Search
Now showing items 91-100 of 155
Preprint
Numerical crack path prediction under mixed-mode loading in 1D quasicrystals
(2017-03)
Quasicrystals are being implemented in industry since this new class of materials appears to have some peculiar properties. However, the fracture behavior of quasicrystals is not yet clear, which could be a hindrance to its wide usage. This work adopts the generalized linear elastic framework of fracture theory in quasicrystals and develops numerical tools in a finite element environment to compute the fracture quantities. Crack growth is simulated in diverse specimens undergoing an intrinsic mixed-mode loading and ...
Dissertation
Effect of heat treatment and iron content on the microstructure and mechanical properties of a secondary Al-Si-Cu alloy
(2019-05)
In this work the effect of heat treatments on the microstructure and mechanical properties of a secondary Al-Si-Cu alloy is studied. A Design of Experiments (DoE) was developed in order to optimize the heat treatment parameters and analyze the dissolution and fragmentation of the iron-rich inclusions as well as the improvement of the mechanical properties by non-equilibrium heat treatments. The iron-rich intermetallic inclusions were characterized as-cast and after heat treatment both by two-dimensional metallography ...
Aufsatz
On the track of human errors - Procedure and results of an innovative assembly planning method
(2018-03-07)
Manual assembly operations are the endmost place of the production process and with it represent a melting pot for organizational, time-related and qualitative errors of manufacturing. Because competitive advantages are increasingly determined in the manual assembly, the creation of economical and reliable work steps is of fundamental importance for future business success. For that reason, at the institute of the authors, a procedure has been developed to use the knowledge of the Expert System for Task Taxonomy that ...
Aufsatz
Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures
(2017-08-25)
The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF ...
Aufsatz
Assessment of probabilistic distributed factors influencing renewable energy supply for hotels using Monte-Carlo methods
(2017-04-05)
This paper investigates the use of renewable energies to supply hotels in island regions. The aim is to evaluate the effect of weather and occupancy fluctuations on the sensitivity of investment criteria. The sensitivity of the chosen energy system is examined using a Monte Carlo simulation considering stochastic weather data, occupancy rates and energy needs. For this purpose, algorithms based on measured data are developed and applied to a case study on the Canary Islands.
The results underline that electricity ...
Preprint
Large-scale heat pumps: market potential and barriers, classification and estimation of efficiency
(2019-12-20)
Heat pumps powered by renewable electricity have a significant potential to become a critical technology to disruptively decarbonize an economy. An essential step towards this goal is the development of an accurate understanding and model of how heat pumps in large-scale implementations perform in terms of economics, energy, and the environment. In this study, the influence of system design and operating conditions on the Coefficient of Performance (COP) of large-scale (> 50 kWth) electric driven mechanical compression ...
Aufsatz
Increasing energy efficiency of milk product batch sterilisation
(2018-09-07)
The food industry is a large energy consumer and most heat demands in food processing are low-temperature. The aim of this study is to develop and simulate innovative retrofits or redesigns that unlock the heat recovery potential of industrial batch sterilisation processes. The case study focuses on the whey cream process, although the method and results apply to similar batch sterilisation processes. The initial situation is compared to energy efficient designs based on “Energy Storage” and “Rescheduling”. Using a ...
Buch
Rotatives Vibrationsschweißen
(kassel university press, 2017)
Schweißversuche mit den von dem Schweißmaschinenhersteller Fischer Kunststoff-Schweißtechnik GmbH entwickelten Prototypenmaschinen für das neuartige Rotative Vibrationsschweißen zeigen eine vergleichbare erforderliche Prozessführung und die bereits bekannten Ausprägungen der vier Schweißprozessphasen anderer Vibrationsschweißverfahren. Unter Verwendung unterschiedlicher Werkstoffe und Probekörpergeometrien zeigt sich, dass sich die Fügenahteigenschaften von mit dem Rotativen Vibrationsschweißverfahren gefügten ...
Buch
Struktur-Eigenschafts-Beziehung von Mischungen aus thermoplastischem PMMA mit vernetzten PMMA-Kolloiden
(kassel university press, 2016)
Ziel dieser Arbeit war es, ein Compound aus Partikeln aus untereinander vernetzten Polymerketten, sogenannten Kolloiden, und thermoplastischem Matrixmaterial basierend auf dem gleichen Monomer (MMA) aus ingenieurwissenschaftlicher Sicht zu charakterisieren und die Struktur-Eigenschafts-Beziehungen zu klären. Durchgeführt wurden die Untersuchungen an Compounds mit Kolloiden mit verschiedenen Größen, Vernetzungsgraden und Anteilen, die zunächst in Benzol mit dem Matrixmaterial, Plexiglas® 6N, vermischt wurden.
Neben ...
Aufsatz
Injection molded components with functionally graded foam structures – Procedure and essential results
(2015-02-13)
In the past few years, foam injection molding has increasingly gained significance in the field of technical plastic components. This is due to the development of new processes and processing combinations and efforts to produce lightweight products. In this article, a special tool technology will be introduced, which aids the process of expanding the existing areas of applications. The technology enables the production of foam injection molded components with different foaming ratios. This is made possible by core ...