The urgency of developing more sustainable building materials and methods is obvious. Thus, novel building materials such as paper are gaining relevance. Until now, paper in buildings has been used primarily in furniture construction or for temporary structures. The insights resulting from these applications and additional research show that paper also has considerable potential as a building material for permanent load-bearing structures.

For a holistic consideration of paper as a building material, joining techniques must be examined, among other things. Often, glued papers cannot be recycled after their lifespan. For this reason, mechanical fasteners for paper construction should be considered. The goal of this work is to investigate shear-bearing connections of mechanical fasteners in paper both experimentally and numerically/analytically.

Heat pumps have been identified as key technologies for decarbonizing the energy system. Heat pumps coupled to borehole heat exchangers are especially efficient.

In this thesis, a benchmark toolbox is developed to support the comparability of borehole heat exchanger models.

Laminated safety glass (VSG) consists of at least two layers of glass bonded together by a polymeric interlayer. This has the advantage that, in the event of a breakage, glass fragments adhere to the interlayer, and the laminate retains residual load-bearing capacity. To characterize the post-breakage behavior, tensile and bending tests can be performed on fractured VSG. For this purpose, VSG made of thermally tempered glass or annealed glass (float glass), which has been broken in either a defined or undefined manner, can be used.

Possible focus areas for a thesis could include:

- Development of a method for the reproducible production of VSG panes with varying degrees of fragmentation. The fragmentation levels should reflect those observed in head impact tests on windshields.

- Conducting tensile and bending tests on fragmented VSG panes and interpreting the results.

Vacuum insulating glasses (VIGs) are an innovative window technology with the potential to revolutionize energy-efficient buildings. Windows and transparent facade elements are the main sources of heat loss and CO2 emissions in buildings.VIGs consist of glass panes with a vacuum gap that minimizes thermal effects and improves the energy balance of building envelopes. Small spacers in the va- cuumed inter-pane space ensure stability over decades and significantly influence the behavior of VIGs. Investigation of this influence and the development of standards for the use of VIGs are crucial for the introduction of energy-optimized window and facade systems in Germany and Europe. VIGs could thus make a significant contribution to sustainability in construction.

Glass is a ubiquitous material in modern engineering applications, prized for its transparency, strength, and versatility. However, glass is inherently brittle, and its susceptibility to crack initiation and propagation poses significant challenges in structural and safety-critical contexts. Understanding how cracks propagate in indented glass specimens under subsequent loading is therefore critical for enhancing the safety and reliability of glass- based structures and products.

The outcomes of this thesis are expected to contribute to the knowledge base on glass fracture mechanics and safety assessment. Moreover, the findings may have practical implications for improving the design and perfor- mance of glass components in engineering applications, such as architectural glazing, automotive windshields, and electronic displays.

While the glass panes in conventional lattice shells are typically used only as infill elements, activating the full load-bearing potential of glass can contribute significantly to reducing the material and energy resources of substructures for glass facades.

A current research project is investigating the integration of local and linear connection structures in glass supporting structures, which should help to better exploit the structural potential of the glass panes used and thus reduce the steel consumption in substructures to a necessary minimum. This should ultimately enable the construction of transparent glass structures with a wide variety of shapes and applications.

Vacuum insulated glazing is a highly energy efficient glazing system. Yet, its setup (more precisely the array of support pillars necessary to withstand the high loads of atmospheric pressure (10 tonnes/m2)) evokes complex stress distributions and high stress gradients locally. This can result in the formation of so-called cone cracks which can develop into through-thickness cracks and can thus lead to catastrophic failure of these glazing units. In the design of VIGs it is typically assumed that the glass-pillar contact is not of concern if the separation of pillars is limited. Yet, investiga- tions of various VIGs show that cracks occur anyway and failure can originate at a pillar.

Vacuum insulating glasses (VIGs) are an innovative window technology with the potential to revolutionize energy-efficient buildings. Windows and transparent facade elements are the main sources of heat loss and CO2 emissions in buildings.VIGs consist of glass panes with a vacuum gap that minimizes thermal effects and improves the energy balance of building envelopes. Small spacers in the va- cuumed inter-pane space ensure stability over decades and significantly influence the behavior of VIGs. Investigation of this influence and the development of standards for the use of VIGs are crucial for the introduction of energy-optimized window and facade systems in Germany and Europe. VIGs could thus make a significant contribution to sustainability in construction.

In order to reduce the consumption of raw materials, the production of climate-damaging gases, and the generation of waste, the topic of the circular economy has been coming to the fore for some time. The circular economy is a holistic approach that aims to use raw materials and the resulting products efficiently and for as long as possible. It includes repairing, reusing and recycling.

The aim of a current research project is to predict complex crack propagation during the glass breakage process as well as the resulting fragment geometry and size. To this end, ISM+D is creating a database from experimental studies in which glasses with different thermal toughness levels are broken in a targeted manner. The wave propagation in the glass body resulting from the impact is recorded with special sensors. The fracture pattern is analyzed by means of digital image processing.

Possible topics for a thesis (Bachelor or Master):

- Numerical characterization of fracture morphologies in thermally toughened glasses.

- Stochastic modeling of fracture morphologies in thermally toughened glasses

To address the desire for transparent facades, glass 3D printing will be used to create novel joints for facade applications. Figure 1 shows the construction chamber of the glass 3D printer at the TU Darmstadt, which is to print molten glass onto a heated base plate made of glass.

To understand the process of glass 3D printing, the heating of the base plate using a hot plate and gas burner and the subsequent cooling will be studied. In order to know and reduce the risk of breakage during printing, temperatures and stresses during printing will be studied. For this purpose, a thermographic camera is available to measure the temperature of the glass surface, see Fig. 2b. Numerical simulations are possible to calculate stresses during heating. After cooling, residual stresses may remain in the glass, affecting the optical and mechanical quality of the component. The residual stresses can be studied after printing using stress optics, see Fig. 2a. Experiments on heating and cooling the base plate on the glass 3D printer can be carried out in a thesis.

Laminated glass consists of at least two sheets of glass joined by a polymer interlayer. In the event of glass breakage, a residual load-bearing behavior occurs in which tensile stresses caused by bending are removed via the polymer interlayer. Numerical mapping of the material behavior of the interlayer in the case of large deformations, as occurs in the case of failure of one or more glass sheets, is currently not possible. The material behavior in this case depends on temperature and loading duration as well as on the magnitude of the load, so that nonlinear viscoelastic material models are necessary.