Abstract: Based on the critical plane energy method to build a plastic strain energy function on the critical plane, the approach of hot spot plastic strain energy as assessment parameters of fatigue damage is used and the shortcomings that the traditional energy method as a scalar is difficult to describe the direction of crack propagation is overcomed. By the rules of cracks expansion through critical plane, the fatigue life model parameters have a clear physical significance. W-S algorithm process is deduced, so the complex stress state is equivalent to a series of symmetric cyclic stress based on energy and structural damage caused by everyone is calculated. The research, fatigue life prediction of the key component on CII platform under random waves and flow loadings, has theoretical significance and value of engineering application.
Abstract: Boiling is known to be a very efficient mode of heat transfer in earth gravity, however, in microgravity bubble behavior is different because the buoyancy effects are replaced by surface tension effects such as Marangoni convection. The modeling of nucleate boiling with the effect of Marangoni convection in 0 g is accomplished by using Phase Field Method. Numerical simulation is carried out of single nucleating vapor bubble on a heated wall with and without Marangoni convection. The results show that the flow field consists of a major vortex that recirculates colder fluid from the upper region, pulling it toward the hot surface to the point where the bubble meets the heated surface. This type of flow pattern has been observed in various experiments.
Abstract: The dynamic response of the square tube subjected to the impact of a mass was investigated by using experimental and numerical methods. The square tube was impacted by a mass at the velocity ranging from 5.09 m/s to 12.78 m/s, and different progressive buckling modes were obtained. The numerical simulation was also carried out to analyze the buckling mechanism of the square tube. The results show that there is obvious stress wave propagation and strain localization in the tube, which has a significant influence on the buckling mechanism of the tube. The stress wave and inertia of the mass play different roles at various impact velocities. And buckling mechanism at low velocity is mainly caused by stress wave, whereas the buckling mechanism at high velocity is resulted from the inertial of the mass.
Abstract: For lack of structure rigidity foundation and radial force diminishing exponentially with the distance of gland, a newly packing sealing structure with opening and hollow metal ring supporting is designed. Through finite element analysis, it comes out that the disadvantages are divided adding effect of high pressure resistant. The radial force is increased,preload is reduced, and the mechanical seals can be replaced under certain condition.
Abstract: Research slope stability under rainfall condition in geotechnical centrifuge is an ideal test method, however, the influence of high centrifugal force field produced by running geotechnical centrifuge cannot be neglected. Droplet deformation and breakup under different gravity and of different diameters were studied with VOF method, the results shows that the process of droplet deformation and breakup is similar under condition of different g-value and diameters, droplet breakup in a very short time in high gravity field, and with the increase of g-value, the breakup time of droplet became shorter, with the increase of droplet diameter, the breakup time of droplet became longer under same gravity acceleration. Studies in this paper have important significance in developing geotechnical centrifuge artificial rainfall equipment.
Abstract: In this paper, a honeycomb sandwich beam and a plate are studied to verify a method of determining the equivalent properties of these structures. The responses of the structures are obtained from both numerical and physical experiments considering free-free boundary conditions. It is shown that a double-layer effect caused by the bonding-stretching process during manufacturing cannot be ignored. It is also found that at low frequencies, the equivalent method gives good agreement with measurements. However at higher frequency range, the response calculated using equivalent method shift towards higher frequency compared with measurements.
Abstract: The flow past 3D cavity is a common structure, which is located on the surface of the underwater vehicle. The flow mechanism and hydrodynamic characteristics of the cavity have great significance for the design of the underwater vehicle. In this paper, large eddy simulation (LES) is presented to investigate the flow mechanism and hydrodynamic characteristics of the 3D cavity in terms of flow mechanisms, drag and fluctuating pressure. It is found that the motion law of the large vortex inside the cavity, and the drag and fluctuating pressure of the trailing edge is the largest. By the water tunnel experiment, the calculation result agrees with the experiment well, and LES method is verified feasibly.
Abstract: The six degrees of freedom platform in vehicle driving simiulator simulates vehicle motion based on the calculation results of the dynamics model, so good dynamics model is the basis and prerequisite of simulator’s good performance. This paper describes the process of applying the Vortex software to establish vehicle dynamics model and focuses on the problem of damping matching in the vehicle suspension system based on the ride comfort and stability.
Abstract: This paper describes the theoretical and numerical methods to calculate the contact pressure of Mechanical Elastic Wheel (MEW). The structure of MEW was introduced firstly, and then the contact pressure of MEW was calculated with the simplified model of a single layer composite ring according to Elasticity. Considering the structure and force symmetry, 1/2 finite element model of MEW was built. Mooney-Rivilin hyperelastic constitutive model was applied to simulate material nonlinearity, and frictionless contact type was applied to simulate nonlinear contact characteristics. With the Augmented Lagrangian solving method, the contact pressure analysis result of MEW was obtained. The theoretical and simulation values of MEW’s contact pressure are approximate with the deviation of 1.08%, and it indicates the validity of the simulation.
Abstract: A new type of shock absorber was designed. The shape memory alloy (SMA) bars were used as the kernel components for energy dissipation and restoration in the stress mode of pure tension. Their initial deformation was enlarged by the hydraulic system with two pistons of different sizes. In this way, high material utilization and high relative displacement were guaranteed together. The prototype device was fabricated, analyzed and experimental tested. The results show that the shape and amplitude of the force-displacement curve of the device could be easily changed by varying the hydraulic system, the number and/or the characteristics of the SMA bars. The new device can be separately or combined used as shock absorber and/or vibration isolation component for vehicles or other machines.