SOMP_Ansys

This code implements a finite element-based topology optimization algorithm for 3D printed structures. It is written in Python and uses Ansys as finite element solver through the Python interface PyAnsys/PyMAPDL.

Problem formulation

For each element, a density value $\rho_e$ within the range from 0 (void element) to 1 (filled element) is assigned. To enforce the convergence to a predominantly 0/1 configuration (the only physically feasible values, there is no intermediate material), the material properties for each element are obtained from a power-law interpolation, i.e. dependent on $\rho_e^p$, where $p$ is a penalization factor.

The fiber orientation within each element is defined by two angles: in-plane orientation $\theta_e$ and out-of-plane orientation $\alpha_e$.

The problem formulation, for which the three sets of variables are simultaneously optimized, is (SCHMIDT et al, 2020):

$$\begin{aligned} \min_{\boldsymbol\rho,\boldsymbol\theta,\boldsymbol\alpha} c(\boldsymbol\rho,\boldsymbol\theta, \boldsymbol\alpha) & = \sum_e \rho_e^p \boldsymbol{u_e^T} \boldsymbol{k_0}(\theta_e,\alpha_e) \boldsymbol{u_e} \\\ \textrm{s.t. } & \begin{cases} \frac{V(\boldsymbol\rho)}{V_0} \leq f \\\ \boldsymbol{KU} = \boldsymbol{F} \\\ 0 < \rho_{min} \leq \boldsymbol\rho \leq 1 \\\ -\frac{\pi}{2} \leq \boldsymbol\theta \leq \frac{\pi}{2} \\\ -\frac{\pi}{2} \leq \boldsymbol\alpha \leq \frac{\pi}{2} \end{cases} \end{aligned}$$

where $\boldsymbol U$ and $\boldsymbol F$ are the global displacement and force vectors, respectively, $\boldsymbol K$ is the global stiffness matrix, $\boldsymbol{u_e}$ and $\boldsymbol{k_e} = \rho_e^p \boldsymbol{k_0}$ are the element displacement vector and stiffness matrix, respectively, $\boldsymbol\rho$ is the vector of design variables, $\rho_{min}$ is the minimum relative density (non-zero to avoid singularity), $V(\boldsymbol\rho)$ and $V_0$ are the material volume and design domain volume, and $f$ is the prescribed volume fraction.

Filtering

To avoid the appearance of checkerboard patterns and to ensure the mesh-independence of the result, the element sensitivities are filtered by a linear decaying convolution filter (SIGMUND, 2001):

$$\rho_e \widetilde{\frac{\partial c}{\partial\rho_e}} = \frac{1}{\sum_i H^\rho_{ei}} \sum_i H^\rho_{ei} \rho_i \frac{\partial c}{\partial\rho_i}$$

$$H^\rho_{ei} = \max(0, r_\rho - \Delta(e,i))$$

where $r_\rho$ is a fixed filter radius and the $\Delta(e,i)$ operator is the distance between the centers of elements $e$ and $i$.

For orientation smoothing, a similar convolution filter was applied directly to the angles at each iteration, adjusted to reduce the weight of void elements on the average:

$$\begin{pmatrix} \tilde\theta_e \\ \tilde\alpha_e \end{pmatrix} = \frac{1}{\sum_i H^\theta_{ei} \rho_i} \sum_i H^\theta_{ei} \rho_i \begin{pmatrix} \theta_i \\ \alpha_i \end{pmatrix}$$

$$H^\theta_{ei} = \max(0, r_\theta - \Delta(e,i))$$

where $r_\theta$ is independent from $r_\rho$ and is related to the desired minimum fiber curvature.

Finite element formulation

For 2D optimizations, the implementation assumes a 4-node quadrilateral element (Ansys element type PLANE182), whose form functions $N_i$ and strain-displacement matrix $\boldsymbol{B_e}$ are

$$\begin{Bmatrix} N_1 \\ N_2 \\ N_3 \\ N_4 \end{Bmatrix} (r,s) = \frac{1}{4} \begin{Bmatrix} (1-r) (1-s) \\\ (1+r) (1-s) \\\ (1+r) (1+s) \\\ (1-r) (1+s) \end{Bmatrix}$$ $$\boldsymbol{B_e} = \begin{bmatrix} \frac{\partial N_1}{\partial r} & 0 & \cdots & \frac{\partial N_4}{\partial r} & 0 \\\ 0 & \frac{\partial N_1}{\partial s} & \cdots & 0 & \frac{\partial N_4}{\partial s} \\\ \frac{\partial N_1}{\partial s} & \frac{\partial N_1}{\partial r} & \cdots & \frac{\partial N_4}{\partial s} & \frac{\partial N_4}{\partial r} \end{bmatrix}$$

For 3D optimizations, the implementation assumes an 8-node brick element (SOLID185):

$$\begin{Bmatrix} N_1 \\ N_2 \\ N_3 \\ N_4 \\ N_5 \\ N_6 \\ N_7 \\ N_8 \\\ \end{Bmatrix}(r,s,t) = \frac{1}{8} \begin{Bmatrix} (1-r) (1-s) (1-t) \\\ (1+r) (1-s) (1-t) \\\ (1+r) (1+s) (1-t) \\\ (1-r) (1+s) (1-t) \\\ (1-r) (1-s) (1+t) \\\ (1+r) (1-s) (1+t) \\\ (1+r) (1+s) (1+t) \\\ (1-r) (1+s) (1+t) \end{Bmatrix}$$ $$\boldsymbol{B_e} = \begin{bmatrix} \frac{\partial N_1}{\partial r} & 0 & 0 & \cdots & \frac{\partial N_8}{\partial r} & 0 & 0 \\\ 0 & \frac{\partial N_1}{\partial s} & 0 & \cdots & 0 & \frac{\partial N_8}{\partial s} & 0 \\\ 0 & 0 & \frac{\partial N_1}{\partial t} & \cdots & 0 & 0 & \frac{\partial N_8}{\partial t} \\\ 0 & \frac{\partial N_1}{\partial t} & \frac{\partial N_1}{\partial s} & \cdots & 0 & \frac{\partial N_8}{\partial t} & \frac{\partial N_8}{\partial s} \\\ \frac{\partial N_1}{\partial t} & 0 & \frac{\partial N_1}{\partial r} & \cdots & \frac{\partial N_8}{\partial t} & 0 & \frac{\partial N_8}{\partial r} \\\ \frac{\partial N_1}{\partial s} & \frac{\partial N_1}{\partial r} & 0 & \cdots & \frac{\partial N_8}{\partial s} & \frac{\partial N_8}{\partial r} & 0 \end{bmatrix}$$

Material modeling

The materials are modeled as transverse isotropic, suitable for matrices reinforced by unidirectional fibers. The fibers were considered to be aligned with the local $x$ axis, which can be characterised by five independent elastic constants: longitudinal Young modulus $E_x$, transversal Young modulus $E_y$, in-plane Poisson's ratio $\nu_{xy}$, out-of-plane Poisson's ratio $\nu_{yz}$, and in-plane shear modulus $G_{xy}$. From the rule of mixtures for a fiber volume fraction of $V_f$:

$$E_x = E_f V_f + E_m (1-V_f)$$

$$E_y = \frac{E_f E_m}{E_f(1-V_f) + E_m V_f}$$

$$\nu_{xy} = \nu_f V_f + \nu_m (1-V_f)$$

$$G_{xy} = \frac{G_f G_m}{G_f(1-V_f) + G_m V_f}$$

where $E_f$, $\nu_f$, $G_f$ are the fiber properties and $E_m$, $\nu_m$, $G_m$ are the matrix properties. Finally, $\nu_{yz}$ is defined by symmetries in 3D elasticity (CHRISTENSEN, 1988) $$\nu_{yz} = \nu_{xy} , \frac{1 - \nu_{xy} \frac{E_y}{E_x}}{1 - \nu_{xy}}$$

The constitutive matrix $\boldsymbol{C}$ for transverse isotropic materials and the matrices corresponding to the $\theta_e$ and $\alpha_e$ rotations are

$$\boldsymbol{C} = \begin{bmatrix} \frac{1}{E_x} & -\frac{\nu_{xy}}{E_x} & -\frac{\nu_{xy}}{E_x} & 0 & 0 & 0 \\\ -\frac{\nu_{xy}}{E_x} & \frac{1}{E_y} & -\frac{\nu_{yz}}{E_y} & 0 & 0 & 0 \\\ -\frac{\nu_{xy}}{E_x} & -\frac{\nu_{yz}}{E_y} & \frac{1}{E_y} & 0 & 0 & 0 \\\ 0 & 0 & 0 & \frac{2(1+\nu_{yz})}{E_y} & 0 & 0 \\\ 0 & 0 & 0 & 0 & \frac{1}{G_{xy}} & 0 \\\ 0 & 0 & 0 & 0 & 0 & \frac{1}{G_{xy}} \end{bmatrix}^{-1}$$ $$\boldsymbol{T_\theta}(\theta_e) = \begin{bmatrix} c_\theta^2 & s_\theta^2 & 0 & 0 & 0 & -2s_\theta c_\theta \\\ s_\theta^2 & c_\theta^2 & 0 & 0 & 0 & 2 s_\theta c_\theta \\\ 0 & 0 & 1 & 0 & 0 & 0 \\\ 0 & 0 & 0 & c_\theta & s_\theta & 0 \\\ 0 & 0 & 0 & -s_\theta & c_\theta & 0 \\\ c_\theta s_\theta & - c_\theta s_\theta & 0 & 0 & 0 & c_\theta^2-s_\theta^2 \end{bmatrix}$$ $$\boldsymbol{T_\alpha}(\alpha_e) = \begin{bmatrix} 1 & 0 & 0 & 0 & 0 & 0 \\\ 0 & c_\alpha^2 & s_\alpha^2 & -2c_\alpha s_\alpha & 0 & 0 \\\ 0 & s_\alpha^2 & c_\alpha^2 & 2 c_\alpha s_\alpha & 0 & 0 \\\ 0 & c_\alpha s_\alpha & - c_\alpha s_\alpha & c_\alpha^2-s_\alpha^2 & 0 & 0 \\\ 0 & 0 & 0 & 0 & c_\alpha & s_\alpha \\\ 0 & 0 & 0 & 0 & -s_\alpha & c_\alpha \end{bmatrix}$$

where $c_\theta = \cos\theta_e$, $s_\theta = \sin\theta_e$, $c_\alpha = \cos\alpha_e$, $s_\alpha = \sin\alpha_e$.

Sensitivity analysis

The variable updating scheme is the Method of Moving Asymptotes - MMA (SVANBERG, 1987). It is then necessary to calculate at each iteration the sensitivities of the compliance with respect to the design variables:

$$\frac{\partial c}{\partial \rho_e} = -p \rho_e^{p-1} \boldsymbol{u_e^T} \boldsymbol{k_0} \boldsymbol{u_e} = -\frac{p}{\rho_e} \underbrace{\rho_e^{p} \boldsymbol{u_e^T} \boldsymbol{k_0} \boldsymbol{u_e}}_{\substack{\text{element} \ {\text{strain energy}}}}$$

$$\frac{\partial c}{\partial \theta_e} = -\rho_e^p \boldsymbol{u_e^T} \frac{\partial \boldsymbol{k_0}}{\partial \theta_e} \boldsymbol{u_e^T}$$

$$\frac{\partial c}{\partial \alpha_e} = -\rho_e^p \boldsymbol{u_e^T} \frac{\partial \boldsymbol{k_0}}{\partial \alpha_e} \boldsymbol{u_e^T}$$

The derivatives $\frac{\partial \boldsymbol{k_0}}{\partial \theta_e}$ and $\frac{\partial \boldsymbol{k_0}}{\partial \alpha_e}$ need to be integrated since these matrices are not directly accessible as Ansys results. Each integral was numerically evaluated with 2-point Gaussian quadrature.

$$\frac{\partial \boldsymbol{k_0}}{\partial \theta_e} (\theta_e, \alpha_e) = \iiint \boldsymbol{B_e^T} \boldsymbol{T_\alpha} \left( \frac{\partial \boldsymbol{T_\theta}}{\partial \theta_e} \boldsymbol{C} \boldsymbol{T_\theta^T} + \boldsymbol{T_\theta} \boldsymbol{C} \frac{\partial \boldsymbol{T_\theta^T}}{\partial\theta_e} \right) \boldsymbol{T_\alpha^T} \boldsymbol{B_e} d\boldsymbol{\Omega}$$

$$\frac{\partial \boldsymbol{k_0}}{\partial \alpha_e} (\theta_e, \alpha_e) = \iiint \boldsymbol{B_e^T} \left( \frac{\partial \boldsymbol{T_\alpha}}{\partial \alpha_e} \boldsymbol{T_\theta} \boldsymbol{C} \boldsymbol{T_\theta^T} \boldsymbol{T_\alpha^T} + \boldsymbol{T_\alpha} \boldsymbol{T_\theta} \boldsymbol{C} \boldsymbol{T_\theta^T} \frac{\partial \boldsymbol{T_\alpha^T}}{\partial \alpha_e} \right) \boldsymbol{B_e} d\boldsymbol{\Omega}$$

Multiple load cases

For multiple load cases, the compliances are aggregated using a $n$-norm, which is differentiable:

$$\begin{aligned} \min_{\boldsymbol\rho,\boldsymbol\theta,\boldsymbol\alpha} C(\boldsymbol\rho,\boldsymbol\theta,\boldsymbol\alpha) & = \left(\sum_{i \in LC} c_i(\boldsymbol\rho,\boldsymbol\theta,\boldsymbol\alpha)^n\right)^\frac{1}{n} \\\ & = \left(\sum_{i \in LC} \left(\sum_e \rho_e^p \boldsymbol{u_{e,i}^T} \boldsymbol{k_0}(\theta_e,\alpha_e) \boldsymbol{u_{e,i}}\right)^n\right)^\frac{1}{n} \\[10pt] \textrm{s.t. } & \begin{cases} \frac{V(\boldsymbol\rho)}{V_0} \leq f \\\ \boldsymbol{KU} = \boldsymbol{F} \\\ 0 < \rho_{min} \leq \boldsymbol\rho \leq 1 \\\ -\frac{\pi}{2} \leq \boldsymbol\theta \leq \frac{\pi}{2} \\\ -\frac{\pi}{2} \leq \boldsymbol\alpha \leq \frac{\pi}{2} \end{cases} \end{aligned}$$

The new sensitivities are:

$$\frac{\partial C}{\partial \cdot} = \sum_{i \in LC} c_i^{n-1} C^{1-n} \frac{\partial c_i}{\partial \cdot}$$

Continuation method

To facilitate the convergence and avoid local minima, a continuation method in is applied on the penalization factor $p$ as in Castro Almeida (2023). Instead of having a fixed value throughout the whole optimization, it starts at $p = 1$ and is increased each time a convergence in compliance is achieved. The stopping criterion for the continuation is the greyness level of the design, i.e., when the proportion of elements that are neither void nor filled is below a certain level.

$CO_2$ footprint assessment

The environmental impact of the structure is measured in terms of the mass of $CO_2$ emitted during material production and during its use in a long distance aircraft (DURIEZ et al, 2022).

Firstly, the material density $\rho$ was calculated from the fiber and matrix densities $\rho_f$ and $\rho_m$:

$$\rho = \rho_f V_f + \rho_m (1-V_f)$$

The impact of the material production $CO_{2,mat}$ depends on the total mass $M$ and the $CO_2$ intensity of the material $CO_{2,mat}^i$ (mass of $CO_2$ emitted per mass of material):

$$CO_{2,mat} = M \cdot CO_{2,mat}^i$$

where $CO_{2,mat}^i$ depends on the $CO_2$ intensities of the fiber and matrix, $CO_{2,f}^i$ and $CO_{2,m}^i$:

$$CO_{2,mat}^i = \frac{\rho_f V_f CO_{2,f}^i + \rho_m (1-V_f) CO_{2,m}^i}{\rho}$$

The impact of the use phase $CO_{2,use}$ is calculated as the amount of emissions that would be saved if the component was lighter. Reducing the mass by 1 kg in a long distance aircraft leads to a reduction of 98.8 $tCO_2$ during its lifetime:

$$CO_{2,use} = M \cdot 98.8 \mathrm{tCO_2/kg}$$

The value used to compare different designs is the total footprint $CO_{2,tot}$:

$$CO_{2,tot} = CO_{2,mat} + CO_{2,use}$$

Dependencies

The code was tested with the following libraries in Python >= 3.9:

• NumPy >= 1.21.5
• SciPy >= 1.6.2
• Matplotlib >= 3.5.1
• jsonpickle >= 3.0.2
• pyansys 2023.2.11:
  • ansys-mapdl-core
  • ansys-dpf-core

Examples may have additional dependencies:

• mpi4py 3.0.1
• niceplots 2.4.0
• pyvista 0.38.6

Examples

• SimpleExample.ipynb: Jupyter notebook with an example of 2D and 3D optimizations
• SIMP.ipynb, Bracket_SIMP.ipynb: examples of using the SIMP method for 3D optimizations
• global3d.py: example of a complete 3D optimization. Launches multiple optimizations with different materials. Results in examples/global3d.out, visualized with global3d_plots.py
• NaturalFibers.ipynb: Jupyter notebook comparing different materials
• bridge.py: example of a complete 2D optimization. Uses MPI to launch parallel processes with different initial orientations
• Bracket_material_selection.ipynb, Bracket.ipynb, Bracket_printing_direction, Bracket_refine: Jupyter notebook with the optimization steps for the design of a 3D structure

Model files

• For 2D optimization: use 4-node 2D quad elements (PLANE182), with KEYOPT(3) = 3 (plane stress with thk)
• For 3D optimization: use 8-node 3D hex elements (SOLID185)

Usage

Minimal example of an optimization of the model models/mbb3d.db made of bamboo and cellulose with a volume fraction of 0.3. Results are saved in the folder results/

The next sections present all available functions

from optim import TopOpt, Post2D, Post3D

# -------------------- Define materials -------------------
# {t/mm^3, MPa, -, kgCO2/kg}
bamboo     = {'rho': 700e-12, 'E': 17.5e3, 'v': 0.04, 'CO2': 1.0565}
cellulose  = {'rho': 990e-12, 'E': 3.25e3, 'v': 0.355, 'CO2': 3.8}
Vfiber  = 0.5

Ex, Ey, nuxy, nuyz, Gxy, rho, CO2mat = TopOpt.rule_mixtures(fiber=bamboo, matrix=cellulose, Vfiber=Vfiber)

# --------------------- Define problem --------------------
solver = TopOpt(inputfile='models/mbb3d.db', res_dir='results/', dim='3D_layer', jobname='3d')
solver.set_material(Ex=Ex, Ey=Ey, nuxy=nuxy, nuyz=nuxy, Gxy=Gxy)
solver.set_volfrac(0.3)
solver.set_filters(r_rho=8, r_theta=20)
solver.set_initial_conditions('random')

# ---------------------- Run and save ---------------------
solver.run()
solver.save()

# ---------------------- Visualization --------------------
post = Post3D(solver)
post.plot_convergence()
post.plot(colorful=False)

Class TopOpt

Material properties

• TopOpt.rule_mixtures(fiber, matrix, Vfiber)

  Returns Ex, Ey, nuxy, nuyz, Gxy, rho, CO2mat by the rule of mixtures for a material with fiber volume fraction Vfiber. Components fiber and matrix are given as dictionaries with fields 'rho', 'E', 'v', 'CO2'

Problem definition

• TopOpt(inputfile, res_dir, load_cases=None, dim='3D_layer', jobname='file', echo=True)
  • inputfile: path to .db file
  • res_dir: path to folder to store results
  • load_cases: tuple/list of paths to load step files (.sn generated by LSWRITE command - does not need to follow Ansys nomenclature convention). Optional for single load case, .db is executed if no load step given
  • dim: optimization type
    • 'SIMP2D' and 'SIMP3D': SIMP method, 2D or 3D optimization
    • '2D': 2D optimization
    • '3D_layer': 3D optimization, structure will be printed in layers and fibers can rotate in the plane $x'y'$ (defined by the normal vector print_direction)
    • '3D_free': 3D optimization, fiber orientations defined by rotations around $z$ and $x$ respectively
  • jobname: subfolder of TopOpt.res_dir to store results for this optim. Default: no subfolder, stores results directly on TopOpt.res_dir
  • echo: print compliance at each iteration?

All setter functions are optional, the optimization can be performed with the default parameters

• set_material(Ex=1, Ey=1, nuxy=0.3, nuyz=0.3, Gxy=1/(2*(1+0.3)))

  Defines material properties, considered transverse isotropic with symmetry plane $yz$

• set_volfrac(volfrac=0.3)

  Defines the volume fraction constraint for the optimization

• set_filters(r_rho=0, r_theta=0)

  Defines the filters applied on each iteration, defaults to no filtering

  • r_rho: radius of the density filter (adjusts minimum feature size)
  • r_theta: radius of the orientation filter (adjusts fiber curvature)

• set_solid_elem(solid_elem=[])

  List of elements whose densities will be fixed on 1. Indexing starting at 0

• set_print_direction(print_direction=(0.,0.,1.), overhang_angle=45, overhang_constraint=False)

  Defines the printing direction, to verify if the structure is printable without adding supports. Depends on r_rho, so should be called after set_filters()

  • print_direction: vector pointing upwards in the printing coordinate system. Does not need to be unitary
  • overhang_angle: minimum self-supporting angle. Minimum angle with respect to the horizontal at which features may be created
  • overhang_constraint: add overhang constraint to the optimization? Results in self-supported structures

• set_initial_conditions(angle_type='random', theta0=0, alpha0=0)

  • angle_type: method for setting the initial orientations

    • 'fix': initial orientations are given
    • 'noise': gaussian distribution around the given values
    • 'random': random orientation for each element
    • 'principal': initial orientations follow the principal stress directions considering the whole domain with an isotropic material

  • theta0: initial orientation (around $z'$) of the fibers, in degrees. Only used with 'fix' and 'noise'

  • alpha0: initial orientation (around $x'$) of the fibers, in degrees. Only used with 'fix' and 'noise'

• set_optim_options(max_iter=200, tol=0, continuation=False, move=0.2, max_grey=0.3, void_thr=0.1, filled_thr=0.9)

  • max_iter: maximum number of iterations
  • tol: stopping criterion, relative change in the objective function. Defaults at 0, i.e., will run until max_iter
  • continuation: use a continuation method in the penalization factor?
  • move: move limit for variables updating, given as fraction of the allowable range
  • max_grey: stopping criterion for continuation, maximum fraction of grey elements, i.e. nor void nor filled
  • void_thr: elements are considered void if they have density less or equal void_thr
  • filled_thr: elements are considered void if they have density greater or equal filled_thr

Run the optimization

• run()

  Runs the optimization, saves all results within the TopOpt object

• print_timing()

  Prints the optimization timing:

  • total elapsed time
  • time spent solving the finite element model
  • time spent calculating sensitivities
  • time spent updating variables

• save(filename=None)

  Saves object into a JSON file

Design evaluation

• TopOpt.load(filename)

  Returns TopOpt object from JSON file created by save()

• get_printability()

  Returns the printability score of the final design (fraction of self-supported elements) and a boolean list indicating whether each element is self-supported

• get_greyness()

  Returns the greyness of the final design (fraction of grey elements)

• get_mass(dens)

  Returns the mass of the final design

• get_max_disp(load_case=1)

  Returns the maximum nodal displacement for the load_case-th load case, indexing starting on 1

• get_CO2_footprint(dens, CO2mat, CO2veh)

  Returns the $CO_2$ footprint of the final design

  • dens: material density
  • CO2mat: mass $CO_2$ emmited per mass material (material production)
  • CO2veh: mass $CO_2$ emitted per mass material during life (use in a vehicle) = mass fuel per mass transported per lifetime * service life * mass $CO_2$ emmited per mass fuel

• fea(x)

  Returns the aggregated compliance obtained for a specific set of design variables x. Useful to evaluate a design obtained from other optimization, but using the current load cases (given the meshes and design variables are the same)

Class PostProcessor

For 2D optimizations: Post2D(solver)

For 3D optimizations: Post3D(solver)

• plot_convergence(start_iter=0, penal=False, filename=None, save=True)

  Simple plot of the convergence history

  • start_iter: first iteration shown, may be used to eliminate first values that break the compliance scale
  • penal: show subplot with penalization factor evolution?

• plot(iteration=-1, colorful=True, printability=False, elev=None, azim=None, domain_stl=None, filename=None, save=True, fig=None, ax=None, zoom=None)

  Plots the configuration at iteration iteration

  • colorful: color arrows based on their orientation? RGB values based on the vector components:
    • $x$: blue
    • $y$: green
    • $z$: red
  • zoom: only for Post2D. Inner plot with zoom to a specific area can be added by passing a dict with fields
    • 'xmin', 'xmax', 'ymin', 'ymax': area of interest (in model length units)
    • 'xpos', 'ypos', 'width', 'height': position and size of the zoomed plot (fraction of the original axes)
    • 'color': color of the outline boxes
  • printability: only for Post3D. Color arrows according to their printability? Self-supported elements are shown in black, non-self-supported elements are shown in red. If True, ignores colorful
  • elev, azim: only for Post3D. Angles defining the point of view
  • domain_stl: only for Post3D. Filename of the .stl file with the original domain. If defined, plots an outline of the domain

• animate(filename=None, colorful=True, printability=False, elev=None, azim=None)

  Creates an animation where each frame is the plot() for an iteration

• plot_fibers(iteration=-1, layer=None, elev=None, azim=None, filename=None, save=True, fig=None, ax=None)

  Plots continuous fibers obtained as streamlines of the orientation field at iteration iteration

  • layer: only for Post3D. If None, plots all layers in a 3D plot, colored from blue (bottom layers) to red (top layers). If a tuple of integers, plots the selected layers in a 3D plot with the same color scheme. If integer, plots the selected layer in a 2D plot, analogous to Post2D
  • elev, azim: only for Post3D. Angles defining the point of view

• animate_fibers(layer=None, filename=None)

  Creates an animation where each frame is the plot_fibers() for an iteration

Functions specific to Post2D

• plot_density(iteration=-1, filename=None, save=True, fig=None, ax=None)

  Plots the density distribution

Functions specific to Post3D

• plot_layer_density(iteration=-1, layer=0, filename=None, save=True, fig=None, ax=None)

  Plots the deinsties in the layer-th layer, analogous to plot_density() for Plot2D

• plot_layer(iteration=-1, layer=0, colorful=False, printability=False, filename=None, save=True, fig=None, ax=None, zoom=None)

  Plots the layer-th layer, analogous to plot() for Plot2D

• animate_layer(layer=0, colorful=False, filename=None)

  Creates an animation where each frame is the plot_layer(layer) for a iteration

• animate_print(fibers=True, colorful=False, printability=False, filename=None)

  Creates an animation where each frame is a layer plot in the final configuration. If fibers is True, uses plot_fibers(layer) and if fibers is False, cuses plot_layer(layer)

• plot_iso(self, iteration=-1, threshold=0.8, elev=30, azim=-60, filename=None)

  Plots the isosurface of density greater or equal to threshold. Elemental data is interpolated to nodes by PyDPF (Ansys Data Procssing Framework), which needs the results stored in the .rst file.

References

• A. Castro Almeida, E. Duriez, F. Lachaud, J. Morlier. New topology optimization for low CO2 footprint AFP composite structures, Poster session, WCSMO 2023.
• R. M. Christensen. Tensor transformations and failure criteria for the analysis of fiber composite materials, Journal of Composite Materials 22.9, 874-897, 1988.
• E. Duriez, J. Morlier, C. Azzaro-Pantel, M. Charlotte. Ecodesign with topology optimization, Procedia CIRP, Elsevier, 454-459, 2022.
• M. Schmidt, L. Couret, C. Gout, C. Pedersen. Structural topology optimization with smoothly varying fiber orientations, Structural and Multidisciplinary Optimization, Springer, 3105-3126, 2020.
• O. Sigmund. A 99 line topology optimization code written in Matlab, Structural and multidisciplinary optimization, Springer, 120-127, 2001.
• K. Svanberg. The method of moving asymptotes—a new method for structural optimization, International journal for numerical methods in engineering, Wiley Online Library, 359-373, 1987.