Key Engineering Materials Vols. 480-481

Abstract: A new concavo-convex electrode has been designed and employed. And an analysis of the electrical discharge machining (EDM) mechanism of a particulate reinforced metal matrix composite with this new electrode was conducted in this study. It was found that EDM with this new electrode can accelerate the debris discharge during machining so that it has a higher MRR compared to the case where a normal electrode was employed. Moreover, by studying the surface craters, it could confirm that discharge craters tend to connect together for the normal electrode. This indicates an abnormal arcing condition. Thus, the wire electrode was easy to be broken. While for the new electrode, separated craters were observed on the machined surface. This means a stable processing condition. The experiment results reveal the processing mechanism of EDM electrical discharge machining of MMCs by employing this new electrode.

Abstract: Cyclic deformation behaviour is experimentally investigated using an incremental step method under a spectrum straining block loading mode for China grade B cast steel wheel. Results reveal that the material acts cyclically as non-Masing behaviour with a Bausinger effect. Different from monotonic tensile situation, material under fatigue loads was subjected to a plastic dissipation process without a yielding sign. Fatigued areas of specimen fracture surfaces are around 35%. Cyclic stress-strain (CSS) curve exhibits constant lower than monotonic tensile curve. Difference is enlarged as strain level increasing in elastic regime of the monotonic deformation. And this difference sustains a level of around 100 MPa as over yielding point. In addition, randomness is also observed for the present cyclic deformations. It indicates that random CSS relations should be comprehensively applied even if under stress based fatigue analysis.

Abstract: Comb-shaped hyper-branched polycarboxylate admixture polymers, both the water-reducing-type JS and slump-retaining-type BT, were prepared, and their adsorption characteristics with SO42- ions were studied by conductivity loss experiments. The results indicated that the adsorptions were related to both the content of carboxylic acid groups in polymers and the concentration of Na2SO4 solution, adsorptive action was formed by the complexation action between the carboxylic acid groups in polymers and SO42- ions, having nothing to do with polyether side chain in polymer. Comb-shaped hyper-branched polymers in aqueous solution would form association super-molecular structure, which could be destroyed by Na2SO4 solution.

Abstract: Durability is very important property of every cutting material. This property of cutting materials defined theirs life-time. Technical science defines a lot of different factors, that they may be cause of shorter life-time of cutting tool. Maximally possible elimination of these factors is necessary for optimization of cutting materials life-time. Durability of cutting materials is defined in standard ISO 3685. The main part of standard ISO 3685 is T-vc dependence definition for selected cutting materials. One of these cuting materials contained in this standard is cutting ceramic. Standard ISO 3685 contains instructions how to create T-vc dependence for cutting tools made of cutting ceramic. In this standard are only instructions how to create T-vc dependence according to Taylor, but last part of every experiment is analytical expression of tested dependence. The article describes process how to define and analytically express T-vc dependence for cutting ceramic (Al2O3).

Abstract: The realization of object recognition is discussed, the intrinsic relation between factors through high step association analysis is presented to mine the various features using property related analysis, the sensitive recognition features are chosen to improve the recognition efficiency. A multi-agent object recognition model(MAORM) is established, which combines concurrency research results and the specific characteristics of multi-sensor remote sensing image recognition. A majority-decision algorithm based on multi-agent is proposed. Experiment results show the system can effectively identify the bridges, wharfs, ships and so on. Compared with a single remote sensing image, the system can distinguish targets with higher recognition.

Abstract: A new half cymbal style piezoelectric-metal composite structure (HCPCS) membrane is proposed and utilized for piezoelectric synthetic jet actuator (PSJA) to increase its output jet velocity. PSJA specimens with both plane and HCPCS membranes were manufactured. An experimental system with hot-wire anemometer was setup to test the jet velocity. The frequency responses of time-averaged jet velocity were measured for both HCPCS diaphragms and plane membranes. The time-averaged velocity distributions were collected along the exit centerline. Experiments indicate that the HCPCS structure brings a promotion of vibration displacement distortion of diaphragm and stronger driving capability, and that the mean jet velocities synthesized from the optimal HCPCS PSJAs are higher than the optimal plane membrane one. Hilbert-Huang Transform was employed to analyze the instantaneous energy distribution characteristics of the jet. The analysis was done for signals along the centerline. The results show that HHT is an effective method for fluid field analysis.

Abstract: The automatic pig-feeding system gains more and more attention on the urgent need of improving pig-feeding efficiency and reducing labor intensity. An integrated automatic pig-feeding system is presented. It includes two sets of feeding-mechanisms and feeding-tanks which can work together so as to improving feeding efficiency. A drug-tank is integrated to complete the task of pig diseases control and prevention. And a buffer-tank is also integrated to save the remaining diet in the pipeline after feeding process. The whole system has a compact structure as well as fully functions. In addition, the fully automatic pig-feeding process is implemented using PLC and monitoring software. The experiment results show that this system can improve feed efficiency and reducing labor intensity greatly.

Abstract: The scattering phenomenon has an important influence on the reconstructed image in Cone Beam CT (CBCT) imaging systems, and is a long-lasting research topic on CBCT. Focusing on the scatter artifact in the cone beam CT system, we proposed a new scatter correction method that needed to add a beam attenuation grid (BAG) between the X - ray source and the tested object. This study educed the scatter correction algorithm based on the Beer theorem. Through subtracting the scatter distribution image from the original projection image, we can acquire the scatter-corrected projection Images of the tested object. The method has been verified by preliminary experimental results on phantom. The result showed that the method can effectively reduce the scatter artifacts, increase the image contrast and increase the quality of the reconstructed slice image. This method is computationally efficient and easy to implement without the loss of real-time imaging capabilities.

Abstract: Random fatigue limits are experimentally studied on China grade B cast steel wheel. Test data were obtained by employing a so-called small sampling up-and-down test method. Results reveal that fatigue cracks of the present material were commonly initiated from the casting flaw of shrinkage cavities and grew with typical fatigue river-like flowers and striations. To address the scattered test data, randomness of fatigue limits are comparably measured by the existent four approaches, i.e. conventional, Dixon-Mood, Zhang-Kececioglu, and Zhao-Yang approaches. It is verified that Zhao-Yang approach is appropriately applied for the present assessment on random fatigue limits of China grade B cast steel wheel.

Abstract: Four grouped rectangle specimens with thirty four samples, plus eighteen samples for fatigue limits, are tested for constructing the fatigue reliability curves of China grade B cast steel wheel. It reveals that fatigue cracks commonly initiated from the surface weakest phases and grew with typical fatigue striations and sub-cracks perpendicular to the growth direction. Cyclic plastic seems to be strengthened as cyclic stressing level increasing. Fatigue reliability curves are constructed on a consideration of addressing the real super long life. They are evaluated by a concurrent probability extrapolation method. And the measured curves verified that appropriate description has been reached on the test data.