Key Engineering Materials Vol. 584

Abstract: Due to lifting large loads and lifting smooth, it is widely used for double beam bridge crane in machinery industry. The numerical analysis of stress and strain field for 200t×28m double beam bridge crane is done under maximum load conditions by using ABAQUS finite element platform in this paper, the distribution and largest area under load of bridge is obtained. At the same time three natural frequencies and mode shapes of double beam bridge crane is analyzed, which the results provide a theoretical basis and reference for double beam bridge crane designer.

Abstract: In order to keep gas turbine disk safe and reliable, and to provide reliable data for the dynamic design or modification of a gas turbine disk, dynamic characteristic of the gas turbine disk has to be obtained. In the paper, the method based on the combination of calculation mode and the experiment mode is proposed to analysis the dynamic characteristic of the gas turbine disk. The modal parameters and the mode shapes are calculated through ANSYS program. On the basis of these modal parameters, the faults of the gas turbine disk are shown and its weak points of the design are illustrated. The reason for deformation is analyzed and relevant measures employed to reduce faults are proposed. By these improvements in question, a guarantee of the gas turbine disk working normally has been available.

Abstract: Through research on Pneumatic Conveying technology and the principle of Laval Jet, we completed the design of key parts of a mud dust conveying system used a new small trenchless drilling robot in municipal road construction.

Abstract: The key problem that affects the cloth hot-bead (CHB) accuracy and efficiency is positioning of CHB. Feature points were found out through analyzing the characteristic of the fabric and computer image processing (CIP) technology. The technological process was determined by those feature points, which were considered as reference to the origin for CHB process. A program is written by Visual Basic (VB), and the running results prove the good feasibility and practicability of the research methods.

Abstract: In order to provide high precise data for urban natural gas pipeline network dynamic modification and to diagnose the urban natural gas pipeline network fault, the dynamic characteristic of the flow-meter system, which is the main component of a natural gas pipeline network, has to be obtained precisely. The experimental modal parameters identification method base on the modal theories is proposed to substitute for the finite element method to identify the modal parameters of the flow-meter System. Multiple-point exciting by a hammer and single-point collecting by acceleration sensor can obtain testing data of the flow-meter System. The initial frequency and damping ratio of the flow-meter System can be distinguished out base on the testing impulse respond functions data. According to these modal parameters, the reasons of its faults under a certain working condition can be analyzed specifically. Simultaneously, the accuracy and reliability of this parameter identification method can be inspected on experiment.

Abstract: In order to optimize the rotation noise spectrum of vehicle alternator cooling fan, a Vector Composition Method was proposed. Based on this method, the relative sound pressure level (RSPL) variations were calculated, which were then used as parameters in the optimization of spectral structure. In this article, the sound pressure level (SPL) variations of the 12^th and 18^th order (of rotation frequency) who had the most prominent fan rotation noises were set as optimization targets, the blade distribution angles were optimized to ameliorate the spectral structure and the distribution of spectral energy. Calculations showed that, the RSPL in orders 12 and 18 were decreased by 9.3dBA and 10.5dBA respectively, comparing with experiment results, the errors were 3.9% and 4.11% respectively. Results suggested that the rotation noise of target orders had been significantly diminished, so the objective of optimizing spectral structure was reached. This method has a guiding significance to the design of blade distribution angles.

Abstract: The online detecting of chatter is the key technology to improve the machining quality. Based on the nonlinear chaos control theory in discrete dynamic system, the processing vibration signal discrete time series is taken as system nonlinear input, the C-C algorithm and correlation integral was used to determine appropriate embedding dim m and time delay τ. Then the phase space is reconstructed by discrete vibration signal. In milling chatters experiment, the time series analysis method is used to get the phase diagram before and after chatter. The chatter phase chart shows the characteristics of chaos and recognized the milling chatter.

Abstract: A team of undergraduate students at Miami University has conducted design and experiments to build a small Chemical-Electrical (CHEM-E) car with the plan to enter the US National American Institute of Chemical Engineers (AICHE) CHEM-E car competition. The purpose of the CHEM-E car is to enhance undergraduate students experiential learning and get the students prepared for the future need of comprehensively research and analysis of real Chemical-Electric car. This team of undergraduate students has proposed an aluminum-air battery car with design consideration of low cost, durable materials, constrained size of the car, power generation and its stability and car speed.

Abstract: The computerized numerical control (CNC) machining program usually contains a large number of small line segments. The CNC controller must generate a smooth and optimized motion profile to achieve high speed and high precision machining. This paper proposed an adaptive contour error control algorithm. The curvature radius of the tool path is obtained by analyzing the geometry relationship. The algorithm uses the curvature information and a simplified servo error model to realize contour error estimation and adaptive control. The target feet rate filter (TFF) and planning unit merging (PUM) are introduced to obtain a smooth profile. Experiments result demonstrated the efficiency of the proposed algorithm.

Abstract: Because of the serious interference coming from the negative frequency in low frequency correction, the traditional correction methods no longer work. This paper proposes an improved ratio method to correct the frequency, phase and amplitude of spectrum peak when the spectral line locates near the left end in spectrum. The Hilbert Transform is used to diminish the impact of interference of the mirror frequency. The barycenter of two spectral lines is used to obtain the correcting value. A new formula is developed when the frequency is less than the frequency resolution. One of the spectral lines is located in the main lobe and the other is in the first side lobe. Furthermore, the direct current has nearly no impact on this new method theoretically which is a key problem in low frequency correction. The simulation shows that the frequency, phase and amplitude of a theoretical low frequency can be corrected satisfactorily. The result of the correction improves a lot compared with the traditional method. However, this method could not correct the spectrum with multiple components of low frequency.