Obtaining softening factors was added

StructureHelperLogics/NdmCalculations/Cracking/CrackStrainLogic.cs

@@ -0,0 +1,23 @@
+using StructureHelperCommon.Models.Forces;
+using StructureHelperCommon.Services.Forces;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperLogics.NdmCalculations.Cracking
+{
+    internal class CrackStrainLogic : ICrackStrainLogic
+    {
+        public StrainTuple BeforeCrackingTuple { get; set; }
+        public StrainTuple AfterCrackingTuple { get; set; }
+        public double SofteningFactor { get; set; }
+
+        public StrainTuple GetCrackedStrainTuple()
+        {
+            var strainTuple = ForceTupleService.InterpolateTuples(AfterCrackingTuple, BeforeCrackingTuple, SofteningFactor) as StrainTuple;
+            return strainTuple;
+        }
+    }
+}