Modular-topology optimization for additive manufacturing of reusable mechanisms

Abstract

Modular designs have gained popularity because they can generally address manufacturing efficiency, reusability, and sustainability concerns. Here, we contribute to the growing field by proposing a fully automatic design method for modules utilized in several products. Our manufacturing-aware procedure is composed of three consecutive steps: (i) free-material optimization for obtaining the optimal spatially distributed elasticity tensors, (ii) hierarchical clustering of the stiffness tensors directly into a given number of modules while allowing for their flipping, and (iii) single-scale topology optimization with manufacturing aspects to design the final topology of mechanically compatible modules. These aspects include connectivity constraints to ensure the integrity of all modules and the three-field projection to account for manufacturing inaccuracies. We illustrate the entire procedure with the design and fabrication of eight different reusable modules assembled into well-functioning modular inverter and gripper mechanisms. These mechanisms were 3D printed and subjected to mechanical testing using an in-house testing machine and digital image correlation. The experimental results show excellent agreement between the predicted and observed behavior and highlight the potential of the method for scalable additive manufacturing.