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Optimization

LS-OPT papers dealing with optimization

2019

2018

  • Parameter Identification of the *MAT_036 Material Model using Full-Field Calibration

    Christian Ilg, Andre Haufe, David Koch, Katharina Witowski, DYNAmore GmbH, Stuttgart, Germany, , Nielen Stander, Livermore Software Technology Corporation, Livermore, CA, Åke Svedin, DYNAmore Nordic, Linköping, Sweden, Mathias Liewald, Institut für Umformtechnik, Universität Stuttgart, Germany

  • Full-Field Material Calibration using LS-OPT

    Nielen Stander, Anirban Basudhar, Imtiaz Gandikota, Livermore Software Technology Corporation, Livermore, CA, Katharina Witowski, Christian Ilg, Andre Haufe, DYNAmore GmbH, Stuttgart, Germany, Åke Svedin, DYNAmore Nordic, Linköping, Sweden

  • Applications and Potential of Classifiers in LS-OPT 6.0

    Anirban Basudhar, Imtiaz Gandikota, Nielen Stander, Livermore Software Technology Corporation, Livermore, CA, Katharina Witowski, DYNAmore GmbH, Stuttgart, Germany

  • Determination and Optimisation of a Temperature-Dependent-Failure curve for High-Strength Aluminium Alloys applicable for Hotforming

    Julian Schlosser, Universität Aalen, Germany

  • Shape optimization for CFD analysis using LS-OPT, ANSA and LS-DYNA ICFD

    Facundo Del Pin, Livermore Software Technology Corporation, Livermore, CA, USA, Katharina Witowski, DYNAmore GmbH, Stuttgart, Germany, Livermore Software Technology Corporation, Livermore, CA, USA, DYNAmore GmbH, Stuttgart, Germany

  • DIC-based Full-Field Calibration using LS-OPT®: An Update

    Stander,N, Basudhar,A, Gandikota,I, Du Bois,S, Kirpicev,D, Livermore Software Technology Corporation, Livermore, CA, , Witowski,K, Ilg,C, Haufe,A, DYNAmore GmbH, Stuttgart, Germany, Svedin,Å, DYNAmore Nordic, Linköping, Sweden

    This paper extends a 2017 study on full-field calibration using Digital Image Correlation (DIC) and the Finite Element Method to identify parameters of a material model developed for elastoplasticity. DIC is an optical method which provides full-field displacement or strain measurements for mechanical tests of materials and structures. It can be combined with the corresponding fields obtained from a Finite Element Analysis to identify ...

  • Application of a Full-Field Calibration Concept for Parameter Identification of HS-Steel with LS-OPT®

    Christian Ilg, André Haufe, David Koch, Katharina Witowski, DYNAmore GmbH, , Nielen Stander, Livermore Software Technology Corporation, Åke Svedin, DYNAmore Nordic, Mathias Liewald, Institut für Umformtechnik, Universität Stuttgart

    In recent years results of digital image correlation (DIC) techniques have significantly improved in terms of accuracy, resolution as well as the speed of experimental strain measurement. The current availability of 2D or even 3D surface strain history during loading allows new approaches in constitutive parameter identification. In addition, localization (Fig 1.) exhibited in the numerical simulation can be integrated with DIC to identify ...

  • Multi-disciplinary Optimization using LS-DYNA®

    Mr. Azhar Rehmani A. Saiyed, MS, B.Eng., Wayne State University, , Dr. Bijan Khatib Shahidi, PhD, MBA, US Army, TARDEC, Mr. Madan Vunnam, MS, PMP®, US Army, TARDEC

    Crashworthiness, NVH (Noise Vibration & Harshness) are two distinct as well as very inter-connected attributes/disciplines of vehicle development process. As objectives of both are very differing, it is a challenge to design a vehicle equally performing in both with the global objectives of mass reduction and comfort. LS-OPT® is the tool, which can perform a multi-disciplinary optimization. Here we will perform a frontal crash of the vehicle ...

  • Classification-based Optimization and Probabilistic Analysis Using LS-OPT®

    Anirban Basudhar, Imtiaz Gandikota, Livermore Software Technology Corporation, Livermore CA, USA, , Katharina Witowski, DYNAmore GmbH, Germany

    LS-OPT is a standalone Design Optimization and Probabilistic Analysis package with an interface to LS-DYNA® that is capable of solving a variety of reliability assessment and single or multi-disciplinary design problems. It consists of a flexible framework with various methods that are suited to specific types of problems. The solution methods in LS-OPT are broadly categorized as direct or metamodel-based. Metamodel-based methods build ...

  • Optimisation of Fixturing Clamps to Improve Panel Measurement Robustness

    Ben Crone, Arup, , Michael Buckley, Jaguar Land Rover, Amelia Agnew, Arup

    Tolerance measurement of sheet metal parts – such as those used in body in white assembly – is a critical task for the automotive industry that can lead to significant financial losses as a result of poor gauge R&R design and data misinterpretation. Current measurement systems use clamps to load panels onto fixtures. However, since non-rigid parts deflect with clamping pressure and under their own self-weight, measurement reproducibility and ...

  • Shape Optimization with LS-DYNA® Suite For MDO (Multidisciplinary Design Optimization)

    Ryo Ishii, JSOL, , Masayoshi Nishi, Nihon Emsco Co. Ltd.

    LS-DYNA has been able to optimize several different calculations to meet each criterion with LS-OPT® freely. In previous year, we showed MDO (Multidisciplinary Design Optimization) would be great powerful solution that LS-DYNA suite including LS-OPT and LS-PrePost® would be able to solve crucial problem during development of product. In this study, we are trying shape optimization to solve trade-off which occurs in the process of product ...

2017

  • MDO Collision/NV/Stiffness Optimization with LS-OPT

    Ryo Ishii, Masahiro Takeda (JSOL Corporation), Yuuki Tanaka (TOYOTA AUTO BODY CO.,LTD), Masayoshi Nishi (Nihon Emsco Co. Ltd.)

    LS-DYNA is heavily used to analysis transient phenomenon like car crash and makes a huge achievement about physical simulation in a wide variety of industry. For the goal of LS-DYNA, “one- model, one-code” as solution it give you, a wide variety of function has been developed at each section. Nowadays, LS-DYNA has been developed further and become possible to evaluate Frequency domain analysis and Acoustic analysis as FRF/SSD/Acoustic_BEM/_FEM etc. This paper is intended for MDO (Multidisciplinary Design Optimization) with LS-DYNA and LS-OPT. The object is automotive which has many complicated parts. It is so hard to meet the demand for couple of standard for the safety/NV/strength. LS-DYNA can calculate for not only the crash but strength and NV (noise, Vibration) evaluation. The MDO evaluating some linear analyses simultaneously is the common case, but optimization with combination of both linear and non-linear analysis like car crash would be not so common case. It would be possible for LS-DYNA and LS-OPT to consider this case. So, the purpose of this paper is challenge to this case, which means the confirmation to benefit and effect to car design process. When MDO with collision consideration is regarded useful for car design process and estimation of performance, the usage of this type MDO would become widely used.

  • Efficient Global Optimization Using LS-OPT and Its Parallelization

    Anirban Basudhar (LSTC)

    This article presents the implementation of Kriging-based efficient global optimization (EGO) in LS- OPT, which can be used for both unconstrained and constrained optimization. Additionally it proposes a parallelization technique based on a multi-objective formulation that provides multiple sampling choices. Like any surrogate-based method, the proposed method displays some variation in the results depending on the initial DOE. Further investigation is being conducted to reduce this variation, especially for constrained optimization. The methodology for Pareto-based parallel EGO is different for constrained and unconstrained optimization in some respects. Only the methodology and results for unconstrained optimization are presented in this paper. Analytical examples with known global optima are used to demonstrate the efficacy and the efficiency of the algorithm.

  • Application of Digital Image Correlation to Material Parameter Identification using LS-OPT

    Nielen Stander (LSTC), Katharina Witowski, Christian Ilg, Andre Haufe, Martin Helbig, David Koch (DYNAmore GmbH)

2016

  • LS-OPT® Status and Outlook

    Nielen Stander, Anirban Basudhar (Livermore Software Technology Corporation)

    Features added to the recently released LS-OPT Version 5.2 are discussed. An outlook of the next version, which includes Statistical Classification and Digital Image Correlation, is given.

  • Design optimization with Modal Assurance Criteria (MAC)

    Sumie Kinouchi, Ryo Ishii, Masahiro Okamura (JSOL Corporation)

    Simulation-based optimization is one of the efficient tools for product design optimization. This paper introduces the application example of modal analysis with LS-DYNA and mode tracking of LS-OPT , to improve the body stiffness. The mode tracking is a powerful tool to track a specific mode by evaluating the scalar MAC value even if the sequence of modes is changed due to the modification of the design variables by the optimizer. For the connection in the car body model, adhesive bonding is included as well as spot welding.

  • LS-OPT®: Status and Outlook

    Nielen Stander, Anirban Basudhar, Imtiaz Gandikota (LSTC), Katharina Witowski (DYNAmore GmbH), Åke Svedin, Christoffer Belestam (DYNAmore Nordic AB)

  • Finding the best thickness run parameterization for optimization of Tailor Rolled Blanks

    Niklas Klinke (Mubea Tailor Rolled Blanks GmbH), Axel Schumacher (University of Wuppertal)

2015

  • Optimization of a Lower Bumper Support regarding Pedestrian Protection Requirements using ANSA and LS-Opt

    Isabelle Wetzstein, Beate Lauterbach, Matthias Erzgräber, Lothar Harzheim (Adam Opel AG, Rüsselsheim)

    A variety of pedestrian protection requirements must be considered during the vehicle development process, in order to improve the protection of vulnerable road users.This paper deals with the optimization of a glass fiber mat reinforced thermoplastic (GMT) lower bumper support geometry, using ANSA linked with LS-Opt, to meet the EuroNCAP requirements for pedestrian protection. To optimize the components geometry, a parameterized model of the component was built with ANSA-Morphing. LS-Opt was used to find design variables describing the lower bumper support geometry that enable an optimized EuroNCAP rating for Pedestrian Protection lower leg.

  • X760 Bumper Automation and Optimisation Process

    Dr Tayeb Zeguer (Jaguar Landrover)

    Currently the bumper system is developed through a wide variety of individual virtual test methods, the majority of which also have to be verified with physical testing. This paper will describe a new process that produced a one combined virtual process to encompass the full bumper as a system development method by creating One model for a bumper as one system with multiple attributes and requirements and using only one code “ LS-DYNA and LS-OPT”.

  • Multi-scale Material Parameter Idenfication Using LS-DYNA and LS-OPT

    Nielen Stander, Anirban Basudhar, Ushnish Basu, Imtiaz Gandikota (Livermore Software Technology Corporation, Livermore CA, USA), Vesna Savic (General Motors Company, Detroit MI, USA), Xin Sun, Kyoo Sil Choi, Xiaohua Hu (Pacific Northwest National Laboratory, Richland WA, USA), Farhang Pourboghrat, Taejoon Park, Aboozar Mapar (Michigan State University, East Lansing MI, USA), Sharvan Kumar,Hassan Ghassemi-Armaki (Brown University, Providence RI, USA), Fadi Abu-Farha (Clemson University, Clemson SC, USA)

    Ever-tightening regulations on fuel economy, and the likely future regulation of carbon emissions, demand persistent innovation in vehicle design to reduce vehicle mass. Classical methods for computational mass reduction include sizing, shape and topology optimization. One of the few remaining options for weight reduction can be found in materials engineering and material design optimization. Apart from considering different types of materials, by adding material diversity and composite materials, an appealing option in automotive design is to engineer steel alloys for the purpose of reducing plate thickness while retaining sufficient strength and ductility required for durability and safety. This paper serves as an introduction to the LS-OPT® and LS-DYNA® methodology for multi-scale modeling. It mainly focuses on an approach to integrate material identification using material models of different length scales. As an example, a multi-scale material identification strategy, consisting of a Crystal Plasticity (CP) material model and a homogenized State Variable (SV) model, is discussed and the parameter identification of the individual material models of different length scales is demonstrated. The paper concludes with thoughts on integrating the multi-scale methodology into the overall vehicle design.

2014

  • Optimization Design of Bonnet Inner Based on Pedestrian Head Protection and Stiffness Requirements

    Xiaomin Zeng, Xiongqi Peng (Shanghai Jiao Tong University), Hongsheng Lu (Shanghai Hengstar Technology Co. Ltd), Edmondo Di Pasquale (SimTech Simulation et Technologie)

    Pedestrian head impact with bonnet is one of the major causes for pedestrian severe injury or fatality. This paper proposes a multidisciplinary design optimization method for bonnet inner based on pedestrian head protection along with stiffness requirements. The static stiffness and headform collision procedure with regard to a particular industrial bonnet are analyzed. Parametric design and optimization analysis of this bonnet are carried out. Optimization solution significantly achieves better head protection effect under the premise of meeting the stiffness requirements, which validates the feasibility of this multidisciplinary optimization method and provides an approach for the optimal design of engine bonnet inner. This work shows the importance of a simultaneous approach of different disciplines in bonnet design.

  • The Optimization of Servo Press Method for Sheet Metal Forming

    Jun-Ku Lee, Hyun-Cheol Kim (Theme Engineering, Inc.)

    Recently in the field of sheet metal forming, servo press, which can control the speed and position of the tool using a servo motor, is attractive method. Development process of servo press method is accelerated as the capacity of servo motor become bigger. In the future, it’s expected as a great alternative plan to replace conventional press method in order to improve quality, increase productivity, maintain integrity of tools, and reduce energy consumption. Motion control in servo press method has to be effectively optimized depending on the shape and characteristics of the material. However, in the industrial field, the controls of motion relied on experience or intuition of most skilled worker, so the workers can’t avoid many trials and errors to find the optimized motion. We try to implement the servo press method using a finite element analysis with LS-DYNA® in order to shorten the trials and errors [1]. And ®furthermore, we try to find optimal motion with LS-OPT [2].

  • LS-OPT®: New Developments and Outlook

    Nielen Stander, Anirban Basudhar (LSTC)

    New features available in LS-OPT 5.1 are discussed and illustrated. The main features include three new solver types, Parallel Feedforward Neural Networks, seamless variable de-activation for iterative methods, exporting of selected metamodel formulae, subregion-based Global Sensitivity Analysis, enhanced histogram visualization features and Viewer-based categorization of simulation results.

2013

  • An Adaptive Surrogate-Assisted Strategy for Multi-Objective Optimization

    Nielen Stander (LSTC)

    A sequential metamodel-based optimization method is proposed for multi-objective optimization problems. The algorithm, designated as Pareto Domain Reduction, is an adaptive sampling method and an extension of the classical Domain Reduction approach (also known as the Sequential Response Surface Method). In addition to standard benchmark examples, a Multidisciplinary Design Optimization (MDO) example involving a vehicle impact is used to demonstrate that the accuracy conforms to the Direct NSGA-II “exact” method while using a small fraction of its computational effort.

  • LS-OPT Parameters Identification on Concrete Sample Tests for an Impact Simulation on Concrete Slab

    Nicolas Van Dorsselaer, Vincent Lapoujade (DynaS+), Georges Nahas, Bertrand Ciree, François Tarallo, Jean-Mathieu Rambach (Institut de Radioprotection et de Sûreté Nucléaire)

    The dynamic behavior of Concrete is one of the most common and difficult problem of simulation in Nuclear, Defense and Civil fields. In most cases, the data available for modeling problems is much reduced; engineers are obliged to predict the behavior with non sufficient information. Due to this lack of experimental sample based input parameters, the result of simulation becomes “engineer dependent”, leading to much different results than people doing the same modeling problem. In previous paper ([5], [6]) presented during last LS-DYNA Conferences, we showed that a probabilistic approach for concrete modeling can be used to reduce these differences due to the modeling choices. But one of the main conclusions of these papers was that all these modeling techniques never replace experimental concrete sample tests to obtain the right material behavior before simulation. This paper is based on a work realized for an international OECD benchmark initiated by IRSN and CNSC. The main goal of IRIS_2012 Benchmark was to evaluate the ability of simulation to reproduce experimental tests of impacts on concrete slabs. Contrary to the earlier benchmark (IRIS_2010), experimental results of concrete sample tests was this time available in order to calibrate numerical constitutive laws before simulations on real tests. This paper, as the rest of our previous papers about IRIS_2010, will present the use of LSTC products capabilities in this kind of approach. In a first time, a complete LS-DYNA concrete model based on compressive strength will be created using automatic parameters generation capabilities of LS-DYNA. Then this model will be compared to experimental sample results of several cylindrical sample tests (simple compression and confined compressions at several confinement pressures). After sensitivity analysis to identify which parameters of the concrete model can be used to fit experimental results, LS-OPT parameters identification will be performed simultaneously on all cases. Based on the VTT Punching test simulation of IRIS_2012, we will compare the results between simulation with parameters automatically generated, simulation with fitted parameters and experiment. This comparison will be focused on missile velocity after impact and slab concrete damage. We precise that all the calculations presented here are performed with LS-DYNA solver, coupled with LS-OPT software for the probabilistic part of the studies (DoE studies, Monte Carlo Analysis, Robustness and Optimizations).

  • Using LS-OPT for Parameter Identification and MAT_FABRIC with FORM=-14

    David Dubois (Autoliv), Jimmy Forsberg (DYNAmore Nordic AB)

    This work was carried out as a methodology development project in a joint venture between Autoliv and DYNAmore Nordic AB. The outset of the project was to obtain a better component behavior due to a more realistic material behavior in the simulation of airbag models. The observation underlying the project was that the current fabric model used in most airbag models is *MAT_FABRIC and FORM=14. In FORM=14 there is no consideration taken to a stiffened response due to a bi-axial stress state in the fabric. To consider the bi-axial stress state, FORM=-14 was implemented some years ago but has, until now, not been used. The objective with this implementation is to increase the stiffness in the fabric when subjected to a bi-axial stress state. This paper presents a resume of the features found in *MAT_FABRIC, a methodology to fit the simulation model to material test data using LS-OPT and finally a comparison between the behavior of the different FORM options.

2012

  • An Efficient New Sequential Strategy for Multi-Objective Optimization using LS-OPT

    Nielen Stander (LSTC, Livermore, CA, USA)

    A new surrogate-assisted Multi-Objective Optimization algorithm has been implemented in LS-OPT® . The algorithm, known as Pareto Domain Reduction, is an adaptive sampling method and an extension of the classical Domain Reduction approach (also known as SRSM). A Multidisciplinary Design Optimization (MDO) example involving a vehicle impact is used to demonstrate that the accuracy is very close to the NSGA-,, 3H[DFW ́ PHWKRG while using a small fraction of the computational effort.

  • LS-OPT® Version 5: A New Flowchart-Based Interface for Process Simulation and Optimization

    David Björkevik, Christoffer Belestam (DYNAmore Nordic, Linköping, Sweden), Katharina Witowski (DYNAmore GmbH, Stuttgart, Germany), Nielen Stander (LSTC, Livermore, CA, USA), Trent Eggleston (Leawood, KS, USA)

    This paper provides an overview of the new flowchart-based interface for LS-OPT®. The primary purpose of this development was to provide an interface for process simulation and optimization. An example of a manufacturing process is used to demonstrate problem setup and GUI functionality.

  • LS -OPT® Version 5: A Flowchart -based Interface for Process Simulation and Optimization

    David Björkevik, Åke Svedin, Christoffer Belestam (DYNAmore Nordic), Katharina Witowski (DYNAmore GmbH), Nielen Stander (LSTC), Trent Eggleston

    Goals, the manufactoring process and other new features of LS-OPT Version 5

  • Efficient detection of permissible design spaces in an early design stage

    Marco Götz, Wolfgang Graf (Institute for Structural Analysis, TU Dresden, Germany), Martin Liebscher (DYNAmore GmbH, Germany)

    The design of structures and processes is one of the main challenges for engineers. The traditional PHWKRG μWU\ DQG HUURU¶ H[SORUDWLRQ RI GLIIHUHQW YDULDQWV LV GXH WR DQ LQFUHDVLQJ QXPEHU RI GHVLJQ parameters not further possible. State of art is the application of various optimization methods, varying on the type of optimization task e.g. topology optimization, nonlinear parameter optimization or multi- criteria optimization under consideration of different constraints. Common for the most methods is the non-applicability in an early design stage, because of a lack of information. 7RGD\¶V GHVLJQ SURFHVV LV characterized by division of work and decomposition due to the multidisciplinarity of design. Therefore it is required to have knowledge about the structure or process of interest. In an early design stage this information is a priori not available. In this contribution, a method is presented to get additional information by detecting permissible design spaces. These design spaces gives the engineer independent continuous ranges for each design parameter and allow the necessary decomposition for further design stages. The detection of permissible design spaces is feasible by a visual interpretation only two-dimensionally. For n-dimensional tasks the presented approach is a possibility to overcome this problem. The approach detects for existing data sets in higher dimension permissible design spaces with regard to design constraints. A two-dimensional example illustrates the principle of the procedure and an example from automotive industry shows its applicability.

  • Cross Car Beam Multi Optimization

    francesc Volart, Sergio Faria (Gestamp BIW)

  • Efficient optimization of structural designs using methods of global sensitivity analysis with reduced meta-models

    Uwe Reuter, Gustavo Canon Falla (Department of Civil Engineering, TU Dresden, Germany), Martin Liebscher, Zeeshan Mehmood (DYNAmore GmbH, Dresden, Germany)

    Methods of global sensitivity analysis are used to identify significant parameters in order to perform computationally less expensive optimization of structural designs. In most engineering problems, only a few number of design points are available to model structure response for sensitivity analysis. Usually, the initial meta-model is not a good predictor of the actual model response. The optimum solution from the initial meta-model might not lie in the region corresponding to the region where the optimal solution to the actual model response lies. In this paper, optimization of design structures is performed using methods of global sensitivity analysis on reduced meta-models, such as classification based global sensitivity methods. These methods identify significant parameters using only the approximation of the level sets of the model response. The optimization is then carried out on the initial meta-model but only on the domain of significant parameters, under the assumptions: (a) search for an optimum is effective on the domain on which the model response varies the most (b) variation of the model response at the level sets is relatively less prone to approximation errors as compared to the full approximation in very high dimensional models. The results of the optimization using global sensitivity methods with reduced meta-models are compared with already existing methods which use full approximation of the model response for their realization.

2011

  • Process Development for Multi-Disciplinary Spot Weld Optimization with CAX-LOCO, LS-OPT and ANSA

    G. Geissler (DYNAmore GmbH, Germany), T. Hahn (AUDI AG, Germany)

    The number of connection entities in modern car constructions is growing continuously. From that point of view, the identification of the most suitable structural behaviour of various car body configurations with respect to the number and the arrangement of connections becomes a challenge in automotive development. A standard simulation and optimization process was developed and established in a common project with the Audi AG and DYNAmore GmbH. The simulation model assembly process consists of a car body without any connection entities, a structured data format that describe the connections in detail and an automated process that realizes the connections using ANSA. All of these components are administrated and provided through the AUDI specific simulation data management tool CAx Load Case Composer (LoCo). This software is developed by DYNAmore and provides, among other innovative features, the possibility to parameterize components of the simulation model. With that ability at hand, it becomes possible to introduce parameters for the number of spot welds on a specified line. With the automated assembly process, the simulation engineer becomes able to investigate a number of spot weld configurations with a minimal amount of time and specific process knowledge. Connecting this parameterized assembly process with a structural optimization software like LS-OPT, provides the possibility to set up a systematic investigation of spot weld configurations with respect to any simulation response representing structural performance. The reduction of the total amount of connections under consideration of constraints can be one goal of such an investigation. Also the adjustment of a desired structural stiffness or the control of the deformation behaviour by the connection setup might be possible objectives in that context.

  • Using LS-OPT for Meta-Model Based Global Sensitivity Analysis

    Z. Mehmood, U. Reuter, C. Gebhardt (Department of Civil Engineering, TU Dresden, Germany), I. Lepenies, M. Liebscher, H. Müllerschön (DYNAmore GmbH, Germany)

    Popular sensitivity analysis methods such as ANOVA and SOBOL indices are widely used in LS-OPT in order to measure the importance of different input variables with respect to the model response. These methods are applied using meta-models in LS-OPT. In contrast, sensitivity information can be directly extracted from the meta-models using weight-based and derivative-based approaches. Meta-models capture the non-linear relationship of the underlying input parameters to the design response. In this paper, powerful sampling and pre-processing capabilities of LS-OPT are coupled with a user-defined neural network based meta-model in order to perform weight based and derivative based sensitivity analysis. The results of these sensitivity measures are compared with the default SOBOL approach by using an analytical as well as an industry relevant crash analysis example.

  • An Effective Curve Matching Metric for Parameter Identification Using Partial Mapping

    N. Stander (Livermore Software Technology Corporation, Livermore, California, USA), K. Witowski (DYNAmore GmbH, Stuttgart, Germany), M. Feucht (DAIMLER AG)

    This paper describes a new method for curve matching essential to the solution of inverse problems represented by system parameter identification. Hysteretic response curves are specifically addressed as a general class. The method is based on Partial Curve Mapping (PCM) of the experiment curve onto the computed curve. This methodology involves a curve matching metric which is computed using the volume between the test curve and the computed curve section. A number of examples are presented to demonstrate the capability. These examples represent hysteretic curves which are impossible to match without mapping.

  • How to Use LS-OPT for Parameter Estimation – hot stamping and quenching applications

    Arthur Shapiro, LSTC, Livermore, CA, USA

  • Investigation and Application of Multi-Disciplinary Optimization for Automotive Body-in-White Development

    A. Sheldon, E. Helwig (Honda R&D Americas, Inc.), Y.-B. Cho (CSM Software, USA)

    A process has been created for applying multi-disciplinary optimization (MDO) during the development of an automotive body-in-white (BIW) structure. The initial phase evaluated the performance of several different optimization algorithms when applied to structural MDO problems. From this testing, two algorithms were chosen for further study, one of these being sequential metamodeling with domain reduction (SRSM) found within LS-OPT. To use the LS-OPT optimization software effectively within a production environment, adaptations were made to integrate it into an established CAE infrastructure. This involved developing a LS-OPT server and architecture for the parallel job submission and queuing required in the MDO process. This enabled LSOPT to act as an integral part of the enterprise CAE architecture as opposed to a standalone tool. Within this integrated environment, the SRSM method has been applied to an MDO process that combines 7 load cases and takes into account crash and NVH requirements. The objective of the MDO was to minimize mass while constraints enforced the performance requirements of each load case. The thicknesses of 35 parts were considered in this MDO. The application of the SRSM MDO strategy resulted in an optimized design with a 6% weight reduction for the portion of the BIW considered. The optimized design was determined with reasonable computational resources and time considering the computational intensity of the analysis.

  • Design Optimization with Parametric Geometry Variation

    H. Müllerschön (DYNAmore GmbH, Stuttgart, Germany), H. Zimmer, M. Schäfer (SFE GmbH), E. Arvelo (ISES Consultants, UK)

  • Interrelation Analysis for Metal Forming Processes with LS-OPT and LS-DYNA

    H. Müllerschön, M. Liebscher (DYNAmore GmbH, Germany), U. Reuter, S. Pannier (Technische Universität Dresden, Germany), K. Grossenbacher, M. Ganser (BMW AG)

    The aim of this paper is to investigate the evaluation of process sensitivities for metal forming applications. The Finite-Element software LS-DYNA is a suitable tool for the simulation of complex metal forming processes. For the forming engineer it is of interest how individual process parameters contribute to output quantities typically by means of quality measures. Three different approaches will be examined in this study. Firstly, standard methods such as correlation and linear regression analysis are discussed. As an extension of those linear approaches, in LS-OPT there is the possibility for non-linear sensitivity analysis according to Sobol’s principle. The second part of the paper deals with the capability of fringing statistical results on the FE-model in order to visualize contributions of variables to specific responses in space. Statistical information is plotted on the part geometry (FE-mesh) and supports the engineer to detect critical regions. Lastly a methodology is introduced to evaluate feasible design spaces (parameter ranges) by solving an inverse problem. The feasible design spaces are described by means of hyper cuboids and are analyzed by the application of cluster analysis.

2010

  • The Use of LS-OPT in the Development of Jaguar Adaptive Passenger Airbag including: Folding, OOP, Calibration and Optimisation

    T. Zeguer, Jaguar Cars

    Modelling accurately passenger airbags has been a great challenge for both OEM and airbag suppliers. Although JLR suppliers were requested to deliver LS-DYNA models for PAB assemblies, they would use other tools to fold airbags and translate them into LS-DYNA. ...

  • An Overview of LS-OPT® Functionality with a Preview of Version 4.2

    Nielen Stander (Livermore Software Technology Corporation, Livermore, California, USA), David Björkevik, Christoffer Belestam (Engineering Research AB, Linköping, Sweden), Katharina Witowski (Dynamore AG, Stuttgart, Germany), Trent Eggleston (Self)

    This paper reviews the features of LS-OPT® in the areas of design optimization, multi-disciplinary optimization, reliability-based optimization and multi-objective optimization. Relatively new features for solver job distribution are also discussed. A preview is given of the next release, Version 4.2.

  • Global Sensitivity Analysis in Industrial Application with LS-OPT

    Björn Hohage (Audi AG, Ingolstadt, Germany), Anja Förderer, Gordon Geißler, Heiner Müllerschön (DYNAmore GmbH, Ingolstadt, Germany)

    The presented paper is related to a global sensitivity analysis in the field of numerical simulations. The objects of investigation are different car side crash scenarios and the influence of model variable variation on the occupant safety. ...

2009

  • A Study on the Convergence of Multiobjective Evolutionary Algorithms

    Tushar Goel, Nielen Stander (Livermore Software Technology Corporation)

    High computational cost has been a major impediment to the widespread use of evolutionary algorithms in industry. While the clock time for optimization

  • Optimal Resource Allocation for Genetic Algorithm BasedMulti-Objective Optimization with 1000 Simulations

    Tushar Goel, Nielen Stander (Livermore Software Technology Corporation), Yih-Yih Lin (Hewlett-Packard, High Performance Computing Division, Richardson TX), Martin Liebscher (DYNAmore GmBH, Stuttgart, Germany)

    This study pertains to practical application of the GA for industrial applications where only a limited number of simulations can be afforded. Specifically, an attempt is made to find the optimal allocation of the total simulation budget (population size and number of generations) for...

  • Decision Making in Multi-Objective Optimization for Industrial Applications– Data Mining and Visualization of Pareto Data

    Martin Liebscher, Katharina Witowski (Dynamore GmbH, Stuttgart, Germany), Tushar Goel (Livermore Software Technology Corporation)

    Data mining and visualization techniques for high dimensional data provide helpful information to substantially augment the decision making (alternative design selection) in multi-objective optimization environment

  • New Developments in LS-OPT 4.0 - Outlook to V4.1

    Müllerschön H. (DYNAmore GmbH)

  • Adaptive Simulated Annealing for Global Optimization in LS-OPT

    T. Goel, N. Stander (Livermore Software Technology Corporation)

    The efficient search of global optimal solutions is an important contemporary subject. Different optimization methods tackle the search in different ways. The gradient based methods are among the fastest optimization methods but the final optimal solution depends on the starting point.The global search using these methods is carried out by providing many starting points. Other optimization methods...

  • Reliability-based Multi-Objective Optimization and Visualization using LS-OPT® Version 4

    N. Stander, W. Roux, T. Goel (Livermore Software Technology Corporation), D. Björkevik, C. Belestam (Engineering Research AB), K. Witowski (DYNAmore)

    This study the multi-objective optimization of a realistic crashworthiness problem with special reference to the incorporation of uncertainty and the visualization of the Pareto Optimal Frontier(POF). LS-OPT® and LS-DYNA® are used for the optimization based on the C2500 truck model developed by NHTSA. The design problems is set up as a Reliability-Based Design Optimization (RBDO) problem which includes specifications...

  • Aplication Examples of Optimization and Reliability studies in Automotive Industry.

    H. Müllerschön, K. Witowski, M. Thiele (DYNAmore, Germany)

    The aim this paper is to summarize several optimization an robustness applications, which have been performed over the past years in automotive industry with LS-OPT. The examples include Multi-Objective Optimization (MOO), Multi-Load Case Optimization and Reliability Based Design Optimization (RBDO). In addition, user-friendly visualization of optimization and stochastic results is demonstrated.

2008

2007

  • An Overview of New Features in LS-OPT Version 3.3

    N. Stander, T. Goel (Livermore Software Technology Corporation - LSTC), David Björkevik (Engineering Research Nordic), David Björkevik (Engineering Research Nordic)

    This paper summarizes the development status of LS-OPT® Version 3.3 and focuses mainly on the following new features: (i) Radial Basis Function Networks, (ii) Multi-objective Optimization (MOO), (iii) Metamodel-based MOO, (iv) User-defined metamodeling, (v) User-defined queuing

  • Multi-Objective Optimization Using LS-OPT

    Goel T., Stander N. (Livermore Software Technology Corporation)

    Most engineering optimization problems have more than one objective. Often these objectives conflict such that no single solution can be considered optimum with respect to all objectives. Then, the optimum to this problem is a set of solutions known as Pareto optimal set....

  • Reliability Based Design Optimization with LS-OPT for a Metal Forming Application

    H. Müllerschön, D. Lorenz (DYNAmore), Prof. K. Roll (Daimler)

    The purpose of this paper is to account for uncertainties in the manufacturing processes of metal forming in order to evaluate the random variations with the aid of FE-simulations. Various parameters of the Finite-Element model describing the investigated structural model are affected by randomness. This, of course, leads to a variation of the considered simulation responses such as stresses, displacements, and thickness reductions. On this, for the simulation engineer basic questions arise regarding: (1) the dimension of the range of variation of the simulation responses (2) the significance/contribution of the (input) parameters with respect to specific responses and (3) the reliability of the process design with respect to constraints (failure, damage, requirements, ...). In order to find solutions to these questions several methodologies may be applied that are available in the commercial optimization software LS-OPT (Stander et al. [5]). Some of the methodologies, such as Monte Carlo simulation, meta-model based Monte Carlo simulation, stochastic fields, are discussed in this paper and are demonstrated by means of a metal forming problem. For this, a non-robust design with respect to the specified constraints has been detected. By utilizing reliability based design optimization (RBDO) through LS-OPT, the failure probability (violation of constraints) could be reduced significantly.

2005

  • Shape Optimization of a Crashbox using HyperMorph and LS-OPT

    H. Wang (Benteler), H. Müllerschön (DYNAmore), T. Mehrens (HAW Hamburg)

    The aim of this paper is to demonstrate how to improve the performance of a crashbox by the application of shape optimization using HyperMorph and LS-OPT. Two load cases for the crashbox are considered: low speed front crash with initial load in x-direction and low speed crash with initial load 10° rotated with respect to the x-axis. Possible beads and geometry variations are parameterized with HyperMorph. The parameters that define the shape variations in HyperMorph are controlled by LS-OPT and be exchanged via a dedicated interface. The main quality criterion for the crashbox is the smoothness of the force values which occur during the energy absorption. This means, a force-intrusion curve with a horizontal line, after a specific force level is reached, would be the ideal case. The formulation of the optimization problem takes this into account by minimizing the difference between the maximum and the minimum force values of the force-intrusion curve during the folding process. Simultaneously several restrictions regarding the producibility and the folding mechanism have to be considered.

  • FE-Simulation Based Optimization of an Adaptive Restraint System Considering Multiple Front-Crash Load Cases using LS-OPT

    M. van den Hove, B. Mlekusch (AUDI), H. Müllerschön (DYNAmore)

    The purpose of this paper is to explore some interesting aspects of optimization for crashworthiness occupant safety applications and to propose optimization strategies for highly nonlinear problems. With the today’s state of technology it is possible to identify specific load cases and different types of occupants in the car. System parameters of the restraint system, such as trigger time for seat-belt, airbag and steering column can be adapted to particular load cases. This is refered to an adaptive restraint system. In the first part of the paper different optimization strategies are discussed and pros and cons are compared. In addition, a methodology to get a reliable surrogate model using neural networks is introduced. The surrogate model (Meta-Model or Response Surface Model) approximates the relationship between design parameters and a physical response and can be used to visualize and explore the design space. In the second part the application of the Successive Response Surface Scheme (SRSM) for the optimization of an adaptive restraint system is conducted. For this, several front crash load cases are considered. This is performed using LS-OPT (Stander et al. [11]) as optimization software and PAM-Crash as solver for the finite element occupant safety simulations. The procedure of generating an advanced meta-model to get an approximation of the global design space using neural networks is demonstrated for this example. Furthermore, the visualization of multi-dimensional meta-models in two- and three-dimensional design space is illustrated.

2003

  • Analyzing 'Noisy' Structural Problems with LS-OPT: Probabilistic and Deterministic Fundamentals

    Willem Roux, Nielen Stander (Livermore Software Technology Corporation)

    System identification of 'noisy' structural design optimization problems: the sources of uncertainty, the competing roles of bias and variance, and the interaction of uncertainty and deterministic effects. Two test problems are used to clarify the effect of different approaches.

  • Crashworthiness Optimization in LS-OPT: Case Studies in Metamodeling and Random Search Techniques

    Nielen Stander, Willem Roux (Livermore Software Technology Corporation), Mathias Giger, Marcus Redhe (Division of Mechanics, University of Linköping), Nely Fedorova (Snezhinsk Institute of Physics and Technology), Johan Haarhoff (Department of Mechanical Engineering, University of Pretoria)

    This crashworthiness optimization study compares the use of three metamodeling techniques while using a sequential random search method as a control procedure. The three methods applied are (i) the original Successive Linear Response Surface Method, (ii) the Neural Network method and (iii) the Kriging method. It is shown that, although NN and Kriging seem to require a larger number of initial points, the three metamodeling methods have comparable efficiency. The random search method is surprisingly efficient in some instances, but by nature much less predictable.

  • On the Robustness of a Simple Domain Reduction Scheme for Simulation-Based Optimization

    Stander N., Craig K.J. (Livermore Software Technology Corporation)

    This paper evaluates a Successive Response Surface Method (SRSM) specifically developed for simulation-based design optimization, e.g. that of explicit nonlinear dynamics in crashworthiness design. Linear response surfaces are constructed in a subregion of the design space using a design of experiments approach with a D-optimal experimental design...

  • Two-Stage Stochastic and Deterministic Optimization

    T. Rzesnitzek, F. Günther, M. Wozniak (DaimlerChrysler), H. Müllerschön (DYNAmore GmbH)