船舶碰撞仿真分析中的单元尺寸与失效应变关系研究

随着船舶向大型化发展势头迅猛,船舶碰撞所带来的灾难性后果也显著增大.为评估船舶结构的耐撞能力,国内外研究人员分别从试验和数值模拟2个方面开展研究工作.针对船舶碰撞场景的仿真模拟中,经常采用常应变失效准则来定义单元是否失效.然而失效应变取值强烈依赖于单元尺寸大小,因此,开展失效应变与单元网格尺寸关系研究对船舶结构的耐撞性能准确评估意义重大.本文通过对光板及加筋板的耐撞性能的试验研究,并应用非线性有限元软件LS-DYNA对试验结果进行仿真模拟,探讨了光板及加筋板的单元尺寸和失效应变之间的关系.结果表明:光板和加筋板的单元尺寸与失效应变关系曲线明显不同,因此采用常应变失效准则时应区别对待,不能混用.研究结论对船舶结构碰撞有限元仿真具有一定的指导意义.

Study of relation between element size and failure strain in ship collision simulation

With the development of ship towards to the large-scale, the results of accident due to ship collision are more seriously. In order to assess the crashworthiness of marine structures, the research work is conducted by numerical simula-tion and experiment. The constant strain failure criterion is used to simulate the ship collision occasion. It is important to study the relation between failure strain and element size for assessment crashworthiness of marine structures because of the failure strain strongly depending on the element size. In the present study, the results of lateral collision tests on unstiffened plate and stiffened plate are reported. The explicit finite element code LS-DYNA is used to simulate the tests. The result shows that there are great difference in failure strain verse element length between unstiffened plate and stiffened plate. Hence, these conclusions could support the future uses of failure strain for collision simulations.