摘要
[目的]为解决船体梁的动态极限强度快速计算问题,提出动态Smith方法。[方法]首先,以传统的Smith方法为基础,在考虑船体梁在动态载荷下材料的应变率效应、惯性力,以及Smith方法中加筋板单元在不同应变率下的应力−应变关系的基础上,建立计算船体梁在匀速弯矩载荷作用下动态极限强度的动态Smith方法;然后,以箱形梁和船体梁为研究对象,通过与有限元结果进行对比,验证动态Smith方法的准确性。[结果]结果显示,由动态Smith方法与有限元方法计算得到的船体梁的动态极限强度在端面旋转角速度小于1时误差小于10%。[结论]动态Smith方法是在传统Smith方法的基础上的进一步拓展,相较于有限元计算,该方法能提高船体梁动态极限强度的计算效率。
[Objectives]The dynamic ultimate strength of a hull girder is a crucial parameter for assessing ship safety.In the context of ships being subjected to dynamic loads such as wave-induced and slamming loads during navigation,making accurate calculation of the dynamic ultimate strength of the hull girder is of great significance for ship designers to predict structural performance and ensure ship safety.However,existing research on the calculation of the dynamic ultimate strength of the hull girder remains limited,and traditional methods often face challenges in terms of computational efficiency.Therefore,this study aims to address the challenge of efficiently calculating the dynamic ultimate strength of a hull girder and proposes a more efficient calculation method.[Methods]The proposed approach is the dynamic Smith method,which is based on the traditional Smith method.Firstly,considering the strain rate effect of materials under dynamic load,the Cowper−Symonds model is introduced to modify the yield strength of materials.This modification is essential as the dynamic yield strength of materials increases with the increase of strain rate.Secondly,the stress−strain relationship of stiffened plate elements under different strain rates is taken into account.Xiong's empirical formula for the dynamic ultimate strength of stiffened plates is adopted to correct the stress−strain curve,ensuring more accurate calculation of member stress.Finally,the inertia force generated during the dynamic response of the hull girder structure is considered.By calculating the acceleration caused by the change of the neutral axis of the cross-section in the Smith method iteration process,the inertia force of each unit is obtained,and then the impact of inertia force on the dynamic ultimate strength is corrected.[Results]The results show that when the angular velocity of the end-face rotation is less than 1,the error between the dynamic ultimate strength calculated by the dynamic Smith method and that by the finite element method is less than 10%.Specifically,for the box girder model and the hull girder model of a VLCC based on ISSC 2012,the dynamic Smith method shows strong agreement with the finite element results in the low-to-medium angular velocity range.However,when the angular velocity is greater than 1,the error between the two methods becomes larger.[Conclusions]In conclusion,the dynamic Smith method is a significant extension of the traditional Smith method.Compared with the finite element method,it can remarkably improve the calculation efficiency for calculating the dynamic ultimate strength of a hull girder,especially when the end-face rotation angular velocity is less than 1.For the correction of the stress-strain relationship curve in the dynamic Smith method,when the strain rate is less than 0.4,the stress-strain curve is calculated based on strain rate hardening;when the strain rate is greater than or equal to 0.4,the empirical formula is used.This research provides a novel approach to ship safety assessment and provides valuable guidance for ship design and structural strength analysis.
作者
姜焰华
张伟龙
崔进举
王德禹
JIANG Yanhua;ZHANG Weilong;CUI Jinju(3,WANG Deyu1,31 State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;CSSC Seago System Technology Co.,Ltd,Shanghai 200001,China;School of Ocean and Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)
出处
《中国舰船研究》
北大核心
2025年第5期216-224,共9页
Chinese Journal of Ship Research
基金
国家自然科学基金资助项目(52371328,51809167,51979163,U2241266)
高校基本科研业务费专项资金资助项目
船舶CAE研发应用项目资助
工信部项目资助(ZTZB-23-990-030)。
关键词
船体
船体梁
箱形梁
Smith方法
动态极限强度
hulls(ship)
hull girders
box girders
Smith method
dynamic ultimate strength
