Papers by Keyword: Reliability Analysis

Abstract: Monte Carlo Simulation and Response Surface Method are two very powerful reliability analysis methods. Normally, in the reliability analysis of complex structures, the limit state function often can not be expressed in a closed-form. Usually, the codes for probabilistic analysis need to be combined with finite element models. ANSYS Probabilistic Design System (PDS) has provided a package to conduct probabilistic analysis automatically. This paper is going to compare the performance of these methods through an easy engineering problem in ANSYS. The results are going to be derived to show the feature of applying the corresponding reliability methods.

Abstract: In the recent past an increasing number of failure events have been observed for offshore structures due to exceptional environmental loading conditions such as large waves. The occurrence of these failure events indicates a possible improvement in the traditional modeling of environmental characteristics, which are the basis for the load models for structural analysis and design. In this paper, the seasonal and directional effects in the modeling of the significant wave height for structural reliability analysis are studied. The peak over threshold (POT) method is selected to model the extremes in the non-stationary point process for the wave heights. The time-varying parameters are taken into account with a cyclic changing pattern to reflect the seasonal behavior. Both the extreme values and the storm occurrence rate are investigated in the different seasons. The results are utilized for the load characterization of offshore structures to investigate their sensitivity to the changing seasonal effects in reliability analyses. An example of selected structure is discussed.

Abstract: ANSYS software has provided complete and accurate solutions for composite laminate analysis and provided a set of special elements for different composite structures such as laminated plates, beams, solid structures and stiffeners. Fiber composite materials have been widely used to critical components of aircrafts, automobiles, mechanical, and marine structures. Since uncertainties associated with geometric tolerances, material properties, and boundary conditions widely exist in practical engineering problems. The probability approach is the most popular way to quantify uncertain parameters and perform the reliability analysis. The paper researches on the reliability analysis of the composite panels using ANSYS software. The numerical example is given, it is shown that the response surface method (RSM) can reduce the computational efforts comparing with Monte Carlo simulation (MCS).

Abstract: In order to solve the difficulties existing in course of complex system reliability modeling, a novel method was proposed in this paper. According to the analysis sequence, from FMEA to FTA to BN, a BN can be constructed by making full use of the helpful information in the results of FMEA and FTA. The reliability of complex system can be analyzed based on uncertainty-expression ability and bidirectional-reasoning ability of BN. For demonstrating the effectiveness of this method, aim at the failures of gears in wind turbine gearbox, a BN for system reliability analysis was constructed.

Abstract: The reliability indexes of the two unstable modes of the gravity retaining walls were calculated by the first-order second-moment theory through setting up the fundamental model. Results evaluated are compared with the results which is evaluate by the safety factor method, and it shows that there is still a certain degree of probability of failure of gravity retaining walls , even though they meet the checking conditions of "Safety Factor" method .The analysis shows that the failure probability of sliding stability is approximately equal to the failure probability of the entire system stability. And the stability of sliding of the gravity retaining walls should be payed more attention during the process of design checking calculation.

Abstract: A new reliability-based topology optimization method for compliant mechanisms with geometrical nonlinearity is presented. The aim of this paper is to integrate reliability and geometrical nonlinear analysis into the topology optimization problems. Firstly, geometrical nonlinear response analysis method of the compliant mechanisms is developed based on the Total-Lagrange finite element formulation, the incremental scheme and the Newton-Raphson iteration method. Secondly, a multi-objective topology optimal model of compliant mechanisms considering the uncertainties of the applied loads and the geometry descriptions is established. The objective function is defined by minimum the compliance and maximum the geometric advantage to meet both the stiffness and the flexibility requirements, and the reliabilities of the compliant mechanisms are evaluated by using the first order reliability method. Thirdly, the computation of the sensitivities is developed with the adjoint method and the optimization problem is solved by using the Method of Moving Asymptotes. Finally, through numerical calculations, reliability-based topology designs with geometric nonlinearity of a typical compliant micro-gripper and a multi-input and multi-output compliant sage are obtained. The importance of considering uncertainties and geometric nonlinearity is then demonstrated by comparing the results obtained by the proposed method with deterministic optimal designs, which shows that the reliability-based topology optimization yields mechanisms that are more reliable than those produced by deterministic topology optimization.

Abstract: The definition for the constellation availability of the navigation system is given firstly, and then calculates the availability of a single satellite by using Markov processes, and establishes the model based on the state probability of the constellation, to achieve mapping model from component reliability of the single satellite to the constellation availability. Finally, we analysis the regional availability performance of the GNSS by the algorithm, which can fit and satisfy the requirements of contradiction between accuracy and rapidity for analysis of availability for constellation of GNSS.

Abstract: This paper presents the limit state shear design formulas for both normal and high-strength reinforced concrete deep beams using strut-and-tie model (STM). The proposed equations are based on the STMs with six state-of-the-art efficiency factors. These STMs were improved by correcting the bias and quantifying the scatter using a Bayesian parameter estimation method. The statistical parameters of material properties, dimensions, and the accuracy of design equations are considered to develop the resistance models obtained by Monte Carlo simulations. The reliability analysis is performed to determine the strength reduction factors. The calculated values of strength reduction factors are proposed for each of the considered efficiency factors.

Abstract: This study was intend to develop the optimal design method of suspension bridge by the reliability analysis based on minimization of life cycle cost (LCC). The reliability analysis was performed considering aleatory uncertainties included in the result of numerical analysis. The optimal design was estimated based on life-cycle cost analysis depending on the result of reliability analysis. As the effect of epistemic uncertainty, the safety index (beta), failure probability (pf) and minimum life cycle cost were random variables. The high-level distributions were generated, from which the critical percentile values were obtained for a conservative bridge design through sensitivity assessment.

Abstract: Large cooking fires, occurring in industrial oil cookers, present a severe hazard to food processing plants. There lots of reasons and usually the fire extinguishing system invalid turned to be getting more and more attention. The fire extinguishing system has many complex components, and very difficult to evaluate. In view of the existing fuzziness and randomness in reliability comprehensive evaluation for the suppression system, a two-stayed fuzzy assessment model for the evaluation of the petrochemical production unit is established by using the theory of fuzzy mathematics. Average fault ratios, mean time between failures, effectiveness, mean-time-to-repair, and maintenance cost rate, spatial variability and fault density are used as evaluation index system. It is found from the result of evaluation that the variability of the water mist suppression system is reliability step.