Student Works

Type:  Master's thesis

Groupe: Lightweight Structures

Aluminum–silicon cast alloys are widely used in lightweight structures for automotive and aerospace applications due to their high strength-to-weight ratio and castability. However, their long-term performance is strongly influenced by casting defects (such as pores and oxides), microstructural heterogeneities, and environmental conditions (humidity, temperature). To ensure reliable service life prediction, these factors must be systematically investigated under realistic loading scenarios.

This thesis project focuses on the experimental investigation of fatigue damage mechanisms in cast Al-Si alloys under high-cycle (HCF) and very-high-cycle (VHCF) fatigue loading. The work will include:

• Preparation and testing of alloy specimens under defined environmental and loading conditions.
• Use of in-situ monitoring techniques (hysteresis analysis, thermography, potential drop methods).
• Computed tomography (CT) for 3D defect and crack characterization.
• Correlation of experimental results with microstructural features and defect populations.

The results will provide valuable input for mechanism-based life prediction models and contribute to the development of more reliable lightweight structures.

Contact Person: Dr. Sudip Kundu, PhD

Typ: Initiativbewerbungen für Projekt‐/ Bachelor‐/ Masterarbeiten

Gruppe: Prozesskontrolle

Zur Herstellung von Stahlkomponenten für die Automobil‐, Luftfahrt‐, Energie‐ und Offshore‐Industrie werden zahlreiche trennenden, umformende und fügende Fertigungsverfahren eingesetzt, die die Lebensdauer der Komponenten unter Betriebsbeanspruchungen signifikant beeinflussen. In den studentischen Arbeiten der Gruppe Stähle werden der Einfluss der Fertigungsverfahren unter Einsatz kombinierter In‐Prozess‐Messtechnik untersucht, die zugrundeliegenden mikrostrukturellen Eigenschaften charakterisiert und mit dem mechanismenbasierten Ermüdungsverhalten unter realitätsnahen Beanspruchungen korreliert.

Die Arbeiten umfassen grundsätzlich die Durchführung experimenteller Untersuchungen an elektromechanischen, servohydraulischen und elektromagnetischen Prüfmaschinen und die Anwendung mechanischer, thermometrischer, elektrischer, magnetischer, optischer und elektrochemische Messsysteme. Für die mikrostrukturellen und analytischen Untersuchungen werden Licht‐ und Elektronenmikroskopie sowie Röntgendiffraktometrie eingesetzt.

Kontaktperson: M.Sc. Lars Andree Lingnau

Type: Scientific Project, Bachelor’s Thesis, Master’s Thesis

Group: Lightweight Structures

Additive manufacturing enables the production of complex lattice structures with high specific stiffness and strength. In particular, metallic additively manufactured lattice structures are used in lightweight design, energy absorption, and functionally integrated components. Due to the layer-wise manufacturing process, characteristic microstructures, surface roughness, defects, and anisotropies are formed, which significantly influence the mechanical behavior. For a reliable design of such structures, a systematic experimental investigation of their mechanical behavior is therefore required.

This work focuses on the fabrication and experimental characterization of the fatigue behavior of additively manufactured lattice structures made of austenitic stainless steel 316L under mechanical loading. The objective is to analyze and evaluate the damage and failure behavior as a function of lattice geometry and relative density. Particular emphasis is placed on identifying crack initiation mechanisms, damage accumulation within the struts, and deriving characteristic fatigue life parameters. Depending on the type of thesis, the work may include the following tasks:

• Manufacturing of additively manufactured lattice specimens with defined geometric and process parameters.

• Non-destructive evaluation of internal defects (CT) and surface roughness analysis using confocal laser scanning microscopy (CLSM).

• Conducting quasi-static and cyclic tests under defined load amplitudes and stress ratios with appropriate measurement techniques.

• Determination of S–N curves and characteristic material parameters.

• Analysis of damage and fracture behavior using suitable characterization methods (e.g., light microscopy, scanning electron microscopy, computed tomography).

• Correlation of experimental results with geometric parameters, relative density, and manufacturing-induced defects and surface properties.

The aim of this work is to develop an in-depth understanding of the key influencing factors on the fatigue behavior of additively manufactured lattice structures and to provide a basis for simulation-based design and material-oriented optimization.

Contact person: Peter Karentzopoulos