Hello! I’m hoping to use Peregrine for truss optimization but with constant cross section. I understand I can specify the minimum cross section through MinA, but is there a way to keep the cross section constant and have the optimizer vary only connectivity of nodes in the ground structure?
Due to the type of optimization being undertaken, fixing the member designation is not possible. The layout optimization varies member area over a continua, with connectivity being indirectly determined by allowing the areas to become zero if required. To determine the minimum volume layout using fixed member areas would require the problem to be posed in a different way (one that’s potentially much more computationally expensive).
There are plenty of things you could could try with the Filter and Construct Topology components to try to ensure members of the final solution have a similar area, but these areas wouldn’t necessarily be constant. You could also of course modify the output geometry (either determined via layout optimization, or through geometry optimization of your own layout) so that all members have area equal to that of the largest member. This wouldn’t be a minimum volume solution in the truest sense, but would likely be a big improvement over a hand-determined geometry.
If you’re interested in the optimization methods used in Peregrine, there are a number of academic articles discussing the topic. A good place to start is this paper by He et al: Optimization-driven conceptual design of truss structures in a parametric modelling environment - ScienceDirect