Dynamic load
E - 5 Determination of the normal force in bridge hangers under different boundary conditions by means of vibration measurement.
Experiments with different reinforced concrete components were carried out in the drop tower of the TU Dresden. A steel impactor with a velocity of up to 200 km/h hit a reinforced concrete component with and without reinforcement on the upper side, i.e., the side facing the impact. These reinforcement layers consist of a top layer to distribute the load and an underlying damping layer absorbing a large part of the impact's energy, thus protecting the underlying structural member. The material properties of the energy-absorbing layer are the investigation objective of this work. The density and strength of this layer are to be varied to find the material with the optimum properties. The optimization goal is to achieve the highest possible energy absorption while maintaining a low impact force.
The investigations will be carried out in the explicit finite element program LS-Dyna. Models of the old steel concrete component and the impactor will be provided. Furthermore, a material model for the surface layer will be available. The work aims to calibrate the damping layer's material model based on the available tests and the subsequent variation of the material properties.
Details of the task will be specified during the processing time.
Contact person:
Dipl.-Ing. Lena Leicht
Phone: 0351 463-33311
E-Mail:
E - 4 Determination of the normal force in bridge hangers under different boundary conditions by means of vibration measurement.
The actual normal forces in hangers of tied-arch bridges or cable-stayed bridges often deviate from the assumptions made in the design, since it is difficult to achieve the design prestressing condition during their installation. However, the hanger normal force affects both the bearing behavior of the hanger itself and the bending stress of the bridge girder. Therefore, the measurement of the actual hanger force is an important task in the realization or evaluation of structures.
A simple and common method is to determine the forces by their relation to the natural frequencies of the hanger. Depending on the type of hanger (strand or flat steel hanger), different theories are used to describe the deflection behavior. These theories assume known boundary conditions such as the free oscillation length, the anchorage, which, however, is not fulfilled in reality depending on the hanger design.
Within the scope of the project work, the relationship between the normal force and the natural frequencies of the hanger is to be investigated experimentally using a laser vibrometer under various boundary conditions (hanger type, articulated/rigid anchorage). The investigation should determine how much the normal forces determined under different boundary conditions differ and to what extent the determination of the hanger normal force with unknown boundary conditions is possible. For data processing, knowledge of programming (Python or Matlab) is an advantage.
Contact person:
Dipl.-Ing. Ronghua Xu
Phone: 0351-463-33776
E-mail:
E - 3 Numerical investigation on the influence of the impactor shape on the waveform in the "Split-Hopkinson-Bar" experiment
The Split Hopkinson Bar is a test device for dynamic material testing. A projectile (impactor) is accelerated via a gas pressure gun and generates a load wave which is introduced into the specimen via a long bar. The material and the geometry of the impactor determine the shape and length of the generated load wave.
Within the scope of the diploma thesis different impactor shapes shall be investigated numerically. By means of parameter studies, correlations between impactor shape and waveform are to be derived. The FEM software ANSYS is recommended. Promising impactor geometries can be fabricated and tested in experiments.
Details of the task will be specified during the processing time.
Contact person:
Dr.-Ing. Birgit Beckmann
Phone: 0351 463-38687
E-mail:
E - 1 plates under impact
The design of structures is usually carried out by drawing up a structural analysis. As the name implies, primarily static loads occur. In special cases, however, loads can also act dynamically on structures. The prediction of the load-bearing capacity, the vibration response and the damage that may occur are considerably more complex than in the static case. The impact of a falling mass on reinforced concrete slabs and the derivation of a design model are currently the focus of a research project at the Institute of Solid Structures. The aim of your diploma thesis is to research existing models, to compare them and, if necessary, to verify them with actual test results. The task will be concretized depending on the current test series and the interests of the students.
Contact person:
Dipl.-Ing. Nicholas Unger
Phone: +49 351 463-32005
E-mail: