Applied Mechanics and Materials Vols. 37-38

Abstract: Metal matrix composites (MMCs) were produced by Ni-induced pressureless infiltration using Fe alloy. The mainly fabrication process was that Ni and Al2O3 powders mixture was pressed and sintered after milled, and then the sintered Al₂O₃ ceramics were infiltrated by Fe alloy at 1600°C with 4h holding time. While the SEM and EPMA analyses indicated that the interface between ceramics and Fe alloy reaches a full homogeneity after infiltration and Fe alloy could infiltrate Al₂O₃ ceramic preforms and the maximum infiltration distance was more than 400 μm. This would increase the strength of interfacial due to excellent bonding interface. The fracture strength is about 63.0 MPa.

Abstract: The boronizing layers of 45 steel of drilling pump liner have been remelted with laser, and the wear resistance properties, phase transition and microstructures of the boronizing layers before and after laser remelting were analyzed. The results show that laser remelting enhances surface abrasive wear resistance properties by 40% ~90%. Laser remelting achieves improvements mostly by means of alternating boronizing layer morphologies, eliminating FeB and defects within boronizing layer, improving the interface bonding intensity, fining the microstructures, redistributing boron concentration and generating lots of alloy phases. The strong support to material surfaces by martensites gained during remelting process within transition area is also beneficial to improve wear resistance properties. It is shown from the practice that the laser remelting compound technology followed boronizing shall be widely used in surface hardening of petrochemical key parts.

Abstract: In this paper, the microstructures with extreme properties are designed through the generalized shape optimization, which is implemented with the help of the smooth curves representation of the level set description and the numerical analyses of the eXtended Finite Element Method (X-FEM) with the fixed mesh work. The parameters of basic level set features are defined as the design variables. To calculate the given effective computation of microstructures, the energy method and homogenization method are physically identical. But the energy method is advantageous in computing efficiency and numerical implementation. Combining with the CONLIN algorithm, the periodic microstructures with the maximum elastic properties are obtained with the flexibility of handling the topological changes and solid-void boundaries. Numerical examples show the great interests in the microstructure design with the level set method and X-FEM.

Abstract: Based on the constrained variational principle, the mixed multi-variable natural neighbor Galerkin method for couple-stress elasticity is proposed for three-dimensional problems. The displacements and micro-rotations are taken to be independent nodal degrees of freedom, and the geometrical constraints between them are enforced through Lagrange multipliers. The C⁰-continuous non-Sibsonain interpolation is used to obtain the discrete equations. The proposed method is tested by the numerical example and the results show that strong size effects are observed when the length of deformation field and the characteristic length of the material are comparable.

Abstract: According to model analysis of gilling machine’s hauling box, this paper presents the research on the complex structure’s model analysis. Before the analysis of box, the paper inducted general analysis process, then the box was divided into 8 modules, advanced function MPC and super-element were used to process connection among these modules, the processed model was analyzed by finite-element software Nastran. The result from Nastran include natural frequencies and mode shapes, which are similar to actual work condition. It can be concluded that the process for complex structure is accurate. The result is useful to find the reason of box vibration, and it is also used for optimization design.

Abstract: Based on single vendor and single buyer, vendor supplies buyer with a product, and the vendor split order into many equal shipments to delivery. Aimed at minimizing the total cost of vendor and buyer, JIT purchase model based on actual freight rate was proposed. Actual freight rate is transformed into alternating ranges of a constant charge per kilogram followed by a constant fixed charge. For the actual freight rate, by calculating the solutions for all weight ranges and comparing them, the optimal solution was derived. Numerical results show that the algorithm can obtain the optimal solution, and the model is verified.

Abstract: Different spherical shape models of precision ball-lapping are presented and discussed in this paper. A selective analysis of spherical surface morphology model of rotated dual-plates (RDP) ball-lapping is presented. With combined shape errors of three contact points, the spherical surface morphology is more close to the real surface of precision ball. Simulations show that the spherical surface morphology model of RDP method can well express the shape errors of precision balls. The wear rate is easily obtainable as an empirical function of the contact forces, velocities and material properties of the surfaces in contact. The expansion of the net material removal rate gives the rate of the spherical harmonics. The modeling method can capture the change of single point in the process of lapping. Then the parameters, such as lapping speed, preload, and entry point orientation can be studied using this model in the subsequent research.

Abstract: With the rapid growing of domestic rural market, it is important to develop rural logistics system. Up to now, the general two-direction logistics mode was investigated in order to achieve high efficiency. However the mode was still based on qualitative analysis. This paper proposed a novel rural two-direction logistics system model based on SPN theories. By utilizing the mathematic characteristics of SPN, quantitative parameters of the model were deduced. Finally, compared with the general logistics mode, the proposed logistics mode can improve the logistics efficiency.

Abstract: SERVQUAL, a basic framework adopted wildly in evaluating service quality, was applied in the modern logistics with 32 theory indexes. In order to select the appropriate indexes, an empirical study was conducted by subject degree analysis and importance analysis with questionnaires by experts from logistics industry. An evaluation system consisted of 13 indexes from four dimensions, delivering reliability, service efficiency, equipment assurance and customer empathy, was constructed consequently. An empirical evaluation result of the typical logistics enterprises in Hunan Province proved its feasibility.

Abstract: It is crucial to solve the conflict scale economies and product variety for product family plan. Therefore, from the view of functional parameters and structural characteristics of product family, a strategy was studied to work on product variety optimization and modular platform-based design based on similarity analysis. First of all, PCA (Principal Component Analysis) was performed to identify the key functional parameters. And then, a cluster analysis and a similarity analysis were carried out to provide a similar estimation for the products. Finally, according to the comprehensive analysis it would be helpful to layout the modular platform.