Dear students,
Some calls for proposals may still be in preparation. Initiative enquiries can be directed to the academic staff if you cannot find a suitable thesis here.
Fatigue behavior of additively manufactured, heat-treated AISI 316L in the VHCF-regime
Research Project, Bachelor Thesis
Additive manufacturing using powder-bed-based laser beam melting (PBF-LB/M) of AISI 316L enables the production of components with unrestricted designs. However, in addition to resulting in a unique, hierarchically developed microstructure, this process also induces high macroscopic residual stresses that must be reduced through heat treatment. The aim of this experimental work is to investigate the fatigue behavior of high-temperature-treated PBF-LB/M AISI 316L in the VHCF regime. Tests will be conducted on an ultrasonic fatigue testing machine, and the influence of the heat treatment on the fatigue performance will be evaluated.
Further Information: David Chodorowski
Damage Analysis of PBF-LB/M Manufactured AISI 316L Specimens Subjected to Various Load Types
Research Project
Laser-Powder Bed Fusion (PBF-LB/M) allows for the fabrication of topology-optimized components with complex geometries. These cause graded load conditions consisting of tension/compression, bending, and torsional loads. To investigate the influence of these types of load conditions on the damage behaviour, the fracture surfaces of PBF-LB/M manufactured AISI 316L specimens, which were loaded with varying amounts of tension/compression, bending, and/or torsion during fatigue tests, are to be analysed and categorized. Thereafter, the extent to which the load condition and the damage mechanism are connected must be examined.
Further Information: Paula Rahm
Development of a dynamic clamping device and sonotrodes for an ultrasonic welding process of aerospace-relevant materials
Study Project
To realize dynamic ultrasonic welding amidst current aviation material trends and the growing interest in ultrasonic welding, a moving clamping system is required. The objective of this project is the development and design of a movable clamping device that traverses in sync with the welding process. This fixture must enable the continuous welding of polymer composite components. Core tasks include concept generation, the mechanical design of the motion kinematics, and ensuring a constant clamping force.
Contact: Moritz Liesegang
Ultrasonic welding of thermoplastics and thermosets with expanded process monitoring
Master Thesis
The objective is the experimental investigation of the ultrasonic welding of aerospace-relevant thermoplastics with thermosets using various energy directors and flash traps. A central component of the work is the utilization of expanded process monitoring. Core tasks include a literature review, the systematic execution of welding experiments, and the analysis of the generated process data.
Contact: Moritz Liesegang
Influence of Surface and Atmosphere on Ultrasonic Welding of Automotive Electrical Connections
Master Thesis
The growing demand for high-performance electrical connections in modern vehicle manufacturing drives the advancement of ultrasonic metal welding. The objective of this master thesis is the experimental investigation of ultrasonic welding for electrical contacts under varying surface conditions and environmental atmospheres. Core tasks include systematic experimental execution in targeted, modified process environments, as well as the subsequent mechanical and electrical characterization of the weld joints.
Contact: Moritz Liesegang
Investigation of the Murakami-Endo Parameter √area for Evaluating the Fatigue Strength of Sonotrodes
Master Thesis
Sonotrodes in ultrasonic technology operate deep within the very high cycle fatigue (VHCF) regime, where material failure is primarily driven by microscopic internal defects. The objective of this project is to apply and validate the empirical Murakami-Endo model, which links the fatigue limit directly to material hardness and defect size √area. Core tasks include the digital measurement of actual material defects on fracture surfaces, statistical evaluation for defect size estimation, and comparing the calculated strength limits with experimental VHCF data from ultrasonic testing rigs.
Contact: Moritz Liesegang
Simulation of the Thermomechanical Deformation Behaviour of Fibre-Reinforced Polymers Under Dynamic Loading
Master Thesis
The dynamic deformation behaviour of fibre-reinforced polymers is largely determined by the complex interaction between the fibre and the matrix. The objective of this project is the simulation-based investigation of the near-fibre boundary regions under dynamic loading conditions. Throughout the study, fibre content and material properties will be systematically varied within the models. Core tasks include model generation, executing the dynamic simulations, and specifically analysing the local temperature evolution along with the resulting material softening.
Contact: Moritz Liesegang
Hot-melt bonding and ultrasonic welding of highly filled graphite-PPS for use in heat exchangers
Research Project, Bachelor Thesis
Highly filled graphite-polyphenylene sulphide (PPS) has enhanced thermal conductivity, making it particularly suitable for heat exchangers and thermal management in electronics, mobility and mechanical engineering. Joining this material is challenging, primarily due to the brittleness and low surface energy of PPS. The aim of the thesis is to develop a robust process window for hot-melt bonding and ultrasonic welding, as well as to evaluate the mechanical and microstructural properties of the joint zone with a view to heat exchanger-related applications. The thesis will be supervised in collaboration between the WKK and LRF departments. This will provide you with combined insights into process engineering and materials science! The thesis is highly practice-oriented and will take place predominantly in the laboratory.
Contact: Moritz Liesegang, Simon Ettmüller
Characterization of the electrical and magnetic material properties during high-frequency fatigue of WAAM-fabricated CrNi steels
Bachelor Thesis, Master Thesis, Diploma Thesis
Besides topology optimization, Additive Manufacturing allows for the targeted adjustment of material composition and, consequently, material properties. Knowing the relationship between these factors is therefore essential for producing such structures. As a basis for designing these graded structures, the magnetic, electrical, and mechanical properties of additively manufactured 316L and 17-4PH samples will be determined as a function of the build direction. Additionally, the local change in properties during cyclic loading is to be analyzed in interrupted tests. These findings will then serve as the basis for manufacturing graded structures.
Contact: Marc Alexander Hoffmann
Interfaces in composite materials and multi-material joints
Masterthesis
Many properties of composite materials and material composites are determined by the interfaces between the individual materials. The aim of this thesis is to analyse the interfaces of ultrasonically welded composite materials in detail and correlate them with process parameters.
Contact: Moritz Liesegang
Frequency dependence of plastic deformability during ultrasonic welding of metals
Masterthesis
Ultrasonic welding is an innovative and promising joining technique for hybrid material systems. The joining of dissimilar material types is interesting for high-performance structures, e.g. in electronics or aviation. The plastic deformability of metallic joining partners during the process is a basic prerequisite for a successful process and the production of robust welded joints. This work therefore aims to investigate the plastic deformation of metal-safe materials during the ultrasonic welding process as a function of the working frequency.
Contact: Moritz Liesegang
Design of ultrasonic welding sonotrodes
Bachelor thesis or research project for Master students
Sonotrodes are tools that transmit the vibration into the components during ultrasonic-assisted processes such as ultrasonic welding. To do this, the sonotrode must be acoustically designed so that the natural frequencies match those of the rest of the system. The design is comparatively complex, depending on the geometry of the sonotrode and the material used, and is typically carried out using finite element simulation.
In this work, ultrasonic welding sonotrodes are to be designed using CAD and FEM, which differ in terms of geometry and the materials used.
Contact: Moritz Liesegang
Ultrasonic welding of metal/glass-joints - Interface formation
Bachelor thesis or research project for Master students
Ultrasonic welding is a fast method of joining multiple materials. Brittle materials such as glass are challenging but desirable joining partners. In particular, the understanding of glass as a joining partner is interesting due to its state as an overcooled melt rather than a solid material. In this work, experiments will be carried out on the joining of metal and glass, which has been the focus of research at the WKK decades ago, with a focus on interface formation.
Contact: Moritz Liesegang