Fundamental Study of Wave Impact Load on Ship Bow (1st Report)

Abstract

As part of their studies conducted regarding the wave impact loads acting on the ship bow and the structural responses thereto by a series of drop tests, the authors analyzed the scale effect, or the influence of the scale of bow models therein used on the results of the drop tests.It is often claimed that the estimated impulsive pressure determined by a model test varies with the scale of the model. To see if such a claim was well-founded or not, the authors carried out the drop test using a 1/15 scale model and compared the results with those obtained using the 1/3 scale model in the previous tests. The results of this comparative study may be summarized as follows.At first, the maximum impulsive pressure obtained using the 1/15 scale model was considerably smaller than that determined using the 1/3 scale model. This difference became small with large relative impact angle α. Such a difference must have come from the difference in relative size of the pressure gauges fitted to these two models. On the other hand, the equivalent static pressure Peq obtained using the 1/15 scale model and that obtained using the 1/3 scale model remained the same, if the size of the panel was proportional to the size of the model. That is, Peq didn't vary with the scale of the model.Further, investigation was made of the effects of the size and the location of the panel on Peq. Peq indicated a considerable change according to the size and location of the panel when the impact angle α was 0°, but the change became smaller with large α of, say, α=5°.