Advanced Materials Research Vols. 452-453

Abstract: Instantaneous frequency is an import parameter to diagnose faults of rotating machinery. This paper puts forward an algorithm based Hilbert-Huang Transformation (HHT) to estimate the instantaneous frequency of rotating machinery and develops an instantaneous cymometer based embedded system technology. In order to estimate instantaneous frequency of rotating machinery, the vibration signal is decomposed into a series of intrinsic mode functions (IMF) first by the method of empirical mode decomposition (EMD), then one of the intrinsic mode functions is analyzed with the Hilbert transformation to acquire an estimate value of instantaneous frequency. An instantaneous cymometer is also described in this paper, which is designed to measure the average frequency and instantaneous frequency of rotating machinery in real time. The average frequency is acquired from measuring the cycle of key-phase signal, and the instantaneous frequency is from the above-mentioned method based HHT. The instantaneous cymometer is consisted of an embedded system, which is connected to a PC with an Ethernet. The embedded system is based on an ARM chip (Samsung S3C4510) A/D conversion, EMD and Hilbert transform are completed on the embedded system, and then the results are compressed and sent to the PC by TCP/IP.

Abstract: The deformation processes of a deformable warhead was numerically simulated using LS-DYNA three-dimensional finite element code to determine the influence factors of deformation control on the deformation quality. The relationships among optimal deformation time interval, deformation chord length, and deformation control parameters were established. The result shows that the phase angle of deforming charge should be taken within the range of 60–90°. a larger deforming charge phase angle is favorable when it comes to increasing the fragment density in the target direction. Meanwhile, the thickness of deforming charge is less important than the phase angle in terms of the influence of the deformation chord-length.

Abstract: This study proposes a voxel-based method, independent of image sources, for the evaluation, quantification, symmetry ratio definitions, and assessment of the optimal symmetry plane. Craniomaxillofacial bones can be evaluated through their symmetry ratio and the optimal symmetry plane can be used as a guide for oral and maxillofacial surgical planning and reconstruction after the removal of facial tumors, or as a guide for orthognathic surgery in jaw correction. This quantification analysis technique can be used in growth tracing planning, pre- and post-surgical comparisons, and the planning of follow-up therapy.

Abstract: The μLSF is a micro-plastic forming method with the laser-induced shock load generated by the plasma in confined medium. It is characterized in the high-pressure and ultra-high strain ratio. This paper developed the model of metal micro-bulk forming by laser shock, simulated the process of forming and compared the influence law of forming depth under the conditions of different laser energy ranging from 3J to 10.6J and sheet thickness ranging from 0.13mm to 0.30mm on. It showed that there exists a threshold for magnitude of the laser energy. The forming depth increased with the increase of magnitude when the magnitude was smaller than the threshold. However, it decreased with the increase of magnitude when the magnitude was larger than the threshold. When the magnitude of the laser energy was chosen, the forming depth presented non-linear reduction with the increase of sheet thickness.

Abstract: The main purpose of this research is to find a solution for the coating/substrate of the wheel-slide which is the key component of civil aircraft flaps and slats, firstly, the simulation test is designed based on wheel-slide’ s working environment. Further, stress analysis of the coating/substrate is researched, and the results are as the input parameters of the finite element model. Then the finite element software, ANSYS, is applied to simulate the contact stress of coating/substrate in wheel-slide, and the stress’s distribution of coating/substrate are analyzed under different load, different coating thickness, different elastic modulus ratio of coating and other parameters. So the stress field characteristics are gained to guide the conduct of modeling experiments. The results can be applied to explore the failure of mechanism coating/substrate system, and provide theoretical guidance to design the coatings.

Abstract: The machining of transitional region of free surface is a kind of very important machining technique. Because of the complicated shape of the transitional region of free surface, it is very easy for cutting tool to dry cutting with machined surface. In order to machin-transitional region of free surface, using the method of curves of cross sections base on CNC machining theories and technology of mechanical manufacture. And researching ball tool path generation, a improving method for building tool path of interface-free was raised, and using this method to do some machining simulation at last.

Abstract: International thermonuclear experimental reactor (ITER) soft x-ray (SXR) diagnostic camera is an indispensible component used to measure signal intensity of SXR, which can reflect the internal properties of plasma. In this paper, the preliminary structural design and working principle of SXR camera is demonstrated, to investigate its seismic performance, modal analysis has been performed to obtain natural frequencies, effective mass and mode of vibration in first ten modes by means of ANSYS software. Then according to two parallel seismic analysis methods used in ITER, the calculations have been performed and the corresponding results have been illustrated respectively, the stress intensity and displacement are all within the allowable margin, which indicates that the design is reasonable and feasible. It will also provide beneficial reference for subsequent work.

Abstract: The concept of delay time and its maintenance theory are introduced, considering failure modes of system have different probability of occurrence and repair time, two revised model are established with the defects follow homogeneous processes and non-homogeneous process, The revised model could improve the expected unit downtime and optimize inspection interval.

Abstract: Due to compressor fouling, gas turbine efficiency decreases over time, resulting in decreased power output of the plant. To counteract the effects of compressor fouling, compressor on-line and off-line washing procedures are used. The present research is aimed to propose a method of mathematical modeling of offline washing interval which will be estimated as the RUL of compressor based on Proportional hazards model. Application of the proposed prediction method to the case of Civil Aero-engine proved its effectiveness.

Abstract: The heavy shell ring rolling mill which produces the large shell ring used in nuclear power, large-scale hydrogenation reactor and coal liquefaction reactor was taken as subject investigated. Because the size of shell ring is very large and the material of shell ring is special, the double drive rolls was taken in the shell ring rolling mill. Based on the elastic-plastic FEM and MARC software platform, the three dimensional thermal-mechanical coupled model of shell ring rolling process was built in this paper. First, the heat simulation text of the shell ring material has been carried out on the Gleeble-3500 thermal simulation test machine and the material properties were obtained. Then, considering the characteristics of heavy shell ring hot rolling mill with two drive rolls, the key problems such as geometry, material and thermo-boundary conditions were solved, the thermo-mechanical coupled finite element model of heavy shell ring hot rolling has been establised. At last, based on explicit dynamic FEM, the thermo-mechanical simulation of heavy shell ring rolling process was made. The stress field, strain field and temperature field were studied, the metal plastic deformation and its influence factors were investigated. The conclusions are agreement with the real rolling process. The conclusions are significant for designing equipments of shell ring rolling mill and developing new rolling schedule.