Surface-based Inflatables

Project Overview
Surface-based inflatables are composed of two thin layers of nearly inextensible sheet material joined together along carefully selected fusing curves. During inflation, pressure forces separate the two sheets to maximize the enclosed volume. The fusing curves restrict this expansion, leading to a spatially varying in-plane contraction and hence metric frustration. The inflated structure settles into a 3D equilibrium that balances pressure forces with the internal elastic forces of the sheets.
We present a computational framework for analyzing and designing surface-based inflatable structures with arbitrary fusing patterns. Our approach employs numerical homogenization to characterize the behavior of parametric families of periodic inflatable patch geometries, which can then be combined to tessellate the sheet with smoothly varying patterns. We propose a novel parametrization of the underlying deformation space that allows accurate, efficient, and systematical analysis of the stretching and bending behavior of inflated patches with potentially open boundaries.
We apply our homogenization algorithm to create a database of geometrically diverse fusing patterns spanning a wide range of material properties and deformation characteristics. This database is employed in an inverse design algorithm that solves for fusing curves to best approximate a given input target surface. Local patches are selected and blended to form a global network of curves based on a geometric flattening algorithm. These fusing curves are then further optimized to minimize the distance of the deployed structure to target surface. We show that this approach offers greater flexibility to approximate given target geometries compared to previous work while significantly improving structural performance.
Code

To compute the mechanical properties of different fusing curve patterns, we apply numerical homogenization and simulate unit cells of the fusing patterns under periodic boundary condition

Physics-based simulation of the deployment of several surface-based inflatables

We employ a two-scale optimization approach. If the coarse-scale optimization does not fully reproduce the target shape, we run a nested optimization with simulation in the loop to fine-tune the fusing curve geometry

We built physical prototypes to validate our design algorithms. Here we show the deployment process of two surface-based inflatables with the same target shape, but the first one is optimized using the parallel tube pattern while the second one is optimized using the Cosine Curve pattern family which covers a much larger range of mechanical properties. We see that the second structure approximate the target shape much closer and has better structural stability

Deployment process of other physical prototypes. The video is played at 3x speed

Computational Homogenization for Inverse Design of Surface-based Inflatables

Y. Ren; F. J. Panetta; S. Suzuki; U. Kusupati; F. Isvoranu et al. 

ACM Transactions on Graphics. 2024. Vol. 43, num. 4. DOI : 10.1145/3658125.

This work is built upon the inverse design framework introduced in a previous project from GCM, where the design algorithms focus on networks of parallel tubes. See the SIGGRAPH 2021 talk below for more details!

Computational Inverse Design of Surface-based Inflatables

J. Panetta; F. Isvoranu; T. Chen; E. Siefert; B. Roman et al. 

Acm Transactions On Graphics. 2021. Vol. 40, num. 4, p. 40. DOI : 10.1145/3450626.3459789.