Advanced Materials Research Vols. 102-104

Abstract: An integrated approach based on genetic algorithm (GA) and an artificial neural network (ANN) is presented for structural optimization of a high power density magneto-gel brake. For this method, the GA method is employed for obtaining the optimal configuration of the brake by minimizing the dimensions of the brake. Subsequently, a two-layer BP neural network model is trained to obtain the correlation between main design parameters and performance of the brake, and then it is used to predict the performance of the magnetic gel brake with high power density. The coupled method incorporating the ANN with GA can reduce substantially the computation time during optimizing brake performance. Meanwhile, the proposed method’s validity is demonstrated by comparisons between the experiment and existing data.

Abstract: The process of creating a CAD model from an object is mainly made up of two steps: the data collection through digital measurement and the construction of parameterized and revisable model. This paper discusses the measuring process and technical problems of the Coordinate Measuring Machine (CMM) and non-contact sensor. Through comparative analysis, we determine the application scope of those approaches in measuring different dimensions of the same objects considering the time efficiency and tolerance requirement. This paper divide the objects into two categories: freeform feature objects and regular feature objects. As for the freeform feature objects, people could fit wrap-around B-spline surfaces to construct the model. Regular feature objects for mass produce contain machined surfaces which should be precisely measured and modeled. The model of regular feature object should be constructed by three-dimensional modeling software, so that it is parametric and revisable for changing and improving the original design. Sizes and position of important surfaces of the model are acquired from CMM, and those of non-important features are fitted though point cloud processing. Some profile can’t be measured directly from CMM but should be precise, so this paper proposed two methods to construct profile line and analyze error by comparing it with point cloud.

Abstract: Via putting forward the new concept of “direction angle” for the first time, particularly via discovering and bringing to light the vivid, audio-visual geometrical background of integral geometry′concepts “support line” and “support function” in disc cam mechanisms with a flat-bottomed translating follower, this paper successfully obtains package formulae for judging the outward convexity of cam profile's, for calculating the equations and perimeter of cam profile’ as well as the area of cam end surface’.

Abstract: Based on the lever set function and the augmented Lagrange multiplier method, the topology optimization design of structure was achieved and the final cloud data were saved in matrix. The trigonometric patch method was explored to approach the optimized level set surface and the boundary data extraction was realized by each ridge line parametric equation. Together with the standards of the digital manufacturing, the cloud data were sorted through programming and exported by complying with the data format of digital manufacturing. The Wire Electrical Discharge Machining was proposed here to achieve the manufacturing on G01 code, which was proved to be practical by NC Viewer. This process fulfilled the whole courses from topology optimization to digital manufacturing, which makes the foundation for the promotion and large-scale production of topology optimization in future.

Abstract: Force behaviors of the loading platform of rotating stereo garages is analyzed, equations describing the load capacity and the deformation limit state are proposed for the key sections by applying the second-order moment into the reliability analysis of the main beam. Considering random parameters subject to normal distribution, a reliability model of the main beam of the loading platform is set up based on multiple failure modes and the reliability is analyzed and calculated by using second-order moment. Simulation results show that the reliability model is significant to guide designing on the reliability of rotating stereo garages and improves rotating stereo garages.

Abstract: To achieve smaller weight, stronger strength and higher stiffness, tube hydroforming is widely used in the industry. The front beam is analysed the front beam part is redesigned based on the technics, and automotive structural lightweight and integration are achieved under the precondition of ensuring vehicle performance and security. Then, the hydroforming process of front beam is analyzed by numerical simulation based upon the elastic-plastic finite element method, Belytschko-Tsay shell element theory and dynamic explicit solution, the internal pressure loading path as the main hydroforming process parameters is discussed in detail. The present analysis provide basis for its applications.

Abstract: In recent years, in view of the absence of kinematics analysis function of mechanisms in the virtual assembly system, the method of kinematics analysis of mechanisms based on dynamics of multibody systems in virtual assembly environment is presented. A mechanism is considered as a multibody system and the kinematics equations are established based on Descartes coordinate system. All the kinematics parameters, just like position, speed and acceleration, can be obtained through solving the kinematics equations. In addition, the realization method of mechanism motion simulation in virtual assembly system is also proposed which contains the hiberarchy, data structure, module classes and simulation process of the system. The method is implemented and validated based on the prototype system VAPP(Virtual Assembly Process Planning).

Abstract: Disc cutter is the key part in Tunnel Boring Machine (TBM). Wear and tear of disc cutter is the main reason of low efficiency and high cost of this machine. Forces and deformations of disc cutter ring are foundation for its design and assembly. In this paper, the analysis of stress and deformation are carried to study their distribution; Wear mechanism of disc cutter ring is presented; modal analysis is carried to study the vibration of disc cutter ring. The results show the yield strength and rigidity of disc cutter ring is very high; disc cutter ring can avoid resonance and meet the engineering requirement. The results are very helpful for digital design of disc cutter ring used in different geology conditions.

Abstract: Full face rock tunnel boring machine (TBM) plays an important role in boring rock of tunnel. The failure of disc cutter is the main reason leading to low efficiency of TBM. In this paper, analysis of force and motion for disc cutter are carried by using ABAQUS to study stress distribution and concentration in disc cutter and rocks. Influence of different rocks on stress in disc cutter is analyzed. By combination the failure modes of disc cutter and its stress distribution, methods of decreasing failures of disc cutter are presented. Wear resistance and service life of disc cutter are improved by matching the materials of disc cutters with rocks. The results are useful for structural optimization and strengthening treatment of material of disc cutter.

Abstract: This paper adopted explicit dynamics FEM software ANSYS/LS-DYNA and carried out the numerical simulation calculation of 9 roller horizontal straightening and 8 roller vertical straightening for 60 kg/m heavy rail with original curvature. The reductions of straightening rollers are taken as the main effective factor to the residual stress in the straightening regulation. It adopted orthogonal experimental method to obtain the main effective factors for straightness and residual stress. In the assurance of meeting the straightness, it obtained the regulation in which the residual stress is the smallest, so it makes the important theoretical and actual sense to formulate the rational straightening process and improve the straightening quality of rail.