## Promovierende

Yerkyekhulan Bagdat

## Name: Yerkyekhulan Bagdat (Stipendiat)

E-Mail: bagdayer(at)b-tu.de

#### Titel der Dissertation:

Models and algorithms for optimization of local production chains (Arbeitstitel)

#### Beschreibung:

Design of algorithms for the distribution of production steps among the existing
local production facilities. To produce a particular product, numerous combinations of different individual steps of manufacturing with many different tools are possible. The task here is the algorithmic planning of this process design. Based on the properties of the product and the characteristics of the tools, appropriate models and algorithms should be designed which are capable of finding feasible production chains and that are optimized with respect to processing time, usage of materials, and production costs. In particular productivity should be increased by utilizing the provided machinery by parallel production in different process chains.

#### Kurz-Vita:

• 2008 – 2012: Bachelor of mathematics at National university of Mongolia
• 2013-2016: Master of mathematics, with a specialisation in Functional  analysis and Operator theory at National university of Mongolia

• International mathematical Competition for university students 2011- honourable, 2012- bronze medal
Thawin Hart-Rawung

## Name: Thawin Hart-Rawung (Stipendiat)

E-Mail: thawihar(at)b-tu.de

#### Betreuer:

Prof. Dr.-Ing. habil. Markus Bambach

#### Titel der Dissertation:

Development of a material modelling and alternative technique of a hot stamping process (Arbeitstitel)

#### Beschreibung:

Hot stamping is currently one of the most effective methods for weight reduction of the body-in-white in the mass production of cars, due to the very high strength-to-weight ratio. Two types of hot stamping processes are in use, direct and in-direct hot stamping. For direct hot stamping, the sheet metal is heated to approximately 950°C, reaching the austenite phase region, and held for a certain time. Then, it is formed to the desired geometry and simultaneously quenched to room temperature inside the forming die. Due to the rapid cooling, martensite develops. For indirect hot stamping, the material is formed at room temperature. Then, it is heated above austenitisation temperature and quenched in a forming die. For some components, the strength of hot stamped steel is adapted locally to achieve the desired crash performance.

Finite Element Method (FEM) has been used to help to design the forming die of a hot stamping process. FEM for the hot stamping process is very challenge due to the complexity of the process including effect of deformation, temperature, and microstructure evaluation. Therefore, improving the accuracy of a material model can be help to improve the quality of the workpiece and reduce the cost and time during the die manufacturing process.

In this research, the attempts to improve the accuracy of a material model as well as implement the modelling in the actual application.

#### Kurz-Vita:

Thawin Hart-Rawung was born in Khon Kaen, Thailand 1989. He graduated his Bachelor’s  Degree  in  Industrial  Engineering  at  King  Mongkut’s  University  North  Bangkok, Thailand  in  2011, and  later  on,  continued  Master’s  degree  in  Production  Engineering  at  The  Sirindhorn International  Thai-German Graduate  School  of  Engineering  (TGGS). In November 2016, his master thesis won the TGGS outstanding award.  After the graduation, he started working as an application engineer at Dyna Forming Engineering and Technology, DFETECH, Thailand. The core business of this company is to provide consultancy and sale of FEM softwares. He was responsible in the technical support, including software training,  onsite  support  and  technical  seminar  for  customers  in  the  fields  of  sheet  and  bulk  forming  within  Asian region. During working, he had an opportunity to further enhance my FEM skill by participating in the seminar on the advance knowledge in “Blast and Penetration Modeling” and “Crash and Safety Analysis” for one week at Singapore and China respectively. Due to his strong background in FEM, now he conducts his research on the implementation of the FEM in a hot stamping and related application.

Fabian Kathöfer

## Name: Fabian Kathöfer (Stipendiat)

Betreuer:

Prof. Dr. Florian Pyczak

Title der Dissertation:

Material Development for TiAl forming and repair

Beschreibung:

TiAl alloys are relatively new high temperature materials and several production problems, e.g. due to the poor hot workability, are not yet solved. Additional features are needed to add for TiAl alloys for local production. They must differ significantly in composition compared to the ones used for mass production. The processes for local production exhibit special conditions such as high cooling rates, high local degrees of deformation or strong temperature gradients that can significantly change microstructure compared to conventionally cast or forged components. This is especially important for TiAl alloys where microstructure and properties are very sensitive to manufacturing conditions and chemical composition. For this reason, alloys for local production must be adapted to the process, since the currently available TiAl forged or cast alloys are not robust enough to exhibit acceptable properties und the occurring process conditions or to withstand locally high levels of deformation without damage.
The research project will include two aspects of dealing with TiAl alloys. It is focused on how to modify the composition of the TiAl alloy to create a phase constitution

1. that allows isothermal forming at lower temperatures
2. that allows components to be locally repaired using AM method or sintering patches or a further geometrical detailing based on a forged basic shape.

Short Bio:

2011 - 2014 Bachlor of Science in Physics at University of Rostock Topic: "Structural properties of tungsten carbid-based materials consolidated by FAST" 2014 - 2016 Master of Science in Physics at University of Rostock Topic: "Synthesis and analysis of iron cobalt based systems"

Athar Safari

## Name: Athar Safari (Stipendiatin)

#### Betreuerin:

Prof. Dr.-Ing. habil. Sabine Weiß

#### Titel der Dissertation:

ESR: New Tool Material Suitable for Forging of Titanium Aluminides (Arbeitstitel)

Venkateswaran Santhanakrishnan Balakrishnan

## Name: Venkateswaran Santhanakrishnan Balakrishnan (Stipendiat)

E-Mail: santhven(at)b-tu.de

#### Betreuer:

Univ.-Prof. Dr.-Ing. Holger Seidlitz

#### Titel der Dissertation:

Mixed and hybrid construction with metals and composites (Arbeitstitel)

#### Beschreibung:

Development of mixed constructions with metals and fiber composites using both the thermoplastic and thermoset materials. Design and development of robust and reliable process chain for the local repair and restauration of composite based mono- and multi- material design in the automotive construction.

#### Kurz-Vita:

Master of science in Material process and technology of composites at École centrale de Nantes, France

Bachelor of Engineering in Mechanical Engineering at Easwari engineering college, Anna University, India

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