Browsing by Author "Cheng, Tiffany"

Now showing 1 - 4 of 4

Open Access
Cross-sectional 4D-printing : upscaling self-shaping structures with differentiated material properties inspired by the large-flowered butterwort (Pinguicula grandiflora)
(2023) Sahin, Ekin Sila; Cheng, Tiffany; Wood, Dylan; Tahouni, Yasaman; Poppinga, Simon; Thielen, Marc; Speck, Thomas; Menges, Achim
Extrusion-based 4D-printing, which is an emerging field within additive manufacturing, has enabled the technical transfer of bioinspired self-shaping mechanisms by emulating the functional morphology of motile plant structures (e.g., leaves, petals, capsules). However, restricted by the layer-by-layer extrusion process, much of the resulting works are simplified abstractions of the pinecone scale’s bilayer structure. This paper presents a new method of 4D-printing by rotating the printed axis of the bilayers, which enables the design and fabrication of self-shaping monomaterial systems in cross sections. This research introduces a computational workflow for programming, simulating, and 4D-printing differentiated cross sections with multilayered mechanical properties. Taking inspiration from the large-flowered butterwort (Pinguicula grandiflora), which shows the formation of depressions on its trap leaves upon contact with prey, we investigate the depression formation of bioinspired 4D-printed test structures by varying each depth layer. Cross-sectional 4D-printing expands the design space of bioinspired bilayer mechanisms beyond the XY plane, allows more control in tuning their self-shaping properties, and paves the way toward large-scale 4D-printed structures with high-resolution programmability.
Open Access
Material programming for 4D-printing : architected mesostructures for bioinspired self-shaping
(Stuttgart : Institute for Computational Design and Construction, University of Stuttgart, 2024) Cheng, Tiffany; Menges, Achim (Prof.)
Material, structure, and function are tightly intertwined in nature. The movement of plants, for instance, is often encoded through the structuring of tissue materials, allowing plants to change shape over a range of spatial-temporal scales when powered by environmental stimuli. In contrast, the human practice of design and production relies on discrete parts for sensing, actuation, or control. Individual components are sourced worldwide to be assembled into complex systems that demand significant energy for operation. This divergence from nature's strategy is changing the climate and contributing to environmental degradation. This dissertation presents a bioinspired approach to design and fabrication as an alternative to conventional methods of making. The interplay of cellulosic materials, mesostructures, and adaptive response is managed through the developed computational fabrication framework, resulting in hygromorphic 4D-printed systems powered by the free-flowing moisture inputs of the environment. The framework is also generalizable to diverse materials and processes, as showcased through the upscaling of the methods to an industrial robot platform to construct self-shaping hybrid materials systems. Finally, the framework's applicability is proven through the transfer of design principles from biology to self-adjusting wearables for the body and weather-responsive facades for buildings. The presented material programming approach has wide-ranging potential across scales and disciplines, demonstrating that by harnessing biobased materials, material-efficient structures, and environmental input for energy, bioinspired 4D-printing can overcome the competing resources between nature and technology.
Open Access
Plants as inspiration for material-based sensing and actuation in soft robots and machines
(2023) Speck, Thomas; Cheng, Tiffany; Klimm, Frederike; Menges, Achim; Poppinga, Simon; Speck, Olga; Tahouni, Yasaman; Tauber, Falk; Thielen, Marc
Because plants are considered immobile, they remain underrepresented as concept generators for soft robots and soft machines. However, plants show a great variety of movements exclusively based on elastic deformation of regions within their moving organs. The absence of gliding parts, as found in the joints of vertebrates and insects, prevents stress concentration and attrition. Since plants have no central control unit (brain), stimulus-sensing, decision-making and reaction usually take place noncentrally in the hierarchically structured materials systems of the moving organs, in what can be regarded as an example of physical intelligence. These characteristics make plants interesting models for a new group of soft robots and soft machines that differ fundamentally from those inspired by animals. The potential of such plant-inspired soft robots and machines is shown in six examples and is illustrated by examples applied in architecture and medicine.
Open Access
Weather-responsive adaptive shading through biobased and bioinspired hygromorphic 4D-printing
(2024) Cheng, Tiffany; Tahouni, Yasaman; Sahin, Ekin Sila; Ulrich, Kim; Lajewski, Silvia; Bonten, Christian; Wood, Dylan; Rühe, Jürgen; Speck, Thomas; Menges, Achim
In response to the global challenge of reducing carbon emissions and energy consumption from regulating indoor climates, we investigate the applicability of biobased cellulosic materials and bioinspired 4D-printing for weather-responsive adaptive shading in building facades. Cellulose is an abundantly available natural material resource that exhibits hygromorphic actuation potential when used in 4D-printing to emulate motile plant structures in bioinspired bilayers. Three key aspects are addressed: (i) examining the motion response of 4D-printed hygromorphic bilayers to both temperature and relative humidity, (ii) verifying the responsiveness of self-shaping shading elements in lab-generated conditions as well as under daily and seasonal weather conditions for over a year, and (iii) deploying the adaptive shading system for testing in a real building facade by upscaling the 4D-printing manufacturing process. This study demonstrates that hygromorphic bilayers can be utilized for weather-responsive facades and that the presented system is architecturally scalable in quantity. Bioinspired 4D-printing and biobased cellulosic materials offer a resource-efficient and energy-autonomous solution for adaptive shading, with potential contributions towards indoor climate regulation and climate change mitigation.