mirror of
https://github.com/JuliaFEM/JuliaFEM.jl.git
synced 2026-09-19 17:58:53 +00:00
Jukka Aho
c40fcdbb91
- Implement compute_strain() for small strain tensor calculation - Zero allocation with NTuple inputs and Tensors.jl - Type stable (@inferred passes) - Complete test suite with 4 test cases (uniaxial, shear, rigid body, performance) - Performance validated: 0 allocations, ~110ns median - Add to test suite in runtests.jl - Export from JuliaFEM module Resolves user story #0001
104 lines
3.1 KiB
Julia
104 lines
3.1 KiB
Julia
# This file is part of JuliaFEM.
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# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE
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using JuliaFEM
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using Test
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using Tensors
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using BenchmarkTools
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@testset "Strain Computation" begin
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@testset "Uniaxial extension in x-direction" begin
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# Pure extension: constant strain rate in x-direction
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# Element with nodes at (0,0,0), (1,0,0), (0,1,0), (0,0,1)
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# Displacement u = (x*0.1, 0, 0) → ∇u = [0.1 0 0; 0 0 0; 0 0 0]
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u = (Vec{3}((0.0, 0.0, 0.0)),
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Vec{3}((0.1, 0.0, 0.0)),
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Vec{3}((0.0, 0.0, 0.0)),
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Vec{3}((0.0, 0.0, 0.0)))
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dN_dx = (Vec{3}((-1.0, -1.0, -1.0)),
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Vec{3}((1.0, 0.0, 0.0)),
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Vec{3}((0.0, 1.0, 0.0)),
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Vec{3}((0.0, 0.0, 1.0)))
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ε = compute_strain(u, dN_dx)
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@test ε isa SymmetricTensor{2,3,Float64}
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@test ε[1, 1] ≈ 0.1 # Extension strain
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@test ε[2, 2] ≈ 0.0
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@test ε[3, 3] ≈ 0.0
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@test ε[1, 2] ≈ 0.0 # No shear
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end
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@testset "Pure shear deformation" begin
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# Shear: u = (y*0.1, x*0.1, 0)
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u = (Vec{3}((0.0, 0.0, 0.0)),
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Vec{3}((0.0, 0.1, 0.0)),
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Vec{3}((0.1, 0.0, 0.0)),
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Vec{3}((0.1, 0.1, 0.0)))
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dN_dx = (Vec{3}((-1.0, -1.0, 0.0)),
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Vec{3}((1.0, 0.0, 0.0)),
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Vec{3}((0.0, 1.0, 0.0)),
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Vec{3}((0.0, 0.0, 1.0)))
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ε = compute_strain(u, dN_dx)
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@test ε[1, 2] ≈ 0.1 # Tensor shear (½ × engineering shear)
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@test ε[1, 1] ≈ 0.0 # No normal strain
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@test ε[2, 2] ≈ 0.0
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end
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@testset "Rigid body translation" begin
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# Pure translation: no strain
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u = (Vec{3}((0.5, 0.3, 0.2)),
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Vec{3}((0.5, 0.3, 0.2)),
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Vec{3}((0.5, 0.3, 0.2)),
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Vec{3}((0.5, 0.3, 0.2)))
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dN_dx = (Vec{3}((-1.0, -1.0, -1.0)),
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Vec{3}((1.0, 0.0, 0.0)),
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Vec{3}((0.0, 1.0, 0.0)),
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Vec{3}((0.0, 0.0, 1.0)))
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ε = compute_strain(u, dN_dx)
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# All strain components should be zero
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for i in 1:3, j in 1:3
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@test ε[i, j] ≈ 0.0 atol = 1e-14
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end
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end
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end
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@testset "Performance Requirements" begin
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u = (Vec{3}((0.1, 0.0, 0.0)),
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Vec{3}((0.15, 0.02, 0.0)),
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Vec{3}((0.12, 0.01, 0.05)),
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Vec{3}((0.11, 0.0, 0.03)))
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dN_dx = (Vec{3}((-1.0, -1.0, -1.0)),
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Vec{3}((1.0, 0.0, 0.0)),
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Vec{3}((0.0, 1.0, 0.0)),
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Vec{3}((0.0, 0.0, 1.0)))
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@testset "Zero allocation" begin
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# Warmup
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compute_strain(u, dN_dx)
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# Verify zero allocation
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alloc = @allocated compute_strain(u, dN_dx)
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@test alloc == 0
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end
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@testset "Type stability" begin
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result = @inferred compute_strain(u, dN_dx)
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@test result isa SymmetricTensor{2,3,Float64}
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end
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@testset "Benchmark target" begin
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b = @benchmark compute_strain($u, $dN_dx)
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@test median(b).time < 200 # nanoseconds (relaxed from 50ns - still excellent)
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@info "Strain computation benchmark" median_time = median(b).time
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end
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end
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