Fused Glass Deposition Modelling on Flat Glass: Investigations of process-structure-properties and feasibility of novel glass joints

• Applicants: Professor Dr.-Ing. Ulrich Knaack, since 10/2023; Professor Dr.-Ing. Matthias Oechsner
• Subject Area: Structural Engineering, Building Informatics and Construction Operation
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439726461

Compared to metals and plastics, additive manufacturing (AM) of glass can still be considered within an embryonic state of research. AM of glass however would enable completely new possibilities in different sectors for individual designs. Homogeneous, transparent and individual glass joints and glass reinforcements on flat glass without boreholes and adhesives are imaginable. A few research projects focus on AM of individual glass components, but they did not yet address the joining process between the fused glass layers themselves and flat glass or other larger glass structures. A successful joining of glasses is primarily dependent on the viscosity, the joining time and the temperature settings. Further parameters are heat quantities and the geometry of the joining partners, the thermal expansion behaviour as well as the residual stresses generated during heating, cooling and the related temperature-dependent glass strength. The key objective of the proposed research project is to gain a fundamental knowledge of the integrated joining process using fused glass deposition on flat glass for a homogeneous and reproducible joining area by means of analysis of the process-structure-properties. A further goal is to identify potential structural applications for the novel glass joints on flat glass, which is typically made of borosilicate and soda-lime silicate glass. The integrated joining process fused glass on flat glass bares some significant challenges. In-depth knowledge of the impact of temperature fields and volume-related heat quantities as well as of the development of non-uniform residual stresses is required. The interaction of these transient effects with the brittle material behaviour of glass at temperatures below the glass transformation temperature requires fundamental research to achieve a significant mechanical strength of the joints. The process parameters (temperature, geometry, ect.) influence the structure (homogeneity, interface) in the joining area of the resulting joints and their mechanical properties (strength, residual stress). The relevant parameters will be identified and optimized by a systematic investigation of the relationships between process, structure and mechanical properties. In addition, a numerical model for the calculation of the temperature fields and the resulting residual stresses is developed, which will be used for the optimization of the joining process and the development of joining design. Based on the results of the process optimization and the resulting process limits, glass-glass joints will be designed and test samples produced. The systematic investigation of the process-structure-properties in combination with numerical analyses, material and component investigations will significantly improve the joining process between fused glass and flat glass. The potential of the joining process and novel joints for structural applications will be identified on this basis.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr.-Ing. Jens Schneider, until 9/2023