船舶结构冰载荷的监测识别方法及时空特性分析

Method of Monitoring and Identifying Ice Load on Ship Structures and Analysis of Its Spatial-Temporal Characteristics

冰载荷是主导极地船舶结构抗冰设计的环境载荷,对冰激应变的实船测量是获取冰载荷的重要途径。在我国北极科考期间,对“雪龙2”号极地考察船开展了冰载荷现场监测。论文基于对正应变测点布放位置敏感性的分析,合理制定光纤光栅传感器的安装方案,采用影响系数矩阵法对冰载荷进行识别。在此基础上,针对平整冰区冲撞式破冰工况下冰载荷的整体和局部时空分布特性开展研究。结果表明:肋骨腹板上靠近且垂直于外板的挤压正应变比平行于外板的弯曲正应变更适合于作为冰激应变的观测量;海冰沿船体表面擦碰及受船体下压作用而发生弯曲破坏,冰载荷在船体首肩部呈现自水线下潜至船底的整体空间移动特性;高压力区形状和面积变化不明显、组成部分缺失以及主次压力区转换等瞬时演变形式分别是海冰纯挤压、剥落和非同时挤压等局部破坏模式的外在表现。结果可为船舶结构冰载荷的监测识别技术与时空分布特性研究提供参考。

Ice load is an environmental load that dominates the ice-resistant design of polar ship structures,and fullscale measurement of ice-induced strains is an important way to obtain ice loads.During the Arctic research expedition,field measurement of ice loads was carried out on the icebreaker R/V°Xue Long 2".In this paper,the installation of fiber optic sensors was reasonably developed based on a detailed sensitivity analysis of the arrangement of normal strain measuring points,and the influence coefficient matrix method was adopted to identify the ice load.On this basis,the global and local spatial-temporal distribution characteristics of ice loads were deeply studied under the scenario of crash-breaking in level ice.The results show that the compressive strain that is close to and perpendicular to the hull plate is more suitable as a measurement of ice-induced strains than the bending strain that is parallel to the hull plate.The glancing impact of sea ice along the hull and the bending failure caused by the downward pressure of the hull result in global characteristics of ice loads,which presents as the spatial movement of diving from the waterline to the bottom of the ship at the bow shoulder.The instantaneous evolution forms of high-pressure zones with little change in shape and size,loss of components,and shift of primary and secondary pressure zones are the external manifestations of local failure modes of the sea ice,namely pure crushing,spalling,and non-simultaneous crushing.This paper will be a useful reference for the development of monitoring and identification technology and the study of spatial-temporal distribution characteristics of ice loads on ship structures.