Papers by Keyword: Probabilistic Analysis

Abstract: The paper examines a complex methodology for calculating the slope stability of a tailing storage facility based on comparing the results obtained through deterministic and probabilistic approaches. The analysis is performed in GeoStudio software, based on the limit equilibrium method, and with a probabilistic approach that uses a Monte Carlo simulation to compute a probability distribution of the resulting factor of safety. A slope stability assessment of tailing dam was conducted on the example of Ferrexpo Poltava Mining, and a conclusion was reached about their reliability and safety. The results of the deterministic analysis showed that the calculated factor of safety is by those established in Ukrainian regulatory standards. It has been recognized that the factor of safety is not a consistent measure of risk for tailings dam. Considering the variability inherent in the soil materials of tailings dam is a way to achieve more accurate results. The importance of obtaining a failure probability and a reliability index due to tailing dam stability was highlighted by comparing deterministic and probabilistic approaches.

Abstract: Probabilistic method and fracture mechanics model were combined to analysis the failure probability of structure with multiple site cracks. Comparing the result with probabilistic model showed that, accounting the actual failure mode and the interaction of cracks, combination of probabilistic method and fracture mechanics model get better approaching to determine failure probability during structural integrity analysis.

Abstract: Metal structures and components made of fiber reinforced plastics are often tied using bolts, rivets or adhesive bonding methods. To avoid the disadvantages of these techniques, hybrid transition structures can be used. Two different concepts are investigated and a numerical approach to calculate the failure properties of such transition structures is proposed. This is done using cohesive zone models for a wire concept and probability functions in an extended failure tree analysis for a foil concept. Numerical results based on the finite element method are presented.

Abstract: In this paper, we focus on the interaction fluid-structure and specifically the vibro-acoustic problem. For the coupling fluid structure finite elements models, the importance of the size reduction becomes obvious because the fluid freedom degrees will be added to those of the structure. A method of condensation will be used to reduce the matrixes size. A numerical vibratory study is leaded on a structure 3D wing of aircraft in air taking the acoustic aspect into account. In this context, we focused very specifically on a deterministic and stochastic analysis through numerical simulations in 3D dynamic fluid-structure interaction problems.

Abstract: This paper presents an investigation of the effect of load variation on gear tooth surface micropitting, for an application in planet gears in a wind turbine gearbox. To study the effect of load variation, two methods are employed: an experimental testing of gear micropitting under variable loading and a probabilistic analysis of gear contact stress and specific lubricant film thickness variations using the ISO Technical Report ISO/TR 15144-1:2010. The load variation of wind turbine gearbox is derived from SCADA (Supervisory Control and Data Acquisition) data recorded in operation. Both experimental and analytical results show that high levels of contact stress, load variations and repeated load cycles are determinant factors for the initiation and propagation of micropitting of gear tooth surfaces.

Abstract: The leak less distant transportation of large amounts of hazardous matters (for example natural gas) through a pressurized pipelines is a serious challenge. The pipeline should be able to withstand the full range of ambient conditions as well as the Earth’s crust movements, varying soil chemical state at present and after months or years of exploitation. During the previous years the formal risk assessments were carried out on the base of the failure intensity. Since that time the procedure of the risk assessment has become more sophisticated. At present risk management is being more and more mandated by regulations.

Abstract: This paper illustrates a technique that may be used to evaluate the risk of structural failure of each aircraft in a fleet when a crack has been detected in a particular member aircraft, or the risk of failure for that member has become too high. When a crack is detected, the calculated risk of failure for other aircraft in the fleet will increase significantly, and the aircraft operators need to decide which aircraft should be temporarily grounded for unscheduled inspection and which ones be allowed to fly. The proposed method applies the Bayesian inference to update the risk assessment by updating the equivalent initial flaw size distribution, which is one of the key inputs for risk analysis. To illustrate the method, a hypothetical fleet aircraft is considered and the single flight probability of failure of each aircraft in the fleet is revised after the occurrence of a failure in one fleet aircraft.

Abstract: The static voltage stability of power system with wind farm is simulated by fuzzy simulation. This method is able to calculate not only the expectations and standard deviations of diagonal elements of Jacobian reduction matrix with the uncertain parameters but also the static voltage stability indicator based on the credibility theory. The method is characterized in that the impact of the assumptions of distribution function type of uncertain parameters and parametric statistics is avoided by this method. The calculated results are impacted only according to the actual changed range and the types of membership functions of uncertain parameters. Finally the calculation results based on that method are compared with the calculation results based on two-point estimation method and Monte Carlo simulation method. The results show that the superiority and accuracy based on the method is proved.

Abstract: Survey of existing timber structures often includes the need to allocate mechanical properties to structural timber members. This task has to take into account the huge variability of timbers properties (within and between species), characteristic that differentiates this material from other structural materials (e.g. concrete and steel). For many decades, and still now, the application of visual strength standards is the main or only procedure used for this task. Despite the large number of other non and semi-destructive technique developed their regular application to in situ assessment of timbers mechanical properties is still almost non-existent. The present paper discusses possible ways to use and combine information from visual grading standards and non and semi-destructive techniques to predict the reference properties of timber members in service. The discussion has in mind studies conducted over the last years and the information provided by different guidelines, standards or papers recently published.

Abstract: Currently, the composite materials make important great strides, considering their high mechanical properties. The studies relating to the conceptual, technical aspect and modeling of their mechanical behavior are more than desirable. The mechanical properties of the composite material depend on several factors as the nature of fibers, the fiber/matrix ratio, compatibility, homogeneity... In this study, we present the results of an experimental analysis of the behavior of the composite material, under a static and a dynamic loading. The composite material is composed respectively of the glass and metal fiber reinforcement. A various dimensions of the mesh are considering. The resin used is polyester Resow 55 E. The dynamic test ( Knoop test) is carried out on various specimens made up of an polyester resin RESOW 55 E reinforced with varied powder nature. It makes it possible to measure the hardness of composite materials. The analysis of the results shows clearly that the mechanical properties are strongly influenced by the dimensions of the elementary mesh of the fiber grid reinforcement. Based on experimental results, a Weibull modulus has been established for each specimen.