克服衝擊載重不連續之擬動態實驗技術

Pseudodynamic Technique for Overcoming Load Discontinuity at End of Impulse

楊青昊(Ching-hao Yang)

指導教授 ： 張順益

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2008年)

摘要

在傳統的擬動態試驗過程中，為了克服衝擊載重作用結束時外力不連續所引起的振幅誤差，往往被迫採取較小的積分時間步長，此積分時間步長可能遠小於滿足精確度的要求。然而，使用較小的積分時間步長經由逐步積分法所求得的位移增量也會變小，當位移增量小於或接近於量測儀器解析度的範圍可能會造成不正確的試驗結果。因此，在本研究中主要是以在衝擊載重結束後增加一小步積分時間步長的方式來減少由於外力不連續所引起的振幅誤差。經由數值模擬與擬動態試驗的結果可以發現只要此一小步的積分時間步長夠小，便可以有效的減小因外力不連續所引起的誤差。

關鍵字

擬動態實驗 ； 時間步長 ； 外力不連續

並列摘要

In the traditional pseudodynamic tests, it is found that a very small time step, which might be smaller than that required for accuracy consideration in a period, is generally needed to reduce the extra amplitude distortion from an impulse as a load discontinuity occurs at the end of the impulse. However, a small time step might lead to a very small displacement increment, which might be small than the resolution of the displacement transducer. As a result, the displacement increment cannot be accurately imposed upon the specimen due to the limited resolution of the displacement transducer and inaccurate responses will be obtained. Alternatively, this difficulty might be overcome if a small time step is additionally performed right after the end of the impulse so that the extra amplitude distortion caused by the discontinuity can be reduced. Both numerical experiments and actual pseudodynamic tests attested to the extra amplitude distortion caused by the load discontinuity at the end of the impulse can be effectively reduced by conducting an extra small time step right after the end of the impulse. Hence, reliable shock responses can be obtained form pseudodynamic tests.

並列關鍵字

pseudodynamic test ； time step ； discontinuity in impulse

參考文獻

[9]Chang, S.Y., “Shock Response form Pudodynamic Test,” Peer Review Paper, 2008.

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