Computer aided generative design with overall thickness control to facilitate manufacturing and structural performance
Methods, systems, and apparatus, including medium-encoded computer program products, for computer aided design of physical structures using generative design processes, where the three dimensional (3D) models of the physical structures are produced in accordance with a design criterion that limits a minimum thickness of the generatively designed 3D models, include: obtaining a design space for an object to be manufactured and one or more design criteria including a thickness constraint; iteratively modifying a generatively designed 3D shape of the modeled object in the design space in accordance with the one or more design criteria, including measuring a current thickness for the 3D shape using an overall relationship of a volume of the 3D shape with respect to a surface area of the 3D shape; and providing the generatively designed model for use in manufacturing the physical structure using one or more computer-controlled manufacturing systems.
1 . A method comprising:
obtaining one or more boundary conditions and one or more design criteria, including a minimum thickness value, for a modeled object to be produced;
iteratively modifying a geometry of a three-dimensional shape of the modeled object in accordance with the one or more design criteria and the one or more boundary conditions to produce a three-dimensional computer-aided design model of the modeled object, wherein the geometry of the three dimensional shape is represented in computer memory by a discretized volume having density values or distance-to-boundary values assigned to discrete cells of the discretized volume, and the iteratively modifying comprises, in each of multiple iterations of the iteratively modifying, performing operations comprising
measuring a current thickness of the modeled object by calculating a non-dimensional quantity that uses a current volume and a current surface area of the three-dimensional shape defined by the density values or the distance-to-boundary values assigned to the discrete cells of the discretized volume in the computer memory, wherein the calculating does not include evaluating thickness at multiple points within the three-dimensional shape, thereby reducing computation time for the measuring and avoiding any computational failure at an individual point within the three-dimensional shape, and
modifying the density values or the distance-to-boundary values assigned to the discrete cells of the discretized volume in the computer memory to update the geometry of the three-dimensional shape based on a difference between the current thickness and the minimum thickness value, making one or more portions of the three-dimensional shape thinner while also keeping the current thickness of the modeled object above the minimum thickness value, thereby preventing production of thin regions in the three-dimensional computer-aided design model that would result in structural performance degradation or manufacturing difficulties for the modeled object,
until the geometry of the three-dimensional shape converges to a stable solution or a predefined number of shape modification iterations have been performed; and
providing the three-dimensional computer-aided design model of the modeled object.
2 . The method of claim 1 , further comprising obtaining the minimum thickness value by calculating a single global measure of thickness for a sample model.
3 . The method of claim 1 , further comprising obtaining the minimum thickness value including receiving a user input specifying a percentage of an input model.
4 . The method of claim 1 , wherein the obtaining comprises obtaining the one or more boundary conditions using a set of input solids.
5 . The method of claim 4 , wherein the iteratively modifying comprises modifying a topology of the three-dimensional shape in addition to the geometry of the three-dimensional shape.
6 . The method of claim 5 , wherein the iteratively modifying uses one or more level-set based topology optimization methods, and a same gradient used in the one or more level-set based topology optimization methods for an objective of the one or more design criteria is used as a proxy for a thickness control gradient.
7 . The method of claim 1 , wherein the current thickness value is a dimensionless quantity normalized with respect to a sphere.
8 . The method of claim 7 , wherein a lower limit for the dimensionless quantity is dependent on an initial three-dimensional shape of the modeled object.
9 . The method of claim 8 , wherein the iteratively modifying comprises a second set of iterations following a first set of iterations, the first set of iterations comprises the multiple iterations of the iteratively modifying, and the second set of iterations comprises applying a local thickness constraint using the minimum thickness value.
10 . A system comprising:
a non-transitory storage medium having instructions stored thereon; and
one or more data processing apparatus configured to run the instructions to perform operations comprising:
obtaining one or more boundary conditions and one or more design criteria, including a minimum thickness value, for a modeled object to be produced;
iteratively modifying a geometry of a three-dimensional shape of the modeled object in accordance with the one or more design criteria and the one or more boundary conditions to produce a three-dimensional computer-aided design model of the modeled object, wherein the geometry of the three dimensional shape is represented in computer memory by a discretized volume having density values or distance-to-boundary values assigned to discrete cells of the discretized volume, and the iteratively modifying comprises, in each of multiple iterations of the iteratively modifying, performing operations comprising
measuring a current thickness of the modeled object by calculating a non-dimensional quantity that uses a current volume and a current surface area of the three-dimensional shape defined by the density values or the distance-to-boundary values assigned to the discrete cells of the discretized volume in the computer memory, wherein the calculating does not include evaluating thickness at multiple points within the three-dimensional shape, thereby reducing computation time for the measuring and avoiding any computational failure at an individual point within the three-dimensional shape, and
modifying the density values or the distance-to-boundary values assigned to the discrete cells of the discretized volume in the computer memory to update the geometry of the three-dimensional shape based on a difference between the current thickness and the minimum thickness value, making one or more portions of the three-dimensional shape thinner while also keeping the current thickness of the modeled object above the minimum thickness value, thereby preventing production of thin regions in the three-dimensional computer-aided design model that would result in structural performance degradation or manufacturing difficulties for the modeled object,
until the geometry of the three-dimensional shape converges to a stable solution or a predefined number of shape modification iterations have been performed; and
providing the three-dimensional computer-aided design model of the modeled object.
11 . The system of claim 10 , wherein the operations further comprise obtaining the minimum thickness value by calculating a single global measure of thickness for a sample model.
12 . The system of claim 10 , wherein the operations further comprise obtaining the minimum thickness value including receiving a user input specifying a percentage of an input model.
13 . The system of claim 10 , wherein the one or more data processing apparatus are configured to run the instructions to obtain the one or more boundary conditions using a set of input solids.
14 . The system of claim 13 , wherein the one or more data processing apparatus are configured to run the instructions to iteratively modify a topology of the three-dimensional shape in addition to the geometry of the three-dimensional shape.
15 . The system of claim 14 , wherein the iterative modification uses one or more level-set based topology optimization methods, and a same gradient used in the one or more level-set based topology optimization methods for an objective of the one or more design criteria is used as a proxy for a thickness control gradient.
16 . The system of claim 10 , wherein the current thickness value is a dimensionless quantity normalized with respect to a sphere.
17 . The system of claim 16 , wherein a lower limit for the dimensionless quantity is dependent on an initial three-dimensional shape of the modeled object.
18 . The system of claim 17 , wherein the iterative modification comprises a second set of iterations following a first set of iterations, the first set of iterations comprises the multiple iterations, and the one or more data processing apparatus are configured to run the instructions to apply a local thickness constraint using the minimum thickness value in the second set of iterations.