Other research topics

H - 7 Development of a simplified FE model to describe the bond behavior of fiber optic sensors

Unlike conventional strain gages (SGs), distributed fiber optic sensors (DFOS) enable quasi-continuous strain measurement along the sensor length. Due to the wide range of applications, e.g., to determine crack widths, prestressing losses, deflections, etc., DFOS offer enormous potential in structural health monitoring and can contribute to the preservation of aging infrastructure. However, the magnitude of the measured strains do not correspond to the true component strains due to the multi-layer sensor design. The DFOS strains are attenuated depending on the sensor type and the adhesive stiffness, which is why an engineering interpretation of the measurement results is highly relevant. In the course of the student work, a simplified FE-model using bar and spring elements has to be developed, which represents the interaction between the DFOS and the substrate (e.g. the concrete). Discontinuities, e.g. in the area of cracks, are to be considered. As a result, the simplified FE model can be used for determining the actual strains in the concrete and crack widths. The use of the FE software SOFiSTiK is recommended.

Contact person:
Max Herbers, M.Sc.
Telefon: +49 351 463-39620
E-Mail:

H - 6 Numerical calculation on the influence of creep, shrinkage and pre-stressing on the measurement with fiber optic sensors

Within the scope of the student work, numerical calculations are carried out on reinforced concrete and prestressed concrete components, taking into account the nonlinear and time-dependent material behavior of concrete. Based on the models, conclusions can be drawn about the influencing factors mentioned and suggestions for their compensation can be derived. The use of the FE software ATENA is recommended for the analysis.

Contact personr:
Max Herbers, M.Sc.
Phone: +49 351 463-39620
E-Mail:

H - 5 Investigation of different influencing parameters for the transmission of acoustic signals in acoustic emission analysis (SEA).

Acoustic signals are everywhere in our life. In everyday life they can be processed by our brain to get the needed information, e.g. from a conversation. In construction, they can also be used in combination with various measurement techniques for building diagnostics. Sound emission analysis (SEA) is a non-destructive testing method that can draw conclusions about a change in the condition of the structure based on the analysis of the sound waves emitted by the structure.

For a successful building diagnosis, the quality of the measured signals is crucial, which can be influenced by many parameters. These parameters can basically be divided into three groups, the sound source in the building component, the propagation path of the acoustic signals from the source to the sensor, and the measurement system. While the first two depend on the material properties of the component, parameters from the last group, e.g. the coupling of the measurement sensor, can be influenced by the measurement setup. A good coupling not only ensures a good signal quality, but also the reproducibility of the measurements.

Within the scope of the project work, various influencing parameters such as coupling means, the contact pressure of the measuring sensor with respect to the sensor coupling are to be investigated by means of tests on small-format specimens. Details of the task will be specified during the processing time.

Contact person:
Dipl.-Ing. Ronghua Xu
Phone: 0351 463-33776
E-mail:

H - 4 Numerical simulation of the propagation of ultrasonic waves in damaged concrete.

The complex damage development in concrete, which takes place at different scales, is reflected in a change in the propagation behavior of the ultrasonic waves. In a transmission measurement, constant voltage waves from an ultrasonic transducer are transmitted into the concrete from one side of the component. After the stress waves have traveled the length of the path in the concrete, picking up information about its current damage state, they are registered by the receiver on the other side and converted into an electrical signal. As a result, the received signal contains information about the change of sound propagation, which allows to conclude about the damage development in the concrete by comparing successive signals.

The aim of this diploma thesis is to integrate the progressive damage into the numerical modeling of the propagation of ultrasonic waves in concrete.

Contact person:
Raúl Enrique Beltrán Gutiérrez, M. Sc.
Phone: 0351 463-33675
E-Mail:

H - 3 Textile reinforcement from natural fibers

The textile use of natural fibers in technical products is becoming increasingly important. Within this thesis, the use of natural fibers in building products will be analyzed. This includes i) product development as well as ii) testing of the developed product.

Textile concrete is a composite building material consisting of textile reinforcement and concrete. While currently the focus is mainly on research and development of reinforcement textiles made of carbon and glass, renewable and regionally available fibers (for example from hemp) could be an economically and ecologically viable alternative for many application areas.

For the production of the novel reinforcement, an existing process, which is currently used for the production of carbon reinforcement at the Institute of Textile Machinery and High Performance Textile Materials (ITM), will be transferred to natural fibers. The process will initially be carried out by hand and will be used to produce initial prototypes for subsequent trials.

As a result of the specific properties of the starting materials, there are significant differences in the load-bearing behavior between textile and reinforced concrete. For this reason, test concepts and design models have been developed over the last decades at the Institute of Solid Construction (IMB) and at the ITM in order to test the load-bearing properties. Based on these models, the manufactured prototypes shall be tested, optimized and validated within the scope of this thesis (project work, master thesis, diploma thesis, ...).

The work is mainly aimed at students of the faculties of civil or mechanical engineering. The assignment will be adapted according to the progress of the project and the student's specialization.

Contact person:
Dipl.-Ing. Enrico Baumgärtel
Phone: 0351 463-42631
E-mail:

H - 2 Design of a novel specimen for the investigation of cracking during pull-out testing

The main objective of the work is to develop a new type of specimen for the study of local crack patterns near the steel reinforcement during a pull-out test. A sketch of the possible experimental setup is shown in Fig. 1. Other shapes will also be considered. The first part of the work consists of extensive literature research on composite. The focus is on experimental methods for specimens with openings. Based on the literature research, an optimal shape of such a specimen should be designed. The shape of the specimen, the position of the opening, the bond length, and the rebar diameter must also be investigated. Technical drawings of the concrete formwork to create the specimen should be made. In addition, the concreting procedure should be specified. Based on these instructions and prototype drawings, the newly developed specimens will be concreted. During the experimental part of the work, the bond stress-slip relationships of the newly developed test specimen will be compared with the standard tests and the possible differences will be evaluated especially in relation to the literature review from the first part of the work. The repeatability of the experimental procedure will also be investigated. The thesis can be written in German or English.

Prerequisites: CAD software knowledge (AutoCad, Solidworks...), ability to work independently and evaluate data critically.

Contact person:
M. Eng. Petr Máca
Phone: 0351 463-37321
E-mail: