Advanced Materials Research Vol. 544

Abstract: Parameter uncertainty of general systems is inherent in most engineering problems. Based on the regularity of oil whip and resonance for rotor system, the reliability problem of rotor system with oil whip and resonance is studied by applying random perturbation technology and reliability theory considering the correlation of the multi-order natural frequency. The reliability mode and the failure probability of rotor systems are defined. The second-order joint failure probability is obtained by using the numerical integration method. The presented method provided the theoretic basis for the reliability design of the rotor system. A numerical example demonstrated that the proposed method is effective.

Abstract: Considering stability is the necessary condition for closed-loop control system to work properly, a new function reliability analysis method by inducting and defining the concept of stability reliability was proposed to describe the function reliability of closed-loop control system completely. As an example, the stability reliability calculation method and process to analyze the function reliability of a flight autopilot were demonstrated.

Abstract: New product development~(NPD) is a quite risky and uncertain process. In order to reduce the risks and uncertainties, the firms need to evaluate their new product at each step carefully and make accurate decisions. This paper focuses on uncertain go/no-go decisions in the NPD process. To do so, a probabilistic approach is firstly proposed to elicit a probability distribution of the gate-team's judgement. Secondly, a probabilistic approach is proposed to perform group and multicriteria aggregation with the random interpretation of group weights and criteria weights.

Abstract: Kansei Engineering~(KE) has been developed as a methodology to deal with consumers' subjective impressions and images of a product into the design elements of a product. One central step amongst KE is to generate the Kansei profiles of the products. Kansei is a quite subjective, ambiguous, and uncertain concept, which is frequently represented in linguistic forms. Toward this end, this paper tries to cope thoroughly with the uncertainties of Kansei in KE. A probabilistic approach is proposed to generate Kansei profiles involving the ``individual" uncertainty, ``group" uncertainty, and the partial semantic overlapping of Kansei. Our approach results with a probability distribution on a set of linguistic Kansei labels.

Abstract: A helical hydraulic rotary actuator for part-turn motion control is presented. Because of its compact structure and large output torque, strength study for the helical hydraulic rotary actuator becomes very necessary. Using AWE, influences of multi-start thread engagement length, thread start number, spline pressure angle and piston material on strength of the actuator’s key parts are studied in depth, so as to optimize the actuator’s strength and structure. The results show that the influences of nut width, thread start number and piston material on multi-start thread root strength of nut are notable, the influence of pressure angle on spline tooth root strength of output shaft is visible, and stress concentration on multi-start thread root and spline tooth root is very obvious.

Abstract: Crack closure concept is often used to explain the crack propagation behavior in cracked components. The effective stress intensity factor range is considered as a driving force of fatigue crack growth based on the traditional crack closure concept. The crack closure process and the plastic deformation near the crack tip were discussed in this paper. The standard compact tension specimen with the plane-stress condition was used to study the crack closure. A dynamic crack propagation method was proposed to simulate the effect of previous fatigue crack growth on the successive crack growth behavior. To obtain the accurately numerical results of stress and strain components, the Jiang and Sehitoglu cyclic plasticity model was implemented into ABAQUS as UMAT. With the detailed stress and strain response taken from the finite element (FE) simulation, the whole process of crack closure was described by the load curve. The load corresponding to maximum crack closure length is firstly proposed to describe the effect of fatigue damage. According to the results of FE simulation, the cyclic plasticity of the material near the crack tip persists during the crack closure period and should not be ignored.

Abstract: In this paper, based on the working environment and characteristics of PMSM system in EV, the influencing factors and their action mechanism on the weak links with high failure rate are analyzed, concluded from the failure modes of PMSM system in EV. Temperature, as the most influential factor, is emphatically studied, combined with the related test results. The action mechanism of temperature on some typical components (winding insulation, bearing, permanent magnet and IGBT) is studied in detail, laying a foundation for further reliability expectation and test. This indicates that PMSM reliability can be tested and enhanced from its working temperature.

Abstract: In order to increase the validation of preventive maintenance modes decision generally gotten by analyst’s subjective and qualitative judgment in reliability-centered maintenance analysis (RCMA), a projection model of intuitionistic fuzzy multiple attribution decision making for preventive maintenance modes in RCMA was presented. An illustration was used to validate the model of decision making about preventive maintenance modes in RCMA for vehicle equipment. The results indicate that the model is suitable to select the optimum preventive maintenance mode. Compared with the fuzzy comprehensive model that describes fuzzy information only by degree of membership, the intuitionistic fuzzy model more precisely and entirely describes fuzzy information come from RCMA by degree of membership, non-membership and hesitation. Then it is more adequate in group decision making for RCMA. It may be used in developing decision support system for RCMA.

Abstract: Analytical Target Cascading (ATC) is a method to partition the optimization of a complex system into a set of subsystem optimizations and a single system optimization according to the structure of the complex system, and coordinate subproblems toward an optimal system design. The constructed new optimization problem owns a hierarchical structure, which better matches the real organization structure of complex system design, so the ATC method provides a promising way to deal with the complex system. For each design problem at a given level, an optimization problem is to minimize the discrepancy between its responses and propagated targets. In ATC, for feasibility of subproblems, the target-response pairs are translated into the relaxation terms in which the weight coefficients is used to represent the relative importance of responses and linking variables matching their corresponding target, and achieve acceptable levels of inconsistency between subproblems when top level targets are unattainable in the hierarchical decomposition structure. Furthermore, weighting coefficients influence convergence efficiency and computational efficiency so that the suitable allocation of weight coefficients is a challenge. This paper adopts the Quadratic Exterior Penalty Method to deal with the weight coefficients that achieve solutions within user-specified acceptable inconsistency tolerances. Meanwhile, the method prototype will be tested on a numerical example and implemented using MATLAB and iSIGHT.

Abstract: Shipbuilding is a very important industry for its irreplaceable role into the sea transport and oceans exploration. But ship production design is a very complex process, causing the inefficiency of the shipbuilding. At the same time, the current situation of most shipbuilding enterprises is the multi-project environment and the resources among them are shared, the large and complex systems are hardly to simulate. In this research, a multi-resources oriented hierarchical timed petri net (HTPN) are constructed to model the ship production design process under the multi-project environment and a WFPN software is developed based on HTPN. To evaluate the efficiency and applicability of WFPN, a case study is conducted and the results show that it’s practicable. Beside on it, the analyses of the resource loads are also providing a way to promote the efficiency of the shipbuilding enterprises.