Applied Mechanics and Materials Vol. 441

Abstract: Tube has a complex structure in space, in order to machining tubes of different radius and avoid interference, a new type of Triz bending machine is developed, which has up to eight dies by moving and rotating the head of the machine. The key technology of tube coordinates transformation is solved by the vector algorithm. For the springback problem, a compensation is add to the final working parameters, which can reduce the testing time and the quantity of scraps. Finally the tube bending simulation system for the new machine is developed based on Visual Studio 2010 and Open GL.

Abstract: A horizontal plates flock like Lotus leaves can attenuate incident surface water waves. This paper tries to simulate a numerical wave tank by FLUENT CFD software using k-ω turbulence model in a two-dimensional domain. And a 2nd-order Stokes wave is made by the boundary wave-making method, and attenuated by three kinds of horizontal plates flocks with different relative lengths (flock length/wave length). A flock of horizontal plates consists of multiple plates interspersed with gaps. However the leaves have both movement and deformation in waves, giving rise to a difficult fluid-structure interaction problem. Here a simpler case is studied, involving rigid, infinitely thin plates fixed at the still water level. The Four time steps are tried to find such appropriate time step-not only to make satisfied wave contour but also to decrease computing time. The simulations show that the amplitude of the transient wave decreases while the relative breadth increases. The velocity vectors of water partical near the attenuator are showed, and the velocities behind the attenuator do not follow a perfect wave velocity distribution.

Abstract: The critical velocity for an infinite cylindrical shell subjected a moving load with a constant velocity is analyzed in this paper. It is found that the critical velocity problem can be translated into a distribution of the real roots of a quadruplicate equation, which can be solved by using Descartes sign method and complete discrimination system for polynomials. Our research shows that the number of the critical velocities for an infinite cylindrical shell always is even number. Furthermore the longitudinal wave velocity is not one critical velocity for the shell. Our results are different from the conclusion drawn by other authors that there are three critical velocities in an infinite shell, and the longitudinal wave velocity is the maximum critical velocity. Then further studies are needed to clarify these questions.

Abstract: Aiming at the present deficiency of operation examination for marine engine, a simulation system of marine engine based on virtual reality is developed. In this paper, the virtual scene and 3D entity model of marine engine is constructed by 3DS MAX according to the actual situation of engine room and the specific operation requirements, and then the 3D model is driven by DirectX in the environment of Visual C++6.0 to achieve the functions of VR scene roaming, human-computer interaction and operation examination. The VR simulation system developed as a part of the whole marine engine simulator can supply an almost real environment for the crew operation examination, which will greatly improve the operation ability of crew, being of important significance for the reform of crew examination in China.

Abstract: A numerical simulation model based on the finite element method (FEM) and wave analysis is proposed to study the acoustic field of a linear instructions and ultrasonic phased array (LUPA) transducer. The ultrasonic wave propagation in the isotropic solid is studied. The delay law controlling for electronic scanning of a LUPA transducer is analyzed. The ultrasonic wave propagation in the inspection material can be visualized in the form of displacement cloud images by FEM modeling. Experiments show that the model can efficiently and accurately predict the radiation field of beam focusing, steering and electronic scanning of a linear phased array transducer. By employing the proposed method, parameters can be conveniently changed to study the acoustic field of the ultrasonic beam in the medium. It is very helpful for designing and applying the linear phased array transducer and flaw inspection in NDT field.

Abstract: A robust and efficient parameter identification method of the stress relaxation model based on Altenbach-Gorash-Naumenko creep equations is discussed. The differential evolution (DE) algorithm with a modified forward-Euler scheme is used in the identification procedure. Besides its good convergence properties and suitability for parallelization, initial guesses close to the solutions are not required for the DE algorithm. The parameter determination problem of the stress relaxation model is based on a very broad range specified for each parameter. The performance of the proposed DE algorithm is compared with a step-by-step model parameter determination technology and the genetic algorithm (GA). The model parameters of 12Cr-1Mo-1W-1/4V stainless steel bolting material at 550°C have been determined, and the creep and stress relaxation behaviors have been calculated. Results indicate that the optimum solutions can be obtained more easily by DE algorithm than others.

Abstract: Cartilage with complex structure is a porous viscoelastic material. The direction of arrangement of collagen fibers in different layer regions directly affects the mechanical properties of the cartilage layer region. It is very important to use the method of numerical simulation for studying cartilage damage and repair through experimental measurements of cartilage mechanical parameters of the different layers. Because of the relatively small size of the cartilage, it is very difficult to measure mechanical parameters of cartilages by tensile test. The paper for main problems in the tensile test of cartilages, first by porcine articular cartilage compression testing, measuring the displacement of cartilage areas of different layers, according to the characteristics of the displacement determines the size of areas of different layers of cartilage, and then designed the cartilage and substrate stretching models. Model includes two forms of direct bonding and embedding bonding to simulate stretching process of different layers of the cartilage area in numerical way, displacement fields and stress-strain fields of stretching cartilage in different layer regions are derived. The numerical results show that using the way of embedded bonding can make stress of articular well-distributed without stress concentration, so it is a good way of bonding methods. Paper of the research work laid the foundation for measuring mechanical parameters of cartilage by stretch experiment.

Abstract: With the improvement of modem science and technology, asynchronous motor plays more and more important role in modem industrial life, and asynchronous motor has the broadest application and requirement in all kind of motors. The paper firstly builds the mathematical model of asynchronous motor in dq coordinate system, then establishes the simulation models of asynchronous motor based on Matlab/Simulink. The last the paper gives the simulation results and analyzes the simulation results. The results prove that the theoretical analysis of asynchronous motor in dq coordinate system is correct completely, and it lays a solid foundation for the study of control method for asynchronous motor.

Abstract: By comprehensive considering of deviations in the bar lengths, elastic deformations and the joint clearances, the simulation research on Movement Precision of Mould-cut main mechanism is carried out. The influencing degree of each influencing factor to its output Precision has been discussed in detail which provides the proof for improving the output Precision of Mould-cut main mechanism.

Abstract: Aiming at the coupling effect of target radiation measurement error and trajectory correction threshold to the hitting accuracy on the Last revised bullets, the optimal design solution based on Monte - Carlo method is proposed, and the CEP curve under the conditions of different correction threshold and target measurement errors by simulation is obtained. Moreover, objective indicators of measurement error and the corresponding threshold of amendments are given. A design basis for system development is obtained.