Reliability Analysis for Trans-Scale Safety and Arming Device Based on FORM+G-PCM Method

Fairing separation is an important action in rocket or missile flight process, the ability to achieve safe separation is one of the key factors which decide the success of launch. For the high cost of fairing separation exercise test, the test environment is difficult to simulate and the test samples are limited, reliability analysis based-simulation method for payload fairing separation is proposed. Considering the law motion and working conditions of the low-altitude high-speed payload fairing, the separation system's main failure modes and failure criteria are proposed, its simulation model by Aided 3D modeling software, the aerodynamic calculation software, finite element software and multi-body analysis software is established. In order to get fairing separation mission's reliability, each failure modes during separation process is analyzed combining with classic reliability analysis methods. Finally, one example demonstrates that it is feasible and practical to analyze separation system's failure mechanism and failure mode by utilizing simulation technology combining with reliability analysis methods.

In recent years, time‐variant reliability issues have garnered widespread attention, particularly due to their consideration of the cumulative effects of material degradation and the time dependency of stochastic process loads. Methods based on the outcrossing rate are typically employed for time‐variant reliability analysis. However, they fail to effectively capture the correlations among multiple failure modes. To address this limitation, this paper proposes a time‐variant reliability analysis method that accounts for the correlation of multiple failure modes by integrating copula and PHI2. The method first utilizes Copula to analyze the correlations among various failure modes, followed by applying the PHI2 method for the time‐dependent reliability analysis of each individual failure mode. Ultimately, case studies confirm that the proposed method proficiently evaluates the time‐variant reliability of systems with multiple failure modes, yielding a maximum relative error below 5% compared to MCS and significant performance enhancements.

Efficient system reliability analysis illustrated for a retaining wall and a soil slope

This paper presents a general mechanical system reliability modeling and analysis method, which consider the correlations of failure modes. Firstly, the performance functions which mathematically represent the failure modes are linearized based on FORM (First Order Reliability Methods), and the correlation coefficient matrix of those functions is calculated. Then, the PFTA (Probabilistic Fault Tree Analysis) method is adopted to establish the system reliability model which can take the correlations into account. Finally, effective algorithms such as G-FOMN (General First Order Multinormal Method) are used to quantify the system reliability, and the sensitivities of the system reliability index with respect to each failure mode, as well as the mean value and standard deviation of each random variable are also calculated. An engineering example demonstrates the applicability of the proposed method.

Flood defenses are crucial elements in flood risk mitigation in developed countries, especially in deltaic areas. In The Netherlands, the VNK2 project is analyzing the reliability of all primary flood defenses as part of a nationwide flood risk analysis. In this project, as in most other reliability analyses of flood defenses, prior probabilities of relevant parameters such as ground conditions use to be based on sparse site investigation data and/or expert judgment. What is largely neglected is the observed performance during extreme events such as excessive seepage or sand boils. Using this information and thereby reducing uncertainties contributes to identifying weak spots or to increasing reliability where positive signs of performance are observed. Ultimately, this contributes to focusing investments in flood defenses where they are needed the most. This paper proposes a methodology based on Bayesian Inference for updating uncertainties and focuses on the failure mechanisms uplift and piping. Attention is paid to the system reliability effects in this failure mode, too. The methodology is applied to a case study in The Netherlands, the prior probabilities stem from the VNK2 project. The results suggest that depending on the observation, the probability of failure can either increase or decrease by about a factor 10. The findings clearly contradict the common perception, at least in The Netherlands, that if a structure survives an extreme (load) event its reliability always increases. That is only true unless bad performance-related observations have been made. ratios, a more objective approach consistent with the reliability analysis methods and the level of detail as applied in the VNK2 project is lacking. Calle (2005), Schweckendiek (2010) and Zhang et al. (2011) have illustrated very similar approaches to incorporate survival information for piping and slope stability respectively. However, both do not consider system reliability aspects or indirectly related observations (i.e., not using the same function for performance and observation) as required for uplift and piping. 1.2 Objectives and approach This paper aims at overcoming the shortcomings of previous approaches by providing a method to update the reliability of flood defenses with field performance observations. The method should allow using observations of physical processes that are related to the failure mode in question, for example, by common random variables. Bayes’ theorem is used for updating the probability of failure, where the observation is described in terms of an observational limit state providing inequality type of information (Ditlevsen, 1996). The focus in this paper is on levee reliability, the failure mode uplift and piping and the related field observations.

This paper proposed a new reliability analysis method which is based on the background of the reliability work of ultra-high pressure liquid pump. According to the specific characteristics of the ultra-high pressure liquid phase pump, we studied the typical failure mechanism of key components. At the same time, based on the failure mechanism describing the law of degradation, taking into account the changes in the structural characteristics, a degenerative process model based on the failure mechanism was proposed. This kind of reliability modeling method can effectively compensate for the lack of relevant data in the prediction process of new equipment reliability. Meanwhile, it can study the failure process of key components in detail, and can provide reference for instrument industry to carry out reliability modeling work. The method takes the performance model of the ultra-high pressure liquid pump as the core to realize the injection of failure mechanism. Through real-time degradation simulation, the reliability simulation was completed and the reliability was predicted. And during the simulation process, taking into account the different cycle lengths in the co-simulation process, we increased the simulation step length to improve the simulation efficiency. This kind of reliability analysis method provides the theoretical basis and technical support for the reliability analysis of the ultra-high pressure liquid phase pump.

PurposeDegraded failures and sudden critical failures are quite prevalent in industries. Degradation processes commonly belong to Weibull family and critical failures are found to follow exponential distribution. Therefore, it becomes important to carry out reliability and availability analysis of such systems. From the reported literature, it is learnt that models are available for the situations where the degraded failures as well as critical failures follow exponential distribution. The purpose of this paper is to present models suitable for reliability and availability analysis of systems where the degradation process follows Weibull distribution and critical failures follow exponential distribution.Design/methodology/approachThe research uses Semi-Markov modeling using the approach of method of stages which is suitable when the failure processes follow Weibull distribution. The paper considers various states of the system and uses state transition diagram to present the transition of the system among good state, degraded state and failed state. Method of stages is used to convert the semi-Markov model to Markov model. The number of stages calculated in Method of stages is usually not an integer value which needs to be round off. Method of stages thus suffers from the rounding off error. A unique approach is proposed to arrive at failure rates to reduce the error in method of stages. Periodic inspection and repairs of systems are commonly followed in industries to take care of system degradation. This paper presents models to carry out reliability and availability analysis of the systems including the case where degraded failures can be arrested by appropriate inspection and repair.FindingsThe proposed method for estimating the degraded failure rate can be used to reduce the error in method of stages. The models and the methodology are suitable for reliability and availability analysis of systems involving degradation which is very common in systems involving moving parts. These models are very suitable in accurately estimating the system reliability and availability which is very important in industry. The models conveniently cover the cases of degraded systems for which the model proposed by Hokstad and Frovig is not suitable.Research limitations/implicationsThe models developed consider the systems where the repair phenomenon follows exponential and the failure mechanism follows Weibull with shape parameter greater than 1.Practical implicationsThese models can be suitably used to deal with reliability and availability analysis of systems where the degradation process is non-exponential. Thus, the models can be practically used to meet the industrial requirement of accurately estimating the reliability and availability of degradable systems.Originality/valueA unique approach is presented in this paper for estimating degraded failure rate in the method of stages which reduces the rounding error. The models presented for reliability and availability analyses can deal with degradable systems where the degradation process follows Weibull distribution, which is not possible with the model presented by Hokstad and Frovig.

Reliability and safety analysis for systems of fusion device

PurposeAs a clean and renewable energy source, wind energy will become one of the main sources of new energy supply in the future. Relying on the stable and strong wind resources at sea, wind energy has great potential to become the primary energy. As a critical part of the wind turbine, the gearbox of a wind turbine often bears a large external load. Especially at sea, due to the effects of ocean corrosion, waves and wind, the burden of the wind turbine gearbox is greater, which brings great challenges to its reliability analysis. This study aims to systematically review the reliability research in wind turbine gearboxes and guide future research directions and challenges.Design/methodology/approachThis study systematically reviews some design requirements and reliability analysis methods for wind turbine gearboxes. Then, it summarizes previous studies on wind load uncertainty modeling methods, including the processing of wind measurement data and the summary of three different classifications of random wind speed prediction models. Finally, existing reliability analysis studies on two major parts of the gearbox are described and summarized.FindingsFirst, the basic knowledge of wind turbine gearboxes and their reliability analysis is introduced. The requirements and reliability analysis methods of wind turbine gearboxes are explained. Then, the processing methods of wind measurement data and three different random wind speed prediction models are described in detail. Furthermore, existing reliability analysis studies on two common parts of wind turbine gearboxes, gears and bearings, are summarized and classified, including a summary of bearing failure modes. Finally, three possible future research directions for wind turbine gearbox reliability analysis are discussed, namely, reliability research under the influence of multiple factors on gears, damage indicators of bearing failure modes and quantitative evaluation criteria for the overall dynamic characteristics of offshore wind turbine gearboxes and a summary is also given.Originality/valueThis paper aims to systematically introduce the relevant contents of wind turbine gearboxes and their reliability analysis. The contents of wind speed data processing, predictive modeling and reliability analysis of major components are also comprehensively reviewed, including the classification and principle introduction of these contents.

This study proposes a system reliability analysis of rack storage facilities subjected to forklift colliding events. The proposed system reliability analysis consists of two steps: the first step is to identify dominant failure modes that most contribute to the failure of the whole rack facilities, and the second step is to evaluate the system failure probability. In the first step, dominant failure modes are identified by using a simulation-based selective searching technique where the contribution of a failure mode to the system failure is roughly estimated based on the distance from the origin in the space of the random variables. In the second step, the multi-scale system reliability method is used to compute the system reliability where the first-order reliability method (FORM) is initially used to evaluate the component failure probability (failure probability of one member), and then the probabilities of the identified failure modes and their statistical dependence are evaluated, which is called as the lower-scale reliability analysis. Since the system failure probability is comprised of the probabilities of the failure modes, a higher-scale reliability analysis is performed again based on the results of the lower-scale analyses, and the system failure probability is finally evaluated. The illustrative example demonstrates the results of the system reliability analysis of the rack storage facilities subjected to forklift impact loadings. The numerical efficiency and accuracy of the approach are compared with the Monte Carlo simulations. The results show that the proposed two-step approach is able to provide accurate reliability assessment as well as significant saving of computational time. The results of the identified failure modes additionally let us know the most-critical members and their failure sequence under the complicated configuration of the member connections.

System reliability analysis of rock wedge stability considering correlated failure modes using sequential compounding method

Reliability is importance property of a healthcare system. Methods for this system reliability analysis are considered in the paper. These methods have to include reliability analysis of technical part, and organization and human components of a health care system. Importance reliability analysis is proposed for this reliability analysis. The importance reliability analysis allows to estimate the influence of every healthcare system component to the system reliability and functioning.

Bayesian networks inference algorithm to implement Dempster Shafer theory in reliability analysis

Modification of thermoplastic coatings for improved cathodic disbondment performance on a steel substrate: a study on failure mechanisms

Offshore system safety and reliability considering microbial influenced multiple failure modes and their interdependencies