Field outputs, plots and files#

The solvers return the Ritz constants \(\boldsymbol{c}\), from which the fields are calculated at points or over a grid, plotted, and saved with the model.

Field outputs#

object	displacements, strains, stress resultants	other outputs
`Shell`	`Shell.uvw()`, `Shell.strain()`, `Shell.stress()`
`MultiDomain`	`MultiDomain.uvw()`, `MultiDomain.strain()`, `MultiDomain.stress()`, `MultiDomain.calc_results()`	`MultiDomain.force()`, `MultiDomain.force_out_plane()`, `MultiDomain.reaction_pd()`, `MultiDomain.reaction_resultant()`
`StiffPanelBay`	`StiffPanelBay.uvw_skin()`, `StiffPanelBay.uvw_stiffener()`

The methods of Shell store the fields in the dictionary Shell.fields and the coordinates of the points in Shell.plot_mesh; the strains and stress resultants include the non-linear terms of the strains of the model by default. Those of MultiDomain evaluate the domains of a group, or one domain eval_panel, at a grid or at the Gauss-Legendre points, and MultiDomain.force() integrates the stress resultants along a line of constant \(x\) or \(y\). The eigenvalues, eigenvectors and Ritz constants of an analysis may be kept in the dictionary Shell.results, which is saved with the shell.

Plots#

plot_shell(): contour plot of one field of a Shell, with matplotlib;
MultiDomain.plot(): contour plot of the domains of a group, each domain placed at x0, y0 in the plane of the group;
MultiDomain.plot3d(): interactive 3D plot of the deformed assembly with plotly, which must be installed, each domain placed in the global coordinate system by x0, y0, z0, point_x and point_xy, see Shell.global_frame();
StiffPanelBay.plot_skin() and StiffPanelBay.plot_stiffener(): contour plots of a bay.

Saving and loading#

Shell.save(), StiffPanelBay.save() and MultiDomain.save() write a zip file with the inputs in JSON and the arrays, e.g. the fields and the results, in NumPy’s format, and panels.shell.load(), panels.stiffpanelbay.load() and panels.multidomain.load() read it back; the matrices are not stored and are calculated again. File objects, e.g. io.BytesIO, are accepted in place of file names. The format and the attributes stored are described in panels.json_io.

Examples#

A shell saved after a linear buckling and a static analysis, with the eigenpairs, the Ritz constants and the stress resultants, gives the same matrices and results once loaded:

def _shell(model='plate_clpt_donnell', **kwargs):
    kw = dict(a=0.6, b=0.4, stack=[0, 45, -45, 90], plyt=0.2e-3,
              laminaprop=LAMINAPROP, rho=1600., m=7, n=6, model=model)
    if 'cylshell' in model:
        kw['r'] = 0.8
    kw.update(kwargs)
    s = Shell(**kw)
    s.Nxx = -1.
    s.y1w = 1.
    s.add_point_load(0.3, 0.2, 0, 0, -10.)
    s.add_point_load(0.6, 0.2, -5., 0, 0, cte=False)
    s.add_pressure_load(-1.e3, x1=0.1, follower=False)
    s.add_point_pd(0.2, 0.1, 1.e6, 0., 1.e6, 0., 1.e6, 1.e-4)
    return s

@pytest.mark.parametrize('model', SHELL_MODELS)
def test_shell_after_analysis(model):
    s = _shell(model)
    kC, kG, eigvals, eigvecs = _shell_lb(s)
    s.results['eigvals'] = eigvals
    s.results['eigvecs'] = eigvecs
    c = _shell_static(s)
    s.increments = [0.5, 1.]
    s.results['c'] = c
    s.stress(c, gridx=7, gridy=5)
    data = _save(s)
    # the saved object is not modified
    assert s.matrices['kC'] is not None
    assert s.lam is not None
    s2 = load_shell(io.BytesIO(data))
    for k in ('eigvals', 'eigvecs', 'c'):
        assert s2.results[k].dtype == s.results[k].dtype
        assert_array_equal(s2.results[k], s.results[k])
    assert s2.increments == [0.5, 1.]
    for k, v in s.fields.items():
        if v is None:
            assert s2.fields[k] is None
        else:
            assert s2.fields[k].shape == v.shape == (5, 7)
            assert_array_equal(s2.fields[k], v)
    for k, v in s.plot_mesh.items():
        assert_array_equal(s2.plot_mesh[k], v)
    assert all(v is None for v in s2.matrices.values())
    kC2, kG2, eigvals2, eigvecs2 = _shell_lb(s2)
    _assert_same_matrices(kC2, kC)
    _assert_same_eigenpairs(eigvals2, eigvecs2, eigvals, eigvecs)
    assert_array_equal(_shell_static(s2), c)
    s2.stress(c, gridx=7, gridy=5)
    for k, v in s.fields.items():
        if v is not None:
            assert_array_equal(s2.fields[k], v)

A contour plot of the bending moment Mxx of a Shell with the options of plot_shell():

def test_plot_shell_options(shell_c, tmp_path):
    s, c = shell_c
    filename = tmp_path / 'shell.png'
    ax = plot_shell(s, c, vec='Mxx', deform_u=True, deform_u_sf=10.,
                    colorbar=True, cbar_title='Mxx', invert_y=True,
                    title='title', clean=False, colormap=1,
                    texts=[dict(x=0.1, y=0.1, s='text')],
                    filename=str(filename), dpi=20,
                    gridx=8, gridy=6, num_levels=5)
    assert filename.exists()
    assert ax.get_title() == 'title'
    assert ax.yaxis_inverted()