Here is a MishWE: It is a free-vibration problem for the solid cylinder. Code is included below.
With tol set to the machine-precision tolerance:
40.832225 seconds (16.47 k allocations: 1.946 GiB, 0.78% gc time)
Natural frequencies: [0.0, 0.00018759, 0.000189618, 0.000225355, 0.000231742, 0.000251527, 2548.64, 2548.64, 2561.31, 4102.08, 4706.11, 4706.11, 5126.58, 6865.78, 6865.78, 6952.23, 6959.68, 6974.56, 6974.56, 7042.6, 7048.24, 7611.43, 7699.75, 7706.07, 7709.31, 8003.19, 8011.69, 8954.67, 8954.67, 9157.43, 9157.43, 9364.48, 9364.48, 9410.67, 9418.92, 9690.55, 9904.97, 10061.3, 10284.8, 10421.0, 10421.0, 10439.3, 10447.4, 10466.4, 10466.4, 10737.7, 10737.7, 10769.4, 10769.4, 11232.3, 11232.3, 11566.2, 11570.2, 11667.7, 11862.7, 11866.8, 11963.5, 11963.5, 12005.3, 12005.3, 12308.1, 12308.1, 12585.3, 12659.7, 12659.7, 12690.2, 12690.2, 12885.7, 12937.8, 13462.4, 13462.4, 13465.8, 13470.2, 13524.4, 13525.6, 13803.8, 13803.8, 14269.2, 14272.8, 14283.8, 14304.1, 14310.9, 14315.5, 14384.6, 14384.6, 14525.2, 14525.2, 14634.6, 14634.6, 14665.0, 14676.4, 14752.6, 14762.0, 14989.2, 14989.2, 15141.5, 15288.9, 15291.7, 15423.2, 15423.2, 15506.5, 15778.2, 15807.1, 15819.9, 15851.2, 15945.8, 15947.0, 16038.1, 16042.5, 16125.9, 16125.9, 16153.2, 16153.2, 16227.3, 16256.1, 16257.4, 16387.8, 16387.8, 16416.8, 16416.8, 16649.4, 16963.8, 16963.8, 16966.0, 17089.9, 17116.7, 17131.6, 17141.1, 17158.1, 17321.4, 17321.4, 17723.3, 17836.3, 17836.3, 17837.1, 17837.1, 17850.6, 17856.7, 17858.3, 17871.9, 17919.2, 17919.2, 17923.8, 17923.8, 17941.3, 17941.3, 17995.3, 18028.7, 18037.8, 18151.1] [Hz]
With tol set to 10^10 times the machine-precision tolerance (ten orders of magnitude bigger tolerance!):
41.223566 seconds (16.47 k allocations: 1.946 GiB, 0.78% gc time)
Natural frequencies: [0.0, 0.000187664, 0.000189626, 0.000225381, 0.000231761, 0.000251539, 2548.64, 2548.64, 2561.31, 4102.08, 4706.11, 4706.11, 5126.58, 6865.78, 6865.78, 6952.23, 6959.68, 6974.56, 6974.56, 7042.6, 7048.24, 7611.43, 7699.75, 7706.07, 7709.31, 8003.19, 8011.69, 8954.67, 8954.67, 9157.43, 9157.43, 9364.48, 9364.48, 9410.67, 9418.92, 9690.55, 9904.97, 10061.3, 10284.8, 10421.0, 10421.0, 10439.3, 10447.4, 10466.4, 10466.4, 10737.7, 10737.7, 10769.4, 10769.4, 11232.3, 11232.3, 11566.2, 11570.2, 11667.7, 11862.7, 11866.8, 11963.5, 11963.5, 12005.3, 12005.3, 12308.1, 12308.1, 12585.3, 12659.7, 12659.7, 12690.2, 12690.2, 12885.7, 12937.8, 13462.4, 13462.4, 13465.8, 13470.2, 13524.4, 13525.6, 13803.8, 13803.8, 14269.2, 14272.8, 14283.8, 14304.1, 14310.9, 14315.5, 14384.6, 14384.6, 14525.2, 14525.2, 14634.6, 14634.6, 14665.0, 14676.4, 14752.6, 14762.0, 14989.2, 14989.2, 15141.5, 15288.9, 15291.7, 15423.2, 15423.2, 15506.5, 15778.2, 15807.1, 15819.9, 15851.2, 15945.8, 15947.0, 16038.1, 16042.5, 16125.9, 16125.9, 16153.2, 16153.2, 16227.3, 16256.1, 16257.4, 16387.8, 16387.8, 16416.8, 16416.8, 16649.4, 16963.8, 16963.8, 16966.0, 17089.9, 17116.7, 17131.6, 17141.1, 17158.1, 17321.4, 17321.4, 17723.3, 17836.3, 17836.3, 17837.1, 17837.1, 17850.6, 17856.7, 17858.3, 17871.9, 17919.2, 17919.2, 17923.8, 17923.8, 17941.3, 17941.3, 17995.3, 18028.7, 18037.8, 18151.1] [Hz]
The code:
using FinEtools
using Arpack
E = 70000*phun("MPa")::FFlt;
nu = 0.33::FFlt;
rho = 2700*phun("KG/M^3")::FFlt;
radius = 0.5*phun("ft");
leng = 2*phun("ft");
omegashift = (2*pi*100) ^ 2; # to resolve rigid body modes
nr = 10
nL = 40
tol = 1e10 * eps(1.0)
neigvs = 150
fens, fes = H8cylindern(radius, leng, nr, nL)
geom = NodalField(fens.xyz)
u = NodalField(zeros(size(fens.xyz,1),3))
applyebc!(u)
numberdofs!(u)
MR = DeforModelRed3D
material = MatDeforElastIso(MR, rho, E, nu, 0.0)
femm = FEMMDeforLinear(MR, IntegDomain(fes, GaussRule(3,2)), material)
K = stiffness(femm, geom, u)
K .= 0.5 * (K .+ transpose(K))
femm = FEMMDeforLinear(MR, IntegDomain(fes, GaussRule(3,3)), material)
M = mass(femm, geom, u)
M .= 0.5 * (M .+ transpose(M))
@time evals,evecs,nev,nconv = eigs(K + omegashift*M, M; nev=neigvs, which=:SM, tol = tol)
evals .-= omegashift;
fs = real(sqrt.(complex(evals)))/(2*pi)
println("Natural frequencies: $fs [Hz]")