Auxetic honeycombs have proven to be an attractive advantage in actual engineering applications owing to their unique mechanical characteristic and better energy absorption ability. The in-plane dynamic crushing behaviors of the honeycombs with various cellwall angles are studied by means of explicit dynamic finite element simulation. The influences of the cell-wall angle, the impact velocity, and the edge thickness on the macro/microdeformation behaviors, the plateau stresses, and the specific energy absorption of auxetic honeycombs are discussed in detail. Numerical results show, that except for the impact velocity and the edge thickness, the in-plane dynamic performances of auxetic honeycombs also rely on the cell-wall angle. The "> <"-mode local deformation bands form under low-or moderate-velocity impacting, which results in lateral compression shrinkage and shows negative Poisson's ratio during the crushing. For the given impact velocity, the plateau stress at the proximal end and the energy-absorbed ability can be improved by increasing the negative cell angle, the relative density, the impact velocity, and the matrix material strength. When the microcell parameters are the constant, the plateau stresses are proportional to the square of impact velocity.

As a new type of electrical contact material, Ag/SnO2 has poor processing performance and large contact resistance, which limits its application so far. In order to improve the machinability and electrical performance of the Ag/SnO2 electrical contact materials, a new kind of nanoAg/SnO2 electrical contact material doped rare earth element Ce was prepared by sol-gel-chemical plating method. The purity of the powders was analyzed by X-ray diffraction (XRD) and the crystallite size of the nanoparticle was calculated according to the Scherrer equation. The distribution of Ce-doped SnO2 powers were studied using scanning electron microscopy (SEM). In parallel, rated making and breaking experiments on nanoAg/SnO2 were conducted. The results of XRD and SEM show that the nanoSnO2 powders are small, uniform and with no obvious phenomenon of reunion, and thus significantly improve the density, strength and machinability of the sample. Furthermore, the results of arc erosion show that the nanoAg/SnO2 electricity contact materials doped element Ce have superior fusion welding resistance properties.

Twist-bend coupling is a very important way to reduce the fatigue loads for megawatt blades. This paper studied the twist-bend coupling properties of 5MW wind turbine blades using finite element method. Twist angle, flapwise bending angle and coupling parameter are given for each aspect by applying same loading condition. Simulated results show that material can greatly affect the coupling properties while the influence induced by the structure of blade can be ignored.

In order to improve the machinability and electrical performance of the Ag electrical contact materials. A new kind of nano-Ag/SnO2-TiO2 electrical contact materials were prepared by liquid phase in-situ chemical route. The distribution state of elements titanium in copper and their effects on the microstructures and properties have been studied. The results of SEM show that SnO2-TiO2 powders are small, uniform and with no obvious phenomenon of reunion. At last, Ag/SnO2-TiO2 electrical contact materials were prepared by powder metallurgy method and electrical performance were done. Test results show that the electrical properties of Ag/SnO2-TiO2 are superior to the electrical properties of Ag/SnO2. Hence Ag/SnO2-TiO2 may become a new contact material which can replace Ag/SnO2.

Stochastic finite element method and reliability technique are used to determine the safety degree of the turbine blade with parametric uncertainty. The material, geometric parameters and rotating speed of blade exhibit notable random fluctuations, so the conventional deterministic analysis of blade can’t provide complete information. The stochastic analysis can tackle the uncertainties in structural parameters and obtain the probabilistic characteristic of the vibration characteristic. In this paper, the study focuses on the reliability assessment of the blade with uncertainty parameters based on the stochastic finite element method (SFEM) and the mean-variance method. The perturbation stochastic finite element method (PSFEM) is used to calculate probabilistic characteristic of the natural vibration of the turbine blade. Based on the stochastic finite element method, the mean-variance method is used to calculate the resonance reliability of the blade. The example shows that the present method is valid.