API Examples

The public API lives in anystruct.api.

For a shorter manual/report version, see Compact API Report Example.

Units and sign conventions

Geometry setter dimensions are in millimetres unless the docstring says otherwise.
Material yield and elastic modulus are in MPa.
Flat plate pressure and stresses are in MPa, and compression is positive.
Cylinder stresses and pressure are in MPa, and compression is negative.
Cylinder force input uses Nsd/Qsd in kN and Msd/Tsd in kNm.

Flat plate with girder

This example uses all flat-plate geometry setters, PULS metadata, all supported buckling methods, special provisions, and the optional numeric ML model bundle hook.

from pprint import pprint

import numpy as np

from anystruct.api import FlatStru


class DemoIdentityScaler:
    """Small sklearn-like scaler used only to demonstrate the ML bundle API."""

    def transform(self, rows):
        return np.asarray(rows, dtype=float)

    def inverse_transform(self, rows):
        return np.asarray(rows, dtype=float)


class DemoValidityModel:
    def predict(self, rows):
        return np.ones(len(rows), dtype=int)


class DemoNumericUfModel:
    def predict(self, rows):
        # The real model should return raw [buckling UF, ultimate UF] rows.
        return np.asarray([[0.4, 0.5] for _ in rows], dtype=float)


def demo_numeric_ml_bundle(prefix):
    return {
        f"{prefix} validity predictor": DemoValidityModel(),
        f"{prefix} validity xscaler": DemoIdentityScaler(),
        f"{prefix} UF reg predictor": DemoNumericUfModel(),
        f"{prefix} UF reg xscaler": DemoIdentityScaler(),
        f"{prefix} UF reg yscaler": DemoIdentityScaler(),
    }


def show(title, result):
    print(f"\n{title}")
    pprint(result)


flat = FlatStru("Flat plate, stiffened with girder")
flat.set_material(mat_yield=355, emodule=210000, material_factor=1.15, poisson=0.3)
flat.set_plate_geometry(spacing=700, thickness=18, span=4000)
flat.set_stresses(
    pressure=0.2,
    sigma_x1=50,
    sigma_x2=50,
    sigma_y1=100,
    sigma_y2=100,
    tau_xy=5,
)
flat.set_stiffener(hw=360, tw=12, bf=150, tf=20, stf_type="T", spacing=700)
flat.set_girder(hw=600, tw=15, bf=220, tf=25, stf_type="T", spacing=2800)
flat.set_fixation_parameters(kpp=1, kps=1, km1=12, km2=24, km3=12)
flat.set_puls_parameters(
    sp_or_up="SP",
    puls_boundary="Int",
    stiffener_end="Continuous",
    up_boundary="SSSS",
)

print("Available methods:", flat.get_available_buckling_methods())

flat.set_buckling_parameters(
    calculation_method="DNV-RP-C201 - prescriptive",
    buckling_acceptance="ultimate",
    stiffened_plate_effective_aginst_sigy=True,
    min_lat_press_adj_span=0,
    buckling_length_factor_stf=1,
    buckling_length_factor_girder=1,
    stf_dist_between_lateral_supp=4000,
    girder_dist_between_lateral_supp=4000,
    panel_length_Lp=4000,
    stiffener_support="Continuous",
    girder_support="Continuous",
    pressure_side="both sides",
    load_factor_stresses=1.0,
    load_factor_pressure=1.0,
    fabrication_method_stiffener="Fabricated",
    fabrication_method_girder="Cold formed",
)
show("DNV-RP-C201 buckling", flat.get_buckling_results())
show("Special provisions", flat.get_special_provisions_results())

flat.set_buckling_parameters(
    calculation_method="SemiAnalytical S3/U3",
    buckling_acceptance="buckling",
)
show("SemiAnalytical S3/U3 buckling", flat.get_buckling_results())

# Numeric ML requires the five sklearn-like objects for the selected prefix.
# SP + integrated boundary uses the "num SP int" prefix.
flat.set_ml_buckling_model(demo_numeric_ml_bundle("num SP int"))
flat.set_buckling_parameters(
    calculation_method="ML-Numeric (PULS based)",
    buckling_acceptance="ultimate",
)
show("ML-Numeric buckling", flat.get_buckling_results())

Unstiffened flat plate

Use the same material, geometry, stress, PULS, and buckling calls. Skip the stiffener and girder setters.

from pprint import pprint

from anystruct.api import FlatStru


unstiffened = FlatStru("Flat plate, unstiffened")
unstiffened.set_material(mat_yield=355, emodule=210000, material_factor=1.15, poisson=0.3)
unstiffened.set_plate_geometry(spacing=700, thickness=18, span=4000)
unstiffened.set_stresses(
    pressure=0.2,
    sigma_x1=50,
    sigma_x2=50,
    sigma_y1=100,
    sigma_y2=100,
    tau_xy=5,
)
unstiffened.set_puls_parameters(sp_or_up="UP", puls_boundary="GL", up_boundary="SCSC")
unstiffened.set_buckling_parameters(
    calculation_method="SemiAnalytical S3/U3",
    buckling_acceptance="buckling",
)
pprint(unstiffened.get_buckling_results())

Cylinder, stress input

This orthogonally stiffened shell example uses shell geometry, longitudinal stiffeners, ring girders, fabrication and limit-state controls, exclusion switches, and stress input.

from pprint import pprint

from anystruct.api import CylStru


cyl = CylStru(calculation_domain="Orthogonally Stiffened shell")
cyl.set_material(mat_yield=355, emodule=210000, material_factor=1.15, poisson=0.3)
cyl.set_imperfection(delta_0=0.005)
cyl.set_fabrication_method(stiffener="Fabricated", girder="Fabricated")
cyl.set_end_cap_pressure_included_in_stress(is_included=True)
cyl.set_uls_or_als(kind="ULS")
cyl.set_shell_geometry(
    radius=6500,
    thickness=24,
    tot_length_of_shell=20000,
    distance_between_rings=3300,
)
cyl.set_shell_buckling_parmeters(eff_buckling_length_factor=1.0)
cyl.set_length_between_girder(val=3300)
cyl.set_panel_spacing(val=680)
cyl.set_longitudinal_stiffener(
    hw=260,
    tw=23,
    bf=49,
    tf=28,
    stf_type="L-bulb",
    spacing=680,
)
cyl.set_ring_girder(hw=500, tw=15, bf=200, tf=25, stf_type="T", spacing=3300)
cyl.set_exclude_ring_stiffener(is_excluded=True)
cyl.set_exclude_ring_frame(is_excluded=False)
cyl.set_stresses(sasd=-200, smsd=0, tTsd=0, tQsd=5, psd=0, shsd=-60)

pprint(cyl.get_buckling_results())

Cylinder, force input

For shell domains, set_forces can be used instead of set_stresses. Call set_shell_buckling_parmeters before requesting buckling results so the column buckling check has an effective length factor.

from pprint import pprint

from anystruct.api import CylStru


force_cyl = CylStru(calculation_domain="Longitudinal Stiffened shell")
force_cyl.set_material()
force_cyl.set_imperfection()
force_cyl.set_shell_geometry(
    radius=6500,
    thickness=20,
    distance_between_rings=3000,
    tot_length_of_shell=12000,
)
force_cyl.set_shell_buckling_parmeters(eff_buckling_length_factor=1.0)
force_cyl.set_panel_spacing(700)
force_cyl.set_longitudinal_stiffener(
    hw=260,
    tw=12,
    bf=80,
    tf=20,
    stf_type="T",
    spacing=700,
)
force_cyl.set_forces(Nsd=-1000, Msd=0, Tsd=0, Qsd=0, psd=0.1)

pprint(force_cyl.get_buckling_results())

Cylinder, ring stiffener

Use the ring stiffener setter in ring-stiffened shell or panel domains.

from pprint import pprint

from anystruct.api import CylStru


ring_cyl = CylStru(calculation_domain="Ring Stiffened shell")
ring_cyl.set_material()
ring_cyl.set_imperfection()
ring_cyl.set_fabrication_method(stiffener="Fabricated", girder="Fabricated")
ring_cyl.set_end_cap_pressure_included_in_stress(True)
ring_cyl.set_uls_or_als("ULS")
ring_cyl.set_shell_geometry(
    radius=6500,
    thickness=20,
    distance_between_rings=3000,
    tot_length_of_shell=12000,
)
ring_cyl.set_shell_buckling_parmeters(1.0)
ring_cyl.set_panel_spacing(700)
ring_cyl.set_ring_stiffener(
    hw=300,
    tw=12,
    bf=120,
    tf=20,
    stf_type="T",
    spacing=3000,
)
ring_cyl.set_forces(Nsd=-1000, Msd=0, Tsd=0, Qsd=0, psd=0.1)

pprint(ring_cyl.get_buckling_results())

Project file facade

Project files can be loaded and saved through the public facade without constructing GUI objects.

from pathlib import Path
from tempfile import TemporaryDirectory

from anystruct.api import (
    ProjectHydrationDefaults,
    ProjectState,
    load_project_state,
    open_project,
    save_project_state,
)


with TemporaryDirectory() as tmp:
    project_path = Path(tmp) / "api_project.txt"
    state = ProjectState(
        project_information="API example",
        theme="dark",
        points={"p1": [0, 0]},
        buckling_method="SemiAnalytical S3/U3",
    )

    saved_path = save_project_state(state, project_path)
    loaded_state = load_project_state(saved_path)
    opened_project = open_project(
        saved_path,
        ProjectHydrationDefaults(structure_types={}),
    )

    print(loaded_state.project_information)
    print(opened_project.transfer.theme)

Supported domains and methods

Flat plate domains:

Flat plate, unstiffened
Flat plate, stiffened
Flat plate, stiffened with girder

Cylinder domains:

Unstiffened shell
Unstiffened panel
Longitudinal Stiffened shell
Longitudinal Stiffened panel
Ring Stiffened shell
Ring Stiffened panel
Orthogonally Stiffened shell
Orthogonally Stiffened panel

Flat plate buckling methods:

DNV-RP-C201 - prescriptive
SemiAnalytical S3/U3
ML-Numeric (PULS based)