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Aufbauend auf dem auf der AALE 2025 vorgestellten Beitrag „Entwicklung eines robotergestützten Systems zur standardisierten Applikation von Hautpflegeprodukten“ untersucht dieser Beitrag die experimentelle Machbarkeit eines bild- und kraftgeregelten Cobot-Systems. Der kollaborative Roboter kombiniert eine geschlossene Kraftregelung mit RGB-D-basierter Echtzeit-Bildverarbeitung. Die dosierte Applikation und gleichmäßige Verteilung des Produkts erfolgen über zwei modulare Endeffektoren die einen hygienischen sowie schnellen Werkzeugwechsel ermöglichen. Im Fokus stehen die Validierung der Dosiergenauigkeit und Reproduzierbarkeit, das Eincremeverhalten unter Kraftregelung sowie die kamerabasierte Segmentierung und Abdeckungsanalyse der Zielareale. Die Ergebnisse zeigen eine mit einer Eppendorfpipette M4 vergleichbare Dosierpräzision sowie eine gleichmäßige Flächenabdeckung. Ergänzend wurden grafische Benutzeroberflächen entwickelt, die den Applikationsprozess visuell unterstützen und eine strukturierte Datenarchivierung zur reproduzierbaren Erfassung von Cremeverteilung und Armarealen ermöglichen. Die vorgestellten Resultate bestätigen die Machbarkeit einer reproduzierbaren, standardisierten Applikation und bilden die Grundlage für weiterführende Untersuchungen und zukünftige topische Anwendungen.
Der Spannungszustand
(2013)
An jedem belasteten Bauteil treten z. T. sichtbare Verformungen und im Bauteil immer unsichtbare Spannungen auf. Die Gesamtheit der Spannungen werden in Normal- und Tangentialspannungen (Schubspannungen) eingeteilt. Das Studienbuch gibt Einblick durch grundlegende Erläuterungen zum Thema Spannungszustand, sowie Beispiele und Übungen für die praktisch zweckmäßige Anwendung verschiedener analytischer Berechnungsmethoden für den ein- zwei- und dreiachsigen Spannungszustand ausgehend vom Spannungstensor des CAUCHY Modelles.
Structural analysis is a major part of all manufacturing and testing industries. The need for high level accuracy of the results in the testing field has increased progressively, resulting in development of advanced state of art techniques. In order to acquire the vibrational characteristics of a structure, a detailed Finite Element Analysis (FEA) modelling is performed. Also, Experimental Modal Analysis (EMA) is conducted to extract the dynamic characteristics of a structure. The results obtained from both the processes are correlated for validation purposes. Based on the correlation (good or bad) the structural analysis is validated. In most cases the correlation is not satisfactory; it is mainly because of the boundary conditions that differ in FE and EMA.
This research study explains in detail how important the boundary conditions are for modal validation. But the most imperative part, as the first step of correlation, is the geometry analysis. If the geometrical correlation is not accurate, the later part of correlation will turn out to be an assumption based on inaccuracies. Assumption of a geometrical correlation, without being sure of the differences, will lead to inaccurate results for validation.
A reference plate is tested and simulated by using EMA and FEA techniques respectively. EMA is conducted by using a 3D SLDV for measuring the output response and the input force of excitation is induced by a Scalable Automatic Modal hammer (SAM). This plate is then scanned using ATOS Triple Scan II GOM 3D geometry scanner. The scanned results are compared with the FE model of the reference plate.
The results presented show the importance of geometrical correlation for modal validation and provide results of deviations that were observed on a reference plate. With these conclusions, working on modal validation can be developed by reducing the inaccuracies for the presentation of correlation.
The existence of free boundary conditions is frequently assumed for Experimental Modal Analysis (EMA) of a structure. However, free-free conditions can only be approximated because the structure must be supported in some manner. Therefore, comparing simulated data with experimental data can be deceiving, because these suspensions falsify modal parameters especially structural damping and stiffness. The current scenario of structural analysis is more towards focusing on modal updating or correlation, rather than the simulation results (FE) or the experimental results. So it is imperative to bridge the gap between FE and EMA, by carefully studying various parameters.
To overcome these drawbacks, levitation is suggested as a truly free-free suspension method. The levitation method was developed to allow a non-destructive, adaptable, and completely contactless approach for material testing: the structure under test is suspended on a thin film of pressurized air providing an aerodynamic bearing, levitating the specimen. Two suspension devices were constructed. Pressurized air is circulated into a casing with a single outlet (“air cushion”) or a fine grid of outlets (“air bed”).
A study was performed to investigate the influence of the support conditions on the modal parameters eigenfrequency and damping. Tested specimens were a brass plate, a stainless steel plate and two composite material probes. The tested suspension methods were (a) foam mat, (b) air cushion and (c) air bed. Modal tests were performed using a Scanning Laser Doppler Vibrometer (SLDV) and an automatic modal hammer for excitation. Evaluations of the measurements were performed manually.
The results showed that the detected eigenfrequencies of the metallic specimen have a variation below ±0.3% for the tested suspension methods. This variation is 10 times higher for the composite plates and lies between ±3%. The damping ratios of the levitation suspensions show the different material behavior of metallic and composite specimen: damping ratios of metallic specimen lie between 0.05–0.5% whereas damping ratios of composite plates are ten times higher and lie between 0.3% and 3%. The damping ratios measured with the air cushion are smaller than the damping ratios for the air bed supporting the hypothesis that a laminar air film under the specimen leads to less additional damping.
The study shows that EMA can be performed on metallic and composite specimens using contact-less suspension methods. Especially for light-weight material specimens where EMA cannot be performed or where the results are not reliable, the contact-less suspension (levitation method) can be used.
Experimental Modal Analysis (EMA) on a lightweight material has proven to be very challenging in the recent past. The applications of these materials have increased invariably in various fields and so have a high demand for Research & Development (R&D). A lightweight material is very sensitive in terms of vibration. EMA on these materials in free - free boundary condition is very complicated as the hammer excitation becomes very difficult. In order to acquire valid results, the conditions are modified, and in consequence, obtain inaccurate dynamic characteristics.
Some of the major challenges faced are: (a) material getting displaced from its original position after every hit, (b) difficulties in obtaining a single hit, (c) reproducing the same excitation force level for averaging output response. Overcoming these crucial challenges can result in reducing the inaccuracies in the results. Scalable Automatic Modal hammer (SAM) is developed to overcome these challenges and enables the ability to reproduce the same force level of excitation. This advanced hammer excitation technique has the capability to avoid the double hit, adjust the repeatability of force level and automatizes the entire excitation process.
In this research paper, a light weight material is experimented under free-free boundary condition and the obtained results are analyzed. The input hammer excitation is provided by SAM and the output contactless response is measured by Scanning Laser Doppler Vibrometer (SLDV).
The conclusions provided will reflect the importance of repeatability and reproducibility of hammer excitation force level in order to acquire accurate results. The controlling of SAM, by changing various parameters, in order to precisely excite lightweight structures will be demonstrated.
A semiconductor based hydrogen sensor system was optimized by various modifications, which allow an improved detection of very low concentrations of hydrogen in air. The foundation for new investigations on the sensor structure are modifications of substrate and gate structures. Establishment of reference structures is a major aim. A possible drift compensation could be the use of aluminum or alloys for sensor system in order to stabilize signal in Metal Oxide Semiconductor (MOS) respectively Metal Electrolyte Insulator Semiconductor (MEIS) structures. Gold is more likely not capable to function for drift compensation as a pure metal. Nafion™ treatment for cover up the palladium gate seems not to be suitable as a reference, besides could be an option to stabilize sensor signal responses and protect sensors from environmental influences.
The advancement of 3-dimensional printing technology over the past ten years has raised interest in and accessibility to these devices. Due to its consistent growth and demand, 3D printing is becoming a consumer-friendly, reasonably priced craft. Due to technological advancements, it is becoming increasingly integrated into broader fields of science and research, as well as the manufacturing sector. The need for customized solutions is constantly growing across several industries. The 3D extrusion of hydrogels is advancing in the field of biomaterials with a broad spectrum of biomedical applications. Hydrogel extrusion prints heads often use stepper motors or pneumatic pressure systems to push the substrate onto a surface. These techniques are well-suited for materials with high viscosity. While these systems are usually bound to the syringe volume, a refillable reservoir enables them to print above the syringe’s limitations. We developed a low-cost standalone heating system for flexible tubes to control the temperature, hence avoiding jellification and clogging of the tubing system leading to the nozzle of the print head. The system connects to an in-house made peristaltic pump, which forces the e.g. gelatin through the nozzle with low pulsation, enabling us to extrude multiple layers of precise tempered gelatin. The heating system is based on easily available materials and electronic components and does not require expensive tools.
This study presents the characterization of 316L stainless steels fabricated by selective laser melting (SLM), focusing on the influence of printing parameters on microstructure and mechanical properties. The choice of process parameters is crucial for achieving desired material properties, as it directly affects the microstructure and mechanical behavior, which is important when optimizing for potential applications in several fields, such as aerospace and automotive. In this study, different scanning speeds were tested to identify optimal settings, followed by the evaluation of the effects of orientation relative to the build plate and hatching strategies to enhance performance. To assess the impact of these factors, tensile tests, microhardness measurements, and X-ray diffraction (XRD) analyses were conducted. Tensile tests revealed that higher laser scanning speed generally reduces ultimate tensile strength and elongation, likely due to an increase in porosity and a less homogeneous fusion of layers. The analysis of samples printed with different orientation relative to the build plate highlighted a strong mechanical anisotropy, with the samples printed vertically exhibiting lower tensile strength and ductility compared to horizontally printed samples. Microhardness testing further confirmed an anisotropy in material properties. XRD analysis reveals a preferential orientation of austenitic grains depending on building direction. This, in turn, influences the anisotropic behavior. These findings highlight the critical role of process parameters in tailoring the microstructure and mechanical performance of SLM-produced parts, thereby providing insights into the optimization of additive manufacturing for specific applications.
Studies of ultrafast dynamics in substrate-free nanoparticles at ELI using Timepix3 optical camera
(2025)
We present a novel application of the Timepix3 optical camera (Tpx3Cam) for investigating ultrafast dynamics in substrate-free nanoparticles at the Extreme Light Infrastructure European Research Infrastructure Consortium (ELI ERIC). The camera, integrated into an ion imaging system based on a micro-channel plate (MCP) and a fast P47 scintillator, enables individual time-stamping of incoming ions with nanosecond timing precision and high spatial resolution. The detector successfully captured laser-induced ion events originating from free nanoparticles disintegrated by intense laser pulses. Owing to the broad size distribution of the nanoparticles (10-500 nm) and the variation in laser intensities within the interaction volume, the detected events range in occupancy from near-zero to extremely high, approaching the readout limits of the detector. By combining time-of-flight and velocity map imaging (VMI) techniques, detailed post-processing and analysis were performed. The results presented here focus on the performance of Tpx3Cam under high-occupancy conditions, which are of particular relevance to this study. These conditions approach the limitations imposed by the camera readout capabilities and challenge the effectiveness of standard post-processing algorithms. We investigated these limitations and associated trade-offs, and we present improved methods and algorithms designed to extract the most informative features from the data.
This publication presents an improved manufacturing method for tetrahedral metal effect pigment particles that demonstrates reduced flowlines in injection-molded polymer components compared with conventional platelet-shaped pigment particles. The previously published cold forming process for tetrahedral particles, made entirely from aluminum, faced manufacturing challenges, resulting in a high reject rate due to particle adhesion to the micro-structured mold roller. In contrast, this study introduces a new manufacturing method for tetrahedral particles, now consisting of metallized UV-cured thermoset polymer. These particles, dispersed in amorphous matrix thermoplastics, have shown to maintain their shape during the injection molding process. The manufacturing technique for these novel particles is based on UV imprint lithography, omitting the reject rates compared with the previously presented cold rolling process of tetrahedral full aluminum particles. Thus, the novel manufacturing technique for tetrahedral pigment particles shows increased potential for automation through roll-to-roll manufacturing in the future.

