BioBuild RP4.1

Adaptive building envelopes respond autonomously to the position of the sun, temperature, and weather, and can thus reduce the energy demand of buildings. A key challenge is to implement the required motion in a durable, low-wear manner. Owing to their high strength combined with elastic deformability, fiber-reinforced polymers (FRPs) are particularly well suited for load-bearing compliant mechanisms that do not require conventional mechanical hinges. However, their fiber reinforcement usually limits deformation to uniaxial bending with a single-curved geometry. Double-curved shape changes have therefore hardly been achievable with conventional FRP structures to date.

Subproject RP4.1 within the DFG Research Training Group GRK 3123 “BioBuild” of the Universities of Stuttgart and Freiburg investigates how this limitation can be overcome. Previous work has shown that elastomeric interlayers reduce material stresses during the bending of FRP components and thereby increase their fatigue strength. Building on these findings, RP4.1 integrates elastically deformable zones into the composite in a targeted manner to enable non-developable, double-curved geometries.

The approach is based on a UV-reactive elastomer system that is applied as a film and can be cross-linked to different degrees. The exposure time determines the stiffness, while photomasks define the geometry of the flexible zones. The pattern of stiff and flexible zones governs how the component deforms. Particular attention is paid to the transition between the elastomeric zone and the composite, as it represents a potential weak point during deformation. In parallel, the Materials Testing Institute (MPA) is extending a microplane-based finite element model in MASA, a software developed at the University of Stuttgart, to predict the interlaminar adhesion and the deformation behavior of the new multilayer materials. Bio-based resins are contributed by the research group of Prof. Hartmann at the University of Freiburg. The aim is a method for developing fiber composite components for adaptive facades with diverse, precisely adjustable motion patterns.

Project Duration
April 2026 – March 2030

Project Team
University of Stuttgart, Institute for Textile and Fiber Technologies (ITFT)
Bedi Berk Karanlik, Dr.-Ing. Larissa Born

University of Stuttgart, Materials Testing Institute (MPA)
Saeid Saberi Alkouhi, Dr.-Ing. Serena Gambarelli

University of Freiburg, Institute of Macromolecular Chemistry
Prof. Dr. Laura Hartmann

Funding
The Research Training Group GRK 3123 “BioBuild – Bio-inspired Materials and Systems for Responsive Building Components” is funded by the German Research Foundation (DFG) under the grant numbers GRK 3123/1 – 543816109 and EXC 2120/2 – 390831618.