On the water impact and elastic response of a flat plate at small impact angles
On the water impact and elastic response of a flat plate at small impact angles
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DOI：
10.1007/s007730070019
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发表时间：
2000-10
影响因子：
2.6
通讯作者：
S. Okada;Y. Sumi
中科院分区：
文献类型：
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作者：
S. Okada;Y. Sumi
众所周知，瓦格纳关于平面物体与水面之间碰撞的理论不能应用于非常小的碰撞角，因为被困空气的影响。我们把注意力集中在小碰撞角的碰撞问题上，由于理论和实验上的困难，这一问题还没有得到详细的研究。为了研究从捕集空气冲击到瓦格纳型冲击的过渡冲击行为，我们通过落下一块板并以0.5°的增量将冲击角β从0°增加到4°来进行精确的压力和应变测量。根据实验结果，所测得的压力的时间历程被确定为属于三种模式：瓦格纳型，捕获的空气型，和中间型。在过渡冲击过程中，在冲击开始时在龙骨附近观察到瓦格纳型图案，捕获的空气图案朝向板的边缘。随着冲击角度的增加，瓦格纳型压力模式占主导地位。虽然在过渡冲击过程中出现了高峰压力，但板中测得的最大应变对冲击角度并不敏感。研究发现，结构响应可以通过使用的平均压力在冲击，这导致了一个新的设计方法，为小的冲击角估计。
It is well known that Wagner's theory for the impact between a flat body and a water surface cannot be applied to very small impact angles because of the effects of the trapped air. We focus our attention on the impact problem with a small impact angle, which has not been studied in detail owing to theoretical and experimental difficulties. In order to investigate the transitional impact behavior from a trapped-air impact to a Wagner-type impact, we carried out precise pressure and strain measurements by dropping a plate and increasing the impact angle,β, from 0° to 4° by increments of 0.5°. Based on the experimental results, the time histories of the measured pressures were identified as belonging to three patterns: the Wagner type, the trapped-air type, and the intermediate type. During the transitional impact process, the Wagner-type pattern was observed near the keel at the beginning of the impact, with the trapped-air pattern toward the edge of the plate. The Wagner-type pressure pattern dominated with increasing impact angle. Although high peak pressures appeared in the transitional impact process, the maximum strains measured in the plate were not so sensitive to the impact angle. It was found that the structural response can be estimated by using the average pressure at impact, which leads to a new design approach for small impact angles.