Microcoining ripples in metal foils

Experiments, upper bound models, and finite element simulations are used to determine forming loads needed to microcoin surface ripples in thin metal foils. Coining is traditionally performed in a closed die, however enclosing all non-patterned surfaces is difficult to directly scale down to sub-millimeter foils. We find different forming regimes can exist at this small scale in an open pressing configuration. We explore the effects of the metal foil thickness and its work hardening behavior, two primary factors controlling the microcoining ripple forming load. For very thin foils, the load needed to coin a ripple pattern is lower than the load needed to compress the foil so that the open pressing configuration behavior is effectively closed with pattern formation without thickness change. For moderate thickness foils, the load needed to coin significantly drops as the entire foil compresses. For thick foils approaching bulk materials, the pattern will not completely form as the die macroscopically indents into the metal. Work hardening is found to raise the forming load for the thin, effectively closed die scenario, however it is a secondary effect at moderate thickness. This insight is used to microcoin patterns in extremely hard, thin metal foils

Shape Memory Alloy Actuator Design: CASMART Collaborative Best Practices

Upon examination of shape memory alloy (SMA) actuation designs, there are many considerations and methodologies that are common to them all. A goal of CASMART's design working group is to compile the collective experiences of CASMART's member organizations into a single medium that engineers can then use to make the best decisions regarding SMA system design. In this paper, a review of recent work toward this goal is presented, spanning a wide range of design aspects including evaluation, properties, testing, modeling, alloy selection, fabrication, actuator processing, design optimization, controls, and system integration. We have documented each aspect, based on our collective experiences, so that the design engineer may access the tools and information needed to successfully design and develop SMA systems. Through comparison of several case studies, it is shown that there is not an obvious single, linear route a designer can adopt to navigate the path of concept to product. SMA engineering aspects will have different priorities and emphasis for different applications

The More, the Better? Exploring the Effects of Modal and Codal Redundancy on Learning and Cognitive Load: An Experimental Study

This study explores how receiving identical information from different sources affects learning and cognitive load, focusing on two types of redundancy: modal redundancy, where redundant information comes from two visual sources (images and written text), and codal redundancy, where redundant information comes from two sources of different modalities which utilize the same symbol system (spoken and written text). Using a 2 × 2 between-subjects design involving modal (yes/no) and codal (yes/no) redundancy, 158 participants completed twenty learning tasks, consisting of ten construction and ten recall tasks. Additionally, they rated their cognitive load by indicating their perceived task difficulty and mental load. Overall, results indicate positive main effects of modal redundancy and negative effects of codal redundancy on learning and cognitive load. Furthermore, significant interaction effects suggest that modal redundancy may counterbalance the negative effects of codal redundancy, implying a compensatory mechanism in cognitive processing for construction tasks. These results highlight the importance of considering both modal and codal redundancy and their interaction in instructional design

Managing Extension’s Internal Brand: Employees’ Perceptions of the Functions and Descriptors of Extension

Employees of UF/IFAS Extension were surveyed to determine their perceptions of the brand’s core identity. More specifically, they evaluated the importance of various functions the organization provides and the effectiveness of various terms for describing Extension work. Respondents included county faculty, county non-faculty, state faculty, and state non-faculty to gain perspectives of groups representing Extension’s brand in Florida. Results indicated employees perceived the core functions were providing research-based information, helping solve problems, providing training for clientele, and providing expertise. Education, training, and providing solutions were perceived to be the most effective terms for describing Extension work to the public. Given that these terms are viewed as most effective internally, these terms should also be used in external communications to provide consistency. “Extension” as a term was not viewed as particularly effective for representing to the public what Extension does. When comparing groups of Extension personnel, there were statistically significant differences, indicating Extension lacks a shared identity across the organization, which could be harmful. State-level faculty, in particular, had less positive viewpoints compared to other respondent groups. It was recommended that interactions be increased between state-level and county-level employees to help mitigate potential issues that would arise because of the organization being geographically distributed in the state and to help build shared identity. Future research was recommended to address the public’s views of functions and descriptors of Extension

Networks in the spectral induced polarization

Die spektrale induzierte Polarisation (SIP) ist ein geoelektrisches Verfahren, bei dem die komplexe, frequenzabhängige Impedanz des Untergrunds gemessen wird. Im Vergleich zur Gleichstrom-Geoelektrik werden bei der SIP zusätzliche Parameter gemessen, die Hinweise auf hydraulische Parameter des Materials liefern können. Dies geschieht in der Regel mittels empirischer Gleichungen. Um eine hohe Allgemeingültigkeit zu erzielen, ist es notwendig, theoretische Modelle der SIP auf mikroskopischer Skala des Porenraumes zu entwickeln. In dieser Arbeit wird ein existierendes, semi-analytisches Membranpolarisations-Modell auf 2D und 3D Impedanz-Netzwerke erweitert, welche numerisch gelöst werden und eine Gesamt-SIP-Antwort zu erhalten. Das Originalmodell verwendet zwei, mit einem elektrolytischen Fluid gefüllte Zylinder unterschiedlicher Größe, um einen Membranpolarisations-Effekt an deren Übergang zu simulieren. Das Modell ist bereits in der Lage, Grundeigenschaften von SIP-Spektren aus Labormessungen zu reproduzieren. Um eine realistischere Abbildung von porösen Materialien, zu erreichen, werden unterschiedliche Zylinderkombinationen des Originalmodells zu einem Netzwerk vereinigt. Im Vorfeld der Netzwerkerweiterung wird das Originalmodell in mehreren Punkten überarbeitet, um mehrwertige und asymmetrische Elektrolyte sowie konzentrationsabhängige Ionenmobilitäten zu unterstützen. Anschließend wird das Originalmodell einer Sensitivitätsanalyse unterzogen. Die konstruierten Netzwerke werden mit realen Sandsteinen verglichen, für die sowohl die geoelektrischen als auch die petrophysikalischen Eigenschaften gemessen wurden. Die geometrischen Parameter des Netzwerkes (wie die Radien, Längen und ihre Häufigkeitsverteilungen) werden so gewählt, dass sie gemessene makroskopische Parameter, wie spezifische innere Oberfläche und Porosität wiedergeben. Hierzu werden mittels Quecksilberporosimetrie gemessene Radienverteilungen auf drei unterschiedliche Weisen interpretiert, die zunächst eine qualitative und dann eine quantitative Anpassung der simulierten SIP-Spektren an die gemessenen ermöglichen. Die Simulationsergebnisse zeigen, dass das entwickelte Netzwerkmodell grundsätzlich in der Lage ist, gemessene SIP-Daten mit den hydraulischen Eigenschaften des untersuchten Materials in Verbindung zu bringen und zum Verständnis des Polarisationseffektes auf mikroskopischer Skala beizutragen.Spectral induced polarization (SIP) is a geoelectric method in which the complex, frequency-dependent impedance of the soil is measured. Compared to DC geoelectrics, SIP measures additional parameters that can provide information on hydraulic parameters of the material. This is usually done using empirical equations. In order to achieve a high general validity, it is necessary to develop theoretical models of the SIP on a microscopic scale of the pore space. In this thesis, an existing semi-analytical membrane polarization model is extended to 2D and 3D impedance networks, which are solved numerically to obtain a total SIP response. The original model uses two cylinders of different sizes filled with an electrolytic fluid to simulate a membrane polarization effect at their transition. The model is already capable of reproducing basic properties of SIP spectra from laboratory measurements. In order to achieve a more realistic image of porous materials, such as sandstones, different cylinder combinations of the original model are combined into a network. Prior to the network expansion, the original model is revised in several points to support multivalent and asymmetric electrolytes as well as concentration-dependent ion mobilities. The original model is then subjected to a sensitivity analysis in order to examine it for equivalent parameters. The constructed networks are compared with real sandstones, for which both the geoelectric and petrophysical properties have been measured. The geometric parameters of the network (such as pore radii, pore lengths and their frequency distributions) are selected to reflect measured macroscopic parameters such as specific internal surface area and porosity. For this purpose, radius distributions measured by mercury porosimetry are interpreted in three different ways, which make first a qualitative and then a quantitative fit of the simulated SIP spectra to the measured ones possible. The simulation results show that the developed network model is basically able to link measured SIP data with the hydraulic properties of the investigated material and to contribute to understanding the polarization effect on a microscopic scale