Applied Mechanics and Materials Vols. 16-19

Abstract: This research aimed to propose an initiative design method for tooth profiles based on the given small sliding coefficients. A simplified derivation of the mathematical model of tooth profiles is presented. A design example is provided to illustrate the approach. The results show that tooth profiles designed by the proposed method have the small sliding coefficient. It is significant to improve the wear and friction properties and raise the life span of gears.

Abstract: The basic ideas of expressing uncertain variables with blind number were introduced. The mechanical structure time-dependent characteristics variation in stochastic process was deduced. A time-dependent reliability calculation model was built with blind number theory. The numerical method based on blind number was applied to solve this complicated computing model. A LabVIEW program was compiled, and a frame beam’s time-dependent reliability was computed. The result shows the method based on blind number is very convenient and effective in solving the complicated reliability calculation model. In this method, the structure time-dependent reliability can be predicted quickly based on the historical data.

Abstract: The uncertainty variable in mechanical design is expressed in blind number and the relation among variables is expressed in the operation rule of blind number; By combining the reliability design theory with blind number calculating method, the reliability of the mechanical elements with arbitrary distribution parameters and discrete test data is discussed; and a numerical method for mechanical reliability based on blind numbers is presented. Besides, the typical examples show that the method is reasonable and effective.

Abstract: Modeling of friction force has been a challenging task in mechanical engineering. Traditional way, such as mathematical modeling approaches, was found quite difficult to achieve satisfactory performances due to some immanent nonlinearity and uncertainties in systems. This paper aims to develop fuzzy modeling techniques to characterize the friction dynamics. The proposed fuzzy modeling approach has two folds, that is, extraction of fuzzy rules using data mining techniques; setup of static model based on the fuzzy rules. The results obtained demonstrate that our proposed method in this paper has good potential in many mechanical systems with unknown nonlinear friction.

Abstract: Towards the large models of complex industry products, parallel rendering is often adopted to increase the resolution, performance and scalability for 3D product visualization. In this paper, we are targeting the interactive visualization of the complex CRH3 product assemblies in a virtual environment. To render CRH3 model and assembly animation, a PC Cluster-Based sort-first parallel rendering system for virtual assembly is presented and some combined strategies are discussed. With this approach, our experimental results show that high resolution display and parallel speedup with relatively low overhead in CHR3 virtual assembly can be achieved.

Abstract: Using software Pro/E and Pro/MECHANICA of the PTC, a method that establish a precise geometry and physical model(virtual prototyping) for the grinding tool of internal grinding machine, and simulate the dynamic and static characteristics of this virtual prototyping is introduced. Through simulation analysis, the weak links of the original design was found, thenthrough intensive design the static stiffness of the grinding tool increased two times, and the first stage of the inherent modal frequency was increased by 25%. Moreover, vibration dynamic response on nodular cast iron and steel shown the quantitative analysis results that nodular cast iron has good damping effect. Put the technology to practical application, the processing defects—chatter marks of surface quality when grinding round obtain a fundamental solution.

Abstract: Aiming at a clinical case of a 52-year-old male patient, the patient’s mandible will be 3 Dimensional (3D) reconstructed and the surgery will be planed. This patient who suffered from mandibular tumor needed to undergo surgery. This study used a Toshiba 64-row Spiral CT to scan patient’s maxilla and mandible. 368 layers consecutive maxillary and mandibular CT images which scanning slice thickness is 1mm were obtained. The original images which format were DICOM were import to Mimics. After decided the bone threshold value the contour lines of every layers were extracted. Every image was passed the processing steps of edge division, selective editing, filling holes, wiping off redundant data and 3D reconstruction. After these steps the 3D geometric model of maxilla and mandible was obtained. The dimension of mandibular tumor and accurate location of the removal part were determined. These steps provide accurate original data for the manufacture of mandibular Rapid Prototyping (RP) model.

Abstract: Reverse Engineering (RE), as the important technology for learning and mastering the advanced technology, as well as shortening the period of product design and development, has already become the highlight in the manufacturing industry. But there are some inner un-measurable parts, like couplers. The inner form information of the coupler can not be fully captured without any cutting, which is one of the bottlenecks in RE. Therefore, an effective method needs to be explored for reconstructing lumen model. Taking model reconstruction of coupler lumen as a case, an assembly reverse method is proposed by analyzing the parts functions and restraint relations in coupler. The method in detail is that, firstly, all parts are assembled in the coupler body lumen, then, according to assembly relations and the enveloping space determined by movement scope of individual parts, the coupler lumen shape can be obtained. The method proposed is successfully applied in model reconstruction of heavy haul coupler, and which provides a common solution of model reconstruction for inner un-measurable parts.

Abstract: The nonlinear dynamic behavior of a rotor-bearing system is analyzed with its finite element model based on the analysis of the discrete model, with considering some other important influencing factors such as, material damping, gyroscopic effect, inertia distribution, shear effect and so on, which make the description of the system more embodiment avoiding the casualness of selection with system parameters. With the comparison of the results on the bifurcation map and three-dimensional spectrum, significant difference is appeared with the addition of the considered factors. It is suggested that the substitution of continuum model for the discrete ones can get more accurate and abundant results. Furthermore, these results can provide more accurate verification and reference for the experiment and nonlinear dynamic design of the complex rotor system.

Abstract: It’s necessary to apply numerical prototype technology in developing processes of a TBM, and the application of VR system can enormously enhance the simulation effect. In the article, hardware configuration of a VR system for TBM motion simulation was discussed and the module function was analyzed. According to the practical working condition, motion analysis of TBM key components was carried out, and motion model was formulated. A model processing method using Deep Exploration and Creator was introduced, for transforming numerical models from CAD software to VR environment, and for dealing with the accompanying data loss. The article also discussed scene graph constructing method based on OpenGL Performer and developed a TBM motion simulation program.