Applied Mechanics and Materials Vol. 711

Abstract: In laser induced thermal crack propagation (LITP) cutting brittle materials, according to the laser absorption ability, materials are divided into the body absorption and surface absorption. This paper indicates the fracture mechanism of LITP cutting surface absorption brittle materials. The crack extension appears in the lower surface firstly in this stress distribution state, then the crack extends to the upper surface and the laser scanning direction with the LITP cutting. The stress field of cutting ZrO₂ ceramic is studied by finite element software ANSYS. The crack propagation process of cutting silicon wafer is studied by finite element software ABAQUS. According to the fracture mechanism, the curve cutting the ZrO₂ ceramic experiments and the cooling lower surface cutting the silicon wafer experiments are carried out in this paper. Optical microscope and laser scan confocal microscope (LSCM) photographs of the curve path the ZrO₂ ceramic and separation surface cutting the silicon wafer are obtained to examine the cutting quality. The quality of the curve path is very good. The quality of the separation surface in cutting the silicon wafer with the cooling lower surface is better than conventional environment.

Abstract: Present work describes an approach to identify creep properties of P91 with finite element simulations and neural networks. The small punch test was used to determine the material property under high temperature. Results showed that, the neural networks could be used to evaluate the creep property together with the small punch creep test and finite element simulations.

Abstract: Based on MMW-1A vertical multifunctional friction and wear tester for the study,taking steel 45 as the research object, randomly changing the experiment load, speed, sliding distance and the size of the contact area, then the data we collect are processed and analyzed by principal component analysis, and obtained linear regression models by principal component regression, regression model has been tested with good fitting effect. The results showed that the principal component analysis method is also suitable for experimental study of friction and wear, explore new methods in the analysis of tribology. It shows that load, speed and sliding distance have a weakening effect on the friction coefficient, on the contrary, the contact area has a promoting role to the friction coefficient.

Abstract: Geopolymers are prospective cement substitutes because their production generates smaller amounts of carbon dioxide and they have sufficient mechanical strength. Geopolymers have attracted increasing interest from construction industries because of their recyclability and eco-friendliness. The compressive strength of geopolymers is known to be associated with their Si/Al ratio. Fused slag from gasification processes using low-grade coal (FSLC) and spent catalyst slag (SCS) were used as raw materials for making geopolymers; the Si/Al ratio was controlled by mixing different ratios of FSLC and SCS. The compressive strength of a geopolymer with a Si/Al ratio of 1.04 had the highest strength (125.6 MPa). Scanning electron microscopy (SEM) analysis was also in good agreement with the compressive strength measurements of compressive strength. There were many small crystallites in the geopolymer matrix. Using transmission electron microscopy (TEM), these crystallites were found to be single crystals, which have a perfect crystal structure. It is speculated that the formation of small crystallites 10-30 nm in size, as well as large single crystals with diameters greater than 80 nm, in the matrix of a geopolymer during the geopolymerization process might increase its compressive strength.

Abstract: The magnesium hydroxide (Mg(OH)₂, MH) was modified using oleic acid (C₁₇H₃₃COOH, OA) by wet techonlogy. The modification effect of MH was evaluated by activation index and oil absorption rate. The optimum technological conditions were as follows: the concentration of magnesium hydroxide slurry was 35wt%, the oleic acid 2wt% ,temperature 70 °C, time 40 min and a stirring rate 2200 rpm. Additionally, the structure and morphology of the improved modified MH powders were characterized by SEM, XRD, FTIR, TGA-DSC. Compared with the unmodified MH, the modified MH had better dispersibility and hydrophobicity.

Abstract: The nitrogen-doped diamond-like carbon film was prepared on Ti6Al4V alloy by using plasma enhanced chemical vapor deposition (PECVD) technique,and its biocompatibility was studied.The surface morphology,chemical composition and contact angle were measured by scanning electron microscope (SEM),X-ray photoelectron spectroscopy(XPS),Raman Spectrometer and contact angle measuring device. Finally, the proliferation rate and cellular morphology of 3T3-E1 osteoblast cells on different sample surfaces were tested and Image J software was used to statistically analyze the count of the adhered cells. The results showed that cell adhesion and proliferation were significantly (P<0.05) increased on nitrogen-doped diamond-like carbon films , which illustrated that N doping improved the biocompatibility of DLC films. This finding has potential clinical application value to modify titanium alloy for new bone formation.

Abstract: The established BP neural network model can forecast one of the wood-plastic composite molding equipment the screw of extruder with co-rotating twin-screw has been presented. The content of fiber and lubricant, the appropriate temperature of the extruder and the target yield are determined as the variable inputs, while the outputs are the diameters of the screw stem. This intelligent BP network model can forecast the condition of actual production precisely by setting the input properties of the material and the integration of products in order to fit the requirements of the wood-plastic composited production more successfully. Through the analysis of BP neural network model, the former simple method of choosing the screw stem’ diameters only depend on yield can be modified more efficiently.

Abstract: With the development of the smart grid, the security and reliability of power communication are directly related to the safe reliable operation of power system. Not only are enough power communication communications capabilities required in power system production operation sector, but also high reliability. The richness of communication reliability research methods will help improve the reliability of electric power communication management. This paper summarizes the power communication reliability research methods and analyzes their advantages and disadvantages, which is benefit for the guidance of network reliability assessment under the actual operation.

Abstract: Based on the feature of electromagnetic induction communication system (EMICS), three methods are described to assess the quality of electromagnetic induction setting signals, include threshold value assessment, quality grading assessment and input/output signal comparison. The implementation plan and quality assessment models of EMICS are presented, with analyzing the characteristics and limitations of each method.

Abstract: For there is a lower level of fusion grid decision-making process and decision-making are not smart enough ,this paper presents a power grid's management and control task demand – knowledge matching model, to help staff accurately and rapidly access to the necessary knowledge, before making a decision.At the same time,in order to solve the problem ,this paper, in the TBM framework ,presents a grid knowledge clustering-ensemble method. Then, knowledge clustering-ensemble model is applied to the electrical network management control decision-making process. Test of the fault diagnosis has proved that ,the model is able to maintain the original good performance of the evidence theory and TBM framework, also can get more useful information for decision-making.