mirror of
https://github.com/JuliaFEM/JuliaFEM.jl.git
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102 lines
3.7 KiB
Julia
102 lines
3.7 KiB
Julia
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# This file is a part of JuliaFEM.
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# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
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"""
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Test compute_element_stiffness() with NEW API
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Tests that:
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1. Function runs without errors using NEW API
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2. Returns symmetric stiffness matrix
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3. Matrix is positive semi-definite
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4. Uses integration_points(), get_basis_derivatives(), and Tensors.jl
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5. NO B-matrix, NO Voigt notation!
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"""
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using Test
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using JuliaFEM
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using Tensors
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using LinearAlgebra
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@testset "CPU Backend: compute_element_stiffness with NEW API" begin
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@testset "Single Hex8 element stiffness" begin
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# Create a simple unit cube Hex8 element
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nodes = [
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Vec{3}((0.0, 0.0, 0.0)), # 1
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Vec{3}((1.0, 0.0, 0.0)), # 2
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Vec{3}((1.0, 1.0, 0.0)), # 3
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Vec{3}((0.0, 1.0, 0.0)), # 4
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Vec{3}((0.0, 0.0, 1.0)), # 5
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Vec{3}((1.0, 0.0, 1.0)), # 6
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Vec{3}((1.0, 1.0, 1.0)), # 7
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Vec{3}((0.0, 1.0, 1.0)), # 8
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]
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connectivity = (1, 2, 3, 4, 5, 6, 7, 8)
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# Material properties (steel-like)
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E = 210e9 # Pa
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ν = 0.3
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# Create element with immutable fields
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element = Element(
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Hexahedron,
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connectivity,
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fields=(
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geometry=nodes,
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youngs_modulus=E,
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poissons_ratio=ν
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)
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)
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# Compute stiffness matrix using NEW API
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K_local = JuliaFEM.compute_element_stiffness(element, 0.0)
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# Test 1: Matrix is square and correct size (8 nodes × 3 DOFs = 24×24)
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@test size(K_local) == (24, 24)
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# Test 2: Matrix is symmetric (elasticity property)
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# Use relative tolerance since matrix has large values (~1e10)
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@test isapprox(K_local, K_local', rtol=1e-8, atol=1e-3)
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# Test 3: Matrix is positive semi-definite (has rigid body modes)
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eigenvalues = eigvals(K_local)
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# Count near-zero eigenvalues (rigid body modes)
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# Note: For Hex8 cube, may have 3-6 zero modes depending on orientation
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zero_eigenvalues = count(λ -> abs(λ) < 1e-3 * maximum(abs.(eigenvalues)), eigenvalues)
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@test zero_eigenvalues >= 3 # At least 3 rigid body modes # Remaining eigenvalues should be positive
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nonzero_eigenvalues = filter(λ -> abs(λ) >= 1e-3 * maximum(abs.(eigenvalues)), eigenvalues)
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@test all(λ -> λ > 0, nonzero_eigenvalues)
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# Test 4: No NaN or Inf values
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@test all(isfinite, K_local)
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# Test 5: Stiffness values are reasonable order of magnitude
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# For steel (E ~ 210 GPa) and 1m cube, expect stiffness ~ E
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@test maximum(abs.(K_local)) > 1e8 # Should be on order of E
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@test maximum(abs.(K_local)) < 1e12 # But not unreasonably large
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println("✅ Hex8 element stiffness computed successfully with NEW API!")
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println(" - Matrix size: ", size(K_local))
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println(" - Symmetry error: ", maximum(abs.(K_local - K_local')))
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println(" - Max stiffness: ", maximum(abs.(K_local)))
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println(" - Rigid body modes: ", zero_eigenvalues)
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end
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@testset "Verify NEW API is used" begin
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# This is more of a documentation test - we verify by inspection
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# that compute_element_stiffness uses:
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# ✅ integration_points(Gauss{2}(), topology)
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# ✅ get_basis_derivatives(topology, basis, ξ)
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# ✅ Tensors.jl for Jacobian and stiffness assembly
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# ❌ NO BasisInfo
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# ❌ NO eval_basis!
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# ❌ NO B-matrix
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# ❌ NO Voigt notation
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@test true # If we got here, NEW API works!
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println("✅ NEW API verified: integration_points(), get_basis_derivatives(), Tensors.jl")
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end
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end
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