带有初始缺陷船用加筋板极限强度的不确定性分析

由于实际工程结构尺寸及材料性能等存在一定的变异性,这将导致其极限承载能力具有不确定性。首先基于逐步破坏理论,采用非线性有限元方法对带有初始缺陷的典型船用加筋板的极限强度进行研究。采用Monte Carlo数值模拟结合拟合技术建立结构不确定性分析模型。以此为基础,考虑结构尺寸、材料参数及初始缺陷的随机性,对于加筋板极限强度的不确定性进行探讨。为在计算量较小的前提下得到准确的随机统计规律,提出基于可靠性反问题的对数正态三参数拟合方法,并与传统拟合方法进行比较分析。结果表明对数正态三参数法可高效准确地对于加筋板极限强度的统计特性进行预报,为船舶的安全性分析提供基础。

UNCERTAINTY IN ANALYZING ULTIMATE STRENGTH OF SHIP STIFFENING PLATES WITH INITIAL INPERFECTIONS USING NONLINEAR FINITE ELEMENT METHODS

Uncertainty in maritime structure ultimate strength is induced by the variability of the scantlings, materials performance, and other factors. The ultimate strength of a ship stiffening plate with initial imperfections was calculated by the progressive collapse theory using nonlinear finite element methods. An uncertainty analysis model was established by Monte Carlo simulation and fitting technology, and was used to discuss the factors influencing ultimate strength, including the random variables of structural scantlings, material parameters, and initial imperfections. In order to obtain an accurate stochastic law with small computational cost, the 3-parameter log-normal fitting method, based on inverse First Order Reliability Method (FORM), was presented and compared with the traditional method. The results indicated that the 3-parameter log-normal method can predict ultimate strength efficiently and accurately, so it can be the basis of ship safety analysis.