From e9c07e79630a2ef8f3ce9666dceabda1cb673dff Mon Sep 17 00:00:00 2001
From: kpne <kpn@kpne.dk>
Date: Mon, 11 Nov 2024 17:40:25 +0100
Subject: [PATCH] Perimeter radius of gyration

---
 SectionProperties/Utility/PerimeterProfile.cs | 14 ++++++
 SectionProperties/Utility/RadiusOfGyration.cs | 13 ++++-
 .../Utility/PerimeterProfileTests.cs          | 47 +++++++++++++++++++
 3 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/SectionProperties/Utility/PerimeterProfile.cs b/SectionProperties/Utility/PerimeterProfile.cs
index e51c036..548d5db 100644
--- a/SectionProperties/Utility/PerimeterProfile.cs
+++ b/SectionProperties/Utility/PerimeterProfile.cs
@@ -53,6 +53,20 @@ internal static ILocalPoint2d CalculateCentroid(IPerimeter perimeter)
             };
         }
 
+        internal static Length CalculateRadiusOfGyrationYy(IPerimeter perimeter)
+        {
+            OasysUnits.Area area = CalculateArea(perimeter);
+            AreaMomentOfInertia inertia = CalculateInertiaYy(perimeter);
+            return RadiusOfGyration.CalculateRadiusOfGyration(area, inertia);
+        }
+
+        internal static Length CalculateRadiusOfGyrationZz(IPerimeter perimeter)
+        {
+            OasysUnits.Area area = CalculateArea(perimeter);
+            AreaMomentOfInertia inertia = CalculateInertiaZz(perimeter);
+            return RadiusOfGyration.CalculateRadiusOfGyration(area, inertia);
+        }
+
         internal static AreaMomentOfInertia CalculateInertiaYy(IPerimeter perimeter)
         {
             IPerimeter centredOnElasticCentroid = MoveToElasticCentroid(perimeter);
diff --git a/SectionProperties/Utility/RadiusOfGyration.cs b/SectionProperties/Utility/RadiusOfGyration.cs
index dd01c3b..b6bc134 100644
--- a/SectionProperties/Utility/RadiusOfGyration.cs
+++ b/SectionProperties/Utility/RadiusOfGyration.cs
@@ -10,6 +10,11 @@ public static class RadiusOfGyration
     {
         public static Length CalculateRadiusOfGyrationYy(IProfile profile)
         {
+            if (profile is IPerimeter perim)
+            {
+                return PerimeterProfile.CalculateRadiusOfGyrationYy(perim);
+            }
+
             return CalculateRadiusOfGyrationYy(ProfileParts.GetParts(profile));
         }
 
@@ -22,6 +27,11 @@ internal static Length CalculateRadiusOfGyrationYy(IList<IPart> parts)
 
         public static Length CalculateRadiusOfGyrationZz(IProfile profile)
         {
+            if (profile is IPerimeter perim)
+            {
+                return PerimeterProfile.CalculateRadiusOfGyrationZz(perim);
+            }
+
             return CalculateRadiusOfGyrationZz(ProfileParts.GetParts(profile));
         }
 
@@ -32,8 +42,7 @@ internal static Length CalculateRadiusOfGyrationZz(IList<IPart> parts)
             return CalculateRadiusOfGyration(area, inertia);
         }
 
-
-        private static Length CalculateRadiusOfGyration(OasysUnits.Area area, AreaMomentOfInertia inertia)
+        internal static Length CalculateRadiusOfGyration(OasysUnits.Area area, AreaMomentOfInertia inertia)
         {
             Length.TryParse($"0 {OasysUnits.Area.GetAbbreviation(area.Unit).Replace("²", string.Empty)}", out Length unit);
             OasysUnits.Area.TryParse($"0 {Length.GetAbbreviation(unit.Unit)}²", out OasysUnits.Area m2);
diff --git a/SectionPropertiesTests/Utility/PerimeterProfileTests.cs b/SectionPropertiesTests/Utility/PerimeterProfileTests.cs
index c15a1a9..168194a 100644
--- a/SectionPropertiesTests/Utility/PerimeterProfileTests.cs
+++ b/SectionPropertiesTests/Utility/PerimeterProfileTests.cs
@@ -6,6 +6,7 @@
 using MagmaWorks.Taxonomy.Sections.SectionProperties.Utility;
 using OasysUnits;
 using SectionPropertiesTests.TestUtility;
+using Utility = MagmaWorks.Taxonomy.Sections.SectionProperties.Utility;
 
 namespace SectionPropertiesTests
 {
@@ -28,6 +29,52 @@ public void MoveToElasticCentroidTest(ISection section)
             Assert.Equal(0, newCentroid.Z.Value, 12);
         }
 
+        [Theory]
+        [ClassData(typeof(SectionGenerator))]
+        public void AreaTests(ISection section)
+        {
+            // skip back to back profiles as they do not convert to a single Perimeter profile
+            if (section.Profile is IBackToBack)
+            {
+                return;
+            }
+
+            // Assemble
+            OasysUnits.Area originalA = Utility.Area.CalculateArea(section.Profile);
+            IPerimeter perimeter = new Perimeter(section.Profile);
+
+            // Act
+            OasysUnits.Area area = Utility.Area.CalculateArea(perimeter);
+
+            // Assert
+            Assert.Equal(originalA.SquareCentimeters, area.SquareCentimeters, 0.05 * area.SquareCentimeters);
+        }
+
+
+        [Theory]
+        [ClassData(typeof(SectionGenerator))]
+        public void RadiusOfGyrationTests(ISection section)
+        {
+            // skip back to back profiles as they do not convert to a single Perimeter profile
+            if (section.Profile is IBackToBack)
+            {
+                return;
+            }
+
+            // Assemble
+            Length originalYy = RadiusOfGyration.CalculateRadiusOfGyrationYy(section.Profile);
+            Length originalZz = RadiusOfGyration.CalculateRadiusOfGyrationZz(section.Profile);
+            IPerimeter perimeter = new Perimeter(section.Profile);
+
+            // Act
+            Length radiusOfGyrationYy = RadiusOfGyration.CalculateRadiusOfGyrationYy(perimeter);
+            Length radiusOfGyrationZz = RadiusOfGyration.CalculateRadiusOfGyrationZz(perimeter);
+
+            // Assert
+            Assert.Equal(originalYy.Centimeters, radiusOfGyrationYy.Centimeters, 0.05 * radiusOfGyrationYy.Centimeters);
+            Assert.Equal(originalZz.Centimeters, radiusOfGyrationZz.Centimeters, 0.05 * radiusOfGyrationZz.Centimeters);
+        }
+
         [Theory]
         [ClassData(typeof(SectionGenerator))]
         public void MomentOfInertiaTests(ISection section)