Visualization of Coupled FEA, CFD and Multi-body Dynamics Simulations using EnSight Darin McKinnis Computational Engineering International (CEI) Clinton Stone MSC-Africa Simulating Reality (Pty) Ltd Paul Adams Scientific Visualization Lead ERDC MSRC - Vicksburg, MS

Presentation Overview Introduction & Trends in the CAE Industry Discussion of CAE Coupling Technologies Post-processing Challenges Technology Demonstrator Projects Conclusion

Introduction The CAE Industry in the 1980-90’s was… Independent CAE companies Emerging new technologies Maturing independent CAE disciplines (FEA, CFD, MDB, etc..) Proprietary ‘Islands’ of technology The CAE Industry in the new millennium is … Integrating with CAD systems Acquisitions, mergers, strategic alliances Consolidation of duplicate technologies Focus on new multi-physics technologies Integration with other analysis disciplines Commitment to Open standards

Introduction Numerical Simulation in many respects has matured in terms of “mono-physics” FEA, CFD, MBD, etc…. Increasing need for solution of much larger and more complex problems Many of these problems involve the solution of “multi-physics” phenomena Flow, Stress, Temperature, Current, Motion Effective methods to handle “multi-physics” solutions is the core focus of much future CAE development.

Introduction Many modern CAE software packages handle multi-physics to a certain degree Thermal-Structural Coupled FEA (Temperature & Stress) Conjugate Heat-Transfer CFD (Fluid Flow and Structure Temp) Rigid & Flexible Body Dynamics (FEA & MBD) Electro-Thermal-Structural (Joule Heating & Stress) … The challenge is to solve problems involving widely varying physics, not suitable to be solved inside a single software package

Presentation Overview Introduction & Trends in the CAE Industry Discussion of CAE Coupling Technologies Fluid Structure Interaction (FSI) Multibody Dynamics & Finite Element Analysis (MBD / FEA) Mesh-based parallel Code Coupling Interface (MpCCI) Postprocessing Challenges Technology Demonstrator Projects Conclusion

Description of CAE Coupling Technology Most CFD codes already handle basic FSI Normally limited to Rigid body boundary motion Mostly limited to rigid body motion by a prescribed function Some packages include a 6DOF dynamics model to handle problems like store separation Normally FSI requires extensive amounts of remeshing Most FEA codes already handle basic FSI Usually very limited in CFD ability (e.g.. Laminar Flow Only) Usually limited to relatively small structural displacements Primarily used to add effects of fluid mass/inertia on structural dynamics response (e.g. Seismic analysis of dams)

Current CFD Implementation Moving rigid walls with remeshing Moving rigid walls with overlapping meshes & 6DOF dynamics model

Description of certain FSI Technology Certain codes are dedicated to handle FSI E.g. MSC.Dytran, LS-Dyna, AutoDyn Very capable in terms of non-linear structural dynamics Normally limited in terms of CFD capability Explicit codes are mainly suited to short-duration events Normally use the ALE approach where the structure & fluid share common interface nodes Euler mesh is “morphed” as the structure deforms Limited to mostly relatively small displacements Focus is usually on the structural response Some codes have more powerful General 3D Coupling

General Coupling in MSC.Dytran

General Coupling in MSC.Dytran

Description of FEA/MBD Technology Certain codes are capable of combining FEA with Multibody Dynamics (MBD) E.g. MSC.ADAMS, LMS.Virtual.Lab, Recurdyn etc Implementation focused on including flexibility into a rigid body dynamics system model Flexible bodies are generated in FEA (Nastran, Ansys, Abaqus) and included as modal deformable bodies into the MDB code These Flex bodies function only in the linear range of deflection Implementation excludes non-linear effects like stiffening or surface contact

Examples of FEA/MDB Coupling

Examples of FEA/MDB & Aero Coupling These simulations make use of the ability to scale the FEA based “modal loads” to apply the dynamically changing aerodynamic loads onto the flexible structure using a “look-up” table approach. The approach ignores advanced CFD effects and interactions.

Description of CAE Coupling Technology Despite the progress already made in FSI & FEA/MDB coupling, the tools are either rather limited or very specialized for specific applications Short Duration, Airbags, explosions, bird-strike, linear flexibility… A growing need exists to make multi-physics coupling more general and powerful One solution is to combine the strengths of multiple CAE tools using technology such as MpCCI

MpCCI: Description and Motivation Mesh-based parallel Code Coupling Interface. Handles data communication between two or more simulation codes Supports non-matching grids and handles data interpolation (conservative and non-conservative) between the grids. Supports parallelization of the codes. Includes an intuitive GUI for setup of the simulation Developed by: Fraunhofer Institute for Algorithms and Scientific Computing SCAI See: http://www.mpcci.org.

MpCCI: Description and Motivation

MpCCI: Description and Motivation Current MpCCI Technology Partners MSC.Software CD-adapco Abaqus Ansys Fluent CEI (EnSight) Others… MpCCI Code Support (v 3.0.x) ABAQUS (V 3.0.3 Dec 2004) ANSYS (V 3.0.3 Dec 2004) Fluent (V 3.0.3 Dec 2004) StarCD (V 3.0.3 Dec 2004) Permas (V 3.0.4 planned April 2005) RadTherm (V 3.0.4 planned April 2005) CFX (V 3.0.5 planned later 2005) Marc & Nastran (V 3.0.5 planned Q3 2005)

MpCCI: Basic Principles Interaction between FEA & CFD codes takes place at a coupling interface via appropriate boundary conditions. Both FEA and CFD will have three or five points (synchronisation points) in the code, where data may be exchanged: SP1: Start of the analysis (increment 0). SP2: Start of an increment. SP3: End of an increment. SP4: Start of an iteration. SP5: End of an iteration.

MpCCI: Basic Principles The user determines coupling algorithm by specifying: the synchronisation points of FEA and the CFD code that communicate which each other; and the data that must be exchanged between these communicating synchronisation points. Weakly coupled solution requires 3 SP’s Uses Alternating Algorithm Strongly coupled solution requires 5 SP’s Uses Parallel Algorithm

MpCCI: Architecture

MpCCI: Core Technology Advanced Coupling Algorithms Advanced Interpolation Technology

Internals of a Non-Linear Solution SP1 SP2 SP4 SP3 CC SP5 - structural - heat transfer - ... increment (time step) loop nonlinear iteration loop start of analysis start of increment (time step) start of iteration end of iteration end of increment (time step) CCI_Check_Convergence()

MpCCI: Weakly Coupled SP1 SP2 SP4 SP3 CC SP5 - structural - heat transfer stress displacement … time step loop iteration loop - fluid flow velocity pressure fluid pressure & temperature updated geometry

MpCCI: Strongly Coupled SP1 SP2 SP4 SP3 CC SP5 - structural - heat transfer stress displacement … time step loop iteration loop - fluid flow velocity pressure fluid pressure updated geometry

Status of MSC.Marc & MpCCI Interface successfully used in: DEBUT Project (Multi-Disciplinary Engineering By Using coupling Technology) fluid-solid interaction problems in airbag gas generators TROPHY Project (Towards Prediction of Hydroplaning: Numerical Simulation and Experimental Validation) hydroplaning simulations

Other MpCCI Technology Projects Damping of piezo elements  StarCD–ANSYS   Aero-elastic in aircraft design  Flower–Nastran   Cabin acoustic in aircraft  ACTI3S–Nastran   Polymer mixers  StarCD–Permas   Airbag gas generator simulations  CFX–Marc   Aquaplaning computations  Numeca–Marc   Vibration in pipeline systems  Fluent–ANSYS   Rubber gaskets  Fluent–ANSYS/ ABAQUS   Wind loads in civil engineering  CFX–InHouse   Aerodynamics in automotive design  StarCD–Nastran/ ABAQUS   Biomechanical simulations  StarCD–Mecano  

Presentation Overview Introduction & Trends in the CAE Industry Discussion of CAE Coupling Technologies Fluid Structure Interaction (FSI) Multibody Dynamics & Finite Element Analysis (MBD / FEA) Mesh-based parallel Code Coupling Interface (MpCCI) Postprocessing Challenges Technology Demonstrator Projects Conclusion

Postprocessing Challenges Any form of multi-code coupled simulation has problems in terms of results visualization Each CAE package is designed to only postprocess its specific results Viewing the different result domains separately significantly reduces the engineering value of the simulation Often sequentially coupled solutions are conducted with very different time scales

Postprocessing Challenges EnSight is unique in its ability to postprocess coupled simulation results. These can either be: Directly coupled with co-simulation or MpCCI Sequentially coupled using tools like iSight-FD or Fiper Manually coupled solutions using loads transfer Decoupled simulations of separate physics portions of a problem Ensight features required for this are: Multi-code readers Results Timeline manipulation Keyframing & Viewport Tracking Multiple Case Support Case Mapping (Pressure from CFD to FEA) Global model repositioning (Frame Mode)

Presentation Overview Introduction & Trends in the CAE Industry Discussion of CAE Coupling Technologies Fluid Structure Interaction (FSI) Multibody Dynamics & Finite Element Analysis (MBD / FEA) Mesh-based parallel Code Coupling Interface (MpCCI) Postprocessing Challenges Technology Demonstrator Projects Conclusion

Technology Demonstrators The following examples will illustrate the use of EnSight to postprocess coupled simulations These examples highlight all of the methods previously discussed for coupling

Technology Demonstrators Helicopter Crash Investigation Sequentially Coupled MBD & FEA simulation

Technology Demonstrators Pickup Truck Crash Investigation Sequentially Coupled MBD & FEA simulation

Technology Demonstrators Aircraft flap & air-brake deployment Sequentially Coupled MBD & CFD simulation

Technology Demonstrators Aircraft flap & air-brake deployment Sequentially Coupled MBD & CFD simulation

Technology Demonstrators Automotive Manifold Coupled CFD & FEA simulation using MpCCI

Technology Demonstrators Flexible Membrane Flutter Coupled CFD & FEA simulation using MpCCI

Technology Demonstrators Biomedical Heart-Valve Coupled CFD & FEA simulation using MpCCI

Technology Demonstrators Bi-Metallic Strip Flow Restrictor Coupled CFD & FEA simulation using MpCCI

Technology Demonstrators Dragline Dynamics & Digging MSC.Dytran solves to system / soil interaction MSC.ADAMS solves the dynamics of the system Co-Simulation coupling with MBD & CFD simulation

Technology Demonstrators Bungee Jumper Co-Simulation coupling with MBD & Non-linear FEA

Technology Demonstrators Sloshing Tank Test rig Co-Simulation coupling with MBD & CFD

Technology Demonstrators - Povray ! Sloshing Tank Test rig Pov-ray now available in EnSIght Standard, no longer requires EnSight Gold (2013) Co-Simulation coupling with MBD & CFD

Technology Demonstrators - Povray ! Flow around bridge footing Flow simulation vs experimental results

Conclusion The future of Computer Aided Engineering will lie in solving more complex multi-physics problems. CAE companies are increasing focus on solver integration and cross-discipline coupling CEI is leading the way in the postprocessing requirements for the future of CAE coupled simulations.

Thank you….