Applied Mechanics and Materials Vols. 16-19

Abstract: The fluid-driven in-pipe robot is developed. Speed control system was model analyzed and the relationship between the load that affect the speed stability and through-flow area was derived, and the speed control system including double closed-loop feedback part was built.

Abstract: The spiral bevel gears of attack helicopter transmission systems are taken as an object in this paper. The numerical analysis model for starved elastohydrodynamic lubrication (SEHL) of spiral bevel gears is established on the basis of the analysis of load tooth contacts analysis and SEHL in elliptical contacts. The SEHL characteristics of spiral bevel gears are also analyzed. The results are as follows: during the course of a gear-tooth meshing cycle of the spiral bevel gear, the extremum of minimal film thickness and maximal film pressure occurs near midpoint of the path of contact, and leans to dedendum. The minimal value of the minimal film thickness is 0.39 um, and the maximal value of the maximal film pressure is 0.69 GPa. The value of minimal film thickness gradually increases with the increasing of meshing point velocity. When the velocity of meshing point exceeds 110 m/s, the increase became tardiness. As the load of meshing point increases, the value of minimal film thickness gently diminishes.

Abstract: In order to increase transmission performance and lubricating condition for meshing pair of the single screw compressor, the contact analysis for the single screw compressor is analyzed. The equations of the former tooth surface of the gate rotor, the back tooth surface of the gate rotor, the top tooth surface of the gate rotor and transition surface between two tooth of gate rotor are constructed respectively. The tooth surface equation of the screw rotor is deduced through using the tooth surface equation of the gate rotor and transform matrix depending on conjugated theory, the contact line equation is moreover acquired. The calculation formula of inducing method curvature is deduced, the inducing method curvature of some points on contact line with the rotation degree of the gate rotor changing is calculated. The computing results show that the contact surface is osculating, which is favor to increase contact strength of the tooth surface. The distribution rules for contact lines of the former tooth surface and back tooth surface of gate rotor is gained through calculation, which provide theory basis for manufacturing screw rotor.

Abstract: This paper introduces the FEA method for cyclic symmetric structures and makes an vibration characteristics analysis to a certain aeroengine compressor blade-disc coupling system based on this method. According to the anslysis results the dynamic characteristics of the blade-disc coupling system are discussed. The analysis method and results in this paper can be used for further study on optimal design and vibration safety verification for the blade-disc coupling system.

Abstract: In this paper, elastic-plastic finite element analysis has been performed in order to obtain the fatigue crack tip parameters under tension-compression loading. Two centre-cracked high-strength aluminum alloy with a crack length of 2mm under different tension-compression loading are analyzed. The analysis shows that the compressive loading has a significant contribution towards the crack tip plasticity and the crack tip stress. In a tension-compression loading the crack tip displacement increases with the increase of the compressive stress and the crack tip compress stress increases with the increase of the compressive stress. The maximum stress intensity Kmax in the tension part of the stress cycle and the maximum compressive stress in the compression part of the stress cycle are the main factors controlling the near crack tip parameters.

Abstract: To reduce the noise error existing in the output signal of fiber optic gyroscopes (FOGs) and increase the precision of the FOGs, this paper established a mathematical model of the FOGs output signal, analyzed the error characteristics of the FOGs output signal, put forward a new de-noising arithmetic based on the wavelet transform, soft and hard threshold compromise filtering, threshold values were determined by multi-dimensions recursion arithmetic. Through experiment, it has been already validated that the proposed approach had the competitive performances on visual quality, signal to noise ratio (SNR) and the standard variation, it is effective in eliminating the white noises existing in the output signal of the FOG.

Abstract: Centrifugal Flying Shear is one of the most advanced equipments, which is widely used in tandem mill production lines because of its simple structure and high shearing precision. In this paper, the working principle of the centrifugal flying shear was introduced; the three-dimensional model of the centrifugal flying shear was established; the structural analysis and the dynamic simulation of the flying shear, with the movement rule and trajectory, were made based on MATLAB/SimMechanics and Solidworks/COSMOS Motion; and the control strategy of realizing scale shearing was proposed. The results obtained provide theoretical basis for design of the electronic control system, and facilitate further analysis of the shearing process and parameter optimization design of similar flying shears.

Abstract: Reverse engineering is a new modern product design technology, which is suitable for designing complex curve and surface, has been becoming a practical and widely-available engineering tool in panel design of automotive, motorcycle and electric vehicle. This paper first expatiates on the basic theory of structured light measurement system, registration algorithm of multi-view point cloud data and the basic principle of curve and surface reverse design, and then gives an application example in the 3D design of electric vehicle front panel.

Abstract: Workflow access control is an important issue in workflow security. Although there exist some standards for security of Web services and access control for services in distributed systems are well studied, there is a lack of comprehensive approach in access control for web services, especially in workflow. This paper proposes a service oriented workflow model and its access control model. The basic authorization unit is task service which is an abstraction of task in the access control model. In this context, we present the dynamic separation of duty based on task services and their conflict relations. Furthermore, we show this model satisfies access control requirements in workflow.

Abstract: To obtain large mechanical output power, a ring type standing wave ultrasonic motor using cantilever type bending transducer is proposed. There is a cantilever on one side of the ring, and four PZT ceramics are set on each end surface of the cantilever. The bending mode of ring is excited by the bending vibration of cantilever transducer. Thus, linear simple harmonic motions are achieved at the particles on the teeth. The working principle of proposed motor is analyzed. The ring and transducer are designed with FEM. The bending vibration modals of transducer and ring are degenerated, and the motion trajectories of nodes on the teeth are analyzed. The analysis results indicate that a standing wave is excited in the ring by the bending vibration of transducer, and the proposed motor has potential good output characteristics. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed motor.