冰致自激振动测量与机理解释

Measurement and explanation for its mechanism of ice-induced self-excited vibration

在海洋平台上观测到了冰致结构的稳态振动,以及冰力和平台响应间的频率锁定现象.通过对实测数据和冰与结构相互作用的破碎机理分析,证明冰致稳态振动属于自激振动.给出了产生冰致自激振动的条件,提出了冰致自激振动的物理机制,指出冰致自激振动发生在冰加载速率的韧脆转变区,整个过程中冰内裂纹的形成与扩展受到了结构运动速度的控制.冰内部的微裂纹行为是解释与描述冰致自激振动的关键要素.

The phenomena of ice-induced steady state vibration and frequency lock-in between ice force and response were observed on offshore platform. The further analysis of full-scale test data and laboratory-conducted compression tests of sea ice under corresponding load speed demonstrates that it is a typical self-excited vibration. The conditions occurring in ice-induced self-excited vibration and physical mechanism are discussed. It is pointed out that ice-induced self-excited vibration takes place at loading rate of ice failure within ductile-brittle region, and in the whole process formation and spread of micro crack in ice are controlled by vibration velocity of the structure. The micro crack behavior in ice is the key factor for describing and explaining ice-induced self-excited vibration.