mirror of
https://github.com/JuliaFEM/JuliaFEM.jl.git
synced 2026-09-27 20:26:58 +00:00
Jukka Aho
ca7e2904cf
* Fix deprecation warnings from tests * Refactor tests so that ´@testset` is usually called in master file `runtests.jl`, not inside test file. Later on we can convert tests to examples. * Syntax of tests now follow more closely syntax used currently in JuliaFEM. We have had earlier studies with different kind of syntaxes, now we have kind of explicit way to do things.
197 lines
7.3 KiB
Julia
197 lines
7.3 KiB
Julia
# 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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using JuliaFEM, Test, SparseArrays, LinearAlgebra, Statistics
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function get_stress_tensor(element, ip, time)
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haskey(element, "displacement") || return nothing
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gradu = element("displacement", ip, time, Val{:Grad})
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eps = 0.5*(gradu' + gradu)
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E = element("youngs modulus", ip, time)
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nu = element("poissons ratio", ip, time)
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mu = E/(2.0*(1.0+nu))
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la = E*nu/((1.0+nu)*(1.0-2.0*nu))
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S = la*tr(eps)*I + 2.0*mu*eps
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return S
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end
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""" Return stress vector in "ABAQUS" order 11, 22, 33, 12, 23, 13. """
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function get_stress(element, ip, time)
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S = get_stress_tensor(element, ip, time)
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return [S[1,1], S[2,2], S[3,3], S[1,2], S[2,3], S[1,3]]
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end
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""" Return principal stresses. """
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function get_stress_principal(element, ip, time)
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S = get_stress_tensor(element, ip, time)
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return sort(eigvals(S))
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end
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""" Make least squares fit for some field to nodes. """
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function lsq_fit(elements, field, time)
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A = SparseMatrixCOO()
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b = SparseMatrixCOO()
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volume = 0.0
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for element in elements
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gdofs = get_connectivity(element)
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# increase integration order by 1 from default
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for ip in get_integration_points(element, 1)
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detJ = element(ip, time, Val{:detJ})
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w = ip.weight*detJ
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N = element(ip, time)
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f = field(element, ip, time)
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add!(A, gdofs, gdofs, w*kron(N', N))
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for i=1:length(f)
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add!(b, gdofs, w*f[i]*N, i)
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end
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volume += w
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end
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end
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@info("Mass matrix for least-squares fit is assembled. Total volume to fit: $volume")
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A = sparse(A)
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b = sparse(b)
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A = 1/2*(A + A')
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SparseArrays.droptol!(A, 1.0e-6)
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SparseArrays.dropzeros!(A)
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nz = get_nonzero_rows(A)
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F = ldlt(A[nz,nz])
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x = zeros(size(b)...)
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x[nz, :] = F \ b[nz, :]
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nodal_values = Dict(i => vec(x[i,:]) for i in nz)
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return nodal_values
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end
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#=
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test subjects:
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- surface pressure load in curved surface
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- verification of elements wedge6 and wedge15
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- stress interpolation from gauss points to nodes
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from Code Aster, for linear model
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N38 -8.85861895037377E-01 -3.46944695195361E-18 -3.46944695195361E-18
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coords of N38 = (1.0, 0.0, 0.0)
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N49 -4.50934684240566E-01 -4.46908405333021E-01 -5.92329377847994E-01
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coords of N49 = (0.521002, 0.515482, 0.68032) # quite middle of surface
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Analytical solution
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uᵣ(r) = b³p/(2Er²(a³-b³)) * (a³(ν+1) + r³(-4ν+2)), where
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a = inner surface radial distance, b = outer surface ...
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if a=0.9, b=1.0, ν=1/3, E = 24580 and p = 7317 equation yields
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-9/10 for radial displacement
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http://mms2.ensmp.fr/emms_paris/plasticite3D/exercices/eSpherePress.pdf
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=#
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function test_wedge_sphere(model, u_CA, S_CA)
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mesh_file = @__DIR__() * "/testdata/primitives.med"
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mesh = aster_read_mesh(mesh_file, model)
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body = Problem(Elasticity, "hollow sphere 1/8 model", 3)
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body_elements = create_elements(mesh, "HOLLOWSPHERE8")
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update!(body_elements, "youngs modulus", 24580.0)
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update!(body_elements, "poissons ratio", 1/3)
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add_elements!(body, body_elements)
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bc = Problem(Dirichlet, "symmetry bc", 3, "displacement")
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el1 = create_elements(mesh, "FACE1")
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update!(el1, "displacement 3", 0.0)
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el2 = create_elements(mesh, "FACE2")
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update!(el2, "displacement 2", 0.0)
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el3 = create_elements(mesh, "FACE3")
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update!(el3, "displacement 1", 0.0)
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add_elements!(bc, el1, el2, el3)
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load = Problem(Elasticity, "pressure load", 3)
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load_elements = create_elements(mesh, "OUTER")
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update!(load_elements, "surface pressure", 7317.0)
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add_elements!(load, load_elements)
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analysis = Analysis(Linear)
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add_problems!(analysis, body, load, bc)
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run!(analysis)
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X = load("geometry", 0.0)
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u = load("displacement", 0.0)
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nids = sort(collect(keys(X)))
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umag = Float64[norm(u[id]) for id in nids]
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um = mean(umag)
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us = std(umag)
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rtol = norm(um - 0.9) / max(norm(um), 0.9) * 100.0
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@debug("Displacement field statistics", mean=um, std=us, rtol=rtol)
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@test rtol < 1.5 # percents
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@debug("Verifying displacement against Code Aster solution.. ")
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pass = true
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for nid in keys(u_CA)
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rtol = norm(u[nid] - u_CA[nid]) / max(norm(u[nid]), norm(u_CA[nid])) * 100.0
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@debug("Node id $nid, rel diff to CA = $rtol %")
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pass &= isapprox(u[nid], u_CA[nid])
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end
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@test pass
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S = lsq_fit(body.elements, get_stress, 0.0)
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@debug("Verifying stress against Code Aster solution.. ")
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for nid in keys(S_CA)
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rtol = norm(S[nid] - S_CA[nid]) / max(norm(S[nid]), norm(S_CA[nid])) * 100.0
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@debug("Node id $nid, S=$(S[nid]), S_CA=$(S_CA[nid]), rel diff to CA = $rtol %")
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# @test isapprox(S[nid], S_CA[nid])
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# http://code-aster.org/doc/default/en/man_r/r3/r3.06.03.pdf
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pass &= (rtol < 10.0) # percents
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end
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@test pass
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# Calculate principal stresses in nodes
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Sp = Dict()
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for (nid, s) in S
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# order is: 11, 22, 33, 12, 23, 13
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stress_tensor = [
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s[1] s[4] s[6]
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s[4] s[2] s[5]
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s[6] s[5] s[3]]
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Sp[nid] = sort(eigvals(stress_tensor))
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end
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node_ids = sort(collect(keys(Sp)))
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for (i, nid) in enumerate(node_ids)
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@debug("$nid -> $(Sp[nid])")
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if i > 9
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@debug("...")
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break
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end
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end
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# Stress state in M141 element
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S_CA_gp = Dict()
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S_CA_gp[1] = [-2.31497155149131E+04, -2.30873958541450E+04, -2.59731750416165E+04, 1.16262216932559E+04, 1.05883267606309E+04, 1.04255059462671E+04]
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S_CA_gp[2] = [-2.20268425477595E+04, -2.59602179285979E+04, -2.45141753387488E+04, 1.08344827948196E+04, 1.02393080182646E+04, 1.18221520216293E+04]
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S_CA_gp[3] = [-2.12175032863505E+04, -2.38106746858742E+04, -2.75848287641255E+04, 1.23383626529382E+04, 9.45231798421561E+03, 1.04600859263009E+04]
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S_CA_gp[4] = [-2.88674347639302E+04, -2.90047144010521E+04, -3.19545639967296E+04, 1.24436733999204E+04, 1.14033189825355E+04, 1.09837505652098E+04]
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S_CA_gp[5] = [-2.76741820176108E+04, -3.20576001061179E+04, -3.04041166591832E+04, 1.16023096459047E+04, 1.10324243354755E+04, 1.24679360552984E+04]
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S_CA_gp[6] = [-2.68141147396280E+04, -2.97733271271234E+04, -3.36672334497799E+04, 1.32004501509553E+04, 1.01961070966382E+04, 1.10204979599285E+04]
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time = 0.0
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for element in body.elements
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element.id == 141 || continue
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for (i, ip) in enumerate(get_integration_points(element))
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S = get_stress(element, ip, time)
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rtol = norm(S - S_CA_gp[i]) / max(norm(S), norm(S_CA_gp[i]))
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@debug("$i $S, rtol=$rtol")
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pass &= isapprox(S, S_CA_gp[i])
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end
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end
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@test pass
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end
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# 1/8 hollow sphere with surface load
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u_CA = Dict()
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u_CA[38] = [-8.85861895037377E-01, -3.46944695195361E-18, -3.46944695195361E-18]
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u_CA[49] = [-4.50934684240566E-01, -4.46908405333021E-01, -5.92329377847994E-01]
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S_CA = Dict()
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S_CA[38] = [-1.94504819940510E+03, -3.47014655438479E+04, -3.40876135857114E+04, 1.70379805227866E+03, 2.16707698388864E+03, 4.32009983342141E-12]
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S_CA[49] = [-2.36067010168718E+04, -2.33820775692753E+04, -1.80606705820104E+04, 8.85783922092890E+03, 1.12122431934777E+04, 1.14035796957343E+04]
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test_wedge_sphere("HOLLOWSPHERE8_WEDGE6", u_CA, S_CA)
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#test_wedge_sphere("HOLLOWSPHERE8_WEDGE15")
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