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1.
WEI Dong ZHANG Shengkun
Ph.D. Candidate School of Naval Architecture Ocean Engineering Shanghai Jiao Tong University Shanghai P. R. China
Professor School of Naval Architecture Ocean Engineering Shanghai Jiao Tong University Shanghai P. R. China 《中国海洋工程》1999,(3)
Stiffened Panels are important strength members in ship and offshore structures,A new methodbased on counterpropagation neural networks(CPN)is proposed in this paper to predict the ultimate compres-sive strength of stiffened panels.Compared with two-parametric polynomial,this method can take more pa-rameters into account and make more use of experimental data.Numerical study is carried out to verify thevalidation of this method.The new method may find wide application in practical design. 相似文献
2.
The new simple design equations for predicting the ultimate compressive strength of stiffened plates with initial imperfections in the form of welding-induced residual stresses and geometric deflections were developed in this study. A non-linear finite element method was used to investigate on 60 ANSYS elastic–plastic buckling analyses of a wide range of typical ship panel geometries. Reduction factors of the ultimate strength are produced from the results of 60 ANSYS inelastic finite element analyses. The proposed design equations have been developed based on these reduction factors. For the real ship structural stiffened plates, the most general loading case is a combination of longitudinal stress, transverse stress, shear stress and lateral pressure. The new simplified analytical method was generalized to deal with such combined load cases. The accuracy of the proposed equations was validated by the experimental results. Comparisons show that the adopted method has sufficient accuracy for practical applications in ship design. 相似文献
3.
The failure of a ship hull girder is governed by buckling and plastic collapse of the deck, bottom and side shell steel stiffened plates. The stiffened steel plating in ships is generally subjected to both in-plane and out-of-plane loading and is more important to understand the characteristics of these panels under buckling. Tests are reported on the collapse load of stiffened plates with and without cutout and with reinforced cutout under uniaxial compression. A generalized computer program for the semi-analytical solutions proposed by various investigators based on strut approach and orthotropic plate approach, and a finite element analysis program based on orthotropic plate approach are developed. The panels are also analysed using the finite element analysis software ANSYS. An approximate method based on strut approach is proposed to calculate the collapse load of stiffened plates with cutouts and initial imperfections. The reduction in strength of the panels due to the presence of square cutout, rectangular cutout and increase in strength due to reinforcement around rectangular cutout are calculated based on the test results. Comparisons are made between the test results and predictions based on semi-analytical solutions and finite element analyses, and the uncertainty parameters calculated are discussed. Based on this study it is concluded that the cutout can be reinforced with a maximum increase in strength up to 19% for plate initiated failures. 相似文献
4.
The present paper is Part I of a series of three papers prepared by the authors on the methods useful for ultimate limit state assessment of marine structures, that have been developed in the literature during the last few decades. It is considered that such methods are now mature enough to enter day-by-day design and strength assessment practice. The aims of the three papers are to conduct some benchmark studies of such methods on ultimate limit state assessment of (unstiffened) plates, stiffened panels, and hull girders of ships and ship-shaped offshore structures, using some candidate methods such as ANSYS nonlinear finite element analysis (FEA), DNV PULS, ALPS/ULSAP, ALPS/HULL, and IACS common structural rules (CSR) methods. As an illustrative example, an AFRAMAX-class hypothetical double hull oil tanker structure designed by CSR method is studied. In the present paper (Part I), the ultimate limit state assessment of unstiffened plates under combined biaxial compression and lateral pressure loads is emphasized using ANSYS, DNV PULS, and ALPS/ULSAP methods, and their resulting computations are compared. Part II will deal with methods for the ultimate limit state assessment of stiffened panels under combined biaxial compression and lateral pressure using ANSYS, DNV PULS, and ALPS/ULSAP methods, and Part III will treat methods for the progressive collapse analysis of the hull structure using ANSYS, ALPS/HULL, and IACS CSR methods. 相似文献
5.
This paper firstly figures out a similar scale model regarding ultimate strength experiment of a typical ultra large container ship (ULCS) through combined ultimate longitudinal bending and torsion analysis, in which the similarity theory is proposed to design the scale model for reflecting the progressive collapse behaviors of true ships in ultimate strength model test. The present study presents the similarity between scale model and true ship in cross-section considering the height of neutral axis, the section modulus, the inertia moment about neutral axis and the polar inertia moment should fit the geometrical similarity theory, and in strength considering buckling strength and shear ultimate strength of plates and stiffened panels should fit the strength similarity theory. Numerical investigations are conducted on the ultimate strength of a 10,000 TEU container ship and the similar scale model under pure hogging bending, pure torsion and combined bending and torsion, respectively. The nonlinear finite element method (NFEM) is adopted considering the effects of initial deformations and both material and geometric nonlinearities. Finally, the numerical results are compared with each other and discussed showing a good agreement in both elastic and inelastic range during the progressive collapse behaviors, which means the similar scale model can represent the true ship regarding ultimate strength test. And the similarity theory is verified quite stable after the uncertainty analysis. 相似文献
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7.
Sang-Rai Cho Joonmo Choung Chang-Min Oh Kang-Su Lee Jung-Yeob Kim 《Ocean Engineering》2010,37(8-9):770-776
CSRs (Common Structural Rules for bulker and tanker), which came into effect in 2006, invoke the concept of the ultimate strength of hull girders. While numerous studies associated with the ultimate capacities regarding global hull girders and stiffened panels have been carried out, there are few application cases of the ultimate strengths for deck machineries and their supporting structures. In the present study, nonlinear finite element analyses have been performed to obtain ultimate capacities for a size 450 DIN type bollard including hull foundation structures for which elastic strength assessments based on allowable stress analyses were jointly carried out by a Mooring Fitting SWL Standardization Committee consisting of four major Korean shipbuilders (DSME, HHI, HHIC, and SHI) in 2003. The plastic hardening property is identified from a comparison of the results of ultimate strength simulations and a bollard tension tests performed by the committee. It is assumed that the ultimate load is the corresponding load point when the deformation slope of the bollard column reaches the critical slip angle. It is concluded that the reinforcements appear to be effective with respect to the allowable stress criterion, but are not substantially effective from the point of view of ultimate capacities. In other words, structural reinforcements based on allowable stress analyses may noticeably increase production costs, but do not remarkably raise the ultimate capacities. 相似文献
8.
Artificial neural networks and their application to assessment of ultimate strength of plates with pitting corrosion 总被引：1，自引：0，他引：1
The potential for the structural capability degrading effects of both corrosion and fatigue induced cracks are of profound importance and must be both fully understood and reflected in vessel's inspection and maintenance programme. Corrosion has been studied and quantified by many researchers, however its effect on structural integrity is still subject to uncertainty, particularly with regards to localized corrosion. The present study is focused on assessing the effects of localized pitting corrosion on the ultimate strength of unstiffened plates. Over 265 non-linear finite-element analyses of panels with various locations and sizes of pitting corrosion have been carried out. The results indicate that the length, breadth and depth of pit corrosion have weakening effects on the ultimate strength of the plates while plate slenderness has only marginal effect on strength reduction. Transverse location of pit corrosion is also an important factor determining the amount of strength reduction. When corrosion spreads transversely on both edges, it has the most deteriorating effect on strength. In addition, artificial neural network (ANN) method is applied to derive a formula to predict ultimate strength reduction of locally corroded plates. It is found out that the proposed formulae can accurately predict the ultimate strength of locally corroded plates under uniaxial in-plane compression. 相似文献
9.
船舶与海洋结构在服役期间会遭受电化学和微生物侵蚀等多种腐蚀环境影响,加筋板作为此类结构的主要受力构件,其表面易产生不规则形态的点蚀,引起构件的强度退化。利用ANSYS有限元软件构建加筋腹板遭受随机点蚀损伤的加筋板有限元模型,研究带板长宽比、带板长细比、加筋长细比和腐蚀体积损失率对加筋板极限强度的影响。研究结果表明,加筋遭受同等腐蚀体积损失率下,带板长宽比变化对极限强度退化的影响很小,但带板长细比和加筋长细比变化产生的影响明显;带板长细比越大,极限强度退化越严重,而加筋长细比越大,极限强度退化反而越小。针对文中研究的加筋板,当加筋长细比为 0.2时,腐蚀体积率为14%的随机点蚀导致结构极限强度退化程度达到约14.0%。因此,加筋的随机点蚀损伤会显著削弱加筋板结构的极限强度,其影响不可忽略。 相似文献
10.
为了研究循环载荷作用下扶强材初始损伤对其极限强度的影响,进行了14组扶强材的循环加载试验和分析。构造了考虑材料累积损伤完整、断筋和大变形的扶强材单元极限承载力计算公式,提出了相应循环载荷作用下损伤扶强材单元的端缩曲线表达式和船体梁极限强度计算的简化逐步破坏法。编制了循环载荷作用下船体梁损伤极限强度计算程序,进行了船体梁极限强度计算,并与有限元结果进行对比。研究结果表明：改进的损伤扶强材模型可较为准确地描述扶强材材料损伤的完整、断筋和大变形的极限承载力退化情况,扶强材腹板断裂的损伤相较初始大变形及材料累积损伤形式承载力下降程度更明显;所提出的循环载荷作用下损伤船体梁极限强度计算的简化逐步迭代方法,能定量地计算扶强材在不同类型损伤下的极限承载力退化程度,具有较高精度,方便易行,可应用于工程设计。 相似文献
11.
The present paper is Part III of a series of three papers on the methods useful for ultimate limit state assessment of ships and ship-shaped offshore structures. It is focused on the methods for the progressive collapse analysis of hull girders under bending moments, in contrast to the previous two papers (Parts I and II), respectively, dealing with methods for the ultimate limit state assessment of unstiffened plates and stiffened panels. An AFRAMAX-class hypothetical double hull oil tanker structure designed by IACS common structural rules (CSR) method is studied as an illustrative example. The ultimate vertical bending moment capacity of the hull structure is then analyzed by ANSYS FEA, ALPS/HULL, and IACS CSR methods, and their resulting computations are compared. 相似文献
12.
A stiffened plate is one of the principal structural components of the hull. During the design phase it is useful to study this structure considering it as a system consisting of monodimensional elements. Therefore, it is appropriate to identify the plate breadth that collaborates with the stiffener in the simplified calculation.The aim of this work is to investigate the effective breadth, regarding both stiffness and strength. The analysis is performed comparing various numerical solutions supplied by a finite-element program with solutions based on the beam theory. Analytic expressions and graphs, derived from the results of the parametric investigation, are proposed to design this kind of structure. 相似文献
13.
Jeom Kee Paik Anil K. Thayamballi P. Terndrup Pedersen Young Il Park 《Ocean Engineering》2001,28(8):51
For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength characteristics of ships with large hatch openings. The primary aim of the present study is to investigate the ultimate strength characteristics of ship hulls with large hatch openings under torsion. Axial (warping) as well as shear stresses are normally developed for thin-walled beams with open cross sections subjected to torsion. A procedure for calculating these stresses is briefly described. As an illustrative example, the distribution and magnitude of warping and shear stresses for a typical container vessel hull cross section under unit torsion is calculated by the procedure. By theoretical and numerical analyses, it is shown that the influence of torsion induced warping stresses on the ultimate hull girder bending strength is small for ductile hull materials while torsion induced shear stresses will of course reduce the ship hull ultimate bending moment. 相似文献
14.
为探究轴压作用下双金属复合海底管道的组合作用与承载性能,对双金属复合海底管道进行了试验研究和理论分析。开展了不锈钢衬管材料性能试验,对比了国际主流不锈钢本构关系模型和试验结果。利用ABAQUS建立了精细化的双金属复合管道轴压试验有限元模型,系统研究了关键参数如复合工艺产生的环向复合应力、钢管初始缺陷幅值等对双金属复合管在轴压作用下力学性能的影响规律。通过对比已有轴压双金属复合管道试验结果,验证有限元模型。基于验证的有限元模型,对轴压作用下双金属复合管道的组合作用以及径厚比和材料强度对承载力的影响进行了分析。结果表明双金属复合管道的轴压极限承载力主要取决于基管的截面屈服荷载,并随着管径和材料强度的提高而增大。并依据分析结果对双金属复合海底管道的设计提出建议。 相似文献
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The main objective of the present study is to examine the residual ultimate strength characteristics of steel plates with cracking damages under axial compressive actions through experimental investigations. The present study is a sequel of the author's previous paper (Paik, J.K., Satish Kumar, Y.V., Lee, J.M., 2005. Ultimate strength of cracked plate elements under axial compression or tension. Thin-Walled Structures, 43, 237–272). In contrast to the previous paper which dealt with transverse cracks located in the direction normal to the axial loading direction, the present paper is concerned with longitudinal cracks which are located in parallel to the axial loading direction. Similar to the previous paper, the orientation/location and size of cracks inside the plates are varied for the present experimental investigations. The details of experimental results are documented. The database and insights developed from the present work will be useful for cracking damage-tolerant design of steel-plated structures and also for condition assessment or health monitoring of aging steel-plated structures. 相似文献
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针对受均匀轴向压力的矩形开孔板剩余极限强度的问题,考虑矩形板中间开圆孔和腰圆孔两种典型形状,四种边界条件下,以板的柔度系数、开孔率为主要影响参数通过大量非线性有限元数值计算分析,采用一种新的拟合方式提出了矩形开孔板轴向受压剩余极限强度的简化计算公式,新经验公式能够很好地反映开孔所导致板极限强度的衰减趋势。将所提出的经验公式计算结果分别与相应的试验结果、非线性有限元计算结果及其他经验公式计算结果进行对比分析。结果表明所提出的经验公式相比已有的经验公式计算更为准确,适用范围更广,可以用来预报不同边界条件下轴向均匀受压开孔矩形板的极限强度。 相似文献
19.
自升式钻井平台插桩是地基土在桩靴荷载作用下发生连续的塑性破坏的动态过程,当地基极限承载力等于桩靴荷载时插桩完成。经典土力学极限承载力理论对土体潜在滑动面做了假设,无法有效分析土体内部的破坏过程。本研究应用有限元法（FEM ）对插桩过程进行了模拟,得到地基土的破坏机制以及中间荷载下土体的应力、应变情况,通过和各理论公式计算的极限承载力进行对比分析,分析影响地基极限承载力的因素。研究表明,基础宽度与硬土层厚度的比值 B/H越大,下卧软土层越容易发生塑性破坏,极限承载力明显下降,当B/H＜0．286时,可以忽略下卧软土层对地基承载力的影响。 相似文献
20.
Investigation of the effects of offshore breakwater parameters on sediment accumulation 总被引：1，自引：0，他引：1
Ali Remzi Birben &#x;smail Hakk&#x;
zler Servet Karasu Murat &#x;hsan Kmürcü 《Ocean Engineering》2007,34(2):284-302
Littoral sediment transport is the main reason for coastal erosion and accretion. Therefore, various types of structures are used in shore protection and littoral sediment trapping studies. Offshore breakwaters are one of these structures. Construction of offshore breakwaters is one of the main countermeasures against beach erosion. In this paper, offshore protection process is studied on the effect of offshore breakwater parameters (length, distance and gap), wave parameters (height, period and angle) and on sediment accumulation ratio, one researched in a physical model. In addition to the experimental studies, numerical model in which the formulae of the sediment discharge (i.e. the formulae of CERC and Kamphuis), was used was developed and employed. The results of the experimental and numerical studies were compared with each other. 相似文献