Mastering Truss Structure Optimization with Tree Search (2023)

By: Gabriel E. Garayalde, Luca Rosafalco, Matteo Torzoni, Alberto Corigliano

Published in: Journal of Mechanical Design (J. Mech. Des.)
Paper No: MD-24-1369

Read the Full Paper (DOI: 10.1115/1.4068300)
Abstract

This study investigates the combined use of generative grammar rules and Monte Carlo Tree Search (MCTS) for optimizing truss structures. Our approach accommodates intermediate construction stages characteristic of progressive construction settings. We demonstrate the significant robustness and computational efficiency of our approach compared to alternative reinforcement learning frameworks from previous research activities, such as Q-learning or deep Q-learning.

These advantages stem from the ability of MCTS to strategically navigate large state spaces, leveraging the upper confidence bound for trees formula to effectively balance exploitation-exploration trade-offs. We also emphasize the importance of early decision nodes in the search tree, reflecting design choices crucial for highly performative solutions.

Additionally, we show how MCTS dynamically adapts to complex and extensive state spaces without significantly affecting solution quality. While the focus of this paper is on truss optimization, our findings suggest MCTS as a powerful tool for addressing other increasingly complex engineering applications.

Key Figures

Benchmark Problems
Illustration of the benchmark problems for truss optimization. Shows the starting configurations (s₀) and the corresponding optimal structures (sT) identified via exhaustive search for six different design domains, load cases, and boundary conditions.
Benchmark problems for truss optimization examples 1-6
MCTS Convergence (Case 4)
Impact of the exploration-exploitation parameter (alpha) on MCTS convergence for Case Study 4. This graph compares learning curves (Displacement vs. Episode) for alpha values from 0.1 to 0.5.
MCTS convergence comparison for different alpha values
MCTS Algorithm Flowchart
Visual explanation of the core MCTS algorithm employed in this research. Shows how the search tree is explored and updated through Selection, Expansion, Simulation, and Backpropagation steps to find optimal truss designs.
Flowchart of the Monte Carlo Tree Search algorithm

Keywords

agent-based design
computer-aided engineering
design optimization
design process
Machine learning

Topics

Design
Optimization
Trusses (Building)