Applied Mechanics and Materials Vols. 668-669

Abstract: Rubs between stator and rotor are the most common and destructive faults in starting or running of rotating machinery. Force of radial rubs is the main parts of rubbing system dynamic models, and determines their accuracy directly. Force model is very important for fault diagnosis in theories and its applications. The recent studies on force models of radial rubs are introduced. Their modeling theories and its applications are summarized. The used conditions and applications scopes are analyzed mainly. The advantages and disadvantages of different models are discussed. It is pointed out that describing rubbing force accurately and building useful models will be the future studies, based on rational theories, considering environment factors, choosing all kinds of parameters affected to models.

Abstract: Flexure hinges are regarded as the critical components of the compliant mechanisms, its performance is one of the significant factors which could directly determine the merits and demerits of designed compliant mechanisms. So how to optimize the flexure hinges becomes the key step in designing processes of compliant mechanisms. In view of the presented importance of flexure hinges, this paper proposes a sort of multi-objective optimization method which can rapidly analyze the sensitivity and interactional laws between the performance indexes and the structural parameters of flexure hinges with the Workbench software, then to select the optimal parameters by combining with the actual working conditions of flexure hinges. Finally the finite element analysis is employed to analyze the optimization results and verify the effectiveness of proposed optimization method.

Abstract: S827 wind turbine airfoil was considered as original airfoil, which was created by NREL. Linear perturbation methods were used to get new shape parameters of wind turbine airfoil. Optimization of original airfoil was carried out based on genetic algorithm and XFOIL software, which was used to get aerodynamic performance. Results shows that the lift-drag radio of optimized airfoil was remarkable improved under multiple working conditions. Aerodynamic performance of optimized airfoil was much better comparing with the original airfoil. The optimal design method for wind turbine airfoil used in this paper can be used to optimization design of high lift-drag ratio wind turbine airfoil. Engineering practical value is considered by this method and it is feasible and efficient through example.

Abstract: the article is about longitudinal crack of concrete box girder roof, and it designed a reinforcement model. As the pre stressed material, CFRP could reach 30% of reinforcement efficiency under different loads in design model through external reinforcement upon calculation and analysis. And its crack width greatly reduces. In this way, the reinforcement purpose could be realized, and the mechanical properties of CFRP concrete could be fully played. The effect is obvious.

Abstract: A digital mockup of hard rock tunnel boring machine was built in order to study the design method of these large equipments. Technology of digital mockup is introduced and the application background and practical requirement of tunnel boring machine has been discussed in this paper. The kinematics model and FEM model were built based on this digital mockup. The results of simulation experiment can be used to provide pre-feasibility validation and optimization of the equipment.

Abstract: In this article, finite element method is used to analyze the properties of the reactor core under seismic load, and redesign the center assemblies to resist deformation and impact force. The result shows that the maximum force on the lug boss is decreased while the springs are applied.

Abstract: According to the aging characteristics of composite casing, we have established the composite bushing model of different radius with the ANSYS finite element analysis software, and analyzed the defects in different forms and the action under different mechanical stress. At the same time, we have studied the aging trend of composite casing and compared with the similarities and differences between the aging of composite insulators. The result showed that under the mechanical stress the bigger than the smaller aging deformation was more serious, and the defect forms had no obvious influence on the development of aging. Thus, the composite casing artificial accelerated aging test should increase the role of mechanical force factor, while the composite insulator aging research methods and conclusions should also increase the qualification when applied to silicone rubber composite casing.

Abstract: In order to achieve lightweighting in the Beam Structure of Wave-maker, it’s necessary to have the statics analyzed for model in the finite element method, results showed that the stiffness and strength have the bigger margin, and it can satisfy design requirements fully, which is the allowable deformation is less than 2 mm, maximum yield strength is less than 325 Mpa. At the same time, in order to get each order modal which the beam, and determine the wave frequency that the need to avoid. Carry on modal analysis of the beam in this paper, results showed that the wave frequency of the wave machine is far less than which each order natural frequency, so the resonance phenomenon caused in the process of work is out of consideration. This research method provides a basis for the design of the beam and optimization.

Abstract: To improve energy absorption and economical performance of a vehicle bumper anti-collision beam, the 40% offset static pressure test and finite element (FE) simulation are carried out. Considering factors such as design function, manufacturing cost and repair expense, a reasonable deformation mode of anti-collision beam is proposed. Based on the relationship between deformation and stiffness, a stiffness matching mode of anti-collision beam is proposed. Because the original design of the anti-collision beam is unreasonable, the improvement is carried out by adjusting structural and material parameters. Simulation results show that the total energy absorption of improved anti-collision beam is higher, which meets the requirement of sufficient energy absorption. The reasonable deformation mode is realized by meeting the stiffness matching relationship.

Abstract: Most studies are focused on topology optimization techniques under external static loads. However, all forces are dynamic in real world. Mathematical optimization with dynamic loads is almost impossible in a large-scale problem. Thus, the bi-directional evolutionary structural optimization method (BESO) is extended to the topology optimization problem of structure under transient dynamic loading. Structural stiffness optimization is performed with the objective of reducing the mean compliance during the whole load-time history. By the dynamical analysis, the stiffness optimization model is established based on BESO method. In this method, the material volume is taken as the constraint condition, and the minimum mean compliance of structure is taken as the objective function. A cantilever under harmonic load has been taken as a numerical example to show the effectiveness of the proposed approach.