Mortar autodiff tests...

test/test_mortar_autodiff.jl

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+# This file is a part of JuliaFEM.
+# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
+
+using JuliaFEM.Test
+
+using JuliaFEM.Core: Node, Seg2, update!, Problem, Mortar, assemble!
+
+function get_testproblems(u, la)
+    nodes = Dict{Int64, Node}(
+        1 => [0.0, 0.0],
+        2 => [2.0, 0.0],
+        3 => [1.0, 2.0],
+        4 => [0.0, 2.0],
+        5 => [2.5, 0.0],
+        6 => [4.5, 0.0],
+        7 => [4.5, 1.0],
+        8 => [2.5, 1.0])
+    displacement = Dict{Int64, Vector{Float64}}()
+    reaction_force = Dict{Int64, Vector{Float64}}()
+    for i=1:8
+        displacement[i] = u[:,i]
+        reaction_force[i] = la[:,i]
+    end
+    bc5 = Seg2([3, 2])
+    bc6 = Seg2([8, 5])
+    update!([bc5, bc6], "geometry", nodes)
+    update!([bc5, bc6], "displacement", displacement)
+    update!([bc5, bc6], "reaction force", reaction_force)
+    bc5["master elements"] = [bc6]
+    contact1 = Problem(Mortar, "contact between bodies", 2, "displacement")
+    contact2 = Problem(Mortar, "contact between bodies", 2, "displacement")
+    contact2.properties.formulation = :forwarddiff
+    contact2.assembly.u = vec(u)
+    contact2.assembly.la = vec(la)
+    push!(contact1, bc5, bc6)
+    push!(contact2, bc5, bc6)
+    return contact1, contact2
+end
+
+@testset "test linearization of contact force in undeformed state" begin
+    u = zeros(2, 8)
+    la = zeros(2, 8)
+    contact1, contact2 = get_testproblems(u, la)
+    assemble!(contact1, 0.0)
+    assemble!(contact2, 0.0)
+    @test isapprox(full(contact1.assembly.C1), full(contact2.assembly.C1))
+    @test isapprox(full(contact1.assembly.K), full(contact2.assembly.K))
+end