The oblique impact damage model of hybrid fiber metal laminates is established, and the process of the bullet impacting aluminum alloy-carbon/glass hybrid fiber laminates with multi-angle and high speed is numerically simulated to explore the influence of impact angle on energy absorption, contact force and interlayer failure area of metal fiber laminates. The results show that the kinetic energy consumption decrease with the increase of the impact angle. The impact angle directly affects the energy absorption characteristics of the hybrid fiber metal laminate. As a whole, the failure area of metal layer and fiber layer decreases with the impact angle. The failure area of the carbon fiber layer is smaller than that of the glass fiber layer, and the failure area of the glass fiber layer from the top to the bottom gradually increases, but the failure area of the carbon fiber layer from the top to the bottom has no obvious change. Because of the impact angle, the kinetic energy dissipation, the maximum fiber stress position and failure area of hybrid fiber metal laminates have significant effects.
The high-order accurate finite-difference method is used to simulate the hypersonic flow field around a blunt wedge under the condition of the wall roughness element. The influence of the position of the independent wall roughness element on the interaction between the free flow and the wall is analyzed, and the influence of the position of the roughness element on the wall pressure, the wall friction resistance and wall heat flow are studied. The results show that two compression waves and one expansion wave are formed in the flow field by rough elements, and the wave intensity increases when the position of rough elements move forward. When the center of the rough element is xp≥1.5, a vortex will form at the leading edge of the rough element. The backward moving of the rough element will increase the length of the vortex, inhibit the change of the flow parameters in the first-half of the rough element, promote the change of the flow parameters in the second-half of the rough element, which will reduce the wall friction resistance and inhibit the heating of the incoming flow to the first-half of the rough element.
To study the influence of glass spacing on digital image correlation measurement in the optical path, an experimental method of displacement stepping for digital image correlation measurement was designed under nine working conditions (without glass, single glass, and double glass with different spacings of 20 mm, 70 mm, 120 mm, 170 mm, 220 mm, 270 mm, 320 mm respectively). The results of digital image correlation method and dial gauge method were compared, and the measurement error and standard deviation of digital image correlation measurement under different working conditions were analyzed. The experimental results show that the variation trend of displacement measured by DIC under nine working conditions is consistent with the step change of the specimen displacement, but there exist obvious errors between the nine conditions. Based on the results of dial gauge measurement, DIC measurement results are larger, and the maximum deviation is less than 3 μm. Under the condition of without glass, the relative error of displacement measured by DIC was the smallest, with an average error of 2.92%. Under the condition of double glass spacing of 170 mm, the relative error was the largest, with an average error of 11.37%. The standard deviation of double glass condition with a certain spacing was less than that of single glass condition. In general, when the double glass spacing is within a certain range, the measurement results are more accurate and less discrete than those of single glass, and the thermal protection performance is also better.
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