Dytran™

2008 r1

Release Guide

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This document, and the software described in it, are furnished under license and may be used or copied only in accordance with the terms of such license. Any reproduction or distribution of this document, in whole or in part, without the prior written authorization of MSC.Software Corporation is strictly prohibited.

MSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice. The concepts, methods, and examples presented in this document are for illustrative and educational purposes only and are not intended to be exhaustive or to apply to any particular engineering problem or design. THIS DOCUMENT IS PROVIDED ON AN “AS-IS” BASIS AND ALL EXPRESS AND IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED, EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLY INVALID.

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DT*V2008R1*Z*Z*Z*DC-REL

C o n t e n t sDytran Release Guide

Contents

1 Introduction

2 Eulerian and Fluid-Structure Interaction (FSI)

Overview 8

Geometric Boundary Conditions for Eulerian Domain 9

Speed up of JWL and Blast Models by 1-D Spherical Symmetry Method 11

Static Euler Output 12

BIAS Mesh Capability for Nonuniform Euler 16

Cohesive Friction 19

Other Enhancements and Bug Fixes 21

3 System Information

Software Installation 24

Licensing 25

Release Platforms 26

Memory Requirements 27

4 Using Dytran

Running Dytran on Windows 30

Running Dytran on Unix and Linux 31

Postprocessing Dytran Results 32

Postprocessing Dytran Results of Windows on UNIX 33

Dytran Release Guide

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Chapter 1: Introduction Dytran Release Guide

1 Introduction

Dytran Release Guide6

Dytran™ 2008 r1 is the latest and most comprehensive version of Dytran released by MSC.Software, bringing new simulation technology and improved performance.

Dytran 2008 r1 is available on UNIX (HP-UX PA- RISC 2.0, HP-UX Itanium2, SGI R10K/R12K, IBM RS/6000 (Power 4), Sun SPARC Solaris, Solaris X64, Linux Itanium2 (Red Hat 3, Update 3), Linux Itanium2 SGI Altix (SGI ProPack3 SP6), Linux X8664 (Red Hat 4, Update 5), Linux 32 (Red Hat 3, Update 9), Windows 32 bit (XP, SP2) and Windows 64 bit (XP 64) platforms. Please see System Information in chapter 3 for more details.

Dytran 2008 r1 has many new powerful meshing technologies and capabilities in several key areas, resulting in higher degrees of robustness, performance, and ease-of-use. These include:

• Geometric Boundary Conditions for Eulerian mesh which allows users to directly define flow boundaries on the Eulerian domain faces by simply defining a vector or by defining a square covering a number of Eulerian faces. This facilitates using different mesh sizes in a model without re-defining the boundary conditions.

• The new 1-D Spherical Symmetry Method dramatically speeds up the JWL and Blast simulations by initializing the pressure wave in 1-D and then mapping the 1-D results into a 3-D model. The method eliminates the need to construct elaborated fine mesh to capture the initial pressure wave propagation.

• “Static” archive output to facilitate the postprocessing of the adaptive Euler results which normally requires multiple archive output files.

• Support for “BIAS” capability for nonuniform MESH, BOX option to add flexibility in defining different mesh densities in and around the areas of interest.

• Cohesive friction capability to predict the viscous behavior of the material such as interaction of mud and tire.

The Dytran 2008 r1 online documentation is available in PDF format on all platforms. The online documentation includes the Reference Manual, Theory Manual, User’s Guide, Example Problem Manual, Release Guide and the Installation Instructions.

Dytran uses the Macrovision FLEXlm™ licensing system. If you already have an MSC.Dytran 2007 r1 license, you will not need to obtain a new authorization code to activate Dytran 2008 r1 on your computer. However, you will need to install the latest FLEXlm 10.8 license server available on Dytran installation CD. The enclosed Dytran 2008 r1 Installation Instructions describe how to install Dytran 2008 r1 on your computer.

If you need assistance while installing Dytran 2008 r1, please call the MSC Technical Support Hotline at 1-800-732-7284, or E-mail your support questions to mscdytran.support@mscsoftware.com.

Chapter 2: Eulerian and Fluid-Structure Interaction (FSI) Dytran Release Guide

2 Eulerian and Fluid-Structure Interaction (FSI)

Overview 8

Geometric Boundary Conditions for Eulerian Domain 9

Speed up of JWL and Blast Models by 1-D Spherical Symmetry Method 11

Static Euler Output 12

BIAS Mesh Capability for Nonuniform Euler 16

Cohesive Friction 19

Other Enhancements and Bug Fixes 21

Dytran Release GuideOverview

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Overview Many new powerful features have been introduced in this release, resulting in higher levels of robustness, performance and ease-of-use. A major emphasis in the Dytran 2008 r1 release has been to dramatically increase the performance of FSI solver. These new capabilities were primarily based on modeling rather than parallel processing techniques.

We believe that MSC.Dytran 2008 r1 provides unprecedented performance capabilities to simulate complex FSI applications with minimum modeling effort, faster throughput and higher fidelity levels.

All new capabilities are supported by examples that are included in the Dytran 2008 r1 Example Problem Manual.

9Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)Geometric Boundary Conditions for Eulerian Domain

Geometric Boundary Conditions for Eulerian DomainFor many applications the Euler modeling can be simplified by using the MESH Generator entry. However this method has some shortcomings with regard to the definition of the boundary conditions at the boundaries of the Euler meshes.

In the past ,one had to create CFACES with Patran to define flow boundaries. Since CFACES only support CHEXA’s, the only way to define flow boundaries for MESH,BOX was to define a PORFLOW entry and a COUPLE entry. Geometric Euler Boundary Condition entries allow to directly prescribing boundary conditions on the boundaries of the Euler domain. This functionality also supports Euler domains consisting of CHEXA’s. Running the simulation with different mesh-sizes is much easier, since the creation of CHEXA’s and CFACES by Patran can be avoided.

The geometric boundary entries are FLOWDIR, WALLDIR, FLOWSQ, and FLOWTSQ. The first two allow the assignment of a boundary condition to all Eulerian boundary faces pointing in a certain direction. FLOWDIR allows a general flow boundary condition, whereas WALLDIR applies a WALLET boundary condition. The FLOWSQ and FLOWTSQ assign flow and time dependent flow conditions to all parts of Eulerian boundary faces that are within a given square.

Figure 2-1 Typical Example for Geometric Boundary Conditions for Euler

FLOW: INXVEL = 20 m/sYVEL = 0 m/sSIE = 2.E+5 J/kgDENSITY= 1.3 kg/m3

Dytran Release GuideGeometric Boundary Conditions for Eulerian Domain

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Figure 2-2 Comparison between the Geometric BCs Method and Old Method by defining GRIDs and CHEXAs

See Geometric Eulerian Boundary Conditions in the Example Problem Manual for more details.

New model with Mesh and Geometric BC Old model with Grids and Chexa’s

11Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)Speed up of JWL and Blast Models by 1-D Spherical Symmetry Method

Speed up of JWL and Blast Models by 1-D Spherical Symmetry MethodThe JWL and blast models requires very fine mesh to reach the correct peak pressure. However, once the blast wave is sufficiently expanded, there is no need for fine elements and it would be computationally very efficient to replace the fine mesh with a much coarser mesh. Furthermore the initial stages of the explosion are spherically symmetric and allow the use of a 1-D model to predict the wave propagation.

In this method, the spherical initialization is done by constructing a 1-D model and results are remapped on a first quadrant of a 3-D model. The method results in significant improvements in simulation time.

Figure 2-3 Radial Velocities Compared Between 3-D and 1-D Models

See Modeling the JWL Explosion using 1-D Spherical Symmtery in the Example Problem Manual for more details.

Comparison with 1-DRadial Velocity at cycle 1

Dytran Release GuideStatic Euler Output

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Static Euler OutputDuring a simulation with adaptive meshing, the Euler mesh changes continuously and “adapts itself” to follow the coupling surface moves and deformations. The Euler mesh adapts to the coupling surface by adding and removing elements. The adaptive algorithm ensures that the coupling surface is contained inside the Euler mesh at all times with the minimum amount of elements.

The adaptive Euler can save a lot of computational time but postprocessing can be a little tricky. Since the geometry can change at any cycle, Euler archives contain only one cycle. This makes postprocessing with Patran cumbersome, especially if one needs to postprocess several cycles. Usually, all one needs to do is to have Dytran output results of all cycles in one big archive and read them into Patran. This is not the case with adaptive meshing. Here, one has to read in a separate archive for each cycle which makes animation a difficult task. For this purpose a postprocessor must have multi-model capability to postprocess the multiple archives each having a different geometry simultaneously.

A new functionally now allows easy postprocessing with Patran. The user defines a box. which consists of virtual elements. All adaptive elements completely inside the box are mapped onto matching virtual elements, making the virtual element real. Virtual elements have grid points that are compatible with real elements. Therefore, virtual and real element have the same geometry and user number, but only the adaptive elements have nonzero element values. When a virtual element is written to output and if it has a matching real element, the values of the real element are written out. The virtual elements that do not have matching real element are written out with zeroes. Since this box is fixed during the simulation, the Euler element geometry does not change. Therefore, archives written with this option can contain multiple cycles and can be postprocessed by Patran. In addition, Patran can also animate the adaptive mesh results. This new functionality is activated by specifying the STATBOX entries on the MESH entry.

The size of the box can be chosen freely but then adaptive element may be created that are outside of the box. The run will continue with a warning and no output will be written for elements that are outside. In general the box should be large enough to contain all adaptive elements that are created during the simulation. For an adaptive run the adaptive meshing summary in the OUT file lists the largest box that surrounds all adaptive elements. This box can be used to define the static output box. This option does not require a significant amount of CPU-time.

The following figures demonstrate how an airbag is inflated by using the Static Euler Output. As shown, there are many Euler elements that are created “statically” in cycle zero. As the airbag is inflated and adaptive mesh expands (cycle 219), the elements in the static mesh that interact with the adaptive mesh are preserved for output while the rest are deleted during computation. This allows postprocessing with only one Euler arhive output.

See Easy Postprocessing with Adaptive Meshing in the Example Problem Manual for more details.

13Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)Static Euler Output

Dytran Release GuideStatic Euler Output

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15Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)Static Euler Output

Dytran Release GuideBIAS Mesh Capability for Nonuniform Euler

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BIAS Mesh Capability for Nonuniform EulerA new capability allows the MESH,BOX to create general nonuniform graded block meshes based on arbitrary biased planes. These meshes were traditionally constructed only by preprocessors such as Patran. A uniform Euler block consists of a number of planes in each direction. These planes are located at fixed distances. MESH, BOX has a new functionality that allows full control over the locations of the planes. This functionality is activated by defining BIAS entries and using them on the MESH entry. The BIAS entries specify the locations of the planes.

The following figures demonstrates how a blast problem can be modeled using the BIAS Mesh capability. See Nonuniformity with MESH,BOX in the Example Problem Manual for more details.

17Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)BIAS Mesh Capability for Nonuniform Euler

Dytran Release GuideBIAS Mesh Capability for Nonuniform Euler

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19Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)Cohesive Friction

Cohesive FrictionA new “Cohesive Friction” model is added to predict the behavior of viscous material. For example, the new friction model can be used to simulate the cohesive behavior of wet soil that is in contact with a tire. The following figures shows a rigid wedge partially submerged in a viscous material. In this example, the cohesive friction model is used to predict the viscous behavior of the material. See Cohesive Friction in the Example Problem Manual for more details.

Dytran Release GuideCohesive Friction

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21Chapter 2: Eulerian and Fluid-Structure Interaction (FSI)Other Enhancements and Bug Fixes

Other Enhancements and Bug FixesThe following bugs are fixed in this release:

• 1-72372224 – Cannot retrieve a float variable TXX01 using a user subroutine

• 1-69143252 – HYDSTAT does not work properly

• 1-67976214 – Mesh card entry in Dytran deck

• 1-67976131 – Error in Mesh card

• 1-64706618 - Memory setting in Dytran Explorer (Not Dytran) as per last run.

• 1-62868391 - NONUNIFORM EULER by MESH,box is not WORKING when COUPLE with Multidomain Eulerian problem (categorized as limitation)

• 1-57518271 - FFCONTR does not work well with small and large format

• 1-57368278 - PARAM, VISCOPLAS is not documented in 2007r1

• 1-56861171 - Default memory settings in Dytran Explorer can not be changed permanently

• 1-56446245 - NZ overflow in outfile

• 1-55355171 - DYMAT26 - Incorrect timestep calculation

• 1-17295105 - DAREA leads to 0 load curve error

• 1-52062841 - CPU Summary in OUT file can contain negative numbers and stars in case of big jobs

• 1-51315118 - The attached dytran deck runs to completion, but the resulting .arc file can not be attached to Patan

• 1-37820721 - dual cpu performance is not beeter than one cpu on linux (v2005r3)

• 1-24739911 - More than 1024 entities for output request SET causes an Error.

• 1-24636316 - Unrealistic results with an axisymmetrical model

• 1-23330751 - Error in Documentation : Page 2-19

• 1-20618137 - RJUNI test gives result that are unexploitable

• 1-17418401 - Core Dump when putting BY 0. in SET (an ice impact model)

• 1-12118649 - wrong results with prestress, MATRIG and angular velocity

• In Dytran2005r3 ,the friction algorithm was changed to fully model friction between metals. The friction algorithms of Dytran2005 and earlier were more suited for friction between non-metals (like soil) and the coupling surface. To activate the old friction method PARAM,COUFRIC was added. Alternatively cohesive friction (PARAM,COHESION) may be used.

• Some airbag simulations may become instable. Even using PARAM,VELMAX may not help. Likely the instability is caused by blending geometry. In these cases, there is often a clump that consists of too many elements and on average the uncovered volume in the clump is rather small. Depending on mass in the clump severe over compression work may occur. This compression

Dytran Release GuideOther Enhancements and Bug Fixes

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work is given by the volume strain rate in the clump. PARAM,CLUFLIM was added that applies a weight to this volume strain rate depending on the quality of the clumps. This parameter can make airbag simulation run stable just like VELMAX does. It should only be used in case of instability.

• In an impact analysis, both impactor and target may be modeled by Eulerian material. If the target is a thick plate tensile stresses occur at the back of the plate. To model the strength of the plate correctly minor void friction has to be permissible under tensile loading. The PMINC entry was extended to specify this maximal permissible void fraction.

• PARAM VISCOPLAS was added.

Chapter 3: System Information Dytran Release Guide

3 System Information

Software Installation 24

Licensing 25

Release Platforms 26

Memory Requirements 27

Dytran Release GuideSoftware Installation

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Software InstallationOn the Windows platforms, Dytran 2008 r1 is easily installed from CD-ROM as it uses the standard Windows Installation Wizard. On Unix and Linux platforms, the MSC.Software standard installation script can be used to install the software on your system.

Dytran 2008 r1 is the successor of Dytran 2007 r1.

25Chapter 3: System InformationLicensing

LicensingDytran uses the FLEXlm license manager as the licensing system for nodelock and network licensing. To run Dytran, you need an authorization code from MSC.Software Corporation. If you already have a license for MSC.Dytran 2007 r1, you do not need to obtain a new license for Dytran 2008 r1.

However, in all cases, you do need a new installation of the license server software. Specifically, the FlexFM license server needs to be at level 10 or higher. For this purpose, an installation of FlexLM v10.8.0 is part of this release on all supported platforms. It is noted that Dytran 2008 r1 is not able to check out licenses when the FlexLM server is lower than version 10.

On Windows and Linux computers, Dytran requires an Ethernet card on your computer, even if your computer is not connected to a network. The FLEXlm licensing mechanism uses the Ethernet card to create the unique system identification encrypted in the license information file.

Dytran Release GuideRelease Platforms

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Release PlatformsDytran 2008 r1was built and tested on the following hardware with the listed software installed as given in Table 3-1 .

Table 3-1 Supported Hardware Configuration

PlatformOperating

System Compiler VersionOpenMP Support Remarks

Windows 32-bit Windows (XP SP2) Intel Compiler V9.1.0331

Yes Ethernet Card

Windows 64-bit Windows (XP 64) Intel Compiler EM64T V9.11

Yes Ethernet Card

SGI R10K/R12K IRIX64 6.5.27 MIPSpro f90 7.4.2 Yes NA

HP-UX PA-RISC 2.0 HPUX B.11.11 HP F90 V3.1 Yes NA

HP-UX Itanium2 HPUX B.11.23 HP F90 V2.8.7 Yes NA

Sun Sparc Solaris Solaris 10 Sun Studio 12 (Sun Fortran 95 8.3 SunOS_sparc Patch 127000-01 2007/07/18)

Yes NA

Solaris x64 Solaris 10 Sun Studio 12 (Sun Fortran 95 8.3 SunOS_i386 Patch 127002-01 2007/07/18)

Yes NA

IBM RS/6000 (Power4) AIX 5.1 XL Fortran 9.1 Yes NA

Linux Itanium2 RedHat 3 Update 3 Intel Compiler 10.1.012 Yes Ethernet Card

Linux Itanium2 SGI Altix SGI ProPack 3SP6 Intel Compiler 10.1.011 Yes Ethernet Card

Linux X8664 RedHat 4 Update 5 Intel Compiler 10.1.015 Yes Ethernet Card

Linux 32 RedHat 3 Update 9 Intel Compiler 8.1.026 Yes Ethernet Card

1For correct operation of the Intel Fortran compiler, MS Visual Studio .NET 2005 must be installed prior to installing the Intel 9.1 compiler. Compiler versions of type Intel 9.1 will probably work correctly. For example, Version 9.1.037 works correctly for Windows 32.

The following platform configurations are no longer supported as of V2008r1:

HP Alpha Linux 32 RedHat9 (replaced by RedHat 3)

Windows 2000 Linux X8664 RedHat 3 (replaced by RedHat 4 Update 5)

Solaris 8 replaced by Solaris 10 IBM RS/6000 Power3 (replaced by Power4)

27Chapter 3: System InformationMemory Requirements

Memory RequirementsIn general, the size of the memory required by Dytran depends on the size of the engineering problem you wish to solve. The default memory size is set to approximately 30MB. This default size is appropriate for smaller problems.

You can change the preset default in the Dytran Explorer so that it fits your personal needs. In addition, you can define the minimum and maximum memory size and use the slider in the front panel to select the desired memory size. On Unix and Linux platforms you can use the command-line option (size=small/medium/large) or you can enter the MEMORY-SIZE definition in the input file.

Dytran traces the usage of memory and prints a summary at the end of the output file of each analysis. The memory size listed in the summary is exact. It reflects the memory required for storing the model in core memory after one integration step. Additional memory required during the analysis is automatically allocated and de-allocated.

When you change the memory setting for an analysis through the Dytran Explorer, the settings are stored to be used the next time that you run the analysis. Under certain conditions, Dytran may stop and issue a message that it cannot allocate the required memory. Since the memory allocation in Dytran is dynamic, the system may require additional memory during an analysis. If the memory is available, it is allocated and de-allocated when it is no longer needed. When your computer runs out of memory, the Dytran analysis may stop when it needs more memory to continue. You may solve this problem by closing applications on your computer that you do not need, or you can decrease the size of the core memory that Dytran allocates for the analysis if you are using substantially more than the analysis requires. You can find the information on the memory size requirements of the analysis in the memory summary at the end of the analysis. We recommend to use Dytran on a computer that has at least 256 MB of RAM.

Dytran Release GuideMemory Requirements

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Chapter 4: Using DytranDytran Release Guide

4 Using Dytran

Running Dytran on Windows 30

Running Dytran on Unix and Linux 31

Postprocessing Dytran Results 32

Postprocessing Dytran Results of Windows on UNIX 33

Dytran Release GuideRunning Dytran on Windows

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Running Dytran on WindowsOn Windows, submit a Dytran analysis by double clicking the Dytran icon. The icon should be available on your desktop. Alternatively, you can use the Start Menu to locate Dytran under the Programs Folder. Once you picked either the icon or the menu entry, the Dytran user environment appears on your screen.

The .Dytran Explorer provides an on-line help system that contains information about the functionality of the Dytran Explorer. The Dytran Explorer provides some basic postprocessing and animation tools.

31Chapter 4: Using DytranRunning Dytran on Unix and Linux

Running Dytran on Unix and LinuxOn Unix and Linux platform you would use the command line interface like:

• dytran jid=xxx to submit Dytran

Dytran Release GuidePostprocessing Dytran Results

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Postprocessing Dytran ResultsDytran results can be postprocessed with Patran. With MSC.Patran 2005, the Direct Result Access (DRA) method is available for native Dytran output files (ARC,THS).

In addition, on Windows, you can use the VisualVrml postprocessing, animation and Visual Time History tool. The tool is built-in inside the Dytran Explorer and offers web-based postprocessing capabilities.

33Chapter 4: Using DytranPostprocessing Dytran Results of Windows on UNIX

Postprocessing Dytran Results of Windows on UNIXIf you wish, you can postprocess the analysis results obtained from a Windows platform on a UNIX computer. In this case, you need to convert the binary result files (.ARC and/or .THS) files to a UNIX format. You can perform this conversion by using the right-mouse button menu in the Dytran Explorer. Point your mouse at the file that you wish to convert, click the right mouse button, and select the Convert to binary… menu item. The converted files will have the sb_ prefix. For Compaq Alpha workstations, the native Windows result files can be used directly without conversion.

Alternatively, when running on windows, you can select the option to output result files in UNIX format by default. To set this option, select the Preferences from the Options menu. Choose Formats and select Convert output files automatically to UNIX-format. If you select this option, the regular Windows result files and the converted UNIX-format files are written at the end of the analysis. You can recognize the UNIX-format files by the UX prefix.

Dytran Release GuidePostprocessing Dytran Results of Windows on UNIX

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