Effect of pitting corrosion on local strength of hold frames of bulk carriers (2nd Report)—Lateral-distortional buckling and local face buckling

Pitting corrosion is typical corrosion observed on coated hold frames of bulk carriers which exclusively carry coal and iron ore. In order to secure the safety of these types of bulk carriers, it is important to understand the effect of pitting corrosion on local strength of hold frames.

In order to investigate this effect, a series of 4- and 3-point bend tests on structural models which consist of web, shell and face plates has been carried out. Artificial pitting was created on the web plate to simulate pitting. In the 4-point bend tests, two equal concentrated loads have been applied vertically at the one-third points of simply supported models so that compression load due to bending would act on the face plate. In this testing condition, lateral-distortional buckling occurred before reaching the ultimate strength and local buckling of the face plate was observed after reaching the ultimate strength. The effect of web plate pitting on the lateral-distortional buckling strength was found to be small but the ultimate strength decreases with increase in the degree of pitting intensity. In the 3-point bend tests, concentrated load has been applied vertically at the center of simply supported models so that compression load due to bending would act on the face plate. In this testing condition, local face buckling occurred just after reaching the ultimate strength. The ultimate strength is found to be decreasing with increase in the degree of pitting intensity.

A series of non-linear FE analyses has been performed to simulate the deformation behavior observed in the tests. It has been revealed that even in the case of randomly distributed pitting corrosion the ultimate strength of the structural models was almost the same as that of the structural models with uniform corrosion corresponding to the average thickness loss.     

夹芯复合材料在潜艇声隐身结构中的应用及其相关技术研究

潜艇的声隐身问题一直是研究的热点，各种新的声学材料和结构不断涌现。首先对复合材料在潜艇声隐身结构中的应用情况进行了分析，对其材料、结构形式、作用效果等方面进行了详细阐述，提出了夹芯吸声复合材料作为水下声隐身结构的发展趋势。然后利用数值计算的方法，对夹芯复合材料的声学性能进行了分析，得到了夹芯复合材料各层材料参数，如厚度、声特性阻抗和损耗等对声学性能的影响规律。最后，评估了典型局部结构壳板应用夹芯复合材料后的力学性能和声隐身性能。结果表明，潜艇非耐压结构的壳板采用夹芯复合材料可以满足结构的力学要求，与钢结构相比声隐身能力得到提高。     

结构局部分析子系统JF的开发

本文阐述了结构局部分析子系统 JF 的设计思想和主要手段,并以实例说明该系统完全适用于铁道车辆主型货车车体结构设计,实现结构分析数据的自动生成,达到预期的目的.     

常导中低速磁悬浮列车受流方式选择及受流器结构设计

对常导中低速磁浮列车的3种受流方式进行了分析比较,得出侧向受流方式是优选方案。提出一种新型的常导中低速磁浮列车侧向受流器设计方案,并分析了它的结构原理。     

基于IACS共同规范的油船极限强度及敏感性分析

基于IACS共同规范研制了双壳油船总纵极限强度的计算程序,计算了一个箱形梁模型和两条油船的总纵极限强度,计算结果表明本文研制开发的计算程序是正确可靠的,可供油船船体结构设计参考和使用。本文还对影响船体梁极限强度的参数进行了敏感性的简要探讨,得出有用的结论。     

An approach to estimating the hull girder response of a ship due to springing

This article describes an estimation method for the hull girder response of a ship due to springing. The linear and nonlinear springing effects on the hull girder are evaluated. Previous studies on the springing response focused mainly on the symmetric response, or vertical response. In this article, however, the springing analysis is extended to asymmetric responses, or horizontal and torsional responses. The Timoshenko beam model was used to calculate the hull girder response and the quadratic strip method was employed to calculate hydrodynamic forces and moments on the hull. To remove irregular frequencies, a rigid lid was adopted on the hull free surface level and hydrodynamic coefficients were interpolated for asymptotic values. Applications to two ships for the symmetric and asymmetric responses were carried out and the effect of springing responses is also discussed.     

基于非线性理论的船舶结构稳定性研究

本文以结构的线性分析为基础，对船舶结构的线性稳定性分析方法进行了改进。同时，采用基于特征值分析的线性稳定性分析方法得到了船舶结构的临界载荷，从该载荷值可以预测出实际结构临界载荷的上限并能较好地反映船舶结构线性性能对其稳定性的影响，据此得出船舶结构的失稳位形。在非线性稳定性分析中，采用NEWTON—ROPHSON方法及弧长法求解考虑非线性时船舶结构的临界载荷，并详细讨论了结构缺陷对稳定性的影响，提出考虑结构缺陷时船舶结构稳定性计算方法。通过不同类型的算例进行分析比较，总结出船舶结构边界条件、几何缺陷变化与船舶结构稳定性之间关系，验证了本文稳定性分析方法的正确性、有效性及对现役散货船船体结构的适用性。     

基于应力和刚度的连续体渐进结构优化

近年来,渐进结构优化已发展成工程优化的一种重要方法。目前,渐进结构优化研究多集中在对单约束条件下优化方法的研究,对多约束条件下优化研究较少。为了更好地模拟实际工况,本文在充分分析了有限元理论和材料的弹性力学关系的基础上,找出约束之间的本质联系,提出了基于应力、刚度双重约束渐进结构优化方法。通过经典算例进行验证,优化结果表明了该方法的可行性与有效性。同时,该方法也为其它多约束结构优化提供了一定的参考。     

有关桥梁结构裂缝的机理及其防治对策探讨

对桥梁结构裂缝的形成机理进行分析,指出砖石砌体结构和钢筋混凝土结构裂缝形成的根本原因,提出相应的防治对策,并简要介绍各种防治措施的施工过程。     

溢油应急培训现状与思考

分析了溢油应急培训现状及存在的实际问题,并在此基础上提出了加强溢油应急培训的意见和建议。