100米自卸砂船结构设计与有限元计算外文翻译资料

 2022-09-20 10:29:32

1. Development of procedure for structural safety assessment of energy saving device subjected to nonlinear hydrodynamic load

Abstract

There have been many attempts worldwide to reduce ships׳ fuel consumption. With fuel-efficiency improvement as their designed purpose, a variety of energy saving devices (ESD) have been developed and deployed. Much research with respect to ESD performance already has been carried out; however, the issue of ESD structural safety has received relatively little attention. According to the current approach to ESD structural safety assessment, the Morison equation, which is calculated for a certain probability-level velocity, is applied, or alternatively, a spectral method based on the assumption of a linear system between wave and response is utilized. Unfortunately, this methodology does not take into account the nonlinearity of hydrodynamic loads. Therefore, a new ESD structural safety assessment procedure that utilizes the neural network and time-domain simulation using the Gumbel fitting method is herein proposed. The procedure entails four main steps: sea-keeping analysis, hydrodynamic load analysis and neural network, ultimate strength analysis, and fatigue strength analysis. The important features of the proposed procedure are, in order, as follows. First, to consider the nonlinearity of hydrodynamic force acting on the ESD, computational fluid dynamics (CFD) analysis is carried out on samples consisting of various wave heights and periods. The neural network is then trained based on the CFD analysis results for the prediction of hydrodynamic loads. Second, to take into account the randomness of the peak hydrodynamic force, a three-hour time-domain simulation is repeated 20 times for each sea state of a wave-scatter diagram, and Gumbel parameters are calculated for long-term analysis. Third, approximate long-term analyses using a contribution coefficient and short-term analysis are performed for an efficient long-term analysis.

DongBeom Lee, Beom-Seon Jang, HyunJin Kim, Development of procedure for structural safety assessment of energy saving device subjected to nonlinear hydrodynamic load, Ocean Engineering, Volume 116, 1 April 2016, Pages 165-183

2. Effect of the nonlinear vertical wave-induced bending moments on the ship hull girder reliability

Abstract

In the present paper the effect of the nonlinear vertical wave-induced bending moments on the ship hull girder reliability is evaluated. A chemical tanker for which the nonlinearity of the vertical wave-induced bending moments was found to be significant is adopted as case study. The nonlinear effects on the vertical wave-induced bending moments of the chemical tanker are accounted for in the reliability assessment problem through model correction factors, which are estimated using direct calculation methods based on linear and nonlinear strip theory formulations and the most likely response wave method. It is verified that the design formulation presently used to define the hull girder vertical wave-induced bending moments underestimates the magnitude of the nonlinear effects. The more accurate predictions provided by the direct calculations methods show that the actual hull girder reliability in sagging is significantly smaller. Possible modified design solutions for the midship cross-section of the chemical tanker are evaluated in order to demonstrate the impact of the increase of the nonlinear vertical wave-induced bending moment in sagging in terms of structural design criteria.

B. Gaspar, A.P. Teixeira, C. Guedes Soares, Effect of the nonlinear vertical wave-induced bending moments on the ship hull girder reliability, Ocean Engineering, Available online 10 February 2016

3. Prediction of fatigue crack growth in a ship detail under wave-induced loading

Abstract

Fatigue life prediction based on fracture mechanics has become the focus of research on the strength of ship structures; however, it is difficult to summarize a general formula for calculating stress intensity factors (SIF) for cracks in ship details, and the application of fatigue crack propagation (FCP) theory is limited to simple structures and simple loads in some way. To address this problem, in the present study, the SIF of a crack in a ship detail was calculated by combining a PATRAN finite element model for the whole ship with the advantages of ANSYS for SIF calculation, incorporating a macrocode written to achieve the transformation. The method was validated by comparison with existing empirical formulas. Also a method of generating the ship fatigue loading spectrum is demonstrated based on the design wave approach. Finally, an example is given of combining the unique curve model of FCP with the proposed SIF calculation method and the fatigue loading spectrum generation method, to predict the fatigue life of a welded hatch corner joint in a vessel with large hatch openings. This serves as a reference for fatigue assessment of other complex ship details.

Xiaoshun Yan, Xiaoping Huang, Yingcai Huang, Weicheng Cui, Prediction of fatigue crack growth in a ship detail under wave-induced loading, Ocean Engineering, Volume 113, 1 February 2016, Pages 246-254

4. A study on the fatigue damage model for Gaussian wideband process of two peaks by an artificial neural network

Abstract

Calculations of the fatigue damage on marine structures with a wideband nature are difficult to be done in spectral approach point of view because the link between the spectrum of stress and the probability distribution is difficult to define. This paper addresses the methodology through which the functional relationship between the probability density function and the response spectrum of a bimodal wide-band process by using the artificial neural network technique. An artificial neural network scheme was used to identify the multivariate functional relationship between the tw

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1. Development of procedure for structural safety assessment of energy saving device subjected to nonlinear hydrodynamic load

Abstract

There have been many attempts worldwide to reduce ships׳ fuel consumption. With fuel-efficiency improvement as their designed purpose, a variety of energy saving devices (ESD) have been developed and deployed. Much research with respect to ESD performance already has been carried out; however, the issue of ESD structural safety has received relatively little attention. According to the current approach to ESD structural safety assessment, the Morison equation, which is calculated for a certain probability-level velocity, is applied, or alternatively, a spectral method based on the assumption of a linear system between wave and response is utilized. Unfortunately, this methodology does not take into account the nonlinearity of hydrodynamic loads. Therefore, a new ESD structural safety assessment procedure that utilizes the neural network and time-domain simulation using the Gumbel fitting method is herein proposed. The procedure entails four main steps: sea-keeping analysis, hydrodynamic load analysis and neural network, ultimate strength analysis, and fatigue strength analysis. The important features of the proposed procedure are, in order, as follows. First, to consider the nonlinearity of hydrodynamic force acting on the ESD, computational fluid dynamics (CFD) analysis is carried out on samples consisting of various wave heights and periods. The neural network is then trained based on the CFD analysis results for the prediction of hydrodynamic loads. Second, to take into account the randomness of the peak hydrodynamic force, a three-hour time-domain simulation is repeated 20 times for each sea state of a wave-scatter diagram, and Gumbel parameters are calculated for long-term analysis. Third, approximate long-term analyses using a contribution coefficient and short-term analysis are performed for an efficient long-term analysis.

受非线性水动力载荷能源节约设备的结构安全性评估过程的发展

摘要

在世界范围内有很多想要减少船舶燃料消耗的尝试。当提高燃油效率成为了设计的目标时，各种各样的能源节约设备（ESD）被开发和采用。已经有很多有关能源节约设备（ESD）性能的研究在进行，但是能源节约设备（ESD）结构安全性的问题只得到了相对较少的关注。根据现在评估能源节约设备（ESD）结构安全性的方法，一般应用用来计算一定概率水平的速度的莫里森方程，或者采用基于波浪和响应间线性系统假定的频谱法。遗憾的是，这一方法没有考虑到水动力载荷的非线性特征。因此，作者在本文中提出了一个新的利用神经网络技术和采用Gumbel拟合法进行时域模拟的能源节约设备（ESD）结构安全性的评估过程。这一过程囊括了四个步骤：耐波性分析，水动力载荷分析和神经网络技术，极限强度分析，疲劳强度分析。本文所提出的过程的重要特点按顺序如下列出。首先，为了考虑作用在能源节约设备（ESD）上的非线性水动力载荷，本文对由各种波高和周期组成的波浪样本进行了计算流体动力学（CFD）分析。然后，基于计算流体动力学（CFD）对水动力载荷预测的分析结果，对神经网络系统进行训练。接着，为了考虑水动力载荷峰值的随机性，对每种海况下的波浪散布图重复进行三小时时域模拟20次，再对Gumbel参数进行长期分析。最后，用贡献系数法估计长期分析的结果，并且为了有效的长期分析，本文还进行了短期分析。

DongBeom Lee, Beom-Seon Jang, HyunJin Kim, Development of procedure for structural safety assessment of energy saving device subjected to nonlinear hydrodynamic load, Ocean Engineering, Volume 116, 1 April 2016, Pages 165-183

2. Effect of the nonlinear vertical wave-induced bending moments on the ship hull girder reliability

Abstract

In the present paper the effect of the nonlinear vertical wave-induced bending moments on the ship hull girder reliability is evaluated. A chemical tanker for which the nonlinearity of the vertical wave-induced bending moments was found to be significant is adopted as case study. The nonlinear effects on the vertical wave-induced bending moments of the chemical tanker are accounted for in the reliability assessment problem through model correction factors, which are estimated using direct calculation methods based on linear and nonlinear strip theory formulations and the most likely response wave method. It is verified that the design formulation presently used to define the hull girder vertical wave-induced bending moments underestimates the magnitude of the nonlinear effects. The more accurate predictions provided by the direct calculations methods show that the actual hull girder reliability in sagging is significantly smaller. Possible modified design solutions for the midship cross-section of the chemical tanker are evaluated in order to demonstrate the impact of the increase of the nonlinear vertical wave-induced bending moment in sagging in terms of structural design criteria.

非线性垂直波浪诱导弯曲力矩对船体梁可靠性影响

摘要

在本论文中，评估了非线性垂直波浪诱导弯曲力矩对船体梁可靠性的影响。采用一艘化学品船作为案例研究，垂直波浪诱导弯曲力矩的非线性在这艘化学品船上非常显著。化学品船垂直波浪诱导弯曲力矩的非线性效应通过模型修正系数在可靠性估计问题中被加以考虑，这些修正系数是通过采用基于线性和非线性切片理论公式以及最大可能响应波理论进行直接计算来估计的。现有用于确定船体梁垂直波浪诱导弯曲力矩的设计公式低估了非线性效应的程度，这点被加以证实。由直接计算法提供的更加准确的预测表明实际船体梁在中垂时的可靠性要更小。为了证明非线性垂直波浪诱导弯曲力矩在中垂时增加对结构设计标准的影响，该化学品船船舯横剖面可能的优化设计方案被加以评估。

B. Gaspar, A.P. Teixeira, C. Guedes Soares, Effect of the nonlinear vertical wave-induced bending moments on the ship hull girder reliability, Ocean Engineering, Available online 10 February 2016

3. Prediction of fatigue crack growth in a ship detail under wave-induced loading

Abstract

Fatigue life prediction based on fracture mechanics has become the focus of research on the strength of ship structures; however, it is difficult to summarize a general formula for calculating stress intensity factors (SIF) for cracks in ship details, and the application of fatigue crack propagation (FCP) theory is limited to simple structures and simple loads in some way. To address this problem, in the present study, the SIF of a crack in a ship detail was calculated by combining a PATRAN finite element model for the whole ship with the advantages of ANSYS for SIF calculation, incorporating a macrocode written to achieve the transformation. The method was validated by comparison with existing empirical formulas. Also a method of generating the ship fatigue loading spectrum is demonstrated based on the design wave approach. Finally, an example is given of combining the unique curve model of FCP with the proposed SIF calculation method and the fatigue loading spectrum generation method, to predict the fatigue life of a welded hatch corner joint in a vessel with large hatch openings. This serves as a reference for fatigue asse

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