ANYbuckling

Buckling of stiffened flat panels, cylinders and curved plates according to DNV standards.

ANYbuckling is the standalone calculation engine extracted from ANYstructure. It has no GUI and only depends on numpy and scipy.

Calculation methods

The ML-based buckling predictions available in ANYstructure are not part of this package.

Installation

pip install ANYbuckling

Optional extras:

pip install ANYbuckling[excel]   # xlwings, needed only for the PULS Excel runner

Quick start

Flat stiffened panel (DNV-RP-C201, prescriptive)

from anybuckling import FlatStru

panel = FlatStru('Flat plate, stiffened')
panel.set_material(mat_yield=355, emodule=210000, material_factor=1.15, poisson=0.3)
panel.set_plate_geometry(spacing=680, thickness=12, span=3300)
panel.set_stresses(pressure=0.01, sigma_x1=50, sigma_x2=50,
                   sigma_y1=100, sigma_y2=100, tau_xy=5)
panel.set_stiffener(hw=260, tw=12, bf=49, tf=28, stf_type='bulb', spacing=680)
panel.set_buckling_parameters(calculation_method='DNV-RP-C201 - prescriptive',
                              buckling_acceptance='ultimate')

results = panel.get_buckling_results()
print(results['Plate']['Plate buckling'])          # plate UF
print(results['Stiffener'])                        # stiffener UFs

Domains: 'Flat plate, unstiffened', 'Flat plate, stiffened' and 'Flat plate, stiffened with girder'. Switch calculation_method to 'SemiAnalytical S3/U3' to run the same panel through the semi-analytical solver.

Cylinder (DNV-RP-C202)

from anybuckling import CylStru

cyl = CylStru(calculation_domain='Longitudinal Stiffened shell')
cyl.set_material(mat_yield=355, emodule=210000, material_factor=1.15, poisson=0.3)
cyl.set_stresses(sasd=-137.6, tQsd=78.3, shsd=-3.9)
cyl.set_shell_geometry(radius=6500, thickness=19,
                       tot_length_of_shell=20000, distance_between_rings=3300)
cyl.set_longitudinal_stiffener(hw=232, tw=12, bf=49, tf=28, spacing=680)
cyl.set_imperfection()
cyl.set_fabrication_method()
cyl.set_end_cap_pressure_included_in_stress()
cyl.set_uls_or_als('ULS')
cyl.set_shell_buckling_parmeters()

print(cyl.get_buckling_results())

Domains cover unstiffened, longitudinally stiffened, ring stiffened and orthogonally stiffened shells and panels, plus unstiffened conical shells, with either stress or force input.

Semi-analytical S3/U3 solver directly

from anybuckling.semianalytical import row_to_s3_input, solve_s3_panel

row = {
    'Length of panel': 3300.0, 'Stiffener spacing': 680.0, 'Plate thick.': 12.0,
    'Stiffener type': 'L-bulb', 'Stiffener boundary': 'Cont',
    'Stiff. Height': 260.0, 'Web thick.': 12.0, 'Flange width': 49.0,
    'Flange thick.': 28.0, 'Yield stress plate': 355.0, 'Yield stress stiffener': 355.0,
    'Axial stress': 50.0, 'Trans. stress 1': 100.0, 'Trans. stress 2': 100.0,
    'Shear stress': 5.0, 'Pressure (fixed)': 0.01, 'In-plane support': 'Integrated',
}
result = solve_s3_panel(row_to_s3_input(row))
print(result.valid, result.buckling_usage_factor, result.ultimate_usage_factor)

The solver also ships a benchmark and verification CLI:

python -m anybuckling.semianalytical --help

Relation to ANYstructure

The classes keep their original ANYstructure names (Structure, CalcScantlings, AllStructure, Shell, CylinderAndCurvedPlate, PULSpanel) because ANYstructure uses this package as a dependency. Fatigue, load combinations, optimization, FE integration, machine-learning prediction, and the GUI remain in ANYstructure.

Development

pip install -e .[dev]
pytest

License

GPL-3.0-or-later. See LICENSE.