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Stereo Camera Setup for 360° Digital Image Correlation to Reveal Smart Structures of Hakea Fruits
(2024)
Abstract
About forty years after its first application, digital image correlation (DIC) has become an established method for measuring surface displacements and deformations of objects under stress. To date, DIC has been used in a variety of in vitro and in vivo studies to biomechanically characterise biological samples in order to reveal biomimetic principles. However, when surfaces of samples strongly deform or twist, they cannot be thoroughly traced. To overcome this challenge, different DIC setups have been developed to provide additional sensor perspectives and, thus, capture larger parts of an object’s surface. Herein, we discuss current solutions for this multi-perspective DIC, and we present our own approach to a 360° DIC system based on a single stereo-camera setup. Using this setup, we are able to characterise the desiccation-driven opening mechanism of two woody Hakea fruits over their entire surfaces. Both the breaking mechanism and the actuation of the two valves in predominantly dead plant material are models for smart materials. Based on these results, an evaluation of the setup for 360° DIC regarding its use in deducing biomimetic principles is given. Furthermore, we propose a way to improve and apply the method for future measurements.
In diesem Beitrag soll deutlich gemacht werden, an welchen Stellen eines Entwicklungsprozesses Bionik die Entwicklungsarbeit in einem Unternehmen stärken kann. Es werden die Arbeitsabschnitte benannt, in denen der Einsatz von Bionik als besonders erfolgversprechend erachtet wird, und was bei der Durchführung beachtet werden sollte. Darauf aufbauend werden konkrete Methoden benannt, die spezifisch für die Bionik sind, und erläutert, in welchen Arbeitsabschnitten ein Einsatz möglich ist.
Stereo Camera Setup for 360° Digital Image Correlation to Reveal Smart Structures of Hakea Fruits
(2024)
About forty years after its first application, digital image correlation (DIC) has become an established method for measuring surface displacements and deformations of objects under stress. To date, DIC has been used in a variety of in vitro and in vivo studies to biomechanically characterise biological samples in order to reveal biomimetic principles. However, when surfaces of samples strongly deform or twist, they cannot be thoroughly traced. To overcome this challenge, different DIC setups have been developed to provide additional sensor perspectives and, thus, capture larger parts of an object’s surface. Herein, we discuss current solutions for this multi-perspective DIC, and we present our own approach to a 360 DIC system based on a single stereo-camera setup. Using this setup, we are able to characterise the desiccation-driven opening mechanism of two woody Hakea fruits over their entire surfaces. Both the breaking mechanism and the actuation of the two valves in predominantly dead plant material are models for smart materials. Based on these results, an evaluation of the setup for 360 DIC regarding its use in deducing biomimetic principles is given. Furthermore, we propose a way to improve and apply the method for future measurements.
Dieser Leitfaden richtet sich in erster Linie an Studierende, die wissen wollen, wie sie ihre eigene digitale Identität souverän gestalten können. Aber er richtet sich auch an alle anderen, die schon immer wissen wollten, was eine digitale Identität beinhaltet und was man tun muss, um sie im eigenen Sinn zu gestalten und vor Missbrauch zu schützen. Wir sind fast alle täglich im Internet und in den sogenannten Social Media unterwegs. Wir nutzen diese digitale Welt, um etwas nachzuschlagen, uns mit Bekannten und Freunden zu treffen, potenziellen Arbeitgebern unsere Stärken zu präsentieren und vieles mehr. Wir werden aber auch von diesen Medien benutzt. Unsere Daten, die wir eingeben, sind ein wertvolles Gut und wir sollten sie nicht leichtfertig mit anderen teilen oder aus der Hand geben. All das wissen wir theoretisch, dennoch verhalten wir uns oft nicht so, wie es angemessen wäre. Aus Bequemlichkeit, aus Unwissenheit oder weil uns die Konsequenzen nicht wirklich klar oder zu abstrakt sind. Dieser Leitfaden soll daher zunächst einmal sensibilisieren, für die Gefahren, aber auch vor allem für die Möglichkeiten, die sich bei der Selbstpräsentation im World Wide Web ergeben können. Gegenstand des Leitfadens ist damit die bewusste Gestaltung der eigenen digitalen Identität. Themen, wie z. B. sichere Authentifizierung im Internet, werden nicht betrachtet.
Wir möchten euch daher einladen herauszufinden, wie ihr euch im Internet geeignet präsentieren, eine eigene digitale Identität kreieren und diese kontrollieren könnt. Dazu findet ihr im ersten Teil dieses Leitfadens Hintergrundinformationen zur digitalen Identität und im zweiten Teil geben wir euch Handlungsempfehlungen zur vorteilhaften Online-Selbstdarstellung.
Biomimetics is the interdisciplinary co-operation of various scientific disciplines and fields of innovation, and it aims to solve practical problems using biological models. Biomimetic research and its fields of application are manifold, and the community is made up of a wide range of disciplines, from biologists and engineers to designers. Guidelines and standards can build a common ground for understanding of the field, communication across disciplines, present and future projects and implementation of biomimetic knowledge. Since 2015, three international standards have been published and defined terms and definitions, as well as specific applications. The scientific literature and patents in several databases were searched for citations of the published standards. Standards or technical guidelines on biomimetics are represented both in the scientific literature and in patents. However, taking into account the increasing number of publications in biomimetics, the number of publications (52) citing the international standards is low. This shows that the perception of technical rules is still underrepresented in the academic field. Greater awareness and acceptance of the importance of standards for quality assurance even in the academic environment is discussed, and active participation in the corresponding International Organization for Standardization committee on biomimetics is asked for.
Mit Ausgabedatum Juli 2018 wurde die Norm DIN ISO 18457 "Bionik - Bionische Werkstoffe, Strukturen und Bestandteile (ISO 18457:2016) veröffentlicht. Aus diesem Anlass blicken wir auf die bisherigen Aktivitäten zurück, die zur Veröffentlichung von insgesamt drei grundlegenden Normen im Bereich der Bionik geführt haben.
Fruits (follicles) of Hakea salicifolia and Hakea sericea (Proteaceae) are characterised by pronounced lignification and open via a ventral suture and the dorsal side. The opening along both sides is unique within the Proteaceae. Both serotinous species are obligate seeders, whose spreading benefits from bush fire events. The different tissues and the course of the vascular bundles must allow the opening mechanism. While their 2D-arrangements are known to some extent from light-microscopy images of cross-sections, this work presents their three-dimensional structures and discusses their contribution to the opening of Hakea fruits. For this purpose, 3D greyscale images, reconstructed from µCT-projection data of both fruits are segmented, assisted by a deep learning algorithm (AI algorithm). 3D renderings from these segmentations show strongly interconnected vascular bundles that build a double-dome shaped network in each valve of H. salicifolia and a dome shaped honeycomb-structure in each valve of H. sericea. However, the vascular bundles of both species show no interconnection between the two lateral valves of the fruit but leave gaps for predetermined fracture tissues on the ventral and dorsal side. The opening of the fruits after a fire or after separation from the mother plant can be explained by the anisotropic shrinkage in the two valves of the fruit.

