A large number of macroscopic pores were introduced into commercially pure aluminum (Al) and Zn-Al eutectoid alloy by air pressure infiltration process to comparatively study the influence of macroscopic pores on the damping behaviors of the materials. Macroscopic pores size are on the order of a millimetre (0.5~1.4mm) and in large proportions, typically high 76vol.%. The damping behavior of the materials is characterized by internal friction (IF). The IF was measured on a multifunction internal friction apparatus (MFIFA) at frequencies of 0.5, 1.0 and 3.0 Hz over the temperature range of 25 to 400 °C, while continuously changing temperature. The damping capacity of the metal materials is shown to increase with introducing macroscopic pores. Finally, the operative damping mechanisms in the metal materials with macroscopic pores were discussed in light of IF measurements.

No abstract

No abstract

With three-dimensional finite element method, the crosshead of plunger pump was analyzed. The distribution law of stress at the crosshead was obtained and the stress concentration coefficient of high stress field was calculated. The life of crosshead was estimated by S-N curve of crosshead and the result of finite element analysis, which provides basis of estimating life of the crosshead.

In order to design reasonable-structure and high-efficiency stirring device, realizing development of high sand ratio, high precision and large discharge, according to blender truck actual working conditions and mixing fluid material characteristics, this paper chooses reasonable agitator paddle structure, paddle combination type and mixing tank structure, concludes calculation methods of stirring power, paddle strength and stirring axis design, providing the theoretical support to blender truck stirring device design calculation.