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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

船舶结构在大浪作用下的响应存在三种非线性。(1)船舶垂直力矩对流体阻力的非线性；(2)外露船体的撞击；(3)船舶弹性特性引起的甩动。通过数值模拟，估计了几种船型的纵向弯矩和剪切力的非线性分布。采用脉动弯曲非载T型角焊接头，研究了板厚对疲劳强度的影响（DEn厚度罚则）。结果表明，良好的焊趾光洁度可以显著提高焊接接头的疲劳强度，几乎可以消除所谓的“板厚效应”。针对随机载荷作用下的疲劳裂纹扩展，采用了几种不同频带宽度的功率谱图，并将平均应力水平由压缩变为拉伸，以识别裂纹闭合效应。将随机加载的各应力r…More range DELTAS_r转换为固定值DELTAS_<eq>（等效应力范围）。利用该DELTAS_<eq>并考虑裂纹闭合效应，表明了用恒幅试验预测随机载荷作用下的疲劳行为的可能性。提出了一种评估包括船体在内的一般形状浮体的波浪荷载和运动响应的数值方法，并用于评估由多个浮体和连接弹性构件组成的复杂结构的结构响应。该方法基于三维震源分布法和波相互作用理论。采用高速估计方法对三维震源分布法中的格林函数进行估计，并将其与波浪相互作用理论相结合，可以实现波浪荷载和运动响应的高效计算。提出了一种新的统计理论，给出了高斯输入每周非线性响应的概率密度函数和极值。通过与停泊在随机波浪中的船舶模型的实测浪涌响应进行比较，可以确定该理论给出了较好的估计。开发了基于低阶有限元的高度非线性结构分析代码，即(1)采用线性Timoshenko梁单元的空间框架分析代码，(2)采用恒矩Mindlin板单元的薄壳分析代码，以及(3)采用恒应变四边形单元的轴对称实体分析代码。通过与粉碎试验结果的比较，对其精度和效率进行了评价。少