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It's difficult to directly measure the pressure on the surface of the material in the impact process. PVDF (Polyvinylidene Fluoride) gauges may help to solve this problem. In this paper, some split Hopkinson pressure bar (SHPB) experiments were carried out with the PVDF gauges as specimens, with the strain gauges pasted on the bars being used as the measurement method. By comparing the results of the strain gauges and the PVDF gauges, it is proved that there is a stress concentration when the PVDF gauges were sandwiched directly in the solid interface. Then, two methods to eliminate the stress concentration are verified by experiments. The first method is adding a cushion, such as electrical tape. The second method is using 502 glue, which is evenly coated on the interface.

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The evaporation and condensation mechanism of two-phase flow is studied. The Euler-Euler pattern is used to express the evaporation and condensation properties of two-phase flow. The research shows that the tracking program can accurately track the interface. The thermal resistance on the confluence of the condensation part and insulation part becomes larger. The working fluids have significant influence of two-phase.