考虑应变率影响的圆管结构冲击试验缩尺修正方法研究  

Research on the modified scale method for impact tests of tubular structures considering the effect of strain rate

作　　者：包杰[1,2] 刘昆[1] George WANG BAO Jie LIU Kun George WANG(School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China Shanghai Merchant Ship Design and Research Institute, Shanghai 200120, China American Bureau of Shipping, Singapore)

机构地区：[1]江苏科技大学船舶与海洋工程学院,江苏镇江212003 [2]上海船舶设计研究院,上海200120 [3]美国船级社

出　　处：《海洋工程》2016年第5期73-82,共10页The Ocean Engineering

基　　金：国家自然科学基金资助项目(51379093);江苏省高校自然科学基金资助项目(15KJD580003)

摘　　要：评估结构耐撞性能最可靠的方法是实尺度碰撞试验,然而对于大尺度结构物的碰撞试验,因其耗资巨大而不易开展,适当开展比例模型试验可以为简化解析算法及数值仿真计算提供验证依据,也可在一定程度上评估结构的耐撞性能。但是在进行碰撞模型试验时,材料应变率的敏感性会使得缩尺模型的动态响应与实尺度结构结果出现偏差,模型试验得到的数据与实际结构的动响应不完全遵循相似关系,这就限制了相似理论在大型结构物冲击问题上的应用。本文给出了一种通过改变冲击质量来修正应变率效应的方法,不同于传统量纲分析法中选取时间、质量和长度为基本量纲,而是以冲击质量、初始冲击速度和动态应力代替,得到计及应变率效应的质量相似关系。以此为基础,将该修正方法应用于船舶-自升式海洋平台的碰撞分析中。研究结果表明,该修正方法可以有效降低由于应变率效应而造成的缩尺误差,修正后的缩尺模型在碰撞冲击载荷下的位移、碰撞力和撞击时间等动态响应参数与实尺度模型结果的一致性更好。本文研究成果可以为大型结构物冲击模型试验设计提供技术支撑。It is known that real scale collision tests are the most reliable method to evaluate collision resistance of structures. But it is too expensive for collision tests of large scale structures to be carried out. So the scale model tests are necessary and significant to provide a basis for validating the analytical method and finite element method. It can also reflect the collision resistance of the structure. However,when we carry out impact model tests,the dynamic response will be different between scale model and real scale structure because of strain rate sensitivity. And the model test data and actual dynamic response do not completely follow the similar relationships. So the application of similarity theory in large structures impact problems is limited by the strain rate effect. This paper provides a method to modify the effect of strain rate sensitivity by changing impact mass. The impact mass,initial impact velocity and dynamic stress are selected to obtain the similar relationship instead of the time,mass and length that are the basic dimensions in traditional dimensional analysis. Then,the modified scaled method is applied in the analysis of collision between ships and jack-up platforms. The modified scale method is verified for the problem of the tubular structure of platform subjected to impact loads. The results show that the modified scale method can effectively reduce the errors caused by strain rate effects,and the dynamic response of displacement,impact force and impact time of modified scale model under impact load are in good consistency with prototypes. The research results can provide technical supports for the design of large structures impact tests.

关 键 词：碰撞试验 应变率敏感性 冲击质量 基本量纲 修正方法 

分 类 号：P751[交通运输工程—港口、海岸及近海工程]