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Time to Flutter of a Maneuvering Viscoelastic Goland Wing

机译:有时间扑腾的粘弹性床翼

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The use of high polymer composite materials in aircraft requires the incorporation of viscoelastic effects during the design process to fully capture the capabilities of these materials. One design analysis of concern is the prediction of flutter for an aircraft wing because flutter may result in the catastrophic failure of the wing. The current analysis assumes that the wing material is elastic which neglects the time dependent memory effect that appears for viscoelastic materials such as polymer composites. Previous work has shown that the viscoelastic effects lead to a flutter time in addition to a flutter speed. This earlier time to flutter theory was limited to constant flight speeds during the analysis so the effects of past maneuvers and mission profiles could not be explored. An expanded theory using an operator mapping is possible and captures the effects of maneuvers. Further, the theory is implemented in Matlab to provide numerical examples using a viscoelastic Goland wing. The results show that the time to flutter for most scenarios is limited to twice the relaxation period of the material, and that the results are sensitive to the functions used to represent the changes in flight velocity. Time to flutter decreases with increasing flight cycles, suggesting a trend similar to the fatigue limit of metals. For the viscoelastic Goland wing considered, 50,000 flight cycles per relaxation period is the maximum limit before flutter occurs instantaneously for a range flight velocities and viscosities.
机译:在飞机中使用高分子复合材料需要在设计过程中掺入粘弹性效果,以完全捕捉这些材料的能力。一个关注的一个设计分析是对飞机翼的颤动预测,因为颤动可能导致机翼的灾难性失败。目前的分析假设机翼材料是弹性的,其忽略了出现粘弹性材料如聚合物复合材料的时间依赖性记忆效果。以前的工作表明,除了颤动速度之外,粘弹性效果还会导致颤动时间。在分析期间,颠簸理论的潮流理论的时间仅限于恒定的飞行速度,因此无法探索过去的机动和使命概况的影响。使用操作员映射的扩展理论是可能的,并捕获机动的效果。此外,该理论在MATLAB中实施,以使用粘弹性橡胶翼提供数值例子。结果表明,大多数情况下颤动的时间仅限于材料的松弛周期的两倍,并且结果对用于表示飞行速度变化的功能敏感。随着飞行周期的增加,颤动的时间减少,表明一种类似于金属疲劳极限的趋势。对于所考虑的粘弹性高尔兰翼,每个松弛时期的50,000个飞行周期是颤动时瞬间发生的最大限制,用于范围飞行速度和粘度。

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