Cross-Sectional 4D-Printing: Upscaling Self-Shaping Structures with Differentiated Material Properties Inspired by the Large-Flowered Butterwort (Pinguicula grandiflora)

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

Towards reconnecting bits of mind and atoms of hand

Thesis: S.M., Massachusetts Institute of Technology, Department of Architecture, 2018.Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages 70-71).Multi-sensory interaction with material is the source of embodied design knowledge in the process of creative design. Through bodily engagement with material in the process of making, the integration of thinking and doing - or mind and hand - results in generating iterative design solutions. While compute raided design (CAD) tools have brought various benefits to the field of design, such as speed and accuracy in modeling, their detachment from physical world eliminates the multi-sensory interaction between designer and material. I argue that in order to overcome the separation of design and making in the context of computer-aided design tools, we need to rethink the interfaces by which designers interact with the digital world. If we aim to bring back material interaction to the computer-aided design process, the material itself should become the interface between designer and computer. I propose Augmented Materials - defined as physical materials embedded with digital and computational capabilities- to fill the gap between physical and digital model making. By embedding functional components such as sensors, actuators and microcontrollers, directly within modules of physical interface, an integrated system emerges that can offer computational capabilities such as speed and precision of modeling, while allowing designers to engage in a hands-on multi-sensory interaction with material. I implement my thesis by introducing NURBSforms, a modular shape-changing interface that lets designers create NURBS-based curves and free-form surfaces in a physical form, just as easily as they do in CAD software. Each module of NURBSforms represents a base curve with variable curvature, with the amount of its curvature being controlled by the designer, and represented through real-time actuation of material. NURBSforms bridges between digital and physical model making by bringing digital capabilities such as such as real-time transformation, programmability, repeatability and reversibility to the physical modality. I implemented two modalities of interaction with NURBSforms, one using direct manipulation, and the other using gestural control. I conclude this work by evaluating NURBSforms interface based on two sets of user studies, and propose potential future developments of the project. My thesis contributes to the fields of Design and Human Computer Interaction by introducing Augmented Materials as a framework for creating computer-aided design interfaces that integrate physical and digital modalities. The NURBSforms interface can be further developed to be used as a pervasive design interface as well as a research and education tool. The software, hardware and fabrication techniques developed during implementation of NURBSforms can be applied to the research projects in the fields of architecture, product design, and HCI.S.M

NURBSforms: A Modular Shape-Changing Interface for Prototyping Curved Surfaces

© 2020 Association for Computing Machinery. We present NURBSforms: A modular shape-changing interface for prototyping curved surfaces. Each NURBSform module represents an edge of variable curvature that, when joined together with other modules, enables designers to construct surfaces and adjust their curvature interactively. NURBSform modules vary their curvature using active and passive shape memory materials: An embedded shape memory alloy (SMA) wire increases the curvature when heated, while an elastic material recovers the flat shape when the SMA wire cools down. A hall effect sensor on each module allows users to vary the curvature by adjusting the distance of their hand. In addition, NURBSforms provides functions across multiple modules, such as ?save', ?reset', and ?load', to facilitate design exploration. Since each module is self-contained and individually controllable, NURBSform modules scale well and can be connected into large networks of curves representing various geometries. By giving examples of different NURBSforms assemblies, we demonstrate how the modularity of NURBSforms, together with its integrated computational support, enables designers to quickly explore different versions of a shape in a single integrated design process

Design based on availability: Generative design and robotic fabrication workflow for non-standardized sheet metal with variable properties

Gefördert im Rahmen des Projekts DEA

Entwicklung bioinspirierter und selbstformender Orthesen per 4D-Druck

Unter dem Begriff „4D-Druck“ versteht man 3D-Druckverfahren, bei denen sich die erzeugten Werkstücke noch nach dem eigentlichen Druckverfahren durch externe Stimuli wie Temperatur oder Feuchtigkeit kontrolliert verformen. Die vierte Dimension ist somit die Zeit bis zum Erreichen einer späteren Gestalt. In diesem Artikel wird ein Ansatz zur Materialprogrammierung für selbstformende Materialsysteme auf der Grundlage biologischer Vorbilder vorgestellt, die per 4D-Druck erstellt werden. Der Ansatz basiert auf einem Berechnungsmodell zur Bestimmung mechanischer Eigenschaften und zur Gestaltung von Formänderungen. Mit Hilfe des 3D-Drucks werden mittels Extrusion die gewünschten Eigenschaften und Verhaltensweisen in einem Multi-Material- und Multi-Layer-System kodiert, das auf der Mesoskala mit einer maximalen Auflösung von 0,5 mm strukturiert ist. Die Methodik wurde anhand einer Fallstudie zum biomimetischen Design evaluiert. Hierbei wurde die Haftstrategie einer sich windenden Kletterpflanze, der Luftkartoffel (Dioscorea bulbifera), die auf der Generierung von Anpresskräften beruht, abstrahiert und auf eine durch 4D-Druck hergestellte Orthese übertragen. Die von den bioinspirierten Mechanismen erzeugten Anpresskräfte wurden anschließend mit Sensoren gemessen. Schließlich wurden die programmierten auf Selbstspannung beruhenden Anpresskräfte und die integrierte Multifunktionalität in eine Reihe prototypischer Handgelenk-Unterarm-Schienen in Form von Demonstratoren übertragen – ein gängiges orthopädisches Hilfsmittel für die Stellungskorrektur oder Entlastung dieses Körperabschnitts. Die aus dem vorgestellten Designansatz resultierenden per 4D-Druck entstandenen Materialsysteme unterstreichen die Vorteile der Übertragung biomimetischer Prinzipien auf orthopädische Hilfsmittel und darüber hinaus

Development of a Material Design Space for 4D-Printed Bio-Inspired Hygroscopically Actuated Bilayer Structures with Unequal Effective Layer Widths

(1) Significance of geometry for bio-inspired hygroscopically actuated bilayer structures is well studied and can be used to fine-tune curvatures in many existent material systems. We developed a material design space to find new material combinations that takes into account unequal effective widths of the layers, as commonly used in fused filament fabrication, and deflections under self-weight. (2) For this purpose, we adapted Timoshenko’s model for the curvature of bilayer strips and used an established hygromorphic 4D-printed bilayer system to validate its ability to predict curvatures in various experiments. (3) The combination of curvature evaluation with simple, linear beam deflection calculations leads to an analytical solution space to study influences of Young’s moduli, swelling strains and densities on deflection under self-weight and curvature under hygroscopic swelling. It shows that the choice of the ratio of Young’s moduli can be crucial for achieving a solution that is stable against production errors. (4) Under the assumption of linear material behavior, the presented development of a material design space allows selection or design of a suited material combination for application-specific, bio-inspired bilayer systems with unequal layer widths

Plants as inspiration for material-based sensing and actuation in soft robots and machines

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

Integrating ionic electroactive polymer actuators and sensors into adaptive building skins: potentials and limitations

Building envelopes separate the confined interior world engineered for human comfort and indoor activity from the exterior world with its uncontainable climatic forces and man-made immission. In the future, active, sustainable and lightweight building skins are needed to serve as an adaptive interface to govern the building-physical interactions between these two worlds. This article provides conceptual and experimental results regarding the integration of ionic electroactive polymer sensors and actuators into fabric membranes. The ultimate goal is to use this technology for adaptive membrane building skins. These devices have attracted high interest from industry and academia due to their small actuation voltages, relatively large actuation and sensing responses and their flexible and soft mechanical characteristics. However, their complex manufacturing process, sophisticated material compositions and their environmental sensitivity have limited the application range until now. The article describes the potentials and limitations of employing such devices for two different adaptive building functionalities: first, as a means of ventilation control and humidity regulation by embedding small actuated apertures into a fabric membrane, and second, as flexible, energy- and cost-efficient distributed sensors for external load monitoring of such structures. The article focusses on designing, building and testing of two experimental membrane demonstrators with integrated polymer actuators and sensors. It addresses the challenges encountered and draws conclusions for potential future optimization at the device and system level

Cross-sectional 4D-printing: upscaling self-shaping structures with differentiated material properties inspired by the large-flowered butterwort (Pinguicula grandiflora)

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