Journal articles on the topic 'TU Chemnitz'

Modern architecture is dominated by the tendency to design organically shaped filigree buildings. The resource and energy efficient construction of multifunctional buildings is as important as a broad variety of possible shapes. Multi-material support structures and shell constructions in lightweight design that also take over e. g. lighting and monitoring are needed for these purposes. Textile reinforced lightweight shell structures have been developed at Technische Universität Chemnitz within the scope of research projects. They consist of a hybrid material from carbon-fiber-reinforced concrete and glass-fiber-reinforced plastic. Thanks to the coupling of the positive material characteristics, the combination of two different composite materials results in a hybrid material with a total thickness of 15 mm, which has a high fatigue strength (XF4) and surface quality (exposed concrete). Furthermore, the hybrid is characterized by excellent compressive strength (120 MPa) and bending tensile strength (150 MPa), low susceptibility to corrosion and free formability. Therefore, it is highly suitable for thin-walled filigree lightweight shell structures. A research pavilion with a size of 4 x 4 x 3 m3 (l x w x h), made from textile reinforced lightweight shells, was built on the campus of TU Chemnitz, to test the theoretical investigations. Specially developed tensile sensors for the active lighting and determination of the elongations were integrated into the different layers. This aimed at an online-monitoring of the shell support structure.

Zusammenfassung. Achtsamkeitsbasierte Verfahren wie Mindfulness-based Stress Reduction (MBSR) etablieren sich zunehmend in der Stressbewältigung, Förderung von Problemlösefähigkeiten, Prävention und begleitendenden Behandlung psychischer Störungen. Derzeit wird die Übertragbarkeit achtsamkeitsbasierter Verfahren auf die psychosoziale Beratung diskutiert. Welche Auswirkungen zeigt ein achtsamkeitsorientiertes Stressbewältigungstraining (AST) im Beratungssetting auf Achtsamkeitsniveau, Lebensqualität, Stress und depressive Symptomatik? In einer randomisiert-kontrollierten Pilotstudie (N = 28) wurde in der Psychosozialen Beratungsstelle (TU Chemnitz) ein Achtsamkeitsorientiertes Stressbewältigungstraining (6 wöchentliche Einheiten à 2 Stunden) im Warteliste-Kontrollgruppendesign (TAU) durchgeführt (Messzeitpunkte: Prä, Post, 3-Monats-Follow-Up). Trainingsteilnehmende wiesen gegenüber der Kontrollgruppe eine höhere Lebensqualität, weniger dysfunktionale und häufiger funktionale Stressbewältigungsstrategien und geringere depressive Symptome auf. Das Potential achtsamkeitsbasierter Verfahren kann erfolgreich in einer ökonomischen Kurzversion im Beratungssetting mit positiven Effekten auf Stresserleben, Lebensqualität und Depression umgesetzt werden. Der Einsatz achtsamkeitsorientierter Kurz-Trainings im Behandlungskontext sowie in der (psychosozialen) Beratung kann zur Überbrückung und Verringerung von Versorgungsengpässen beitragen.

Large-scale curved structures such as wind turbine wings usually require a special and cost intensive transport to the installation destination. These transport and installation costs can be reduced by a flat transport condition and the possibility of layering several structural components. For this reason, the focus at the Department of Lightweight Structures and Polymer Technology at TU Chemnitz was on a novel active material composite, which enables resource-efficient mass production and has a new component architecture. The large-volume multidimensional curvature of the active structure could be achieved by using a shape memory polymer (SMP). The associated reduction of the specific investment costs, the use of materials and the possibility of an integrative design, can contribute to the fact that, for example, the small wind turbines will become an economically viable investment in the future. The active structure influencing was represented by means of a finite element simulation (FEM) for different material composites and could be verified by generic demonstrators regarding its validity.

Veneer plywood is established in building construction, interior finishing and vehicle construction. Particularly in automotive or ship interior applications, the requirements with regard to strength and stiffness properties are increasing. At the same time, the weight of the panel materials used is to be reduced. The development presented here is a new type of lightweight basalt fibre-reinforced poplar veneer plywood and at the same time rigid alternative to the established birch veneer plywood. By adapting the adhesive and the reinforcing semi-finished products, the material and manufacturing costs are comparatively low. The bonding of the fibre reinforcement to the carrier material is achieved by means of adapted wood adhesives (e.g. polyvinyl acetates), which are also used as matrix material for the fibre reinforcement. An application of the reinforcement layer is integrated into the coating process (e.g. with High Pressure Laminate HPL decorative fabrics) of the carrier material. Essential advantages compared to conventional board materials are shown in this paper. The research results were achieved at the Institute for Structural Lightweight Construction of the TU Chemnitz in cooperation with the company Toms Gerber GmbH within the ZiM cooperation project FuBa.

Since energy resources are limited, there is a strong need for efficient technologies, which are suitable for large scale production. Therefore, an innovative Continuous Orbital Winding Technology was developed within the Federal Cluster of Excellence EXC 1075 “MERGE Technologies for Multifunctional Lightweight Structures” at TU Chemnitz. This continuous orbital winding (COW) technology is aiming for mass-production-suited processing of special semi-finished fiber reinforced thermoplastic materials. The new process chain and modular concept allows the implementation of other technologies and special applications, e.g. sensor integration. The COW process is a combination of thermoplastic tape winding and automated thermoplastic tape laying technology.The technological aim is to produce structural components with variable closed cross sections having rotationally symmetric and asymmetric sections. In addition, the machine concept is specifically designed to realize flexible layer constructions. The experimental part geometry was determined and it is intended to carry out pilot studies in order to validate the functionality.The key challenge is the desired processing speed for mass production. Therefore, an exemplary cross-section contour has been derived and used for the realization of the demonstrative concept. In this special concept the number of discontinuous moved assembly units was reduced. Furthermore, the appropriate and effective drive system was dimensioned by using inverse kinematics.For the fundamental experiments unidirectional fiber reinforced thermoplastic tapes are used. These investigations imply the level of consolidation in critical areas. The achievable maximum processing speed is of prime importance. These results will be used for further optimizations and specifications.

The European 3D heterogeneous integration platform has been established by the consortium of the Integrated Project e-BRAINS [1], where technologies of the following relevant main categories of 3D integration are provided to enable future applications of smart sensor systems:3D System-on-Chip Integration - 3D-SOC: TSV technology for stacking of thinned devices or large IC blocks (global level),3D Wafer-Level-Packaging - 3D-WLP: embedding technology with through-polymer vias (TPV) for stacking of thinned ICs on wafer-level (no TSV), and3D System-in-Package - 3D-SIP: 3D stacking of packaged devices or substrates *definitions according to [2] Regarding TSV performance, the applications do not need ultra-high vertical interconnect densities as for 3D stacked Integrated Circuits – 3D-SIC*. Nevertheless, the lateral sizes of the TSVs are preferably minimized to allow for place and route for small “open” IC areas. Smaller TSVs are also preferred in order to reduce thermo-mechanical stress. e-BRAINS' focus is on how heterogeneous integration and sensor device technologies can be combined to bring new performance levels to targeted applications with high market potentials. The consortium, under coordination of Infineon and technical management by Fraunhofer EMFT, is composed of major European system manufacturers (Infineon, Siemens, SensoNor, 3D PLUS, Vermon and IQE), SMEs (DMCE, Magna Diagnostics, SORIN and eesy-ID), the large research institutions CEA Grenoble, Fraunhofer (EMFT Munich & IIS-EAS Dresden), imec, SINTEF, Tyndall and ITE Warsaw, and universities (EPFL Lausanne, TU Chemnitz and TU Graz). Target applications include automotive, ambient living and medical devices, with a specific focus on wireless sensor systems. Concerning the enabling 3D Heterogeneous Integration Platform, the e-BRAINS partners are working close together, where Infineon, Fraunhofer EMFT, imec and SINTEF are focusing mainly on 3D-SOC and 3D-WLP, and the French system manufacturer 3D PLUS and Tyndall on 3D-WLP and 3D-SIP technologies. The focus of this paper is on low-temperature bonding processes for highly reliable 3D integrated sensor systems. One of the key issues for heterogeneous systems production is the impact of 3D processes to the reliability of the product, i.e. the high built-in stresses caused by e.g. the CTE mismatch of complex layer structures (thin Si, ILDs, metals etc.) in combination with elevated bonding temperatures. As consequence, extensive project work was dedicated in the developments of reliable low-temperature bonding processes. Mainly intermetallic compound (IMC) bonding with Cu/Sn metal systems supported by ultrasonic agitation (Fraunhofer EMFT) was successfully introduced in 3D integration technology (see Fig. 2). A copper/tin solid-liquid interdiffusion (SLID) system was investigated using ultrasonic agitation to reduce the assembly temperature below the melting point of tin. Cleaning procedures are important shortly before joining the samples; dry cleaning has best results due to removal of thin oxide layers. Figure 2 shows a cross section of US supported Cu/Sn bonding at 150C. The intermetallic compounds Cu3Sn and Cu6Sn5 as well as pure tin easily can be identified. Due to low temperature assembly the most stable intermetallic compound (IMC) Cu3Sn has a minor share of the metal system. Most importantly there is no gap between top and bottom part of the joint despite the macroscopic assembly temperature is far away from the melting point of tin. But maybe the ultrasonic agitation brings enough energy to the interfaces, so locally melting can occur. In this way robust IMC bonding technology at 150C could be demonstrated with shear forces of 17 MPa and an alignment accuracy of 3 μm, well-suited for 3D integration. Figure 2: Low-temperature IMC bonding technology using ultrasonic agitation (Fraunhofer EMFT) Reliability for SLID contacts is certainly a very challenging objective especially looking for robust solutions in automotive applications. Thermally induced mechanical stress is the main reason for early fails during temperature cycling. Cross sectioned samples were investigated and methods like nanoindentation, Raman spectroscopy, fibDAC, and high local resolution x-ray scattering were applied to measure the intrinsic stresses. It can be shown that low temperature bonding is the right approach to avoid excessive stress cracking the interface or even fracturing the silicon. Also fatigue of metals can be reduced in a range that plastic deformation is no lifetime limiting factor.