Advanced Materials Research Vols. 291-294

Abstract: High speed machining (HSM) technology is used in a broad range of applications to machine ferrous metals and nonmetallic material. The motorized spindle is one of the major elements to keep the machine running at high productivity. In recently years, the requirement of rotational speed and rigidity of motorized spindle is getting higher and higher in order to satisfy the high speed processing. Engineering ceramic is the ideal material for high-speed and high precision electrical spindle due to perfect characteristics of light weight, wear resistance, high temperature, high strength, and so on. So a ceramic motorized spindle is designed for higher speed and rigidity. The shaft and bearing of the motorized spindle are made from ceramic material and other parts are made from metal. Rated power of this electrical spindle is 15Kw; its torque is 14Nm and revolving speed is up to 30,000 rpm as maximum. Motorized spindle is a typical mechatronics product and its dynamic property is very important. The signal of vibration and noise of motorized spindle may display its running status, so the vibration and noise of motorized spindle is an important index in the dynamic performance. This paper monitors the vibration and noise of ceramic motorized spindles using spectral analysis techniques. The effects of rotating speed and lubrication condition on vibration and noise of the ceramic electrical spindle are analyzed. These results are very helpful to the structure optimization and application of the ceramic motorized spindle.

Abstract: A new denoising method for the diesel engine transient speed signal was proposed, especially for the signal seriously corrupted by impulsive noises. This method takes two steps. The first step is to do impulsive noise removing. An improved differential rank impulse detector was used to do impulsive noise detection in this paper. After the impulsive noise was detected, it was replaced by the median value of the window it was in. Then the second step low pass filtering is taking on. Experiments show that the proposed method could remove the noise of the acquired diesel transient speed signals effectively, the denoised signal could reflect the real working conditions of the diesel engine.

Abstract: Vibration protection of pipes in nuclear power plants is a critical factor for the safety of the whole plant. In order to improve the anti-shock ability of pipes in nuclear power plants, the application feasibility of the fluid viscous damper in the plant piping protection is investigated. Then a damper design model intended to be used in nuclear power plants is researched by shock tests. Moreover, the parameters in the mathematical model are analyzed. From the analysis results, the conclusion can be drawn that the design method can be used to calculate the physical dimensions of dampers.

Abstract: Aiming at drawbacks of current methods for predicting the screening efficiency of probability sieve, this paper proposed a method of predict and study the screening efficiency of probability sieve based on higher-order spectrum(HOS) analysis and support vector machines(SVMs). First setting up trispectrum model with the vibration signals, then fitting out polynomial with least square method using the data which get out by the reconstruct power spectrum. Finaly, using support vector machines to predicting the screening efficiency with the coefficient of the polynomial as the sample input. The results show that the relative errors are all less than 2.4% and the absolute errors are all less than 0.021, which is ideal for efficiency forecast.

Abstract: In this paper, the analytic solutions of steady vibration of free orthotropic rectangular plate loaded with vertical steady loading on the elastic half-space was given by combining the general solution of double trigonometrically cosine series with supplementary terms with dynamic integral representations for displacements of the elastic half-space loaded with arbitrary vertical steady loading. This solution not only is four-order derivative, but also has less undetermined coefficients. It can be used to solve the problems of bending and steady vibration of orthotropic rectangular plates on the elastic half-space without be classified and be superimposed. This causes this kind of things, bending and steady vibration of orthotropic rectangular plates with four free edges on the elastic half-space, unionization, simplification and systematization. When the material is isotropic, the solutions are turned into analytic solutions of steady vibration of free rectangular plate on the elastic half-space. At last some computational examples are presented and the results are coincided with those in literatures. Then the method in this paper will be of important practical applications.

Abstract: Time series AR models (AutoRegressive models) are established with the use of the colored noise filtered by vibration signals,so as to study vibration characteristics of the magnetorheological damper under different working currents and frequencies .Because vibration signals are non-stationary and nonlinear , signal processing tool of trispectrum is introduced.The trispectrum are utilized for analyzing dynamic frequency characteristics of the magnetorheological damper. The result shows that the trispectrum slices can quantificationally describe nonlinear coupling, restrain gaussian noise and reserve phase components. Characteristics of the trispectrum is closely related to the current and frequency .The trispectrum slices can be used to describe laws of vibration system effectively.

Abstract: From flat-plate flexural vibration and radiated sound power discussed the inherent relationship between panel vibration frequency of distributed mode loudspeaker and geometric parameters, impedance matrix of soundboard and studied the relationship between soundboard structure of polyester foam sandwich panel and distortion of loudspeaker. Experimental results showed that distortion increases as the cell size and compress modulus, cell ratio, cell open ratio and thickness increases, but the sound sensitivity decreases as the compress modulus increases.

Abstract: With the popularity of the water lubricated rubber stern bearing, researches around rubber bearings are becoming more and more popular in recent years. This paper built a 3D numerical model of water-lubricated rubber stern bearing and did both free boundary and constraint modal analysis using finite element software ANSYS. The results show that free modes of water-lubricated rubber stern bearing are correlating with the constraint modes. The natural frequency distributes intensely in low frequency and the modal shapes mainly focus in the inner lining. Along with mode order increased, the mode shapes become more complicated. The mode shapes mainly embodies in the inner lining.

Abstract: The methodologies and application of hybrid multi-mode positive impulses input shaping of a 3-DOF flexible parallel manipulator in this paper. First, the structural system and the dynamic equations are expressed for a 3-DOF manipulator. Second, the hybrid multi-mode positive impulses input shaping is introduced to reduce the residual vibration of the multi-mode system or to decrease the time-delay of the system response at the same time. The theory of the hybrid multi-mode positive impulses input shapers are presented, and the hybrid two-mode positive impulses input shapers of a 3-DOF manipulator are established and compared with the classic multi-mode positive impulses input shapers. Finally, the numerical simulations are made, and the robust of the input shapers are presented and compared.

Abstract: Oscillatory textures are not only ubiquitous in natural images, but also in some inverse imaging problems involving oscillatory date, such as seismic databases, fingerprint images, et al. In this paper, we propose a three-step denoising scheme for for oscillatory textural images by combining bilateral filtering in spacial domain with wave atoms shrinkage method in transformed domain. That is, we first pre-process noisy image with bilateral filtering, then to process image with wave atoms shrinkage, finally post-process image with bilateral filtering again. Above all, we offer a reasonable interpretation of proposed method from the point of nonlinear diffusion filtering. Numerical experiments illustrate the good performance in comparison to the wave atoms shrinkage method and the bilateral filtering method by using two measures: peak signal-to-noise ratio (PSNR) and structural similarity (SSIM).