TY - JOUR AU - Bolenz, Lukas AU - Ehlert, Thomas AU - Dechert, Christopher AU - Bertling, René AU - Kenig, Eugeny ID - 23789 JF - Chemical Engineering Research and Design SN - 0263-8762 TI - Modelling of a continuous distillation process with finite reflux ratio using the hydrodynamic analogy approach ER - TY - CONF AB - Driven by the CO2-emission law by the European government and the increasing costs for raw materials as well as energy, the automotive industry is increasingly using multi-material constructions. This leads to a continuous increase in the use of mechanical joining techniques and especially the self-piercing riveting is of particular importance. The reason for this is the wide range of joining possibilities as well as the high load-bearing capacities of the joints. To be able to react to changing boundary conditions, like material thickness or strength variation of the sheets, research work is crucial with regard to the increase of versatility. In this paper, a numerical study of the influences on the selfpiercing riveting process is presented. For this purpose, the influence of different process parameters such as rivet length and die depth on various quality-relevant characteristics were investigated. With the help of the design of experiment, significant influences were determined and interactions between the individual parameters are shown. AU - Kappe, Fabian AU - Bielak, Christian Roman AU - Sartisson, Vadim AU - Bobbert, Mathias AU - Meschut, Gerson ID - 34222 T2 - ESAFORM 2021 TI - Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters ER - TY - CONF AB - In many areas of product manufacturing constructions consist of individual components and metal sheets that are joined together to form complex structures. A simple and industrial common method for joining dissimilar and coated materials is clinching. During the joining process and due to the service load cracks can occur in the area of the joint, propagate due to cyclic loading and consequently lead to structural failure. For the prevention of these damage cases, first of all knowledge about the fracture mechanical material parameters regarding the original material state of the sheet metals used within the clinching process are essential.Within the scope of this paper experimental and numerical preliminary investigations regarding the fracture mechanical behavior of sheet metals used within the clinching process are presented. Due to the low thickness of 1.5 mm of the material sheets, the development of a new specimen is necessary to determine the crack growth rate curve including the fracture mechanical parameters like the threshold against crack growth ΔKI,th and the fracture toughness KIC of the base material HCT590X. For the experimental determination of the crack growth rate curve the numerical calculation of the geometry factor function as well as the calibration function of this special specimen are essential. After the experimental validation of the numerically determined calibration function, crack growth rate curves are determined for the stress ratios R = 0.1 and R = 0.3 to examine the mean stress sensitivity. In addition, the different rolling directions of 0° and 90° in relation to the initial crack are taken into account in order to investigate the influence of the anisotropy due to rolling. AU - Weiß, Deborah AU - Schramm, Britta AU - Kullmer, Gunter ID - 30675 KW - Mechanical Engineering KW - Mechanics of Materials KW - General Materials Science SN - 1662-9795 T2 - Key Engineering Materials TI - Numerical and Experimental Fracture Mechanical Investigations of Clinchable Sheet Metals Made of HCT590X VL - 883 ER - TY - JOUR AB - AbstractIn addition to the classical strength calculation, it is important to design components with regard to fracture mechanics because defects and cracks in a component can drastically influence its strength or fatigue behavior. Cracks can propagate due to operational loads and consequently lead to component failure. The fracture mechanical analysis provides information on stable or unstable crack growth as well as about the direction and the growth rate of a crack. For this purpose, sufficient information has to be available about the crack location, the crack length, the component geometry, the component loading and the fracture mechanical material parameters. The fracture mechanical properties are determined experimentally with standardized specimens as defined by the guidelines of the American Society for Testing and Materials. In practice, however, especially in the context with damage cases or formed material fracture mechanical parameters directly for a component are of interest. However, standard specimens often cannot be extracted at all due to the complexity of the component geometry. Therefore, the development of special specimens is required whereby certain arrangements have to be made in advance. These arrangements are presented in the present paper in order to contribute to a holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens. AU - Weiß, Deborah AU - Schramm, Britta AU - Kullmer, Gunter ID - 30674 JF - Production Engineering KW - Industrial and Manufacturing Engineering KW - Mechanical Engineering SN - 0944-6524 TI - Holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens ER - TY - JOUR AB - Powder X-ray diffraction (XRD) patterns of ordered mesoporous CMK-8 and CMK-9 carbon materials are simulated by geometric modeling. The materials are amorphous at the atomic length scale but exhibit highly symmetric gyroidal structures at the nanometer scale, corresponding to regular, continuous nanopore systems with cubic symmetry. Their structures lead to characteristic low-angle XRD signatures. We introduce a model based on geometrical considerations to simulate CMK-8 and CMK-9 structures with variable volume fraction of carbon (vs. pore volume, i.e., variable 'pore wall thickness'). In addition, we also simulate carbon materials with variable amounts of guest species (e.g., sulfur) residing in their pores. The corresponding XRD patterns are calculated. The carbon volume fraction turns out to have a significant impact on the relative diffraction peak intensities, especially in case of CMK-9 carbon that features a bimodal porosity. Likewise, the presence of guest species in the pores may also strongly affect the relative peak intensities. Our study suggests that careful evaluation of experimental low-angle XRD patterns of (real) CMK-8 or CMK-9 materials offers an opportunity to obtain detailed information about the nanostructural properties in addition to the mere identification of the pore systems geometry. AU - Schwind, Bertram AU - Smått, Jan-Henrik AU - Tiemann, Michael AU - Weinberger, Christian ID - 25894 JF - Microporous and Mesoporous Materials SN - 1387-1811 TI - Modeling of gyroidal mesoporous CMK-8 and CMK-9 carbon nanostructures and their X-Ray diffraction patterns ER - TY - JOUR AB - A comparison of infrared spectroscopic analytical approaches was made in order to assess their applicability for internal structure characterization of SiO2 thin films. Markers for porosity and/or disorder based on the analysis of the asymmetric stretching absorption band of SiO2 between 900−1350 cm−1 were discussed. The shape of this band, which shows a well-defined LO–TO splitting, depends not only on the inherent characteristics of the film under analysis but also on the particular geometry of the IR experiment and the specific surface selection rules of the substrate. Three types of SiO2 thin films with clearly defined porosity ranging from dense films to mesoporous films were investigated by transmission (at different incidence angles), direct specular reflection (at different angles), and diffuse reflection. Two different types of substrate, metallic and semiconducting, were used. The combined effect of substrate and specific technique in the final shape of the band, was discussed, and the efficacy for their applicability to the determination of porosity in thin SiO2 films was critically evaluated. AU - de los Arcos, Teresa AU - Müller, Hendrik AU - Wang, Fuzeng AU - Damerla, Varun Raj AU - Hoppe, Christian AU - Weinberger, Christian AU - Tiemann, Michael AU - Grundmeier, Guido ID - 25897 JF - Vibrational Spectroscopy SN - 0924-2031 TI - Review of infrared spectroscopy techniques for the determination of internal structure in thin SiO2 films ER - TY - THES AU - Olenberg, Alexander ID - 42812 SN - 9783843947855 TI - Untersuchung und Optimierung von strukturierten Packungen mittels CFD-Simulationen ER - TY - JOUR AB - Tailor-made ordered mesoporous materials bear great potential in numerous fields of application where large interfaces are required. However, the inherent surfacechemical properties of conventional materials, such as silica, carbon or organosilica, poses some limitations with respect to their application. Surface manipulation by functionalization with chemically more reactive groups is one way to improve materials for their desired purpose. Another approach is the design of high surface-area composite materials. The surface manipulation, either by functionalization or by introducing guest species, can be performed selectively. This means that when several distinct, i.e. , hierarchical, types of surfaces or pore systems exist in a material, each of them may be chosen for manipulation. Several strategies can be identified to achieve this goal. Molecules or molecule assemblies can be utilized to temporarily protect pores or surfaces (soft protection), while manipulation occurs at the accessible sites. This approach is a recurring motive in this review and can also be applied to rigid template matrices (hard protection). Furthermore, the size of functionalization agents (size protection) and their reactivity/diffusion (kinetic protection) into the pores can also be utilized to achieve selectivity. In addition, challenges in the synthesis and characterization of selectively manipulated ordered mesoporous materials are discussed. AU - Tiemann, Michael AU - Weinberger, Christian ID - 25893 JF - Advanced Materials Interfaces SN - 2196-7350 TI - Selective Modification of Hierarchical Pores and Surfaces in Nanoporous Materials ER - TY - JOUR AU - Fuchs, Christian ID - 41431 IS - 1 JF - tripleC: Communication, Capitalism & Critique TI - Engels@200: Friedrich Engels in the Age of Digital Capitalism VL - 19 ER - TY - JOUR AU - Fuchs, Christian AU - Dyer-Witheford, Nick ID - 41599 JF - 国际社会科学杂志 (Journal of International Social Sciences) 2021 (9) TI - 卡尔·马克思与互联网研究 ER -