船舶振動峭度對試驗嚴厲度之影響

THE INFLUENCE OF SHIP VIBRATION KURTOSIS ON THE TEST SEVERITY

為確保船艦上裝備可靠度，裝備需依據任務需求，執行振動環境試驗，其中船舶功能振動試驗常以隨機振動頻譜執行。唯相同之試驗頻譜，可有不同之振動時域信號組合，其時域響應分佈將影響試驗嚴厲度，且實際振動環境響應並非皆呈現Gaussian分佈，亦會影響振動模擬之實際效應。本文模擬探討船舶振動峭度對試驗嚴厲度的影響程度，結果顯示（1）振動信號峭度越高，所誘發之最大響應越高，對裝備強度驗證更嚴厲，頻率越高，差異越大；（2）相同振動頻譜，時域信號峭度越高，振動之疲勞損傷越大，試驗嚴厲度相對較高，裝備自然振頻較低者，影響越大；（3）若船舶振動量測數據顯示振動峭度過高，則執行船舶振動試驗時，建議設定其峭度要求，以確保試驗嚴厲度。

"Functional test under the presence of vibration environment derived from mission profile and interpreted in random spectrum vibration are literally one of the major environmental tests to validate the reliability of shipboard equipment. However, upfront environment test severity reproduced in the above well-accepted test method might be compromised because the planned test spectrum is reconstructed from different time-domain responses, especially when those responses are of non-Gaussian distribution subject to the capability of actual test platform. This paper is dedicated to the influence of vibration kurtosis on test severity where the following conclusions are drawn: (1) Higher vibration kurtosis leads to larger maximum response. (2) Higher vibration kurtosis causes greater fatigue damage under the identical vibration spectrum. In addition, higher test severity usually induces far more fatigue damage against equipment of low natural frequency. (3) Test requirement of vibration kurtosis for ship-board equipment is highly recommended to guarantee test severity if test data exhibits excessive vibration kurtosis."