Advanced Materials Research Vols. 712-715

Abstract: The response surface method is adopted to analyze the structural reliability. This paper presents a new response surface method with the uniform design method to predict the failure probability of structures. It is the response surface method based on Fourier orthogonal basis function (RSM-Fourier). To reduce computational costs in structural reliability analysis, approximate Fourier response surface functions for reliability assessment have been suggested. The method involves the selection of training datasets for establishing a model by the uniform design points, the approximation of the limit state function by the trained model and the estimation of the failure probability using first-order reliability method (FORM). The proposed method is applied to examples, compared with other methods to demonstrate its effectiveness.

Abstract: Aiming at the mispunch problem of emulsion impact hammer, the cone-type piston buffering structure was adopted to minimize the impact. Impact process simulation model of differential connection piston was built using AMESim software, the influences of different buffer length, conical angles and buffer clearance on the terminal velocity and pressure were analyzed according to the model and optimum parameters (half cone angle 5°, length 50mm as well as clearance 0.25mm) were determined. The collision progress between piston and the guide sleeve at 2m/s simulated by LS-DYNA software shows that the maximum stress is 674MPa which locates at at the edge of the liquid inlet hole of guide sleeve, and the maximum stress on interface is less than 400MPa, both of them area lower than the yield strength of materials,so the guide sleeve is of shock resistance. However, it is found to have rebounding phenomenon during the buffering process and the mispunch should be attentively prevented.

Abstract: This paper presents the technical process of machine tool design and multi-objective optimization of large structural components based on Pro/E and SAMCEF. The main contents include: the design process of the machine tool layout and the large structural components; finite element modeling methods of the fixed joint, screw-nut joint and guide-slider joint; the optimization method of large structural components based on response surface model. A precision horizontal machining center is used as an example to verify the correctness and feasibility of the method.

Abstract: Reduction tube using a die is a kind of deformation tubes which are used on railway train as energy absorbers. In this paper, axial compression behavior and energy absorption characteristics of reduction tubes using a die under impact load are investigated. No-linear finite element software LS-DYNA is used to conduct the numerical study. Results for the expansion tube using a die (another kind of deformation tube) and the reduction tube using a die are compared. Assuming two different structures with the same material and sectional area, an analysis shows that the energy absorption of reduction tube is better than the expansion tube. Hence, the reduction tubes using a die are investigated using a series of numerical analysis. The relationship between displacement and load, average load are obtained. The influences of impact mass and impact velocity are discussed.

Abstract: In structural non-probabilistic reliability analysis, the uncertain structural parameters are assumed to be the interval parameters. The commonly used probability model will lose accuracy when there is not enough experimental date for the reliability analysis. Conversely, the interval model only requires the upper and lower bound of the uncertain variable, which is more reasonable compared with the probabilistic model. The interval perturbation method is applied in this paper to compute the non-probabilistic reliability index, where the interval expansion problem has been effectively controlled. The precision of computing the reliability index is effectively improved, solving the problem of the non-probabilistic reliability index in a new way. The numerical results prove that this method is effective and feasible.

Abstract: A 3D viscous numerical wave tank (NWT) was established based on computational fluid dynamics simulation method, and oblique irregular waves were generated by defining inflow boundary conditions. The motions of free surface ship in oblique waves were predicted by solving the Reynolds Averaged NavierStokes (RANS) equations describing the flow around ship. The kinematics equations of rigid body were solved according to the calculation results (forces and moments) in each time step. The heave, roll and pitch transfer functions for container ship model S175 in oblique waves were obtained. The comparisons between simulation results and linear strip theoretical results were carried out, showing good agreement, which demonstrate the present research can provide an effective way to predict seakeeping characteristics.

Abstract: Axle box spring of railway vehicle is the structure of helical spring in series with rubber pad to reduce working stress of helical spring and absorb high-frequency vibration. Rubber pad model was built. Static and dynamic characteristics were researched in axial and radial directions. The results show that the static stiffness of rubber pad decreases with the increase of radial displacement and increases distinctly with the increase of the amount of compression; The dynamic stiffness of rubber pad increases with the decrease of the excitation force in the case of the same excitation frequency and decreases with the decrease of the frequency in the case of the same excitation displacement. Axle box spring method was established and the amplitude-frequency curve of dynamic stiffness of the spring was presented. The results provide a theoretical basis to research the dynamic performance of railway vehicle.

Abstract: With the rapid development of high-speed railways, wheel and rail wear has become increasingly serious due to the acute wheel-rail interaction. During the operation of high speed vehicle, complicated wheel-rail contact force will lead to wheel profile wear, which will worsen the dynamic performance of vehicle system, or even influence the safe operation of vehicles. In order to ensure the vehicle dynamic performance, right now regularly wheel re-profiling has to be adopted. Therefore, the study of wheel profile wear and its effect on vehicle dynamic performance is very important ^[1,. The purpose of the paper is to study the variation characteristics of vehicle dynamic performance with respect to the wheel profile wear through numerical simulation and field test.

Abstract: Because the impact of the connector is very important, the mathematics calculation model for the key components of the integrated general suspension rack for an airborne ejection was established, which were under the two questions of safety hanging and accuracy ejection. The integrated general suspension rack was operated by high pressure gas which was generated by the burning of the ejector cartridge, and the entire movement process of the integrated general suspension rack pushing the piston to unlock the locking mechanism and completely discarding from the airborne was analyze using the dynamic theory of gases. The modified and the original design plan for the integrated general connector were analyzed by the strength analysis. Through analysis, compared with original design, the improved design can well achieve the desired goal. The improved design of the connector is checked by field inspection of high frequency vibration to make sure the integrated general suspension rack can be hanged stably on the airborne and being flung out accurately by the modified design plan.

Abstract: Wind and waves have particularly significant influence upon exertion of naval vessels battle effectiveness. It is urgently necessary to improve the ability of the Navy to carry out combat service in severe sea state normally. This paper aims to obtain the accurate prediction of ship motions with second level predictable time in real waves. According to the characteristics of the ship motion, the research on extremely short-time prediction of ship motion has been carried out based on multi-variable chaotic time series analysis, and the effectiveness of the prediction of ship motion in real wave is highly improved.