Applied Mechanics and Materials Vols. 48-49

Abstract: Considering general weakness in the current development of assembly, the paper analyses the structure of former fuselage and the function of assembly. After a thorough investigation and research on extensive analysis, this paper completes three-dimension structural design of former fuselage assembly using digital flexible assembly technology. The three-dimension structural design includes the design of transmission, the design of power sector and the design of actuator combining innovative design methods. The paper completes modeling of front fuselage assembly based on the modular design thought. The module mainly includes the base module, the guide module, the driver module, the execute module and the connection module. And then, the paper accomplishes overall tooling of front fuselage assembly and collision analysis of assembly by using CATIA software. Finally, the paper also completes making the animation by using 3DVIA Composer software. The animation depicts the movement of former fuselage assembly and completes the dynamic simulation.

Abstract: For solving the difficulty of feature signal extraction from vibration signals, a new method based on Independent Component Analysis (ICA) is proposed to realize separation and filtering for multi-source vibration signals. Firstly, the principal and algorithm of ICA used to separate mixed signals is introduced. Secondly, application in signal separation and filtering with ICA is studied in diagnosis. In addition, imitation and field examples are given. The experiments show it is feasible to separate and extract feature signal from multi-source vibration signals and it is an effective method in signal preprocessing in fault diagnosis.

Abstract: Considering ‘The state of car is the outside and mechanized expression of driver character’, the HRV sets of driver are input which could show the chaos characteristic, the constructed variable named ‘safety time coefficient’ is set up as output, and then a forecasting network on the state of driver is established. And a BP algorithm combing with chaos optimize algorithm is used in the network. The simulation results show that the established network could forecast the state of drivers and the reliability is steady.

Abstract: Feature extraction and expression of three-dimensional MCAD entity model is independent of platform. According to STEP, this paper discusses for a unified MCAD / CAPP / CAFD integrated system to establish the program model and study the key technologies. The STEP neutral file that contains the model is taken to decide the design features of the part. The identification of geometric features and geometric characteristics of features to the mapping process, rule-based reasoning and case-based reasoning with the way things feature-based process planning techniques in the process of reasoning problems. UML object-oriented technology and methods such as functional analysis of the system and structural design, the initial mode of integrated system functional model and structure is established

Abstract: In general, filling velocity of indirect squeeze casting mainly causes gas wrapping and slag inclusion, and it influences quality of casting parts directly. In this paper, filling velocity was researched on by Procast, moreover, models of casting parts and die were modeled. Furthermore, filling of a kind of panel was simulated, and the simulation results were analyzed. In conclusion, the best filling effect can be gotten, when the velocity v is equal to filling time t. As a result, it could offer better casting parameters for similar casting parts in squeeze casting.

Abstract: Bionic walking mechanism is an important part of bionic motion machinery. According to the characteristics of biped walking, a new biped-imitating walking mechanism called Half-Rotating Walking Mechanism (HRWM) was developed using Half-Rotating Mechanism (HRM) which can generate asymmetrical motion. The drive way and walking principle of HRWM were firstly introduced. On the basis of deducing kinematical equations of HRWM, some main factors of ride comfort were presented, which include a new factor named relative amplitude that could be used to valuate the ride comfort of various walking mechanism. The optimization model of HRWM structure was then proposed, which took parameter relationship as design variable. The optimized result could be applicable to different size HRWM. Finally, the calculating result shows that HRWM with optimized parameter relationships has good performance on ride comfort in the process of walking.

Abstract: DMC-PID cascade control strategy was adopted to apply on high accuracy constant temperature air conditioning system because constant temperature room had large inertia, delaying, a few interference factors characteristics. The construction type of DMC-PID cascade control system was designed and the prediction model of inner loop and outer loop was determined, and then MATLAB software was applied to simulate and compare robust stability, tracking performance, anti-jamming capability characteristics of DMC-PID cascade control algorithms with other algorithms. Through studies, the overshoot of DMC-PID cascade control of room temperature reduced 2% in comparison with the PID algorithm, but was much larger than that of DMC algorithm. Its regulation time was nearly the same to that DMC algorithm, but cut down 25% in comparison with the PID algorithm. At last, the simulation result showed DMC-PID cascade control strategy application on temperature control of high accuracy constant temperature room had feasibility and effectiveness, and the control strategy had strong robust stability, tracking performance, anti- disturbance ability characteristics.

Abstract: In order to enhance measurement precision of the piezoelectric micro-actuator, by means of the transformation rule of tensor the research on the Bending Charge Sensitivity Distribution of Piezoelectric Quartz is conducted. First by the theories of elasticity and electromagnetism the torsion stress and bound charge are calculated, and the charge measured by the detection electrodes is obtained, which depend on the piezoelectric coefficient d12. Then using the transformation rule of tensor the piezoelectric coefficient d12 in the new coordinate system is calculated, and according to the unrestrained multipurpose optimization method the optimization Cut is obtained. Finally a special designed experiment is performed, and the experimental results show that the bound charge produced by the optimized Cut is about twice larger than that primitive Cut. This research on the bending charge sensitivity will provide a theoretical foundation for disposing the detection electrodes of a new piezoelectric micro-actuator

Abstract: According to the situation of randomness and fuzziness existing in the actual project, this paper proposed a reliability-credibility model based on fuzzy theory, possibility theory and credibility theory. At firstly, a reliability-possibility distribution curve was constructed by the traditional stress-strength interference model, then, a reliability distribution function was established based on this. This model built a bridge between credibility and reliability in handling randomness and fuzziness. The research results show that the model can hand the situation of random information and fuzzy information coexistence well, and the acceptable level of reliability and the most credible reliability value can be reflected directly in the reliability-credibility distribution curve. Compared with other methods, it obtains more reliability information, accords with the actual engineering situation and guides reliability engineering design much better.

Abstract: This paper presents a basic principle of ultrasonic vibration metallographic sample cutting machine. Ultrasonic vibration cutting machine contains four parts: the ultrasonic generator, the transducer,the horn and the tools. The cutting machine uses ultrasonic fregnency as the tool of small amplitude vibration.It is a special processing because the surface of the work piece material is gradually broken by the beating of the ultrasonic frenquency and the abrasice which wonders in the liquid that is among the workpieces. The results indicates that the method can effectively improve the quality of surface and precision of the processing surfaces of workpieces.