Employing additive manufacturing to create reusable TPU formworks for casting topologically optimized facade panels

Concrete is a building material with excellent structural qualities that can be molded into any shape. However, it is also responsible for approximately 8% of the world's total greenhouse gas emissions. There is a need to reduce material consumption during the design and construction of concrete structures. This research proposes a new manufacturing workflow for the design and fabrication of precast façade panels. Structural topology optimization (TO) is used to design perforated façade panels with optimized material distribution according to the panel's connection to a sub-structure. Structural simulations are conducted to validate the stiffness and strength of the TO panels. Finally, flexible Thermoplastic Polyurethane (TPU) molds are additively manufactured and repeatedly cast. The study results show that TO decreases the panels' volumes within a predefined WWR by anywhere from 23% to 30% of the total volume, while maintaining satisfactory structural performance. Additionally, the study demonstrates the potential of additively manufactured TPU molds for the repeatable casting of concrete while accommodating undercuts in the complex cast geometries. This study is novel as TO has not previously been used for designing façade panels. Furthermore, the use of 3D printed flexible molds made of TPU for repeatable casting of geometries is still in its early stages, with only one publication reporting the investigations at the time of writing this article. This workflow is innovative as a whole as it addresses material saving in the design phase through TO, as well as the creation of reusable 3D printed formworks in the fabrication phase.