Applied Mechanics and Materials Vol. 197

Abstract: Molecular dynamics simulations were carried out to investigate the plastic deformation mechanism of fcc crystalline materials using the conventional Lennard-Jones potential. An fcc structure with square cross-section was prepared, and a tensile load was applied in the longitudinal direction. A weak potential was assigned to a specific (111) plane to induce a slip on the specified plane. Accordingly, a slip was initiated in the weak plane following an elastic deformation. The step-by-step motion of the atoms on the slip plane was studied, and a detailed trajectory is presented. The slip then expanded to other planes, and plastic deformation progressed in the whole model. The weak plane was also set as (110) or (100) plane, where different deformation modes were observed: not only slip but also gradual distortion or brittle fracture occurred.

Abstract: Tool management has been defined as a process improvement that aims at resolving problem related to various tool activities including procurement, storage, database development, selection and consumption, inspection, presetting, delivery, loading, monitoring, replacement planning and inventory control of tools. A tool management system is an organized approach to manage engineering change or improvement. The main objective of the work is to improve control on tool inventory with the help of tool database and new tool introduction system. With this system, we ensure to have more accurate determination of the rate of inflow of tools in stores and consequently, reduction of tools inventory in stores. The system also helps to determine the optimum sequence of execution of orders.

Abstract: The model reconstruction based on the reverse and obverse is a main method in reverse engineering applications at present. A new method is put forward for reverse modeling of mechanical parts, which is based on combining reverse software Geomagic Studio and Imageware with CAD system Pro/E. A detailed scheme is designed and it is put into practice by taking a mechanical part for example. The feasibility and practicability of the method is confirmed for model reconstruction of mechanical parts in reverse engineering.

Abstract: In the mechanical properties test, in order to ensure test results reflect the characteristics of the material itself reliably, the sample’s quality of processing is an essential prerequisite. Performance sample with different shapes were processed into different diameters, different shoulder of the transition area, and different width, to be conducted with tensile tests of mechanical properties. The results show that differences in sample processing on the mechanical test results are different, and we fine some disciplines by analyzing the reasons causing the differences.

Abstract: The manufacturing system in the factory has been changing more complex, and the user who is system engineer or operator wants more powerful and efficient manufacturing system. Therefore the system developer and designer needs to know the factor what is important quality for the manufacturing system with their needs. This paper propose quality model for success manufacturing system. For this work, we extracted the quality attributes from exist work fitting on their needs. And we construct a quality model to consider their relation each other. Finally we expect our model can be help and give guideline to the system engineers or designers when they make a plan to develop the manufacturing system.

Abstract: The rolling bearings are one of the most critical components in rotary machinery. To prevent unexpected bearing failure, it is crucial to develop the effective fault detection and diagnosis techniques to realize equipment’s near-zero downtime and maximum productivity. In this paper, a new fault detection and diagnosis method based on Wigner-Ville spectrum entropy (WVSE) is proposed. First, the local mean decomposition (LMD) and the Wigner-Ville distribution (WVD) are combined to develop a new feature extraction approach to extract the fault features in time-frequency domain of the bearing vibration signals. Second, the concept of the Shannon entropy is integrated into the WVD to define the Wigner-Ville spectrum entropy to quantify the energy variation in time-frequency distribution under different work conditions. The research results from the bearing vibration signals demonstrate that the proposed method based on WVSE can identify different fault patterns more accurately and effectively comparing with other methods based on singular spectrum entropy (SSE) or power spectrum entropy (PSE).

Abstract: Superhydrophobic surfaces on metal substrates are often prepared via roughing the surfaces and lowering their surface energy. The superhydrophobic aluminum surface with a water contact angle of 162.5° and rolling angle less than 6° was fabricated via electrochemical etching and re-deposition using the alkalic Na3PO4 electrolyte and then fluorination treating. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results show that the surface consists of the micrometer-scale lumps and protrusions, and many nanometer-scale mastoids are filled in these protrusions. These hierarchical micro/nanometer-scale binary structures, which are similar to the micro-structures of lotus leaf surfaces, play an important role in achieving superhydrophobicity. The main components of the binary geometric structures are Al2O3, AlPO4, and H2O. The effects of the processing time and processing voltage on the macro-morphology were also investigated. The macro-rough structures appeared on the edge of the aluminum surface firstly, and then spread gradually to the entire surface.

Abstract: This paper presents a novel Rotary Steerable System which used a universal joint to avoid the alternating press in the drilling process. The mechanics model is established on the basis of simplifying structure and supporting of rotation axis in directive RSS. Dynamic model of the offset mandrel is derived by means of Hamilton principle, which could be used to control system design. Location of offset force acting on the offset mandrel is optimized and vibration equation of universal joint is deduced by means of transfer matrix method, then the results of natural frequency are compared with the calculated results of the finite element to verify the kinetic model. Both dynamic model and simulation analysis are expected to provide useful good guidance for the design of control system, detail design, structure optimization and the dynamic vibration of the RSS.

Abstract: STEP-NC is a new data model for data exchange between CAD / CAM and CNC, which provides rich information for CNC machine tools and tells CNC “what to do”rather than “how to do”, overcomes many shortcomings of the traditional G&M codes and has become a hot research issue now. How to efficiently and cost-effectively generate the STEP-NC program is a very crucial problem. Although some domestic scholars have done some research about STEP-NC program generation, most of them do second development base on ST-Developer software. The paper developed a STEP-NC program generation module by using the VC++6.0 and CAD / CAM software. The module can read AP203 file generated by CAD system, identify manufacturing features according to its geometry information and conduct process planning to generate STEP-NC file according to ISO14649 standard. This module has been proved effectively by an instance.

Abstract: To solve the coupling problems cause by flexible structure of Dynamic Tuned Gyroscope (DTG), solutions was proposed through the combination of loop control and decoupling within Individual Channel Design (ICD) framework during the DTG lock loop design. Firstly, theoretical model of DTG and its actual coupling property were presented. Then, the diagonal controller was designed for the diagonal elements and counter-diagonal elements of DTG transfer function matrix under the framework of ICD. The stability and coupling relationship of individual channel were also analyzed for both two cases. Finally, a validation experiment was carried out for a certain type of DTG when it works in tuned state and mistuned state with 20% perturbation of tuned speed. The experimental results show that the diagonal controller for both two cases can stabilize the loop. But in mistuned state, the coupling degree of diagonal elements case grows up to 15%.This shows that the controller robustness for counter-diagonal elements is greater.