Amorphous alloy distribution transformers (AMDT) have been widely used in the power transmission and distribution industry due to their excellent energy-saving performance, but the high noise has effected the wide applications of the AMDT. At present, most of researchers are mainly focusing on the magnetostrictive characteristics of the transformer core, and there are few studies coupling with the acoustic and the structure to estimate the acoustic field characteristics in the tank of the AMDT. According to the structural dynamics equations and the acoustic-vibration coupling characteristics of the closed elastic plate with rectangle shell structure, a coupling model of the elastic plate shell and the acoustic cavity structure is established to analyze and verify the correctness of the model by FEA in the paper. The interaction between the cabinet structure and internal noise of the AMDT is studied. The finite and boundary element coupling analysis methods show the interaction between noise and sound-structure of the transformer cabinet, and a method based on a modal interaction is proposed to determine the sound pressure level of the noise for the AMDT. The research results can provide theoretical guidance for the design and noise reduction of amorphous alloy transformers.

A centrifugal pellet injection system for high velocity impurity pellet injection to control ELMs and research impurity transport has been developed for the Experimental Advanced Superconducting Tokamak (EAST). The system is composed of the dropper, the centrifugal accelerator, vacuum pumping system and the diagnostic unit. The centrifugal accelerator is designed to accelerate the pellet by the rotating arm driven by a KYKY F100 turbomolecular pump with an adjusted rotating velocity from 0 to 42,300 rpm. In order to evaluate the stability of the rotating arm, the stress distribution of the rotating arm at different rotating velocities is analyzed by the stress field simulation, and the result shows the maximum stress of the rotating arm appears at the transition position between the large circular groove and the acceleration groove. By simulation analysis, it is noted that the arm can work steadily at 2500 rad/s (corresponding to about 398 Hz arm rotation frequency) rotating velocity and may be broken at 4000 rad/s (637 Hz). By the bench testing using the Li pellets of 1 mm diameter as injection material, it shows the centrifugal accelerator can work steadily for a long time under the condition that the rotating velocity doesn't exceed 2200 rad/s (350 Hz) and the maximum velocity of the pellet can reach 286 m/s. Based on the results of simulation and bench test, the centrifugal pellet injection system was installed and then injected Li pellets into the plasma steadily and continuously with the rotating velocity <2200 rad/s on EAST.

Foamed concrete possesses characteristics such as high strength-to-weight ratio and low density, and widely used to reduce dead loads on the structure and foundation, contributes to energy conservation, and lowers the labor cost during construction. In this paper, the objective is to propose prediction relation for the compressive strength of foamed concrete by fractal theory. A theoretical relation was derived for the compressive strength relating to porosity based on the fractal model for foamed concrete. The proposed relation stands out compared to empirical model since it employs easily measurable parameter, the fractal dimension of porous structure in foamed concrete. The fractal dimension of porous structure can be calculated from the scaling law of the compressive strength of foamed concrete. The fractal model for porous structure serves as a simple and effective tool for predicting the compressive strength of foamed concrete because of its ease in application. The prediction relation of the compressive strength developed in this paper is found to match well with the measured strength.

This paper shows how experimental test results from a split-Hopkinson tension bar (SHTB) and numerical simulations of the test set-up can be used for mutual verification. Firstly, a SHTB where the tension stress wave is generated by pre-stretching a part of the incident bar is briefly presented. This SHTB is used to carry out tensile tests of four aluminium alloys at high rates of strain, while tests at low to medium strain rates were performed in a servo-hydraulic tensile test machine. Using the test results, the parameters of an anisotropic thermoelastic-thermoviscoplastic constitutive relation and a one-parameter fracture criterion are identified for the materials at hand. Subsequently, the material model is used in explicit finite element analyses of the SHTB tests, including the entire experimental set-up and the stress wave propagation during the test. The numerical predictions were found to represent the observed behaviour in the experimental tests fairly well.

The dynamic fracture behaviour of extruded AA6xxx and AA7xxx aluminium alloys is investigated using an instrumented Charpy test machine and V-notch specimens. The specimens are made from extruded flat profiles with a rectangular cross-section of 10 mm thickness and 83 mm width. The material is in T6 temper, i.e. the peak hardness condition. The alloys have either recrystallized or fibrous grain structure. For each alloy six different Charpy impact tests are carried out in two series. In Series 1, the notch is parallel to the thickness direction of the profile (i.e. through the thickness), while the notch is perpendicular to the thickness direction in Series 2 (i.e. lying in the plane of the flat profile). In each series, the longitudinal direction of the specimen is parallel, 45° or 90° to the extrusion direction. Comprehensive fractographic investigations are carried out for the different tests and alloys. It is found that the dissipated energy is practically invariant to specimen orientation and notch direction for the recrystallized alloy. For the fibrous alloys the dissipated energy is lower when the longitudinal direction of the specimen is 90° to the extrusion direction, i.e. when the notch is parallel with the fibrous grain structure. Further, the energy dissipation is higher for Series 2 than for Series 1 due to substantial delamination and secondary cracking in Series 2. The precipitate-free zones (PFZs) formed adjacent to the grain boundary are weak areas, preferable for crack initiation and growth. This is seen in the fracture surface as facets with high density of small dimples and is more pronounced for specimens with the notch parallel to the fibre direction.

The stress–strain behaviour of extruded AA6xxx and AA7xxx aluminium alloys in T6 temper was studied at a wide range of strain rates. Tensile tests at low to medium strain rates were performed in a standard tensile test machine, while a split-Hopkinson tension bar was used to carry out tests at high rates of strain. Extruded aluminium alloys have anisotropic mechanical properties, and tests were therefore done in three directions with respect to the extrusion direction. It is found that the AA6xxx alloys exhibit no significant rate sensitivity in the stress–strain behaviour, while moderate rate sensitivity was found for the AA7xxx alloys. There seems to be no significant difference between the rate sensitivity in the three tensile directions. The experimental data were used to identify the parameters of a thermo-viscoplastic constitutive relation for the extruded alloys, which includes the effects of strain hardening, strain-rate hardening, thermal softening and plastic anisotropy.

Following Flügge's exact derivation for the buckling of cylindrical shells, the equations of motion for transient dynamic loading of orthotropic circular cylindrical shells under external hydrostatic pressure have been formulated. The normal mode theory is used to provide transient dynamic response for the equations of motion. The effect of shell's parameters, external hydrostatic pressure and material properties on the shell response has been studied in detail. A part of tables and figures are given in this paper.