Advanced Materials Research Vols. 118-120

Abstract: High-performance computer was developed to address the tight schedule and the high reliability problems. For the 100 trillion times supercomputer Dawning 5000A computing nodes A950r-F server's reliability problems, on the bases of the pre-use investigation and stress analysis of the type, the thesis described the reliability accelerated test of A950r-F server implementation process, and obtained a series of accelerated test data. Accelerated test results from the failure analysis give the corresponding improvement measures by the reliability accelerated test of the A950r-F server. The experiment proved the feasibility and effectiveness of the guidelines.

Abstract: Based on the features of distributed knowledge resources environment and taking knowledge mobility in modern design as its supporting goal, this essay focuses on research into knowledge classification systems and representation models of product design. It proposes a six-dimension design knowledge classification system and a cubic knowledge representation model operating in an environment of distributed resources. The six dimensions of design knowledge classification are discipline, product, resource unit, application process, expression pattern, and design domain respectively. Accordingly, the six planes of the cubic knowledge representation model are, therefore, the discipline plane, expression pattern plane, resource unit plane, product plane, application process plane, and design domain plane, clearly represent the application profiles of design knowledge in six dimensions. The six-dimension design knowledge classification system and cubic model are applied to fluid simulation implicit knowledge (expert knowledge) as a real case, and are the basis upon which an application system of fluid emulation expert knowledge service is developed. The design knowledge classification system and representation model proposed in this essay are the theoretical foundations for knowledge flow model development in modern product design and the construction of knowledge management systems for modern design platforms.

Abstract: The selection of adaptable machining parameters is a key part in numerical control (NC) milling process. Deterministic optimal parameters are obtained without considering the uncertainties of machine tools. So a reliable optimization method was introduced in this study. We focus on a response surface methodology (RSM) adapted to reliability-based design optimization (RBDO) based on Diffuse Approximation (DA). A variant of the first order reliability method (FORM) is chosen to calculate the safety index. Case study is investigated for the NC milling operations of ultrahigh strength steel. We show how to get the optimal parameters with the safety index by the reliable optimization method.

Abstract: The recursion relationship between the failure rate and the equipment age before and after preventive maintenance (PM) was built up concerning with the concept of improvement factor. The optimal imperfect PM policy model in finite time horizon of the aging equipments following Weibull distribution was proposed, which can minimize the total relative cost of the equipment PM. The optimal maintenance frequency and optimal maintenance interval under imperfect maintenance were determined by the model, and the reliability after each PM of equipments was considered. The model built in this paper can be used the decision supporting the maintenance plan and providing decision supporting for job shop scheduling.

Abstract: The theory of system multi-state is used in the time-based maintenance strategy, the determine process of product state for component-level and system-level is known. The maintenance model for multi-state system which is based on statistical data and risk loss considered is constructed. The investigation index for availability of maintenance strategy is analyzed and then the simulation is used to determine the maintenance strategy.

Abstract: An innovative nuisance trip calculation method based on Markov model was proposed in this paper which was used to evaluate the effect of repairment on system reliability. By analysis of the availabilities of classic 1 out of 2 (1oo2) repairable system, a new definition of spurious trip was put forwarded where online repair was considered. Compared with the benefits obtained by online repairment, the repair-caused-nuisance-trip was analyzed in this paper. Numerical calculation revealed that the online repair is helpful for anti-spurious trip in 1oo2 redundant system. Dangerous failures, if not repaired or cannot be online fixed, have complex influence on system reliability. The dangerous failure is sometimes benefit for anti-spurious performance if it is not repaired. But Mean Time To Failure Spurious (MTTFs) reduces with the increase of dangerous failure provided that dangerous failure rate is bigger than safe failure rate. Meanwhile, the finding that common cause can reduce the chance of nuisance trip was also proposed in this paper, though the influence is too small to be neglected.

Abstract: Evaluation method of reliability parameter estimation needs to be improved effectively with the advance of science and technology. This paper develops a new method of parameter estimation, which is named E-Bayesian estimation method. In the case one hyper-parameter, the definition of E-Bayesian estimation of the failure probability is provided, moreover, the formulas of E-Bayesian estimation and hierarchical Bayesian estimation, and the property of E-Bayesian estimation of the failure probability are also provided. Finally, calculation on practical problems shows that the provided method is feasible and easy to perform.

Abstract: In order to reduce the sample size and test time, a step-stress accelerated random vibration life testing (ARVLT) method is presented. And the method of parameter estimation is also proposed. Through this testing method, the exaggeration factor K can be obtained rapidly, so that the result can be used as the technical basis of conducting an equivalent accelerated vibration testing of the product. In addition, the reliability of the product under the normal operation stress level can be extrapolated.

Abstract: Effects of thermal exposure on low cycle fatigue behavior of Ti600 alloy were investigated by LSCM, SEM and TEM. The results demonstrated that both the NTE specimens and the TE specimens showed the cyclic softening, within a total strain amplitude range from ±0.45% to ±1.00%. Since the α2 phase precipitated in the αp phase during thermal exposure, the resistance of fatigue crack propagation of αp phase could be increased by the precipitation of α2 phase. Therefore, the low cycle fatigue (LCF) lives of Ti600 alloy after thermal exposure were longer than those without thermal exposure, at the same total strain amplitude.

Abstract: This paper proposes a new life prediction method using time series and grey theory to predict product life based on Constant-Stress Accelerated Degradation Testing (CSADT) data. CSADT degradation data is modeled using time series method and predicted using grey theory. A four electric stress levels CSADT of miniature bulb is conducted to verify the proposed method. A comparison among life prediction by the proposed method, traditional methods, and real life of miniature bulb is processed. The result shows that life prediction by the proposed method is more accurate than traditional methods.