Preprocessor for welding and heat treatment with LS-DYNA Finite Element Model Modelling weld filler

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Transcript of Preprocessor for welding and heat treatment with LS-DYNA Finite Element Model Modelling weld filler

  • www.dynaweld.eu 1

    Heat treatment simulation

    DynaWeld® Preprocessor for welding and heat treatment with LS-DYNA

    followed by welding structure simulation

    Welding structure simulation

    20.07.2018

    DynaWeld GmbH & Co. KG Süd: Herdweg 13, D-75045 Wössingen Nord: Hermann-Löns-Straße 3A, D-21382 Brietlingen Kamen: Herbert-Wehner-Straße 2, D-59174 Kamen E-Post: info@dynaweld.de Web: www.dynaweld.eu

  • www.dynaweld.eu 2

    DynaWeld Preprocessor for welding and Heat Treatment

    Environment Analyse-Controller

    Preprocessor

  • www.dynaweld.eu 3

    Model Setup with DynaWeld

    Material Management

    Welding process Forming tools

    Pre- / postheating Clamps Loads

    Grinding

    Heat treatment process

    Quenching media Generate solver code

    with autodedect of all processes and

    run simulation

    DynaWeld enables the setup of preheating, welding, heat treatment, grinding and

    structural loading in one simulation model...

    … or in multiple stage simulations with initial conditions of prior step.

  • www.dynaweld.eu 4

    Supported processes and analysis features

    • Welding • Resistive Spot Welding • Preheating and Post Weld Heat Treatment • Heat Treatment • Forming • Press Hardening • Grinding and Cutting

    • Implicit analysis • Explicit analysis • Mass scaling, time scaling, selective mass scaling

    • Restart on previous results Process chain→

  • www.dynaweld.eu 5

    Finite Element Model

    Modelling weld filler elements in new „free-motion“-filler technology: The „free-motion“-filler technology enables the best matching of true conditions in a welding structure simulation. Before welding the entire weld filler and during welding the non heated part of the weld filler is present in the simulation, even if it should not be there. Therefore the material state is set to „non active“, which means: no thermal activities, a minimum of mechanical activities. Although mechanical activities should also be zero, we need a little part of stiffness to ensure the small motions of the weld filler elements coming up due to distortions of the entire structure. Even if these stiffness part is rather small, sometimes small influences are still present. It depends on the simulation task and welding conditions, wether these influences can be neglected or should be takten into account. Possible gaps and larger relative displacements can better be detected with the „free-motion“-filler technology. Here we have an additional degree of freedom for free motion by a sliding contact interface. However, when heated up to melting point, materials are fixed permanently due to local changes of contact conditions.

  • www.dynaweld.eu 6

    • Shell- and solid elements, hybrid models, 2D analysis • For body in white existing models for crash or NHV can be used • Pure thermal analysis for heat source adjustment or decoupled analysis are enabled • With LS-DYNA solvers parallelized computation on multiple cores (HPC) • Implicit and explicit analysis • Many different heat source functions enable the simulation of every welding process • Rotation and offset functions normal and transversal for heat source positioning • Import of material data by interfaces to JmatPro, Sysweld, WeldWare • Material models single phase or multi phase available • User defined CCT Diagrams and material data • Material model with crack risk criteria • Process chain simulation enabled by one-code-strategy of LS-DYNA code • Clamps time driven, moving or static • Adaptive („real“) mechanical and thermal joining of welded components Welding contact→ • Resistance spot welding, electro-thermal-mechanical coupled • Multi layered welds

    Preprocessor Overview

  • www.dynaweld.eu 7

    Operation Concept

    DynaWeld is designed to manage „large“ simulation models with a large number of welds.

    Thus the input of the weld plan and the related data for heat input are realized by spreadsheed tables, which can be edited in Excel or similar products. The same is for time driven clamps and other boundary conditions. The implementation in DynaWeld is by csv-files.

    Thereby the management of many welds is not only faster, but the script-based automated control in DynaWeld is generally possible and is in the focus of further development.

    The goal is, to minimize the human based, multiply repeated input of data within a multiple number of menues and submenues of common used GUIs and reduce the input only to necessary process parameters.

  • www.dynaweld.eu 8

    Operation Concept – Vision of Future

    DynaWeld in its future versions will go the way of digitization in the CAE-world and open the door for an efficient use in the industry.

    Due to the structure of DynaWeld all data needed for the simulation can be collected automatically and brought together in one simulation model.

    • Automation of derived variants

    • Automatic actualization of development states

    • Automation of recurring (similar) simulation tasks

    • Automation of process chain

  • www.dynaweld.eu 9

    Operation Concept

    DynaWeld Process Plan Welding

    Transient Welding

    Metatransient Welding

    Surface Heating

    Reorder of weld sequence

    Reverse of weld direction

    Multiple heat sources on same weldline

    Simultaneous welding of multiple welds Multiple welding robots

    Automatic filler activation for multilayered welding

  • www.dynaweld.eu 10

    Input of Heat Treatment Parameter

    Process Start Times automatic or user-

    defined timestepping

    Considers diving into liquid quenching media

    by diving vector or by two nodes

    User defined or auto detected

    quenching surface

    Furnance heating by real simulation with

    heat convection or by temperature curve

  • www.dynaweld.eu 11

    Operation Concept

    DynaWeld Process Plan Boundary Conditions and Loads: Time control

    Load / displacement-control

    • Symmetry

    • Boundary condition

    • Movement

    • Force

    • Pressure

    • Temperature

    • Voltage

    • Current

    Tools and clamps

    • driven by force

    • driven by displacement

    t

    F,u

  • www.dynaweld.eu 12

    Additional Features

    • Dublicate model for variations

    • New process step on results

    • Heat input evaluation

    • Automatic calibration of heat input

    • Performane analysis

    • Autopostprocessing

    • Launch postprocessor on scaled temperature

    • Special DynaWeld post design for temperature scalar values and min-max values

    Preprocessor Additional Features

  • www.dynaweld.eu 13

    Material Models

    • Simplified single-phase-model MAT_270

    • takes also into account transformation strains

    • initial strain (e.g from milling)

    • Multi-phase-model MAT_254 • phase-kinetic-models:

    • Koinstinen-Marburger • generalized Johnson Mehl Avrami Kolmogorov

    • Tempered phases • Yield calculation of hardened sections • Hardeness calculation • elastic/plastic stess utilisation level

    • initial strain (e.g from milling)

    Materials and Models

    Source: Bernd Hochholdinger, DYNAmore Swiss

  • www.dynaweld.eu 14

    Interfaces

    Material Data

    Materials and Models

    single-phase

    multi-phase

  • www.dynaweld.eu 15

    DynaWeld Material

    source: JMatPro®

    EDA® ICME WeldWare®

    User data

    Welding- or heat treatment specific

    parameter

    Material specification

    LS-DYNA® multi phase material

    *MAT_254

    LS-DYNA® other material models

    *MAT_nnn

    LS-DYNA® single phase material

    *MAT_270

    DynaWeld® Material

    Phase extension Flow curve adjustment:

    Base Material Initial strain

    Crack Risk criterion Damage criterion

    Hardness ID Management

  • www.dynaweld.eu 16

    DynaWeld Flow-Curve Adjustment Methode according Loose [*]

    s true

    e true,plastic

    Re

    s true, hardening

    e true

    e plRm

    e plRm

    = plastic strain at ultimate stress

    Rm

    Rm of adjusted curve

    Re of adjusted curve

    Rm-Re

    basic curve

    adjusted curve

    Adjustment factor Yield (Re): Re-adjust / Re-basic Adjustment factor Hardening (Rm - Re): (Rm-adjust - Re-adjust) / (Rm-basic - Re-basic) [*] Loose, T.: Einfluß des transienten Schweißvorganges auf Verzug, Eigenspannungen und Stabiltiätsverhalten axial gedrückter Kreiszylinderschalen aus Stahl, Karlsruhe, Diss. 2007

    The DynaWeld flow curve adjustment takes into account Re and Rm as well as different ratio Re / Rm

    between basic curve and adjustet curve

  • www.dynaweld.eu 17

    Material Data

    Curve display for each material parameter

    Materials and Models

  • www.dynaweld.eu 18

    Process Chain enabled by one-code-strategy

    (Example)

    • Forming

    • Heat Treatment

    • Welding

    • Crash Analysis

    Process Chain