The Experts below are selected from a list of 131214 Experts worldwide ranked by ideXlab platform
Joseph H. Saleh - One of the best experts on this subject based on the ideXlab platform.
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spacecraft attitude control subsystem reliability multi state analyses and comparative Failure Behavior in leo and geo
Acta Astronautica, 2013Co-Authors: Jessica K Wayer, Jean-francois Castet, Joseph H. SalehAbstract:Abstract The attitude control subsystem (ACS) on board a 3-axis stabilized spacecraft is critical for on-orbit operations; its degradation can significantly disrupt mission performance, and its Failure is fatal to the spacecraft. An ACS that fails early on-orbit, for example in the first couple of years on a spacecraft with a 15-year design lifetime, results in significant losses to all stakeholders and constitutes a major financial blow to the satellite operator or insurer—losses can amount to a few hundred mission dollars. Understanding and preventing/mitigating ACS Failure is an engineering and financial imperative. In this work, we first provide a comprehensive statistical analysis of ACS Failure Behavior on orbit. The results indicate that the ACS is a major driver of spacecraft unreliability and contributes up to 20% of all spacecraft Failures. Nonparametric and parametric results, including mixture Weibull distributions, are provided for ACS reliability, and they are complemented with the subsystem’s multi-state Failure analysis. It is shown for example that the ACS is 89% likely to be fully operational after 15 years on-orbit. Results also demonstrate that ACS suffers from both infant mortality and wear-out Failures. The findings are important for satellite manufacturers and equipment providers as they indicate opportunities for improved ground testing and burn-in procedures for the ACS, and they highlight the need to consider additional redundancy, even in stand-by form, especially if increased spacecraft design lifetime is sought. Second, we conduct a comparative analysis of Failure Behavior of the ACS in Low Earth Orbit (LEO) and Geosynchronous orbit (GEO). The results demonstrate a marked difference in Failure Behavior in LEO and GEO: the ACS degrades and fails more frequently, harder (more severe anomalies), and earlier (more infant anomalies/Failures) in LEO than in GEO. We expand on these results and conclude with hypotheses for causal factors of this difference in Failure Behavior.
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spacecraft electrical power subsystem Failure Behavior reliability and multi state Failure analyses
Reliability Engineering & System Safety, 2012Co-Authors: So Young Kim, Jean-francois Castet, Joseph H. SalehAbstract:Abstract This article investigates the degradation and Failure Behavior of spacecraft electrical power subsystem (EPS) on orbit. First, this work provides updated statistical reliability and multi-state Failure analyses of spacecraft EPS and its different constituents, namely the batteries, the power distribution, and the solar arrays. The EPS is shown to suffer from infant mortality and to be a major driver of spacecraft unreliability. Over 25% of all spacecraft Failures are the result of EPS Failures. As a result, satellite manufacturers may wish to pursue targeted improvement to this subsystem, either through better testing or burn-in procedures, better design or parts selection, or additional redundancy. Second, this work investigates potential differences in the EPS degradation and Failure Behavior for spacecraft in low earth orbits (LEO) and geosynchronous orbits (GEO). This analysis was motivated by the recognition that the power/load cycles and the space environment are significantly different in LEO and GEO, and as such, they may result in different Failure Behavior for the EPS in these two types of orbits. The results indicate, and quantify the extent to which, the EPS fails differently in LEO and GEO, both in terms of frequency and severity of Failure events. A casual summary of the findings can be stated as follows: the EPS fails less frequently but harder (with fatal consequences to the spacecraft) in LEO than in GEO.
Taihei Shibata - One of the best experts on this subject based on the ideXlab platform.
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Failure Behavior of cement-treated soil under triaxial tension conditions
Soils and Foundations, 2017Co-Authors: Tsutomu Namikawa, Shota Hiyama, Yoshiya Ando, Taihei ShibataAbstract:Abstract Drained triaxial tension tests were conducted to investigate the tensile and shear Failure Behaviors of cement-treated soils under effective confining pressures. In the tests, tensile force was applied on saturated cement-treated soil specimens at effective confining pressures. The experimental result for a cement-treated soil shows that tensile Failure occurred at low effective confining pressures, while shear Failure occurred at high effective confining pressures. Based on experimental evidence, a Failure criterion for cement-treated soil is discussed. In this study, tensile Failure is assumed to be dominated by the effective minor principal stress and the Mohr-Coulomb Failure criterion is adopted for shear Failure. The observed stress states at Failure lie on the Failure criterion consisting of the tensile and shear Failure surfaces, indicating that the proposed Failure criterion is suitable for cement-treated soils. The experimental results provide a good understanding of the Failure Behavior of cement-treated soils that exhibit tensile and shear Failure modes.
Anatoli Djanatliev - One of the best experts on this subject based on the ideXlab platform.
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IHSI - A Validated Failure Behavior Model for Driver Behavior Models for Generating Skid-Scenarios on Motorways
Advances in Intelligent Systems and Computing, 2020Co-Authors: Bernd Huber, Christoph Sippl, Paul Schmidl, Anatoli DjanatlievAbstract:The automation of the driving task will gain importance in future mobility solutions for private transport. However, the sufficient validation of automated driving functions poses enormous challenges for academia and industry. This contribution proposes a Failure Behavior model for driver models for generating skid-scenarios on motorways. The model is based on results of the five-step-method provided by accident researchers. The Failure Behavior model is implemented using a neural network, which is trained utilizing a reinforcement learning algorithm. Hereby, the aim of the neuronal network is to maximize the vehicle’s side slip angle to initiate skidding of the vehicle. Concluding, the Failure Behavior model is validated by reconstructing a real accident in a traffic simulation using the Failure Behavior model.
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A Validated Failure Behavior Model for Driver Models to Test Automated Driving Functions
Human Interaction and Emerging Technologies, 2020Co-Authors: Bernd Huber, Christoph Sippl, Reinhard German, Anatoli DjanatlievAbstract:This contribution proposes a Failure Behavior model for driver models, which is validated by findings from accident research. Our concept is based on the five-step-method which is used in accident research. Based on this concept, we present a prototypical implementation of an information processing Failure and validate the implemented Failure model on the basis of a real traffic accident. In conclusion, we discuss and interpret the validation results.
Rui Kang - One of the best experts on this subject based on the ideXlab platform.
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Failure Behavior modeling and reliability estimation of product based on vine-copula and accelerated degradation data
Mechanical Systems and Signal Processing, 2017Co-Authors: Dan Xu, Mengli Xing, Qidong Wei, Yunxia Chen, Yong Qin, Jie Xu, Rui KangAbstract:Aiming at the characteristics of Failure mechanism coupling of high-reliability and long-lifetime complex products, a method of multivariate Failure Behavior modeling and reliability assessment is proposed based on vine-copula and accelerated degradation data. The method, considering the coupling modeling under accelerated stress and the relevant acceleration mechanism consistency test, can not only clearly describe the multivariate coupling relationship of the product, but also can carry out the reliability assessment of the product within the affordable time and cost. The Failure Behavior modeling method consists of two parts which are degradation Behavior and correlation relationship among variables. Firstly, degradation Behavior description of Failure Behavior modeling is obtained from, the degradation data of product performance parameters based on the accelerated degradation test, the degradation path of each performance parameter by utilizing drift Brownian motion, then the implementation of accelerated consistency test ensures the true reliability information. Furthermore, the correlation description of Failure Behavior modeling is constructed by Vine-Copula based multivariate damage coupling modeling method describing the pairwise correlation relationship. Afterward, the exact solution of reliability joint distribution of the product with non-strictly monotonic degradation is figured out by Vine-Copula and the equation of reliability estimation based on conditional probability. Finally, the feasibility of the method is verified by utilizing smart electricity meter as the numerical example.
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Critical review of system Failure Behavior analysis method
Proceedings of the IEEE 2012 Prognostics and System Health Management Conference (PHM-2012 Beijing), 2012Co-Authors: Ran Cao, Ying Chen, Rui KangAbstract:Failure Behavior is the state change process of product or part of a product which is relative to its environment, over time performance and can be detected from the outside. According to the different level of analysis, Failure Behavior analysis method can be divided into element Failure Behavior analysis method and system Failure Behavior analysis method. The formal reveals the variety Failure mechanisms under the alone or coupled action of internal cause and external cause using coupling analysis method; the latter focuses on product Failure performance law under the effect of variety Failure mechanisms by means of Failure propagation analysis or state analysis. This critical review from two aspects of element and system investigates and summarizes the current research status of Failure Behavior analysis method. The result shows that coupling analysis method has been mature at present, and there is plenty of supporting software for computer-aided analysis. Failure propagation analysis method consists of graph theory based method, Petri Net method and complex network method. But the above-mentioned methods are unilateral and isolated from each other. System Failure Behavior analysis method needs to synthetically use the current methods — coupling analysis, Failure propagation analysis and state analysis method so that forms an analysis methodology which needs to clear the input and output of each method and improve the interface between application software. The comprehensive methodology that the Failure Behavior analysis follows will provide support to product reliability analysis and design improvement.
Chao Zhang - One of the best experts on this subject based on the ideXlab platform.
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predicting the tensile and compressive Failure Behavior of angle ply spread tow woven composites
Composite Structures, 2020Co-Authors: Yong Cao, Zhenqiang Zhao, Yinglong Cai, Peng Liu, Lu Han, Chao ZhangAbstract:Abstract A meso-scale finite element model is developed to study the progressive Failure Behavior of angle-ply spread tow woven composites under tensile and compressive loading conditions. The size of representative volume element (RVE) for angle-ply woven composites is determined by comparing the model predictions against tensile and compressive experimental results to identify the RVE size that significantly affects the prediction of deformation and Failure modes, due to inconsistencies in the periodic geometric features of the 0/90° layer and the ±45° layer. The validated model is shown to be capable of predicting the effective stiffness, strength and main Failure Behavior of the woven composite under tension and compression loading. The tensile and compressive Failure Behavior of spread tow woven composites are systemically investigated based on the numerically predicted stress distribution and damage contours. It was found that the presence of 45° angle-ply could enhance the crack propagation resistance of the woven composite. This study provides a detailed understanding of the Failure mechanism and modeling strategy for spread tow woven composites.
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Modeling the transverse tensile and compressive Failure Behavior of triaxially braided composites
Composites Science and Technology, 2019Co-Authors: Zhenqiang Zhao, Chunyang Chen, Chao Zhang, Yulong LiAbstract:Abstract The complex Failure Behavior of triaxially braided composites under in-plane transverse load conditions is investigated through quasi-static experiments and meso-scale finite element (FE) simulations. A three-dimensional (3D) progressive damage model for the fiber tows is integrated with a cohesive model for the interfaces to simulate the initiation, accumulation and propagation Behavior of damage in braided composites. The meso-scale FE model predicts well the global stress–strain responses, and the predicted strain distribution contours compare well with the experimental results captured by digital image correlation. The fully validated FE model is subsequently adopted to investigate the Failure mechanism of a triaxially braided composite under transverse tensile and compressive loads. Numerical parametric studies are implemented to evaluate the effect of interface strength on the effective properties of the material and to identify the appropriate definition of through-thickness boundary conditions in the meso-FE simulation. The model presented in this study shows fairly good accuracy in predicting the Failure Behavior of a triaxially braided composite under different loadings, and it can be further employed to study the mechanical performance of similar materials.
