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Dissertation
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Plastic packaging waste management in Germany: Evaluating and optimizing material flows and environmental impacts
(2023)
Since 1990, the annual plastic packaging consumption by private end users in Germany more than doubled. This trend can be attributed to plastic's advantageous properties such as its low weight, cost-effectiveness, and customizable features. However, plastic packaging is also widely criticized due to its dependency on fossil fuels, short lifespan, and potential contribution to marine littering. The tension between the popularity of plastic packaging and the environ-mental challenges associated with a short-term product ...
Aufsatz
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Experimental Analysis of Residual Stresses in CFRPs through Hole-Drilling Method: The Role of Stacking Sequence, Thickness, and Defects
(2023-05-09)
Carbon fiber reinforced plastics (CFRPs) gained high interest in industrial applications because of their excellent strength and low specific weight. The stacking sequence of the unidirectional plies forming a CFRP laminate, and their thicknesses, primarily determine the mechanical performance. However, during manufacturing, defects, e.g., pores and residual stresses, are induced, both affecting the mechanical properties. The objective of the present work is to accurately measure residual stresses in CFRPs as well ...
Aufsatz
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Describing mechanical damage evolution through in situ electrical resistance measurements
(2023-02-27)
The fatigue properties of metallizations used as electrical conductors in flexible electronic devices have been thoroughly studied over the years. Most studies use time-intensive characterization methods to evaluate mechanical damage. For their ease of access, in situ electrical resistance measurements are often performed along with other characterization methods. However, the data are mostly used as an indicator of failure and a thorough analysis is usually missing. This work presents some deeper analysis methods ...
Aufsatz
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Elevated Temperature Mechanical Characteristics and Fracture Behavior of a Novel Beta Titanium Alloy
(2023-02-03)
In the present work, the elevated-temperature deformation characteristics and microstructural evolution of a Ti-5V-5Mo-5Cr-4Al alloy in solution-treatment conditions were studied under a tensile load at temperatures in the range of 25 to 550 °C and strain rates between 0.001 and 0.1 s-¹. The results obtained indicated that, essentially, dynamic recovery (DRV) was the dominant softening mechanism in the case of the regimes considered. An analysis based on transmission electron microscopy (TEM) and the assessment of ...
Dissertation
Lignocellulosic biorefinery with a thermo-biological pretreatment concept
(2023)
There is great interest, not only in technologically advanced societies, in developing innovative sources of raw materials, especially lignocellulosic biomasses such as cereal straw, which do not interfere with food production. In Germany, 4 – 9 million tons of cereal straw, mainly wheat, are utilized annually, corresponding to an energy potential of 57 – 129 PJ/a. Lignocellulose, found in plant cell walls, consists of hemicellulose, cellulose, and lignin, and it requires complex fractionation to enable its polymers ...
Dissertation
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Ultrahochleistungsbetone mit Bewehrung aus Formgedächtnismetallen zur Optimierung der Frisch- und Festbetoneigenschaften
(2023-11)
Formgedächtnislegierungen haben die Eigenschaft sich durch einen thermischen oder spannungsinduzierten Impuls an eine zuvor eingeprägte Form zu „erinnern“. Dies beruht auf einer reversiblen Phasenumwandlung von der Niedrigtemperaturphase Martensit zu der Hochtemperaturphase Austenit. Durch diese Eigenschaft und die sich dadurch gebenden Möglichkeiten finden diese Legierungen auch immer mehr Beachtung im Bauingenieurwesen. Dies ist vor allem im Bereich der Energiedissipation und der externen Vorspannung und dem ...
Dissertation
Structural Design Pedagogy for Architects: Fostering Cross-Disciplinary Integration and Innovation
(2023)
This study develops and presents a qualitative and design-oriented approach to structural
design education as part of architectural education. Existing approaches to structural
design in architectural education for the most part seek to emulate, adapt and
simplify contents and methods typically employed within civil engineering education,
where structures are primarily understood and taught within the framework of static
principles and numerical analysis. In architectural practice, observations however show
that ...