From 08248d393cbd1c2229a9a8c5d5a3bea48ef87064 Mon Sep 17 00:00:00 2001
From: Jukka Aho <ahojukka5@gmail.com>
Date: Sat, 9 May 2026 18:39:17 +0300
Subject: [PATCH] test(materials): add orthotropic elasticity regression

---
 .../test_orthotropic_linear_elastic.jl        | 82 +++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 test/materials/test_orthotropic_linear_elastic.jl

diff --git a/test/materials/test_orthotropic_linear_elastic.jl b/test/materials/test_orthotropic_linear_elastic.jl
new file mode 100644
index 0000000..0f68065
--- /dev/null
+++ b/test/materials/test_orthotropic_linear_elastic.jl
@@ -0,0 +1,82 @@
+# SPDX-FileCopyrightText: 2015-2026 Jukka Aho
+# SPDX-License-Identifier: MIT
+
+using Test
+using Random
+using Tensors
+using JuliaFEM
+using JuliaFEM: OrthotropicLinearElastic, LinearElastic, compute_stress, elasticity_tensor
+using JuliaFEM: material_behavior, StatelessConstantTangent, supported_physics, Elasticity
+using JuliaFEM: required_state_variables
+
+@testset "OrthotropicLinearElastic" begin
+    @testset "traits match isotropic elastic" begin
+        E = 70e9
+        ν = 0.33
+        G = E / (2(1 + ν))
+        mat = OrthotropicLinearElastic(;
+            E1 = E, E2 = E, E3 = E, G12 = G, G23 = G, G31 = G, ν12 = ν, ν23 = ν, ν31 = ν,
+        )
+        @test material_behavior(mat) isa StatelessConstantTangent
+        @test supported_physics(mat) == (Elasticity{3}(),)
+        @test required_state_variables(mat) == ()
+    end
+
+    @testset "isotropic reduction: tangent matches LinearElastic (Mandel)" begin
+        E = 210e9
+        ν = 0.3
+        G = E / (2(1 + ν))
+        iso = LinearElastic(E = E, ν = ν)
+        ort = OrthotropicLinearElastic(;
+            E1 = E, E2 = E, E3 = E, G12 = G, G23 = G, G31 = G, ν12 = ν, ν23 = ν, ν31 = ν,
+        )
+        ε0 = zero(SymmetricTensor{2,3,Float64})
+        _, 𝔻_iso, _ = compute_stress(iso, ε0, NamedTuple(), 0.0)
+        𝔻_ort = elasticity_tensor(ort)
+        @test tomandel(𝔻_iso) ≈ tomandel(𝔻_ort)
+    end
+
+    @testset "isotropic reduction: stress matches LinearElastic for random strain" begin
+        E = 50e9
+        ν = 0.27
+        G = E / (2(1 + ν))
+        iso = LinearElastic(E = E, ν = ν)
+        ort = OrthotropicLinearElastic(;
+            E1 = E, E2 = E, E3 = E, G12 = G, G23 = G, G31 = G, ν12 = ν, ν23 = ν, ν31 = ν,
+        )
+        rng = MersenneTwister(20260509)
+        for _ in 1:12
+            v = ntuple(_ -> randn(rng), 6)
+            ε = SymmetricTensor{2,3}(v)
+            σ_i, _, _ = compute_stress(iso, ε, NamedTuple(), 0.0)
+            σ_o, _, _ = compute_stress(ort, ε, NamedTuple(), 0.0)
+            @test σ_i ≈ σ_o
+        end
+    end
+
+    @testset "orthotropic coupling: σ₁ dominates under uniaxial ε₁₁" begin
+        mat = OrthotropicLinearElastic(;
+            E1 = 200e9,
+            E2 = 10e9,
+            E3 = 10e9,
+            G12 = 5e9,
+            G23 = 4e9,
+            G31 = 4e9,
+            ν12 = 0.03,
+            ν23 = 0.35,
+            ν31 = 0.03,
+        )
+        ε = SymmetricTensor{2,3}((1e-3, 0.0, 0.0, 0.0, 0.0, 0.0))
+        σ, _, _ = compute_stress(mat, ε, NamedTuple(), 0.0)
+        @test abs(σ[1, 1]) > 10 * abs(σ[2, 2])
+        @test abs(σ[1, 1]) > 10 * abs(σ[3, 3])
+    end
+
+    @testset "invalid compliance throws" begin
+        @test_throws ArgumentError OrthotropicLinearElastic(;
+            E1 = 1e9, E2 = 1e9, E3 = 1e9,
+            G12 = 1e9, G23 = 1e9, G31 = 1e9,
+            ν12 = 0.99, ν23 = 0.99, ν31 = 0.99,
+        )
+    end
+end