Abstract: Flapping-wing flying is a kind of rhythmic movement with symmetry of time and space essentially, and this movement is generated and controlled by Central Pattern Generator (CPG). A 2-DOF flapping mechanism was designed according to the flapping-wing flying principle of insects, and the flapping-wing flying CPG model was constructed by nonlinear oscillators. The system responses were studied, and the influences of the model parameters to the system characteristics were analyzed. Through the engineering simulation of flapping-wing flying control model, the first modal vibration of the system was selected, and the different flying modes of bionic aircraft were realized by adjusting system parameters. This kind of bionic control strategy promoted the movement and control ability of flapping-wing flying, and provided a new method to the generation and control of flapping-wing rhythmic movement.
Abstract: In order to assess whether the durability of the designed product meets the requirements or not, the fatigue strength should be analyzed in product designing stage. With the help of ANSYS finite element analysis software, the detail fatigue rating (DFR) method and the linear cumulative damage theory are used to analyze the actuator from three aspects of the static strength, stiffness and fatigue strength. A Stiffness Model of the Actuator has been built in the static strength analysis. The paper also highlighted the theoretical derivation of the DFR and the application in the fatigue strength calculation of the actuator. In practical projects, this method can be applied to similar products, and it can be used as a verification method for design optimization.
Abstract: In order to calculate the damage effect of the surface warships subjected to modern anti-ship missile precisely, the solid modeling technology is applied firstly to simulating the penetration explosion of the anti-ship missile in this paper and initial detonation parameter of typical anti-ship weapon is solved based on mixed explosion theory for typical warhead and the explosion load is simulated by corrected sphere-feeding method. On that basis, material model and physical equation referred to numerical simulation of warship structure damage with the whole circuit described in detail and specifically. Also presented is typical computational example calculated by the general finite element procedure LS-DYNA which indicates qualitative coincidence from the impact effect to response tend between the numerical simulation results and experimental data and the method can be applied to the engineering calculation to analysis the damage characteristic subjected to penetration load which provides the basis for the research of ship blast-resistant.
Abstract: Planetary cage in caterpillar is designed with the static strength theory. While the dynamic characteristics of planetary parts in different working condition is difficult to obtain with the limit of traditional method, so research on reliability and fatigue life prediction of planetary cage is very difficulty which result that designed life is much longer than practical life. The reliability of caterpillar is affected deeply. The dynamic loads suffered by planetary cage in different working condition is obtained based on running simulation with MSC.ATV, and then the fatigue life of planetary frame is calculated with fatigue life prediction system of planetary cage. The study case proves the new method is feasible. Research on planetary cage in caterpillar based on running simulation test resolve not only the technical problem of loads in different work condition but also close connection with engineer, so the research have very important utility significance.
Abstract: Because of the complexity of turnout, the wheel-rail contact of turnout region is more complex than that of railway line. In order to study the wheel-rail contact Geometry relationship of turnout region, using cubic spline interpolation method to get the outline of control sections, the ideal wheel-rail contact relationship in turnout region was obtained by the means of trace line, and then analyze the effect of track-distance roughness on the dynamic wheel-rail Geometry contact, the result shows that appropriate gauge widening can improve the structure irregularity.
Abstract: Switching force and inadequate displacement are two key issues in the conversion of switch rail, which determined some important parameters such as the traction position of switch machine, the displacement of traction point and the length of switch rail. This paper taking the NO.9 turnout of 60kg/m rail in a line of Wuhan rail transit as the research object, using the open architecture of ANSYS software and its secondary development, establishing the calculation procedure of switching force, calculating and studying the influence of switch force and inadequate displacement of switch rail by the stiffness, the number of fastener groups and the friction coefficient of sliding bed on the heel of switch rail.
Abstract: This paper studies the dynamic property of rubber absorber in rail fastening by electro-hydraulic testing machine. Two different types of rail fastening are tested. In one fastening the rubber component is in compressed condition (RCRF). While in another the rubber is in sheared (RSRF). A nonlinear dynamic model of rubber absorber in rail fastening is proposed. The model parameters are obtained by the least square method. The accuracy of the obtained model is verified by measured result. The two results are in good agreement. The dynamic stiffness and damping are analyzed, and the results show that dynamic stiffness and damping are closely related to the frequency and amplitude of excitation. Nonlinear characteristic becomes greater with increasing excitation amplitude for the both rail fastenings. For different excitation frequency, the vibration reduction effect of RSRF is more stable than that of RCRF.
Abstract: The failure mode of steel plate with a center elliptic corroding hole double-sided adhesively bonded by carbon fiber composite patch is identified and studied, and analytical solution to load-carrying capacity of damaged steel plate bonded by composite patch is presented in this paper. Ultimate load of patched steel plate corresponding to each failure mode is derived and calculated respectively, the load carrying capacity of the patched plate is equal to the minimum value of these calculations. Yielding load when yielding occurs near the hole-edge of repaired structure from present method was compared to the results of ANSYS FEA, and the ultimate load of repaired plate from present method was compared to the test results. Results indicate: Repaired by bonded composite patch, static strength and loading carrying capacity of damaged steel plate or structures can be effectively restored. Yielding load and ultimate load of patched steel plate is visibly increased. The present analytical results have a good agreement with FEA and experimental results.
Abstract: The 2008 Wenchuan earthquake with a surface wave magnitude of 8.0 induced numerous infrastructure damages. The typical seismic damages of 61 bridges, 18 tunnels and slope reinforcements are presented. The results show longitudinal or transverse displacement was the most widespread bridge seismic damage and resulted in girder dropping, shear key failure, joint expansion and support damage. Pillar was sheared off or crushed failure due to strong motions and lack of sufficient hoop steels. Tunnel damage was mainly observed at portal, which was mostly caused by slope failure. Strong ground shaking caused multi-direction cracks in the lining, shear failure of lining resulted from serious surrounding rock relative displacement. Investigation of slope reinforcements suggests anchor cable and frame beam had good anti-seismic property. Furthermore, some suggestions about resistant countermeasures to future earthquake are proposed.
Abstract: The implementation of seismic risk assessment of existing structures is necessitated for practical engineers to select the retrofitting strategies. The reliability based approaches are proposed to investigate the behaviour of structures subjected to ground excitation and encouraging evaluation results of various typologies of structures have been obtained exploiting such methodologies. The decision regarding the retrofitting strategies that will rehabilitate the flaws of the structure under prescribed ground motions that have high probability of occurrences at the scenario can be made. This paper addresses the generation of hazard curve by probabilistic seismic hazard analysis from the seismological point of view. The multiple stripe analysis, as one of typical probabilistic based assessment procedures, will be utilized to evaluate the structural seismic fragility. The seismic risk can be estimated based on the numerically integrating the fragility function with the hazard curve.