Applied Mechanics and Materials Vols. 635-637

Abstract: In order to localize and identify the mechanical noise sources on the submarine, a kind of double-layer submarine model with ring-stiffened was established, and the broadband actuators were put on the inner structure to simulate the mechanical equipment. The radiated acoustic field of the submarine model was reconstructed by the near-field acoustic holography method, which was also compared with the theoretical acoustic field. The simulation results showed that the reconstruction pressure amplitude agreed well with the theoretical calculation results, indicating that the acoustic field of submarine model could be reconstructed accurately by the method of near-field acoustic holography, and the mechanical noise sources would be localized and identified accordingly.

Abstract: The good integrated steering trapezoid of the commercial vehicle can reduce the running resistance, making the steering portability, and reduce tire wear. According to the Ackerman principle, establish the outer wheel theory and practice angle deviation minimum, which is as objective optimization mathematical model. Optimizing two important parameters of the steering trapezoid arm value and the steering trapezoid arrangement angle by the optimization toolbox of MATLAB. After optimization, the value of the actual the inner wheel angle deviation between the theoretical is smaller, so the steering characteristic has been significantly improved.

Abstract: In order to reduce the adverse effect of suspension point dynamic load on pumping unit system, according to the suspension point balance principle of conventional type pumping unit, the suspension point direction balance designing scheme is determined. Take CYJ10-3-37HB pumping unit as research object. Establish the virtual prototype simulation analysis model of conventional pumping unit by suspension point direction balance before and after the balance. Through the contrastive analysis of simulation results, the effect of load reduction and energy saving after the pumping unit by suspension point direction balance is determined. The simulation results show that the reduce rate of pumping unit maximum polished rod load is 29.4%, the reduce rate of RMS torque is 15.8%, the load reduction and energy saving effect of suspension point direction balance is obviously. It laid a theoretical basis for the suspension point direction balance device in engineering practice application.

Abstract: The structure and working process of automatic vent valve and gas purification equipment is introduced in this paper. To analyze the flow field in the valve, numerical simulations are also performed in the paper. The results show that the valve can greatly reduce the pressure of products from the oil well and acts very well in the control of the blowout on the wellhead. By using the vent valve and gas purification equipment, the back pressure of the well head can be properly handled, the frozen of the output gas can be avoid when the ambient temperature is extremely low, and the stability and reliability of the well head of the pumping unit can be improved greatly. All these can bring broad allied field for the equipment in our country.

Abstract: A star sprocket is an important component of U-shaped slide chain conveyor, so it is particularly important to be analyzed. It conducts modal analysis of star sprocket by using large finite element analysis software, ANSYS, calculates natural frequencies of the first five and the corresponding modes and analyzes natural frequency affected by sprocket tooth thickness. The result provides basic theory for dynamic optimization analysis of U-shaped slide chain conveyor.

Abstract: Multiple schemes are adapted on truck's outer flow field based on numerical simulation. Comparative analysis with the state of air flow, the pressure distribution, the air movement between the cab and cargo is pursued, then obtain the effect of jet flow velocity to the truck Cd. With the increasing of the jet velocity, Cd increases first and then decreases. The maximum drag reduction can reaches 7.38%.

Abstract: The tests about elastic properties of a commercial vehicle cab suspension air spring were carried out. And the experimental results show that: the higher the initial pressure of the air bag, the greater its carrying capacity, and the bigger the damping; at the same excitation frequency and the vibration amplitude, the dynamic stiffness of the air spring is gradually increased as the initial pressure is increased; in the low frequency range, at the same vibration amplitude and inside pressure, the dynamic stiffness of the air spring is increased as the increasing of the excitation frequency.

Abstract: Mechanized technology of application of dry building mixes is a separate highly qualified branch of in the field of finishing works. Its effectiveness is determined by the use of special mixes intended for mechanized application method and special equipment designed for their use. An important factor in improving the quality of work is the qualification of construction workers, who use new technologies. Without special training, workers can not realize all the possibilities of modern materials and technology, and therefore will not be achieved economic effect.

Abstract: In this paper, a dynamic robust design method is proposed to achieve a desirable dynamic performance in despite of parameter variation. Since it transforms the robustness of a dynamic system into the robustness of its characteristic variables, the complex dynamic robust design problem becomes a relatively simple static robust design problem. This greatly eases complex of this design. The effectiveness of the proposed method is further demonstrated by a comparison with the existing method on design of a practical hydraulic press machine.

Abstract: Based on simulation and test, a method for engine acoustical source characteristic extraction and acoustic optimization was presented. The intake noise of engine of commercial bus with four different acoustical loads was measured and the characteristic of the noise was extracted using the four-load method. The values of intake noise calculated by BEM were compared with the values measured in the vehicle intake noise test. The comparison result showed that the simulation values agreed with the experimental ones at most of the range which indicated that the extracted result was reliable. The anechoic frequency was determined by analyzing the intake noise spectrum measured in the vehicle intake noise test. Finally, an effective scheme adding a Helmholtz resonator and a quarter wave tube was proposed by simulation, applied to the real vehicle and verified in the test. The acoustic performance of the intake system was improved significantly.