The shortage of railway transport capability has restricted the development of China’s economy. High speed rail is vital for the development of the passenger railway, because of its huge transport capacity, safety, comfort, all-day operation, environmentally-friendly operation, and its sustainability. Since 2004, the former China Ministry of Railways has introduced and assimilated advanced foreign technologies, and used this to improve the technologies of the construction of the high speed rail and train, and formed a nationwide cross-industry chain.

The aim of this study is to explore the potential of various plant ramifications as concept generators for creating a brand topology optimization solution for stiffness design of continuum structures under harmonic force excitations. Firstly, a mathematical model is built to identify analytical laws that underlie the optimality of the effective but individual design rules of existing leaf venation morphogenesis. Then, a new evolutionary algorithm is developed to find the optimal topology of stiffened structures under harmonic force excitations. Candidate stiffeners are treated as being alive, growing at locations with a maximum displacement response gradient along the structural surface. Since the scale of the candidate stiffeners can be adaptively expanded or reduced during the simulation, computational resources could be saved, thereby enhancing the flexibility of topology optimization. Finally, the suggested approach is applied to a case study in which the displacement amplitude at specified locations is defined as the objective and the volume of added stiffeners as the constraint. The simulation process shows how the stiffness design of continuum structures can be conducted automatically using this bionic approach.

The labyrinth-honeycomb seal has been widely used in gas turbine engines as an abradable gas path seal to protect the rotor from wear and damage in rubbing interaction. It usually works with a stepped labyrinth because the knife-edged tips could produce a special dynamic sealing system, and then the minimum clearance is possible between the rotor and stationary component. To investigate the high-speed rubbing behavior between a Hastelloy-X honeycomb material and a GH4169 double stepped labyrinth, nine rubbing tests were conducted using a high-speed abrasion test rig while the blade tip speed varied from 150 to 450 m/s, and the incursion rate from 120 to 360 μm/s. The abradability of honeycomb made from Hastelloy-X was fully verified by analyzing the visual rubbing observations, rubbing forces, and impact acceleration. It is shown that compression deformation happens to the honeycomb material during the rubbing process with the labyrinth blade except for a simple cutting mechanism, which is mainly affected by the parameter of incursion rate. Thermal ablation and oxidation were the main damage occurring on the labyrinth tip and appeared more obviously at a higher blade tip speed. Rubbing forces and impact acceleration were obtained from a piezoelectric dynamometer and acceleration sensor during the rubbing process. At a blade tip speed of 300 m/s and incursion rate of 360 μm/s, radial and tangential forces show their maximum values of 716 N and 871 N, respectively. The peak value of acceleration presents 341g with the highest blade tip speed of 450 m/s and the highest incursion rate of 360 μm/s. All testing results provide a great deal of effective information on high-speed rubbing behavior for the abradablility evaluation of a honeycomb.

This paper proposes a novel reliability-based sensitivity analysis (SA) method, namely relative convergence rate of random variables using particles swarm optimization (). The convergence rate of a random variable during the optimum evolution process reflects the sensitivity of the objective function with respect to the random variables. An optimized group strategy is proposed to consider the fluctuation of the convergence rate of a variable during the optimum process. The coefficient of variation (COV) for candidate particles and the relative convergence rate of a random variable can be calculated using the particles in the optimized group. The smaller the COV for candidate particles, i.e., the larger the relative convergence rate, the more sensitive the objective function with respect to the variable. Three examples are available for the application of this method, and the results indicate that the sensitivity of the reliability index with respect to the variable obtained using the technique and gradient of limit-state function is the same in the quantitative sense.

The vertical vibration of a large diameter pile embedded in inhomogeneous soil with hysteretic type damping is investigated based on the 3D axisymmetric model. Firstly, the pile is assumed to be a Rayleigh-Love rod with the consideration of its transverse inertia effect. Following this assumption, the pile-soil system is divided into several segments according to the stratification of the surrounding soil, and the dynamic interactions of the adjacent soil layers are simulated using the distributed Voigt model. Meanwhile, the surrounding soil is discretized into finite annular vertical zones to consider its radial inhomogeneity, and the force equilibrium and displacement coordination are satisfied at the interfaces of the adjacent soil zones and the interface of the pile-soil. Then, the analytical solution in the frequency domain and the semi-analytical solution in the time domain are obtained by solving the vibration governing equations of pile-soil system. Based on the solutions, a parametric analysis is conducted to investigate the influence of the transverse inertia effect on the dynamic response of the large diameter pile and its relationship with the pile parameters and the radial inhomogeneity of the surrounding soil. Finally, a comparison with the measured result and two other calculated results is presented to verify the effectiveness of the present solution.

Yttria-stabilized tetragonal-zirconia polycrystals (Y-TZP) have been shown to have superplastic properties at high temperatures, opening a way for the manufacture of complex pieces for industrial applications by a variety of techniques. However, before that is possible, it is important to analyze the deformation and fracture mechanisms at a macroscopic level based on continuum theory. In this paper, an elastic-plastic material model with a theoretical large deformation is constructed to simulate the true stress-true strain relationships of superplastic ceramics. The simplified constitutive law used for the numerical simulations is based on piecewise linear connections at the turning points of different deformation stages on the experimental stress-strain curves. The finite element model (FEM) is applied to selected tensile tests on 3-mol%-Y-TZP (3Y-TZP) co-doped with germanium oxide and other oxides (titanium, magnesium, and calcium) to verify its applicability. The results show that the stress-strain characteristics and the final deformed shapes in the finite element analysis (FEA) agree well with the tensile test experiments. It can be seen that the FEM presented can simulate the mechanical behavior of superplastic co-doped 3Y-TZP ceramics and that it offers a selective numerical simulation method for advanced development of superplastic ceramics.

An ecofriendly heterogeneous polyoxometalate (POM)-gold catalyst Au/BW₁₁/Al₂O₃ was synthesized and used for solvent-free epoxidation of cyclooctene under mild reaction conditions using molecular oxygen as an oxidant and t-butyl hydroperoxide (TBHP) as an initiator. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), induced coupled plasma optical emission spectrometry (ICP-OES), and Brunauer-Emmett-Teller (BET). The catalyst showed good conversion and high selectivity without use of solvents or environmentally harmful oxidants. Moreover, the catalyst is recyclable up to three cycles with no significant loss in selectivity towards epoxide.