integration methods without stabilization. As a consequence of using such a convenient linearly integrated local form, the derived meshfree and finite element numerical methods become fast and accurate, which is a feature of paramount importance, as far as computational efficiency of numerical methods is concerned. Three benchmark problems were analyzed with these techniques, in order to assess the accuracy and efficiency of the new integrated local formulations of meshfree and finite element numerical methods. The results obtained in this work are in perfect agreement with those of the available analytical solutions and, furthermore, outperform the computational efficiency of other methods. Thus, the accuracy and efficiency of the local numerical methods presented in this paper make this a very reliable and robust formulation.Originality/valuePresentation of a new local mesh-free numerical method. The method, linearly integrated along the boundary of the local domain, implements an algorithm with no further integration required. The method is absolutely reliable, with remarkably-accurate results. The method is quite robust, with extremely-fast computations.

Applications of Explicit FEA in Structural Static and Dynamic Analyses

2013 ◽  
Vol 438-439 ◽  
pp. 1498-1501 ◽  
Author(s):  
Yong Sheng Qi ◽  
Feng Hua Zhao ◽  
Jun Wen Zhou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Nonlinear Problem ◽  
Implicit Method ◽  
Explicit Method ◽  
Natural Period ◽  
Duration Of Action ◽  
Static And Dynamic Analysis ◽  
Highly Nonlinear ◽  
Element Method

Non-convergence often occurs in the solution of highly nonlinear problem by conventional implicit finite element method. As another choice, explicit method is sometimes used by researchers. Through 2 typical static and dynamic examples this paper verifies that explicit finite element method can provide the same exactness of calculation as the implicit method even in the situation that the duration of action exceeds the natural period of structure greatly. At the same time, compared with implicit method, explicit method possesses higher speed, more robust algorithm, and stronger nonlinear capability, so that explicit method can be applied in static and dynamic analysis of structures, especially in large deformation and highly nonlinear problem.

Accuracy and Computational Efficiency of Finite Element Models for Low Velocity Impact on Composite Structures Subject to Progressive Damage and Delamination1

2015 ◽  
Vol 10 (6) ◽  
Author(s):  
Ahmed H. A. Ibrahim ◽  
Ahmet S. Yigit
Keyword(s):  
Finite Element ◽  
Computational Efficiency ◽  
Composite Structures ◽  
Material Behavior ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Contact Modeling ◽  
Velocity Impact ◽  
Composite Damage

There has been growing interest to use composites in load carrying structures where high strength and light weight are of major concern, e.g., oil industry (offshore structures and platforms, pipe systems, and tubings), sports equipment, automobiles, and aircraft industries. Despite extensive research in the last two decades, mechanical behavior of composite structures subject to contact and impact loading is still not well understood. It is well known that composites are highly vulnerable to various modes of failure and damage due to impact by foreign objects. Such impact events are not only dependent on the material behavior but also on the dynamics of the structure. Finite element (FE) packages are capable of simulating impact response of composite structures subject to impact. It requires extensive training and in-depth knowledge to obtain an adequate FE model with proper impact response prediction and acceptable computational efficiency. Limited FE models have the ability to capture composite damage due to impact when internal delamination or fiber/matrix failures are present. Severe nonlinearities are encountered during FE analysis to capture composite damage progression or material degradation. This work investigates different FE modeling approaches by analyzing their prediction of force–time history and force–indentation curve occurring in composite plates as a result of low velocity impact. The objective is to provide guidelines on selecting the most appropriate approach for a given impact situation. Moreover, a computationally efficient approach in contact modeling is presented. The proposed approach yields better computation efficiency for contact modeling on both isotropic and composite materials.

scholarly journals Machine Learning-Based Models for the Estimation of the Energy Consumption in Metal Forming Processes

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 833
Author(s):  
Irene Mirandola ◽  
Guido A. Berti ◽  
Roberto Caracciolo ◽  
Seungro Lee ◽  
Naksoo Kim ◽  
...  
Keyword(s):  
Machine Learning ◽  
Finite Element ◽  
Energy Consumption ◽  
Metal Forming ◽  
Mutual Influence ◽  
Rolling Process ◽  
Ring Rolling ◽  
Gradient Boosting ◽  
Average Error ◽  
Ring Rolling Mill

This research provides an insight on the performances of machine learning (ML)-based algorithms for the estimation of the energy consumption in metal forming processes and is applied to the radial-axial ring rolling process. To define the mutual influence between ring geometry, process settings, and ring rolling mill geometries with the resulting energy consumption, measured in terms of the force integral over the processing time (FIOT), FEM simulations have been implemented in the commercial SW Simufact Forming 15. A total of 380 finite element simulations with rings ranging from 650 mm < DF < 2000 mm have been implemented and constitute the bulk of the training and validation datasets. Both finite element simulation settings (input), as well as the FI (output), have been utilized for the training of eight machine learning models, implemented with Python scripts. The results allow defining that the Gradient Boosting (GB) method is the most reliable for the FIOT prediction in forming processes, being its maximum and average errors equal to 9.03% and 3.18%, respectively. The trained ML models have been also applied to own and literature experimental cases, showing a maximum and average error equal to 8.00% and 5.70%, respectively, thus proving once again its reliability.

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