Добавил тест для прямоугольника

StructureHelperLogics/NdmCalculations/Materials/IPrimitiveMaterial.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace StructureHelperLogics.NdmCalculations.Materials
+{
+    public interface IPrimitiveMaterial
+    {
+        string Id { get;}
+        MaterialTypes MaterialType { get; }
+        string ClassName { get; }
+        double Strength { get; }
+    }
+}