Reliability of Technical Systems
Sufficient crosswind stability is an important criterion in the approval process of railway vehicles. However, crosswind stability is in conflict with demands for lightweight constructions (especially cabin cars) and higher driving velocities. In many countries, the approval process foresees stability predictions based on worst case scenarios, where uncertainties are taken into account by means of safety factors and comparison with reference vehicles. This procedure is a burden for innovations and hinders the interoperability of railway vehicles. 
Influence of the microstructure of metal foams on deformation and failure
Experiments with metal foams reveal large variations of the measured deformation and failure properties and a size effect of the standard deviation. It is assumed that the existence of inhomogeneities in the microstructure, such as density fluctuations and defects of the cellular structure contributes to this behavior. The aim of our investigations is the development of a simulation model that accounts for these inhomogeneities on the level of the microstructure and is therefore capable to represent the variations of macroscopic properties. 
Multibody simulation of the starting phase of turbocharger rotors

This project investigates the stability of rotors that are supported by sleeve bearings. To this end, nonlinear models of sleeve bearings are combined with various models of turbocharger rotors. The multibody simulations should help to gain a better understanding of the stability properties of rotorbearingsystems and yield better predictions of the domains of instability. 
Stochastic FiniteElementMethods
Polynomial chaos expansions of response quantities have been widely used in Computational Stochastic Mechanics and are well documented. Introduced in conjunction with a truncated KarhunenLoeverepresentation of the input random field, they represent global approximations in the Hilbert space of functions of (usually standard Gaussian) random variables. However, the global approximation character may lead to inefficient convergence behavior for higher order response moments or small response probabilities. 
Response Surface Methods
For failure probability estimates of large structural systems, the numerical expensive evaluations of the limit state function have to be replaced by suitable approximations. Most of the methods proposed in the literature so far construct global approximations of the failure hypersurface. The global approximation of the failure hypersurface does not correspond to the local character of the most likely failure, which is often concentrated in one or several regions in the design space, and may therefore introduce a high approximation error for the probability of failure. Moreover, it is noted that global approximations are often constructed for parameter spaces that ignore constraints imposed by the physical nature of the problem.In this study, a robust and efficient local approximation scheme of the limit state function for the estimation of failure probabilities is proposed. The major advantages of the proposed local approximation are that the limit state function is evaluated close to the region of most likely failure only and that it is not necessary to compute zeros of the limit state function. Moreover, an interaction between the importance sampling scheme and the limit state approximation scheme becomes possible. 