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A C# Program that Reads Stresses from a Nastran OP2 file

Purpose of the script

The C# program illustrates the reading of stresses from a Nastran OP2 file using FeResPost .NET assembly.

Program

The listing of the program is presented below:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Globalization;
using System.IO;
using System.Threading;

using FeResPost ;
using std ;

namespace ConsoleApplication1 {

    class printStressMax {

        static void Main(string[] args) {

Thread.CurrentThread.CurrentCulture=new CultureInfo("en-US");
StreamWriter stdout=new StreamWriter(Console.OpenStandardOutput());
stdout.AutoFlush=true;

            // Initialization of the DataBase :

            NastranDb db = new NastranDb();
db.Name="tmpDB";
db.readBdf("../../MODEL/MAINS/orbit_unit_xyz.bdf");
db.readGroupsFromPatranSession("../../MODEL/PATRAN/groups.ses");

            // Groups from Materials :

            Group tmpGroup_Honey_50=db.getElementsAssociatedToMaterials(5);
            tmpGroup_Honey_50=tmpGroup_Honey_50+db.getElementsAssociatedToMaterials(4);
            tmpGroup_Honey_50.Name="Honey_50";

            Group tmpGroup_Honey_72=db.getElementsAssociatedToMaterials(6);
            tmpGroup_Honey_72.Name="Honey_72";

            Group tmpGroup_Al_2024=db.getElementsAssociatedToMaterials(3);
            tmpGroup_Al_2024.Name="Al_2024";

            Group tmpGroup_CFRP=db.getElementsAssociatedToMaterials(10000);
tmpGroup_CFRP.Name="CFRP";

            // Groups created by intersection :

ArrayList tmpAL;
tmpAL=new ArrayList();

tmpAL.Clear();
tmpAL.Add(tmpGroup_Honey_50);
tmpAL.Add(tmpGroup_Honey_72);
tmpAL.Add(tmpGroup_Al_2024);
tmpAL.Add(tmpGroup_CFRP);
            object[] matGroups=tmpAL.ToArray();

db.addGroupCopy(tmpGroup_Honey_50);
db.addGroupCopy(tmpGroup_Honey_72);
db.addGroupCopy(tmpGroup_Al_2024);
db.addGroupCopy(tmpGroup_CFRP);

tmpAL.Clear();
tmpAL.Add("pan_MX");
tmpAL.Add("pan_MY");
tmpAL.Add("pan_MZ");
tmpAL.Add("pan_PX");
tmpAL.Add("pan_PY");
tmpAL.Add("pan_PZ");
tmpAL.Add("pan_SUP");
            object[] panelGroupNames=tmpAL.ToArray();

foreach (string panelGroupName in panelGroupNames) {
                //Console.WriteLine(panelGroupName);
                Group panelGroup = db.getGroupCopy(panelGroupName);
foreach (Group matGrp in matGroups) {
                    Group newGrp=panelGroup*matGrp;
newGrp.Name=panelGroupName+"_"+matGrp.Name;
                    //Console.WriteLine(newGrp.Name);
                    //Console.WriteLine(newGrp.getEntitiesByType("Element").GetLength(0));
                    if (newGrp.getEntitiesByType("Element").GetLength(0)>0)
db.addGroupCopy(newGrp);
                } // foreach (Group matGrp in matGroups)
            } // foreach (string panelGroupName in panelGroupNames)

            // Reading Results :

            db.readOp2("../../MODEL/EXEC_OP2/orbit_unit_xyz.op2","Results");  
            object[] key;
foreach (object obj in db.iter_resultKey) {
                //~ Console.WriteLine("(type=\"{0:S}\")",obj.GetType());
                key=(object[])obj;
Console.WriteLine("RESULT KEY = (\"{0:S} - {1:S} - {2:S}\")",key[0],key[1],key[2]);
            }

            // Retrieving some Results and performing operations :

            String[] layers=new String[0];
            Group targetGrp;
            Result stress,scalar,maxScalar,maxStress,sXZ,sYZ;
            ResKeyList maxRkl;
            object[,] maxScalarData,maxStressData;

            // Maximum Von Mises stress :

targetGrp=db.getGroupCopy("pan_PZ_Al_2024");
            stress= db.getResultCopy("ORBIT_ONE_MS2_Z","Statics",
                "Stress Tensor","ElemCorners",targetGrp,layers);
            scalar=stress.deriveTensorToOneScal("VonMises");

maxScalar=scalar.extractResultMax();
maxRkl=maxScalar.extractRkl();
maxStress=stress.extractResultOnRkl(maxRkl);
maxScalarData=maxScalar.getData();
maxStressData=maxStress.getData();

Console.WriteLine();
Console.WriteLine("Maximum Von Mises stress in panel +Z skins :");
Console.WriteLine();
Console.Write("   {0:F2} Pa ",maxScalarData[0,5]);
Console.Write("on element {0:D} ",maxScalarData[0,0]);
Console.WriteLine("(layer=\"{0:S}\")",maxScalarData[0,2]);
Console.Write("      Sxx = {0:F2}, ",maxStressData[0,5]);
Console.Write("Syy = {0:F2}, ",maxStressData[0,6]);
Console.WriteLine("Szz = {0:F2}, ",maxStressData[0,7]);
Console.Write("      Sxy = {0:F2}, ",maxStressData[0,8]);
Console.Write("Syz = {0:F2}, ",maxStressData[0,9]);
Console.WriteLine("Szx = {0:F2} ",maxStressData[0,10]);

            // Maximum out of plane shear stress :

targetGrp=db.getGroupCopy("pan_PZ_Honey_72");
            stress= db.getResultCopy("ORBIT_ONE_MS2_Z","Statics",
                "Stress Tensor","ElemCorners",targetGrp,layers);
sXZ=stress.deriveTensorToOneScal("Component XZ");
sYZ=stress.deriveTensorToOneScal("Component YZ");
            scalar=Post.sqrt(sXZ*sXZ+sYZ*sYZ);

maxScalar=scalar.extractResultMax();
maxRkl=maxScalar.extractRkl();
maxStress=stress.extractResultOnRkl(maxRkl);
maxScalarData=maxScalar.getData();
maxStressData=maxStress.getData();

Console.WriteLine();
Console.WriteLine("Maximum out of plane shear stress in panel +Z honeycomb :");
Console.WriteLine();
Console.Write("   {0:F2} Pa ",maxScalarData[0,5]);
Console.Write("on element {0:D} ",maxScalarData[0,0]);
Console.WriteLine("(layer=\"{0:S}\")",maxScalarData[0,2]);
Console.Write("      Sxx = {0:F2}, ",maxStressData[0,5]);
Console.Write("Syy = {0:F2}, ",maxStressData[0,6]);
Console.WriteLine("Szz = {0:F2}, ",maxStressData[0,7]);
Console.Write("      Sxy = {0:F2}, ",maxStressData[0,8]);
Console.Write("Syz = {0:F2}, ",maxStressData[0,9]);
Console.WriteLine("Szx = {0:F2} ",maxStressData[0,10]);

            // Maximum "MaxShear" stress :

targetGrp=db.getGroupCopy("pan_PZ_Honey_72");
            stress= db.getResultCopy("ORBIT_ONE_MS2_Z","Statics",
                "Stress Tensor","ElemCorners",targetGrp,layers);
            scalar=stress.deriveTensorToOneScal("MaxShear");

maxScalar=scalar.extractResultMax();
maxRkl=maxScalar.extractRkl();
maxStress=stress.extractResultOnRkl(maxRkl);
maxScalarData=maxScalar.getData();
maxStressData=maxStress.getData();

Console.WriteLine();
Console.WriteLine("Maximum \"MaxShear\" stress in panel +Z honeycomb :");
Console.WriteLine();
Console.Write("   {0:F2} Pa ",maxScalarData[0,5]);
Console.Write("on element {0:D} ",maxScalarData[0,0]);
Console.WriteLine("(layer=\"{0:S}\")",maxScalarData[0,2]);
Console.Write("      Sxx = {0:F2}, ",maxStressData[0,5]);
Console.Write("Syy = {0:F2}, ",maxStressData[0,6]);
Console.WriteLine("Szz = {0:F2}, ",maxStressData[0,7]);
Console.Write("      Sxy = {0:F2}, ",maxStressData[0,8]);
Console.Write("Syz = {0:F2}, ",maxStressData[0,9]);
Console.WriteLine("Szx = {0:F2} ",maxStressData[0,10]);

            // Maximum "BeamStress" stress :

targetGrp=db.getGroupCopy("strut_A");
            stress= db.getResultCopy("ORBIT_ONE_MS2_X","Statics",
                "Beam Axial Stress for Bending Loads","ElemCorners",targetGrp,layers);
            scalar=Post.abs(stress);

maxScalar=scalar.extractResultMax();
maxRkl=maxScalar.extractRkl();
maxStress=stress.extractResultOnRkl(maxRkl);
maxScalarData=maxScalar.getData();
maxStressData=maxStress.getData();

Console.WriteLine();
Console.WriteLine("Maximum beam bending stress in strut A :");
Console.WriteLine();
Console.Write("   {0:F2} Pa ",maxScalarData[0,5]);
Console.Write("on element {0:D} ",maxScalarData[0,0]);
Console.WriteLine("(layer=\"{0:S}\")",maxScalarData[0,2]);
Console.Write("      Sxx = {0:F2} ",maxStressData[0,5]);

Console.WriteLine();
Console.WriteLine();

        } // static void Main(string[] args)

    } // class printStressMax

} // namespace ConsoleApplication1

The compilation of the program is done with Microsoft Visual C# compiler. On my computer, the instructions look as follows:

set FRP=../../../SRC/OUTPUTS/NET/X86_CLR2
set PLATFORM=X86
set LIB=
set INCLUDE=D:/SHARED/FERESPOST/SRC
set PATH=C:/NewProgs/MSYS/1.0/bin;C:/NewProgs/RUBY/Ruby187/bin;C:/Windows/system32
csc.exe -platform:%PLATFORM% -r:%FRP%/FeResPost.dll ..\UTIL\util.cs printStressMax.cs

Explanation

The different parts of the program are discussed briefly below:

• The different libraries and classes used in the program are referenced in the C# source. Then, the real programming begins. In the example presented above, only one "Main" function in "ConsoleApplication1.printStressMax" class is programmed.
• As in most FeResPost examples we present, one first creates a Nastran database object ("NastranDb" class), and reads the finite element model with "readBdf" method. 
• Groups are also read from a Patran session file. Other groups are created by topological operations. In this case, one creates groups by association of elements with materials.
• Results from a Nastran OP2 file are read into the database by calling "readOp2" method of the NastranDb class.
• Then, the extraction of results stored in the database can be done. In the example, one first extracts a group stored in the database by calling  the "getGroupCopy" method, then one extracts "Stress Tensor" result on the element of this group by calling "getResultCopy" method. (In this case the extraction is done at corners of the elements.)
• The rest of the code presents different examples of result manipulation:
• Derivation of Von Mises equivalent stress by calling the "deriveTensorToOneScal" method of Result class.
• Extraction of the maximum Von Mises stress by calling the "extractResultMax" method of Result class.
• Extraction of the corresponding "ResKeyList" object with the "extractRkl" method of Result class. (This method provides the critical FEM entities, or the critical element, node and layer.)
• Extraction of the "Stress Tensor" components on the critical element-node-layer. This is a new Result object.
• Extraction of the Result data in an Array by calling the "getData" method of Result class.
• Printing of the values that have been extracted.
• ...

The example, also presents variants of the scalar derivation as the extraction of stress tensor shear components for the calculation of honeycomb core,  or derivation of scalar result with FeResPost pre-defined "MaxShear" criterion. One also shows that the extraction of other results as beam stresses is possible.

You probably noticed that the example presented here is longer than other similar examples with Ruby or Python languages. In particular, the programming of results printing is particularly tedious with C#. On the other hand, the programming with C# or other languages that use FeResPost .NET assembly can have some advantages:

• The language is compiled, which allows to develop programs distributed as executables or compiled libraries while concealing the sources.
• The execution of compiled programs might be slightly faster than the interpreted Ruby or Python scripts.
• Interfacing with other .NET libraries is made possible.
• You can use FeResPost .NET assembly with other languages that run on the .NET platform. For example: VB.NET, C++.Net, IronRuby...
• ...

References

More information on this example, and the manual explaining the functions used in this example are given in FeResPost Reference Manual.

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