On the Treatment of Uncertainties in Structural Mechanics & Analysis

In this paper the need for a rational treatment of uncertainties in structural mechanics and analysis is reasoned. It is shown that the traditional deterministic conception can be easily extended by applying statistical and probabilistic concepts. The so-called Monte Carlo simulation procedure is the key for those developments, as it allows the straightforward use of the currently used deterministic analysis procedures

Reliability analysis of large scale structures using a non-parametric approach

The paper is devoted to the estimation of small failure probabilities, i.e. on the reliability analysis, using the non-parametric model of the large-scale structure. Two major questions are addressed in this respect: (i) What are the effects of the model uncertainties on the prediction of very small failure probabilities, i.e. on the tails of the response distribution? This question will be answered by studying the differences in the failure probabilities predicted by the non-parametric approach and by the parametric approach, respectively. (ii) The non-parametric model of uncertainties features a very large number of random variables, thus leading to a high-dimensional reliability problem [3]. Due to the non-linear nature of the response, with respect to the space of the input random variables, this problem is very challenging. The performance of methods applicable to igh-dimensional reliability problems (Line Sampling, Subset Simulation) is studied

Reliability analysis of a satellite structure with a parametric and a non-parametric probabilistic model

International audienceThe reliability of a satellite structure subjected to harmonic base excitation in the low frequency range is analyzed with respect to the exceedance of critical frequency response thresholds. Both a parametric model of uncertainties and a more recently introduced non-parametric model are used to analyze the reliability, where the latter model in the present analysis captures the model uncertainties. With both models, the probability of exceedance of given acceleration thresholds is estimated using Monte-Carlo simulation. To reduce the computational cost of the parametric model, a suitable meta-model is used instead. The results indicate that for low levels of uncertainty in the damping, the non-parametric model provides significantly more pessimistic - and hence conservative - predictions about the exceedance probabilities. For high levels of damping uncertainty the opposite is the case

Data and model uncertainties in complex aerospace engineering systems

ABSTRACT: The dynamical analysis of complex mechanical systems is in general very sensitive to random uncertainties. In order to treat the latter in a rational way and to increase the robustness of the dynamical predictions, the random uncertainties can be represented by probabilistic models. The structural complexity of the dynamical systems arising in these fields results in large finite element models with significant random uncertainties. Parametric probabilistic models capture the uncertainty in the parameters of the numerical model of the structure, which are often directly related to physical parameters in the actual structure, e.g. Young’s modulus. Model uncertainties would have to be modeled separately. On the other hand, the proposed nonparametric model of random uncertainties represents a global probabilistic approach which, in addition, takes directly into account model uncertainty, such as that related to the choice of a particular type of finite element. The uncertain parameters of the structure are not modeled directly by random variables (r.v.’s); instead, the probability model is directly introduced from the generalized matrices of a mean reduced matrix model of the structure by using the maximum entropy principle (Soize 2001). In this formulation the global scatter of each random matrix is controlled by one real positive scalar called dispersion parameter

Zuverlaessigkeitsbeurteilung fuer den Sicherheitseinschluss (SE) am Beispiel des Druckwasserreaktors Hauptband. Anhangband 1-3. Anhangband 4-5

SIGLETIB: AC 9227+(Anh1-3)+(Anh4-5)+MF / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Probabilistische Untersuchung des Rissfortschrittsverhaltens von Reaktorkomponenten Abschlussbericht

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman