Study of Standardization for Longitudinal Strength of Ships.

船舶总纵强度标准化研究。

基本信息

批准号：
62420037
负责人：
OHTSUBO Hideomi
金额：
$ 12.67万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62420037/
关键词：
longitudinal strength of ship ship structure response fatigue strength wave load calculation motion response calculation non-linear response Finite Element Method 非線形動的応答船体縦曲げモ-メントサギングモ-メント国際統一規則せん断力分布船体強度不規則波 AI 衝撃荷重 /

项目摘要

There are three non-linearities for the response of ships structures in big waves. (1) non-linearity of gluid resistance against vertical moment of ships (2)slamming of exposed hull (3)whipping due to elastical behavior of ship. Longitudinal moment and shear force distribution for several types of ships were estimated by the authors according to numerical simulations considering those non-linearities.Plate thickness effect in fatigue strength (so called "DEn Thickness penalty code") was investigated using non load carrying T shaped fillet welded joint in pulsating bending. It has been revealed that good finish of weld toe results in remarkable improvement of fatigue strength and almost vanish so called "platethickness effect". Regarding fatigue crack propagation under random loading, several patterns of power spectrum with different band widths in frequency were used, and meanstress level was changed from compression to tension to identify the crack closure effect. The various stress r … More ange DELTAS_r of random loading was converted into fixed value DELTAS_<eq> ( equivalent stress range ). Using this DELTAS_<eq> and considering crack closure effect, a possibility has been shoxun that the fatigue behavior under random loading may be predicted from constant amplitude test.A numerical method was developed evaluation of wave loads, motion responses of general shaped floating bodies including ship hulls and also for evaluation of structural responses of complex structures composed by plural number of floating bodies and connecting elastic members. This method is based on both the three dimensional source distribution method and the wave interaction theory. High speed estimation method was adopted for evaluation of the Green functions in the three dimensional source distribution method and combining this with the wave interaction theory, efficient calculations of wave loads and motion responses can be accomplished.New statistical theory is developed, which gives probability density function and extreme values of a weekly non-linear response to Gaussian input. It is determined that the theory gives good estimates of them by comparing with measured surge respons of a ship model moored in random waves.The highly nonlinear structural analysis codes based on the low-order finite elements, which are (1) analysis code for space frames using linear Timoshenko beam elements, (2) analysis code for thin shells using constant-moment Mindlin plate elements, and (3) analysis code for axisymmetric solid using constant-strain quadrilateral elements, have been developed. Their accuracy and efficiency have been estimated, through the comparison with the results of the crush tests. Less

船舶结构在大波浪中的响应存在三个非线性：（1）流体阻力对船舶垂向力矩的非线性；（2）暴露船体的砰击声；（3）船舶弹性力矩引起的鞭打。作者根据考虑这些非线性的数值模拟估算了几种类型船舶的剪切力分布。使用非承载 T 形材料研究了板厚度对疲劳强度的影响（所谓的“DEn 厚度惩罚代码”）研究表明，良好的焊趾光洁度可显着提高疲劳强度，并且几乎消失所谓的“板厚效应”，即随机载荷下的疲劳裂纹扩展，具有不同频带的几种功率谱模式。使用频率宽度，并将平均应力水平从压缩变为拉伸，以识别裂纹闭合效果。随机载荷的各种应力范围 DELTAS_r 转换为固定值 DELTAS_<eq>。（等效应力范围）并考虑裂纹闭合效应，可以通过恒幅试验预测随机载荷下的疲劳行为。开发了一种评估波浪载荷、运动响应的数值方法。该方法基于三维源分布方法和高速波相互作用理论，可用于评估包括船体在内的一般形状浮体以及由多个浮体和连接弹性构件组成的复杂结构的结构响应。采用估计法评价格林函数在三维源分布方法中，并与波浪相互作用理论相结合，可以完成波浪载荷和运动响应的有效计算。发展了新的统计理论，给出了每周非线性的概率密度函数和极值通过与停泊在随机波浪中的船模型的实测浪涌响应进行比较，确定该理论对它们进行了良好的估计。基于低阶有限元的高度非线性结构分析代码为（1））使用线性空间框架的分析代码Timoshenko 梁单元、(2) 使用恒力矩 Mindlin 板单元的薄壳分析代码和 (3) 使用恒应变四边形单元的轴对称实体分析代码，已通过以下方法估算了它们的精度和效率。与挤压试验结果的比较。