Advanced Materials Research Vol. 705

Abstract: To ensure the normal drilling and well site safety, a monitoring system is necessary in air drilling to monitor the real-time information in total drilling. By using the LMS algorithm and adaptive delayed transversal filter, a mathematical model of underground blasting monitoring is established, and an information monitoring system is also developed based on wireless communication and field bus technologies. The system is characterized by miniaturization, lower cost, convenient operation and transportation, powerful function. The experiment results show that this system can not only provide accurate air drilling parameters and stratum information, but also can monitor the real-time contents of flammable, explosive and toxic gas, which provides a guide for the identify of water-oil-gas layer, supervising drilling and preventing the occurrence of safety accidents in well site.

Abstract: The effect of propeller skew on cavitation distribution, thrust and the torque is studied numerically. With the hybrid grid strategy and the sliding mesh, the Unsteady Navier-Stokes (N-S) and the Bubble Dynamics equations were solved to predict the vapor volume fraction around ships propellers blades. The numerical predictions of the sheet and the tip vortex cavitation of the propeller E779A are in agreement with the results in other literature in general. For propeller models DTMB, the proper increase of the propeller skew angle may enhance the hydrodynamic performance.

Abstract: In this paper, hyper-elastic constitutive models of rubber material have been summed up based on constitutive relation and the Mooney-Rivlin model has been pay more attention. Then through the tension experimental test, data of sealing material under axial experimental are obtained, and M-R model parameters C₁₀ and C₀₁ are fitted by ANSYS. After obtaining the material parameters, compression deformation behavior and the distribution of stress field and resilience behavior of the seal ring are simulated by using ANSYS/LS-DYNA software under different loading conditions.

Abstract: Mechanical excavators play an important role in mining and construction. An excavation machine cuts rocks using its cutterhead which is normally composed of a large number of cutting picks. These picks are installed on a drum with certain attack angles, tilt angles and skew angles. These angles, especially attack and tilt angles, will affect the forces acting on individual picks and the cutterhead. To ensure the reliability and productivity of the excavation machine, these angles have to be kept in their optimal values. However, in manufacturing, these three types of angles cannot be set simultaneously. They have to be respectively set one after another. As a result, the angle which is set previously will be changed by the angles which are determined after it. Understanding the relationship between the values of the final angle and the designed angle is important for optimizing drum and pick design. This paper develops a formula for quantitatively analyzing this relationship, with the research scope limited to attack angle and tilt angle only as the first stage of the study.

Abstract: The hydraulic shock is a very wide spread phenomenon and it is difficult to combat. The paper presents the way of propagation speed determination of the hydraulic shock in the case of gases. The phenomenon is considered to be adiabatic and we can find out the propagation speed of the excess pressure wave, in the case of the pipe with a variable section on length. The dependence between the pipe section and the propagation speed of a ram's thrust is represented graphically.

Abstract: To verify the applicability of a comprehensive constitutive model, which was proposed to analyze size effects in micro plastic deformation, mechanical behaviors of pure copper was adopted as the investigated subject. Unknown parameters were fitted through least square method, and calculated results were compared with experiment data of pure copper as well as those obtained by surface model. Predicted results by the comprehensive model show good agreement with experiment data. Three distinct mechanical domains appear indicating that for pure copper two critical thickness to grain size ratios exist, between which stresses vary rapidly. When concerning the situation of pure copper with only one or several grains across thickness, surface model tends to fail while the comprehensive model performs well, which further verifies the validity and applicability of the comprehensive model.

Abstract: In this work resource saving technique is used for shape optimization of 3D mechanical objects. According to statistical data, appearance of cracks in the areas of barrel support pads of tank wagons often causes damages to the barrels. The shape optimization of barrel support pads of a tank wagon is implemented and, as result, the concentration of stresses is significantly reduced in the barrel support areas. The optimization technique is based on CAD/CAE, design of experiment, approximation and optimization software packages. The shape of the support pads is defined by NURBS polygon points that serve as design parameters. For reduction of computational resources, FE models of tank wagon are replaced with high-quality metamodels which are based on locally weighted polynomials. The specific recommendations for the shape of the pads are given. As the second object truly spatial tetrapod is considered. The optimal curved shape of the tetrapod for lattice structure is elaborated.

Abstract: Numerical simulation was used to obtain the transient concentration of dust in the process of dispersion in a closed vessel in this work. Through the transient concentration of dust obtained by numerical results, the best ignition delay time can be evaluated. For the 5 L vessel and the hemispherical injection nozzle and under the blow pressure of 0.5 MPa, the ignition delay time should be 50-100 ms. Numerical results agree with the data obtained in the experiments under the same condition. It is difficult that dust concentration in the process of dispersion reaches absolutely uniform everywhere in the closed vessel.

Abstract: A new science method called Recursive Fitting Method (RFM) used to calculate the dust explosion rate of pressure rise was introduced. Residual Sum of Squares per Point (RSSR) was introduced to evaluate the fitting goodness of different conditions. Compared with existing methods, the results show that Recursive Fitting Method (RFM) has higher computational accuracy by drawn an experimental curve. And it has better computational repeatability compared with Tangent Method by repeating calculation of the same data. The new method can not only reduce the influence of signal noise but also calculate the correct rate of pressure rise accurately.

Abstract: Composite concrete consists of silicate reinforced cement concrete inner core and polymer concrete external coating layer, has broad application prospects in the filed of machine tool large component producing. Process design of composite concrete has been done on the basis of tests, a small scale composite concrete machine tool bed model has been built for test, the related simulation and test has been done. The results show that the process of composite concrete is reasonable.