Add curvature calculator

StructureHelperCommon/Infrastructures/Exceptions/StructureHelperNullReferenceException.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace StructureHelperCommon.Infrastructures.Exceptions
+{
+    public class StructureHelperNullReferenceException : StructureHelperException
+    {
+        public StructureHelperNullReferenceException(string errorString) : base(errorString)
+        {
+        }
+
+        public StructureHelperNullReferenceException(Exception ex) : base(ex)
+        {
+        }
+    }
+}

StructureHelperCommon/Services/Forces/TupleConverter.cs

@@ -17,6 +17,12 @@ namespace StructureHelperCommon.Services.Forces
             return strainMatrix;
         }
 
+        public static StrainMatrix ConvertToLoaderStrainMatrix(IForceTuple strainTuple)
+        {
+            var strainMatrix = new StrainMatrix() { Kx = strainTuple.Mx, Ky = strainTuple.My, EpsZ = strainTuple.Nz };
+            return strainMatrix;
+        }
+
         public static StrainTuple ConvertToStrainTuple(IStrainMatrix strainMatrix)
         {
             StrainTuple strainTuple = new StrainTuple() { Mx = strainMatrix.Kx, My = strainMatrix.Ky, Nz = strainMatrix.EpsZ };