Reliability Analysis Research And Application Of New Methods

In order to predict the failure probability of a complicated structure, the structural responses usually need to be estimated by a numerical procedure, such as finite element method. To reduce the computational effort required for reliability analysis, response surface method could be used. However the inflexible function form affects the fitting precision of the conventional response surface method. In this thesis, a new sampling strategy is presented, based on which a new artificial neural network (ANN)-based reliability analysis method and an advanced structural reliability analysis method incorporating Kriging technique are proposed and approved firstly. Then both of them are successfully used in the reliability analysis of composite structure. Also, searching for the most probable failure point directly by use of ANSYS optimization module is applied in engineering structure validly.In chapter one, the substance of four kinds of reliability analysis methods commonly used in structural safety are reviewed. Development of artificial neural network (ANN) is surveyed. Recent advancements in composite structural reliability analysis are summarized. Finally, the main work in this thesis is introduced.For implicit limit state equations in most engineering reliability analysis, a new method is presented on the basis of artificial neural network (ANN), where the training samples are appropriately selected, and an ANN reliability method based on the weight linear response surface method is also presented in chapter two.In chapter three, Kriging technique characterized by flexible and adaptive function form, in conjunction with selection strategy of sampling points, is employed to develop a new way for the reliability analysis of the implicit performance problems.The calculation of the most probable failure point can be translated into an optimization problem by introducing a modified joint probability density function (MJPDF) and searching trouble is solved directly through a built-in optimization module of ANSYS. In chapter four, after this method is validated, it is used to analyzethe reliability of the engineering structure.In chapter five, all methods presented in chapter two and three are applied in the reliability analysis of composite laminated structure under load of different level, and the method is programmed with the standard finite element software. It is shown that the results are suitable and reasonable.