Applied Mechanics and Materials Vol. 312

Abstract: A novel prediction model for surface roughness based on Projection Pursuit Regression was proposed in this paper. Based on the new model, the effects of milling parameters on surface roughness in milling can be predicted, and the predicted value of surface roughness in the whole working range can be reached with the limited test data, thus the variation law of quality of machined surface following milling parameters can be obtained. Compared with the least square support vector machine, it can be revealed that on the base of the same samples, the construction speed of this Projection Pursuit Regression is 1~2 higher in order of magnitude than that of the least square support vector machine, while the prediction errors are 40 % of the latter. Thus, the prediction model based on Projection Pursuit Regression can be established fast and be forecasted in high-precision, it is suitable for prediction of surface roughness.

Abstract: Obtaining the effect of regular transverse wave is very significant for it is dangerous for ships to turn in transvers waves. To study ships motion law in regular transverse waves, computer simulation method was used. The simulation were based on ship mathematical model,called MMG(Maneuvering Model Group), and a waveforce mathematical model. In the simulation, the ship sailed in regular waves and calm sea with 0°and 20°rudder angle and the tracks were recorded. Hence, a ship trail was made to verify the truthfulness of simulation result. After analysing the simulation result, there is a diccussion to design a rudder controller, which can reduce the effect of waves. In conclusion, the effect of regular transverse wave on ship turning maneuverablity is obtained and it is feasible to design a rudder controller to reduce the effect.

Abstract: With the increasing of web offset printing machines working speed, the nonlinear dynamics responses are more significant, even the fold mechanism with clearances appears some chaos phenomenon. Based on the dynamic model of fold mechanism, the nonlinear dynamics responses and the chaos movement in pair are studied. Used the performance parameters and dynamics response sensitivities as the goal values, the robust design model is established. By the robust design model, the nonlinear dynamic responses and chaos phenomenon can be under controlled in the same clearance degree. In this way, the performance of fold mechanism may be improved.

Abstract: For the high energy consumption and poor emission of a medium-sized hydraulic excavator, energy consumption point is analyzed combined with the advantages of the electric hybrid system. The energy recovery schematic of the system is designed. Mathematical models of the slewing system are established and theoretical simulation is conducted, and it is compared with the traditional structure. The velocity, displacement, and energy consumption curves of the two systems are concluded under the same conditions. The comparison shows that: energy saving of the electric hybrid slewing system is 37.27% compared with the traditional system. And the electric hybrid slewing system has the characteristics of the better control function and the higher energy utilization.

Abstract: Based on the principle of stress-energy method, the functional relationship among maximum acceleration, static stress, dropping height and thickness of a given cushioning material is obtained. Then the comparison of cushioning performance between different cushioning materials is carried out, and the comparison of cushioning performance properties between honeycomb paper and corrugated paper is made. The conclusion is that the corrugated board has a good buffer capacity at the light load, while the honeycomb paperboard has good energy absorption and dissipation capability at the heavy load.

Abstract: The tire dynamics simulation was done for the different speeds on the dry and wet roads with Magic Formula tire model. The coefficients of Magic Formula tire model under different conditions were obtained by means of the tire test data based on the nonlinear least squares method. The Magic Formula has a good ability to fit the test data for the longitudinal, lateral force and align moment. The tire dynamics simulation results show that at 30mph the wet tire peak longitudinal and lateral forces are only slightly less than the dry peak forces. The wet tire peak longitudinal and lateral forces decreases as the tire speed increases. This shows that the speed has a larger impact on the tire force. The align moment is relatively small. So it can be ignored in the vehicle dynamics analysis.

Abstract: This paper makes use of the method of computational fluid dynamics (CFD) to group the Hydraulic muffler of network grid and makes a fluidic analysis of the rectangular wave input signal of the hydraulic muffler without intubation noise absorption effect. The result manifests that the employment of CFD simulation technology to hydraulic muffler can provide evident theoretical support for further development and study of hydraulic muffler, and is possible to lay a foundation for continuous studies of the hydraulic muffler.

Abstract: Light weight design without loss of stiffness may reduce the cost and promote the performance of machine tools. A new dimension optimization method is promoted to optimize the vertical slide of a horizontal machining center. The influence of the cross section dimensions to the stiffness and mass is analyzed. A program is compiled to search the minimum weight of the vertical slide with sufficient stiffness. Finite element analysis is used to validate the stiffness of the new design. The result shows that the method is effective in machine tools' components design.

Abstract: To research the influence of kinematic pair clearances on the dynamic performance of eccentric swinging sheet transfer mechanism used in Sheet-fed offset J2108, a dynamic model was established based on the clearances characteristics and the continuous contact hypothesis. Consequently, the dynamic characteristics of sheet transfer mechanisms output can be researched quantitatively. The results indicate that sheet transfer mechanisms dynamic response appears strong nonlinear characteristics while considering kinematic pair clearances, which seriously affects the sheet transfer mechanisms stability and precision. Therefore, the study on the nonlinear dynamic response of sheet transfer mechanism can provide foundation to improve the stability.

Abstract: In order to control the flow rate in a butterfly valve accurately, the moment, which acts on the rotation axis of valve plate, caused by flowing fluid must be considered. Taking air as the medium, the parameters of internal flow fields, such as the velocity and pressure, are simulated by CFD for a standard butterfly valve. The distribution of velocity and pressure fields that changes with various openings and a curve of aerodynamic moment are obtained. The results show that, as the opening of valve goes larger, the resultant moment on valve plate is monotonically increased. At the opening of 70°, the moment reaches its maximum. After the opening of 70° the moment begins monotonically decreasing and the resultant moment is close to zero at 90°.