Advanced Materials Research Vols. 694-697

Abstract: In order to reduce the influence of uncertainties on complicated engineering systems performance, a new method is proposed based on the performance measure approach and collaborative optimization (PMA-CO) to implement the reliability-based multidisciplinary design optimization of gear transmission. Both the mathematical model and procedures of PMA-CO are presented. With the adoption of slack factors in the system-level of collaborative optimization, both CO and PMA-CO are applied to the optimization of gear transmission. The proposed PMA-CO improves the reliability of the gear transmission and gained a tradeoff solution between design cost and reliability. Therefore, the PMA-CO is effective and practical in engineering design.

Abstract: Reliability is an important issue to consider for mechanical systems. The state of art is regular checkup and maintenance to ensure normal operations. This is not good enough for safety-critical systems like gearboxes in vehicles and helicopters because the risk of system failure still exists, let alone the manpower and monetary cost required. Prognostics and health management (PHM) was first raised by the U.S. armed force, which should ideally be able to predict faults and schedule maintenance only when necessary by monitoring the system condition. In this paper, inspired by the idea of Built-In Self Test (BIST) in electronic systems, we propose a novel framework to fulfill the task of prognostics and health management with a set of smart sensors, consisting of embedded sensing elements, wireless communication modules and micro-controllers. Both the significance and challenges of the framework are discussed.

Abstract: Fault Tree Analysis (FTA) was used to analyze the reliability of gearbox transmission system of 4LZ-2 combine harvester (4LZ-2 CHGTS). Firstly, the structure and function of the 4LZ-2 CHGTS were made a detailed introduction, and the components were divided into three kinds of A, B and C. Secondly, the Fault Tree (FT) model of the 4LZ-2 CHGTS was estabilished using the "top to down" ideology. Finally, based on the FT, the minimal cut sets (MCSs) were given and the weak link of the system was found out by the qualitative analysis; furthermore, the relative probability importance of each basic event and the reliability of the 4LZ-2 CHGTS were analyzed by the quantitative analysis. The results show that the 4LZ-2 CHGTS is of high reliability, and the fault of gears needs to be taken into a key consideration and control in the design process of the GTS.

Abstract: As there is no definite calculation formula of the height of bearing push-extend reamed of the Push-extend Multi-under-reamed Concrete Pile at present, in the paper, according to the theoretical analysis and the experimental achievements on the failure principle of the soil of the Push-extend Multi-under-reamed Concrete Pile, it is made that using the theory of shear resistance to carry on the analysis, deduce the check formula of the height of bearing push-extend reamed of the Push-extend Multi-under-reamed Concrete Pile, and it is put forward that the reliable theoretical basis of the Push-extend Multi-under-reamed Concrete Pour Pile foundation design for practical engineering.

Abstract: Based on correlation matrix, that paper discused fault diagnosis tree generation method, and show diagnosis tree generation steps by introducing fault diagnosis tree generation process of a equipment system. Finally, apply the diagnosis tree to maintenance the actual equipment to verify its correction and practicality.

Abstract: One new method is presented for computing engineering structure reliability by accelerating convergence based on the analysis of errors in the center point method and borrowing ideas form the merits of the other First-Order Second Moment (FOSM) methods. The accelerating convergence method is based on the first class Chebyshev polynomials. Firstly, the transformation relation of the first class Chebyshev polynomials and the power polynomials is given and expanded to vector formula. Secondly, the outstanding function approximate character of the first class Chebyshev polynomials can supply the high order information for the choosing of approximately surface. An example shows that the method presented in this article has well precision. Although the accelerating convergence method needs choose the format of the structural function properly for get the high precision results, the method can serve as an effective for engineering estimate owing to non-iterative formula and convenience.

Abstract: Virtual technology is used for simulation analysis of engine camshaft bearing-loosening fault. Firstly, dynamic model of engine powertrain and its valve-train is established, and then the model parameters could be set to simulate the camshaft bearing loosening fault, so the vibration acceleration signals on engine cylinder head can be obtained by simulation calculation. Then by analyzing and comparing with the vibration signals in the normal state, camshaft bearing-loosening fault features are extracted. The analytical result based-on model simulation and vibration signal is used to guide the actual engine fault diagnosis.

Abstract: The purpose of this paper is assessing the reliability of power transformer for a switchyard by quantitative fault tree analysis. First step is determines if the fault tree is static or dynamic. To generated exact calculated results, the static entities are computed using standard combinatorial techniques. The dynamic entities are transformed into equivalent Markov models. The results for these various entities are then brought together using techniques employed for generalized fault tree analysis to produce exact calculations. The reliability of power transformer systems of GI Simangkuk switchyard in Indonesia was assessed and the main contributors have been identified. This result will help the decision maker to improve the reliability of power transformer system.

Abstract: The purpose of this paper is to study the importance measures of power transformer system components. Importance measures analysis is a key part of the system reliability quantification process which are most effective towards safety improvement. This paper presented an application and results of the importance measures analysis of a power transformer system of GI Simangkuk switchyard in Indonesia by using Birnbaum importace measures, critically importance measure, and Fussel-Vessely importance measures. These method present the rank of the component importance measures quantitavily according to their contribution to system reliability and safety.

Abstract: In order to improve the efficiency and robustness of reliability-based multidisciplinary design optimization (RBMDO), a new collaborative strategy (named C-RBMDO) which integrates performance measure approach (PMA) and concurrent subspace optimization strategy (CSSO) is proposed. Both the mathematical model and optimization procedure are put forward. The traditional triple-level nested flowchart of RBMDO is decoupled with the sequential optimization and reliability assessment (SORA). The deterministic multidisciplinary design optimization and the multidisciplinary reliability analysis are executed by CSSO and PMA respectively. Finally, the proposed method is verified through the design example of gear transmission.