Enhanced design methods for pressure-actuated cellular structures

Abstract

A biologically inspired concept for shape-variable structures is investigated that can be utilized for automobile, aerospace, power and architecture applications. Similar to the motion of nastic plants, the actuation principle of the energy efficient and lightweight pressure-actuated cellular structures (PACS) bases on the controlled volumetric expansion of pressurized volumes. The advantages of fluidic actuators are combined with the possibility to generate structures that deform between predefined form functions. A holistic process chain is developed in the previous work, which enables to completely design and size PACS from the idea of application and the property analysis up to the design for production of the 3d-structure. In numerical and experimental investigations the so far used basic cell geometry could be identified to cause some conceptual issues. Stress peaks and gaps at the structure’s surface, inaccuracy of deformation and limitations regarding the shape-changing potentials are thereby determined. The herein presented novel approach for the shaping of PACS cells provides relief for all of these four issues. Numerical investigations at different levels of abstraction are performed to confirm the benefits of the modified cell arrangement and the related avoidance of gaps and to evaluate the rise of deformability by at least 50%. The resulting increase of the design and operating envelopes significantly enhances the value of this concept for its applications.