FSP3: Produktion
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Der Versand kühlpflichtiger Molkereiprodukten muss unter Einhaltung eines definierten Temperaturbereichs erfolgen. Die systematische Analyse auftretender Wärmetransportprozesse an Isolierverpackungen verdeutlicht deren Aufbau und Wirkungsprinzip und signalisiert ergebnisrelevante Einflussgrößen auf das Temperaturhaltevermögen.
Die rasant voranschreitende Digitalisierung treibt die Vermarktung und den Vertrieb von Lebensmitteln via Internet voran. Allerdings weisen die meisten Molkereiprodukte eine enorme Empfindlichkeit gegenüber den in der Logistikkette typisch auftretenden Belastungsarten auf. Die Sicherstellung eines hohen Qualitätsniveaus fordert deren verstärkten Schutz durch eine geeignete Versandverpackung.
Forschung zum Schutz und Erhalt von Glocken am Europäischen Kompetenzzentrum für Glocken ECC-ProBell
(2017)
Am 21. und 22. März 2018 fand das 2. Glockensymposium ECC-ProBell® an der Hochschule Kempten statt, das in Zusammenarbeit zwischen dem Europäischen Kompetenzzentrum für Glocken und dem Beratungsausschuss für das Deutsche Glockenwesen veranstaltet wurde. Dieser Konferenzbericht dokumentiert die Beiträge, die auf dem Symposium vorgetragen wurden, und richtet sich an Experten und Fachleute, die an und mit Glocken arbeiten - in den Kirchen und Kirchgemeinden, den Denkmalschutzbehörden und Bauämtern, den Glockengießereien und Installationsfirmen sowie allen Forschern und an Glocken Interessierten.
Das 2. Glockensymposium ECC-ProBell® behandelte folgende Themenschwerpunkte, die als Beiträge in diesem Konferenzbericht enthalten sind:
- Schutz und Erhalt von Glocken
- Glockenläuten - Wohlklang und Lärm
- Glockenläuten als Kultursymbol
- Turmschwingungen und Sanierungskonzepte
- Der musikalische Fingerabdruck von Glocken
- Glocken aus Ersatzmaterialien
In the future more and more conventional power plants, which provide ancillary services such as provision of reactive power for voltage control and primary control power (active power) for frequency control to the transmission system and thus secure the energy supply, are going to be replaced by renewable energy sources. Due to this fact new concepts for providing these services by renewable power sources will be necessary in the future to maintain stability of the network operation. This refers to the delivery of active and reactive power by distributed generation (DG) and distributed storage (DS). Beyond that DG and DS can be found nowadays in households or also called nanogrids. This research work presents a concept of a nanogrid that can provide ancillary services to the distribution grid in the low voltage level and transfer reactive power as well as primary control power to higher voltage levels by upscaling, which means the connection of many nanogrids. The implementation of the concept is done in a real system and also in a simulation environment that uses simplified mathematical models.
Steigende Anforderungen hinsichtlich Leichtbau, passiver Sicherheit und Torsionssteifigkeit bedingen im Karosseriebau zunehmend komplexere Geometrien. Damit geht häufig eine stark eingeschränkte Zugänglichkeit beim Fügen der Karosseriebauteile einher. Dieser Herausforderung kann in vielen Fällen mit dem Einsatz eines neuartigen Fügeverfahrens begegnet werden, welches unter Nutzung des Springbeulens eine form- bzw. kraftschlüssige Fügeverbindung erzeugt. Hierbei wird die während der Zustandsüberführung des springbeulenden Fügeteils auftretende Formänderung zur Erzeugung entsprechender Fügeverbindungen genutzt. Zur Verbesserung deren Eigenschaftsprofils kann diese Verbindung als Bestandteil einer kombinierten Fügeverbindung in Kombination mit Kleben angewandt werden. Das Springbeulen konnte erfolgreich und prozesssicher an im Karosseriebau etablierten Blechen erzeugt werden. Die Bewertung der entwickelten Auslegungsvorschriften sowie der erzeugten Versuchsergebnisse legen zahlreiche Vorteile der Warmblechumformung zur Herstellung der springbeulenden Fügeteile nahe. Die Anwendung des neuartigen Fügeverfahrens wird am Beispiel eines Schottblechs erläutert.
Der moderne Karosseriebau ist geprägt durch den Wunsch nach einer schlanken Prozesskette, die sich durch hohe Prozesssicherheit auszeichnet. Im Umfeld der Fügetechnik rücken zur Erreichung dieses Ziels vermehrt sogenannte „unmittelbare Verbindungen“ in den Vordergrund. Hierbei handelt es sich um Fügeverbindungen, zu deren Erzeugung keine zusätzlichen Verbindungsmittel wie Schrauben oder Niete bereitgestellt werden müssen. Daher werden spezielle Schnappelemente für den Karosseriebau entwickelt, die als integraler Bestandteil aus dem Fügeteil ausgeformt werden. Durch den Einsatz derartiger Schnappelemente lässt sich die Teilevielfalt signifikant reduzieren. Das Fügen derartiger Teile erfolgt hierbei mit geringstem Zeitaufwand und nur mit der ohnehin zur Zuführung des Fügeteils benötigten Handhabungsvorrichtung.
Battery driven vehicles with Voltage Source Inverters (VSIs) are widely used in power electronics for many years. Meanwhile the Pulse Width Modulation (PWM) Techniques to improve efficiency, output voltage quality, current harmonic spectrum and etc. is the topic
which gain massive attention through these years and many studies are accomplished in this regard. Nevertheless, DC-link capacitor as the main bulky and expensive element which is affected by generated current harmonics is the focus of this paper. Here we investigate this factor for single and double inverter with continuous and discontinuous PWM pattern and compare the capacitor values for each case.
Im Rahmen der Regionalisierungsoffensive der Bayerischen Staatsregierung wurde von den Hochschulen Augsburg, Kempten und Neu-Ulm ein gemeinsames Studienkonzept entwickelt, das durch die Kombination der Elemente Teilzeit-Studiengang, digitaler Lehre und Präsenzlehre neue Möglichkeiten für praxisnahe Hochschullehre bietet. Der Studiengang spricht sowohl Schulabsolventen mit dem Ziel eines praxisintegrierten Studiums als auch berufserfahrene Interessenten an, die in Teilzeit eine akademische Weiterqualifikation anstreben. Dadurch ergibt sich eine Studierendengruppe mit heterogenen Lernbiographien, denen mit passenden didaktischen Konzepten entsprochen wird. Durch die Kombination von Blended-Learning Konzepten mit einem neuen Studienzeitmodell wird den Studierenden eine große zeitliche Flexibilität für die Erarbeitung der Studieninhalte gegeben, die es ihnen ermöglicht parallel zum Studium in Unternehmen zu arbeiten.
Die Digitalisierung in der Produktion stellt die Industrie vor große Herausforderungen. Eine Umfrage der IHK Schwaben hat ergeben, dass insbesondere Fachpersonal für das Thema fehlt. Über das Projekt Digital und Regional haben sich daher die drei schwäbischen Hochschulen Augsburg, Kempten und Neu-Ulm der gemeinsamen Aus- und Weiterbildung in diesem Themenfeld durch den Studiengang Systems Engineering gewidmet. Der Studiengang wird an den Hochschulzentren Memmingen und Nördlingen parallel angeboten. Der Studiengang ist als Teilzeit-Bachelorstudiengang mit hohen Anteilen an digitalen Inhalten konzipiert und ermöglicht durch die spezielle zeitliche Organisation eine parallele Beschäftigung in Unternehmen.
The increasing demand for highly compact power converters in many applications such as on-board power supplies and motor drives leads to high power loss densities. Typically, thermal management components and filters take the biggest part of the converter volume. To reduce the size, embedding technology can be used. Embedding of power semiconductors enhances the electrical performance of such devices due to reduced interconnection length. This leads to lower inductance which enables higher switching frequencies and allows more compact filter elements [1]. Direct cooling strategies pursue ways to enhance heat transfer to a coolant while reduce the heat sink size. Products like the “Danfoss ShowerPower”[2] and “Infineon Hybrid Pack”[3] show examples where cooling structures are attached directly on the backside of the power module. By omitting the thermal interface between power module and heat sink, the thermal resistance is significantly reduced. Due to superior thermal properties, water-glycol is usually applied as coolant. However, using a dielectric coolant enables some unique benefits: First, no electric insulation layer to coolant is required, which reduces the thermal resistance, second, corrosion problems are avoided, as dielectric coolants are typically inert, and third, the system stays safe for users in case of coolant leakage. Our approach combines these strategies to create an ultra-compact PCB embedded power module with integrated dielectric cooling. This paper is focused on the experimental thermal performance evaluation of the developed heat exchangers. It continues the theoretical work, which was presented as paper at the CIPS 2018 [5].
The use of packaging technologies which allow thick leadframes and thus a high heat spread with metal substrates close to semiconductors, promise a better thermal performance of power modules, especially when using modern GaN or SiC power transistors with high power density. However, the degrees of freedom in the dimensioning of these metal substrates with regard to area, thickness, symmetry and chip positioning are large and optimization towards minimum thermal resistance results in unnecessarily large and unmanufacturable leadframes with high parasitic inductance, which hinders fast switching. In this paper the influence of geometric parameters of the leadframe on the thermal performance is investigated based on thermostatic 3D FEM simulations of a half-bridge with symmetrical losses. From this thermal analysis the dimensioning for a GaN half-bridge with high thermal requirements for a low inductance commutation cell is derived.
PCB embedding is a novel and promising approach for packaging of power semiconductors. Due to the planar construction the technology enables lower conduction and switching losses, an increase switching frequency and ultimately yields a higher power density. Usually embedding is performed during lay-up of the PCB. Here, a novel concept for fabrication of PCB based power devices is proposed. The bare dies are sandwiched between two circuit boards using Ag sintering and simultaneous lamination of prepregs. The technology is discussed with reference to a 600V / 50A IGBT half bridge module. Using high-Tg isolator material in the PCB, a suitable process window is established and laboratory demonstrators are fabricated. An electrical characterization proves the feasibility of the concept.
This paper presents a modular fabrication concept for printed circuit board embedded power semiconductors. The fabrication is done in a two step approach. First, the Single-Switch-Pre-Packages (SSPP) are built using standard embedding processes. Subsequently, full converters are fabricated by embedding of the SSPP as functional inlays into a PCB-power module. For optimal heat spreading, the semiconductor dies are silver sintered on a thick copper substrate. To exploit further the potential of the substrate, heat exchanger structures are chemically etched on it. Dielectric coolant serves as the cooling medium in this case. Laboratory demonstrators are built and characterization is performed as proof-of-concept. Thermal test indicates an junction to ambient thermal resistance of 0.43 K/W, compared to 0.8 K/W for reference module on a standard cold plate with water glycol. The hydraulic power and coolant temperature were identical for both cases.
The requirements for power electronic assemblies are continuously increasing and are mainly driven by costs, functionality, and reliability. A novel and promising approach is the embedding of power semiconductor devices into PCB-materials. Benefits are the reduction in size and volume of the system. The embedding of semiconductor devices provides a high degree of miniaturization. Also printed circuit board technology in combination with the use of established processes apparently has the potential for low-cost manufacturing. Further functional advantages are the possibility to place passive components and peripheral circuits close to the switching devices, enabling shorter commutating paths. In consequence, they are expected to produce smaller parasitic effects caused by the package, which results in higher possible frequencies and reduced conduction and switching losses. However, there is a significant challenge regarding package design, processing, and materials selection to make use of this potential even at high operating temperatures. To address only one aspect, generally used materials, like epoxy-glass-substrates (FR4) and solder alloys like PbSnAg or SAC are not suitable for temperatures above 150 °C. This work will introduce and evaluate a concept for double-side Ag-sintered semiconductor chips, which are embedded between two organic high-temperature PCBs. A proof-of-concept will be presented by setting up a 30 kW (600 V, 50 A) power package as a demonstrator.
This paper presents a novel approach to embed power semiconductor devices into a printed circuit board. Here, IGBTs and diodes with reinforced top side chip contact are used in an IGBT half bridge with 25 A / 1200 V rating. Thermal simulations highlight the improved thermal impedance caused by the reinforced top contact and the benefits of the insulated copper substrate compared to a commercial DBC-based reference module.
The fabrication process is discussed in detail and preliminary test results are presented. The results of the thermal characterization support the theoretical
considerations.
This paper presents a novel fabrication concept for PCB embedded power semiconductors. Here, the semiconductors are attached to an insulated metal substrate, which is embedded in a second step into an almost-ready PCB. This approach avoids handling of bare dies during PCB production. To demonstrate the feasibility of the concept, a 1200 V / 50 A B6 bridge is designed and fabricated. The performance is evaluated and benchmarked. Compared to a conventional DBCbased power module, the conduction losses are reduced by 21% and the thermal resistance is reduced by 29%. Turn-off losses are 25% lower, while turn-on losses are about the same for both module types. A further optimization of the switching performance is possible, but requires a reduced DC-link inductance and an optimization of the gate resistance.
Due to an increasing demand in miniaturization of power converter, power loss densities increase significantly, which makes their thermal management difficult. One way to face this challenge is PCB embedding of semiconductors. This approach provides a much shorter thermal path from semiconductor to a coolant, than with a usual DBC-based power module. Still, a typically liquid cooling heat exchanger, which is connected to the power module forms a main part of the overall thermal resistance. This paper presents a novel design of a PCB embedded power module with a small size heat exchanger. To meet the requirements of the targeted application a dielectric coolant was used. A parametric study was performed to find out the most suitable cooling concept. Jet impingement on an optimized cooling surface with an increased area is persecuted. The heat exchanger design is described and the thermal performance is evaluated by CFD-simulations. The overall thermal resistance for the IGBT was calculated to Rth junction-coolant = 0.52 K/W. For comparison a reference DBC-based power module on a standard cold plate is considered. Its thermal resistance was Rth junction coolant = 1.03 K/W which is almost two times higher than the embedded version with direct cooling.
The increasing demands on power electronics with high currents and high operating temperatures has led to the establishment of ceramic substrates. More efficient heat distribution, as well as increased thermal durability, are two aspects of the superior properties of ceramic substrates compared to conventional Printed Wiring Boards (PWB). Nevertheless, there is an demand to develop new solutions based on PWBs to provide affordable and highly integrated power electronic devices for electromobility. For cost optimization, it would be advantageous to replace the hybrid technology with a single board in order to reduce materials, parts and interconnections. Unfortunately, mounting techniques like pressure-assisted silver sintering lead to damages of epoxy-glass-substrates due to high bonding pressures and high temperatures during bonding. Recent projects led to the development of high-temperature stable benzoxazin-based wiring boards. Investigations on the quality and reliability of sintered assemblies on these PWB-substrates are still pending and were systematically carried out in this work.
Piezomaterialien finden in der Mikrosystemtechnik ein breites Anwendungsspektrum. Die Machbarkeitsstudie untersucht die Möglichkeiten Piezoplatten in den Herstellungsprozess von modernen Leiterplatten-Multilayer zu integrieren. Die glasfaserverstärkte Epoxidstruktur des PCBs wirkt zum einen als Träger für die spröde Piezokeramik. Des Weiteren kann durch die internen Leiterbahnen eine Kontaktierung der Keramik realisiert werden. Im Vorfeld wurden der Lagenaufbau sowie geometrischen Voraussetzungen für eine Verbindung mittels Lotpaste experimentell überprüft. Als Anwendungsbeispiel wird ein Vibrations-Harvesters aufgebaut und getestet. Die maximale Leistung des Harvesters liegt bei 7,86 mW mit einer Eingangsbeschleunigung von 4g. Der positive Funktionstest demonstriert die grundsätzliche Anwendbarkeit des Ansatzes, auch wenn die elektrische Kontaktierung mittels Lotpaste kritisch zu bewerten ist.
Leiterplattenembedding von Halbleiterbauelementen für die Leistungselektronik – vom Modul zum System
(2018)
Das Einbetten von Halbleiterbauelementen in Leiterplatten ist ein alternativer Ansatz zur Steigerung der Leistungsdichte und Funktionalität von leistungselektronischen Systemen. Diese Arbeit stellt ein neuartiges Verfahren vor, bei dem die Halbleiter nach der Leiterplattenfertigung in Kavitäten eingebettet werden. Die Betriebscharakteristik derartiger Leiterplattenmodule wird systematisch an Hand eines 1200 V / 50 A Demonstrators untersucht. Ein Benchmark mit einem herkömmlichen, kommerziell verfügbaren Leistungsmodul mit identischen Halbleiterbauelementen verdeutlicht die Vorteile der Technologie: die parasitären Widerstände und Induktivitäten des EmbeddedModuls sind gegenüber der Referenz um 86 % bzw. 65 % verringert. Der thermische Widerstand fällt um 29 % niedriger aus. Mit diesen Daten wurde eine theoretische Analyse auf Systemebene durchgeführt, wobei ein 23 kW Antriebsumrichter als Beispielanwendung dient. Alleine durch das Leiterplattenembedding ist eine Steigerung der Ausgangsleistung um 14,5 % möglich. Eingriffe in die Schaltungstechnik sind dazu
nicht notwendig.
Bells are musical instruments exposed to severe loading and stress conditions during ringing. The impact of the clapper leads to local wear with material abrasion and high stresses with possible fatigue cracks. Such damages may only be identified based on tone shifts and increased damping, when they have already propagated to large dimensions. Consequently repair such as welding or even re-casting become necessary. Here procedures for the fatigue life evaluation of bells are presented based on investigations of at least more than 300 culturally and historically important bells in Europe.
From those investigations the most important conclusion is, that each bell is unique in its structure and its setup for ringing and has to be evaluated individually. Thus recent research aimed on a very early crack detection. Then changes of the sound are still very small, so that the musical quality of the bell may not be impaired.
Then still measures can be taken to stop the crack propagation at this early stage without severe repair and the bell continues to ring. Recent research concentrates on the design of the sound of the bell based on the parameters by which the bell setup is defined and the stress conditions are determined.
KEYWORDS
BELL, RINGING, SOUND, FATIGUE CRACK, WEAR, LOADING, SIMULATION,
MEASUREMENT, MONITORING
Viele Studienmodelle des dualen Studiums haben den Nachteil, dass die Studierenden nur vergleichsweise kurze Zeiträume von vier Wochen bis maximal drei Monate am Stück im Unternehmen verbringen. Außerdem ist die inhaltliche Verzahnung von Theorie im Studium und in der Praxis bzw. Ausbildung im Unternehmen nicht immer optimal möglich. Um diese Nachteile auszugleichen, wurde mit dem Studienmodell des Bachelor-Studiengangs Systems Engineering ein Teilzeitstudienmodell mit digitalen Lehrmodellen und unternehmensbezogenen Projekten entworfen. Im Beitrag wird das Studienmodell vorgestellt und aufgezeigt, wie die Interessen der beteiligten Kooperationspartner bei der Entwicklung und Umsetzung Eingang finden.
As part of the regionalization offensive of the Bavarian State Government, the Universities of Applied Sciences Augsburg, Kempten and Neu-Ulm have developed a joint study concept named Digital and Regional (Hochschule Augsburg, 2020). It offers new opportunities for practical university teaching through the combination of the elements of part-time study, digital teaching and classroom teaching. The course appeals to both school graduates with the aim of practically integrated study as well as interested professionals who are looking for part-time enhanced academic qualifications. This results in a group of students with heterogeneous learning biographies, which are matched with suitable didactic concepts. The combination of blended learning concepts with a new study time model gives the students great flexibility in terms of time for the development of the course content, which enables them to work in companies parallel to their studies (Jacob et.al. 2017).
To investigate the combustion and emission behavior of straight vegetable oils (SVO), jatropha oil, soybean oil, and diesel fuel were tested. For this research, a 2.2L common-rail engine with a two-stage turbocharging concept was equipped with a cylinder pressure indication system, an exhaust-gas analyzer, an AVL Micro Soot sensor and a Scanning Mobility Particle Sizer 3936 (SMPS) device to detect the particle-size-distribution (PSD). At a low- and mid-load engine-operating point (EOP), the thermodynamic and emissions were investigated under various exhaust gas recirculation (EGR) rates with respect to the PSD. Moreover, the injection behavior of the three test fuels was analyzed separately using an injection rate analyzer. This procedure facilitates the thermodynamic investigations of the engine process and allows the calculation of the hydraulic delay (HD) as well as the ignition delay (ID). The ID of the SVO fuels compared to diesel fuel was found to be lower at all engine-operating modes, while jatropha oil always showed the shortest ID. In the particulate-nitrogen oxide (NOX) trade-off, the SVO fuels showed higher particulate matter (PM) emissions at the low-load EOP, whereas the PM emissions of diesel fuel overtop the SVO fuels at a higher engine load. With increased EGR-rates, a rise in the particle size was observed for all fuels. At the low-load EOP, the SVO fuels showed larger particles for high EGR-rates. This effect also changed by increasing the engine-load to the mid-load EOP, wherein the particle size of the diesel fuel emissions is higher by applying elevated EGR-rates.
Porosity distribution in laser-sintered polymeric thin sheets as revealed by X-ray micro tomography
(2019)
Laser Sintering (LS) is an additive manufacturing technology that is progressively used to manufacture functional products for end-use applications. However, LS technology provides limited ability to produce thin-walled structures that feature high material quality. A key parameter determining the quality of LS polymeric parts is porosity. This article presents a new approach towards clarifying the porosity characteristics of thin-walled structures produced by LS. Therefore, thin sheets of different thickness built in different orientations within the building chamber are examined by means of X-ray micro tomography. The porosity analysis includes the overall porosity, pore number density, pore size distribution and porosity distribution along the thickness of the thin sheets. The results show that the porosity characteristics strongly depend on the thickness and the build orientation of the thin sheets. This investigation helps to estimate the quality of three dimensional hollow bodies produced by LS and moreover, contributes to a better understanding of the pore formation in LS processes.
The hydrocarbons present in the diesel exhaust gas are analyzed. A mass spectrometer is used for the measurements, and it operates on the basis of an ion‐molecule reaction. This method is especially suitable because it is selective, is as free of fragments as possible, and is highly sensitive to the species that need to be measured. The study shows that numerous hydrocarbons in diesel exhaust gas can be identified. In particular, three molecules, ethyne, ethene and propene, were analyzed online in‐depth on an engine test bench under different engine operating conditions.
The demands of the interlinked production processes of industry 4.0 to engineers are versatile. Engineers shall know the tools to realize production processes automatically, understand different production processes to implement sensor technologies where needed, integrate network technologies to interconnect all components and develop software tools to run the production and to analyze the collected data. Therefore, the qualification of engineers must be adapted to integrate new competences in the engineering education.
Robotics as one of the main components of Industrie 4.0 has to be integrated in today’s teachings. To provide educational institutions a low-cost but industry-oriented robot system, a modular 3D printed robot kit is developed which can be controlled by an industrial controller or a low-cost PC board.
Laser sintering of polymers is widely used for the production of individual products and small-batch series. However, the qualification of laser-sintered polymeric components for new application fields, e.g. in the food and packaging industry, is still limited due to missing knowledge on physicochemical material properties. This work investigates the mass transfer of low molecular weight substances through laser-sintered polyamide 12 sheets in comparison to an extruded polyamide 12 film. Analysis of structural material properties reveals significant differences between both materials depending on the production processes. Despite their apparent porosity, laser-sintered sheets show lower permeation coefficients for water vapor and oxygen compared to extruded films. This might be related to the higher crystallinity of the laser-sintered vs. the extruded material, arising from the slow cooling rate of the polymer in the laser sintering process.
This research brings knowledge of the different permeation behavior of laser-sintered and extruded polyamide 12 in relation to the structural properties.