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《船舶与海洋工程学报》2013,(2)
A geometrically similar scaling was made from small-scale specimen to full-scale stiffened panels and then their collapse behaviour is investigated. It is considered that the stiffened panel compressive ultimate strength test was designed according to geometrical scaling laws so that the output of the test could be used as representative of the stiffened panels of the compressive zone of a tanker hull subjected to vertical bending moment. The ultimate strength of a tanker hull is analysed by a FE analysis using the experimentally developed master stress-strain curves which are obtained by the beam tension test and the compressive test of the stiffened panel, and are then compared with the result achieved by the progressive collapse method. 相似文献
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Five specimens of wide stiffened panel with four stiffeners under axial compression until collapse are studied with a nonlinear finite element analysis and Common Structural Rules to compare with the experimental results. The stiffened panel models have two longitudinal bays to produce reasonable boundary condition at the end of edges. Tension tests have been conducted to obtain the material properties of the steel that are used in the finite element analysis. Three boundary condition configurations are adopted to investigate their influence on the collapse behaviour of the stiffened panels. A displacement transducer was used to measure the initial geometrical imperfections of the stiffened plates. The collapse behaviour of the stiffened panels is analysed in finite element analysis with the measured initial imperfections and with nominal imperfections. An equivalent initial imperfection is validated for the ultimate strength of stiffened panel under compressive load until collapse for the panels under consideration. With the same imperfection amplitude, the shape of the column-type initial deflection of stiffeners affects significantly the collapse shape, but only slightly the ultimate strength and the mode of collapse of the stiffened panels. The 1/2 + 1 + 1/2 bays model with restrained boundary condition BC3 gives an adequate FE modelling and is possible to be fabricated in experiment. 相似文献
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船体梁的总纵强度是反映船舶结构安全可靠的最基本的强度指标。船体结构极限强度评估对于船舶结构初步设计、使用、维护和维修都非常重要,因此船体梁极限强度研究成为近几十年来船舶工程界的热点研究课题之一。到目前为止有两种典型的加筋板和船体梁的极限强度分析方法,它们是直接计算法和逐步破坏分析法。本文基于加筋板单元的平均应力应变曲线和逐步破坏分拆方法,提出了加筋板和船体梁极限强度的简化分析方法,考虑了初始挠度和残余应力对加筋板单元极限强度的影响。数值结果表明,采用本文简化方法得到的结果与有限元计算结果或其它逐步破坏分析结果比较符合。 相似文献
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在老龄化引起的船舶结构安全性问题中,裂纹损伤是结构强度衰减的一个重要因素。文章采用逐步加载法对含裂纹损伤的加筋板压缩剩余极限强度进行试验研究。设计六种典型的穿透裂纹损伤加筋板,对损伤试件进行轴向压缩试验。通过改变裂纹尺寸、位置及倾角参数并根据试验观测结果,探讨了不同裂纹参数下加筋板的屈曲破坏特点和对剩余极限强度影响。试验结果表明,不同的裂纹长度以及裂纹位置改变加筋板结构承载力的分布,影响结构应力应变场,进而改变其失效崩溃模式;倾角为45°的裂纹相对于垂直于加筋的裂纹对加筋板结构的剩余极限强度影响较小,此外初始缺陷对结构的剩余极限强度的影响也不容忽视。 相似文献
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A series of finite element analyses are conducted to investigate the influence of boundary conditions and geometry of the model on the predicted collapse behaviour of stiffened panels. Periodic and symmetric boundary conditions in the longitudinal direction are used to calculate the ultimate strength of stiffened panels under combined biaxial thrust and lateral pressure. The calculated ultimate strength of stiffened panels are compared with those by different FEM (finite element method) code and are assessed. The periodic boundary condition in the longitudinal direction for two spans or bays model provides an appropriate modelling to a continuous stiffened panel and can consider both odd and even number of half waves and thus, is considered to introduce the smaller model uncertainty for the analysis of a continuous stiffened panel. 相似文献
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The hull girder moment capacity of a very large crude oil carrier (VLCC) called Energy Concentration (EC), for which many benchmark studies have been carried out using the simple progressive collapse method (SPCM), is predicted. In this study, three approaches are used to represent the load-shortening behavior, so-called average compressive strength, of a stiffened panel, comprising the hull section: 1) kinematic displacement theory (KDT); 2) nonlinear finite element analysis (FEA); and 3) simple formulas in the common structural rule (CSR) for tankers. Load-shortening curves for various kinds of stiffened panels in EC are compared for five different scenarios with variations of load-shortening approaches and initial imperfections. In order to verify the effect of load-shortening on the prediction accuracy of the hull girder moment-carrying capacity, load-shortening curves are imported into an SPCM-based in-house program called Ultimate Moment Analysis of Damaged Ships (UMADS). Comparison of the hull girder ultimate strength for general heeling conditions, including hogging and sagging conditions, reveals that the load-shortening curves significantly affect the hull girder moment-carrying capacities. Based on our comparison of these capacities with other benchmark results, it is concluded that nonlinear FEA provided the most conservative results, KDT provided the second most conservative results, and the CSR formulas predicted the upper bound. 相似文献
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A series of collapse analyses is performed applying nonlinear FEM on stiffened panels subjected to longitudinal thrust. MSC.Marc is used. Numbers, types and sizes of stiffeners are varied and so slenderness ratio as well as aspect ratio of local panels partitioned by stiffeners keeping the spacing between adjacent longitudinal stiffeners the same. Initial deflection of a thin-horse mode is imposed on local panels and that of flexural buckling and tripping modes on stiffeners to represent actual initial deflection in stiffened panels in ship structures. On the basis of the calculated results, buckling/plastic collapse behaviour of stiffened panels under longitudinal thrust is investigated. The calculated ultimate strength are compared with those obtained by applying several existing methods such as CSR for bulk carriers and PULS. Simple formulas for stiffened panels, of which collapse is dominated fundamentally by the collapse of local panels between longitudinal stiffeners, are also examined if they accurately estimate the ultimate strength. Through comparison of the estimated results with the FEM results, it has been concluded that PULS and modified FYH formulas fundamentally give good estimation of the ultimate strength of stiffened panels under longitudinal thrust. 相似文献
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文章给出了基于弹性大挠度理论和刚塑性分析的加筋板格高级屈曲分析方法(EPM),该方法包括五种失效模式,即正交加筋板格整体屈曲、纵向加筋子板格整体屈曲、纵向加筋和带板的局部屈曲或屈服、纵向加筋的侧倾以及全部屈服,可以考虑初始挠度和残余应力的影响以及双向压缩和侧向载荷的联合作用。以EPM方法为核心开发了加筋板格高级屈曲分析软件系统,包括任务管理、数据输入、屈曲分析、结果查看、能力曲线和文件分析等六个模块。为验证EPM方法的精度进行了系列纵向加筋和正交加筋板格试验模型的比较计算,并计算了四种典型加筋板格的双向应力能力曲线,与板格极限状态分析(PULS)软件和协调共同结构规范(HCSR)方法进行了比较分析。结果表明EPM方法可以分析联合载荷等因素对加筋板格极限强度的影响,文中开发的软件系统可用于加筋板格高级屈曲分析。 相似文献
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This paper is the first of two companion papers concerning the ultimate hull girder strength of container ships subjected to combined hogging moment and bottom local loads. In the midship part of container ships, upward bottom local loads are usually larger than the downward ones. This leads to the increase of biaxial compression in the outer bottom plating and the reduction of the ultimate hull girder strength in the hogging condition. In this Part 1, the collapse behavior and ultimate strength of container ships under combined hogging moment and bottom local loads are analyzed using nonlinear finite element method. Buckling collapse behavior of bottom stiffened panels during the progressive collapse of a hull girder is closely investigated. It has been found that major factors of the reduction of ultimate hogging strength due to bottom local loads are (1) the increase of the longitudinal compression in the outer bottom and (2) the reduction of the effectiveness of the inner bottom, which is on the tension side of local bending of the double bottom. The obtained results will be utilized in the Part 2 paper to develop a simplified method of progressive collapse analysis of container ships under combined hogging moment and bottom local loads. 相似文献
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研究铝合金加筋板结构的极限强度,有利于充分发挥铝合金材料的强度潜力和结构的后屈曲承载能力。本文将广义切线模量理论应用于铝合金加筋板结构的轴压极限强度计算,并推导了适用于加筋板的协调参数、极限弯矩系数及结构系数等相关参数的解析算式,建立了铝合金加筋板结构的强度利用率函数,从而得到结构的极限强度,进一步完善了广义切线模量理论在加筋板结构极限强度研究领域的应用。通过将广义切线模量法计算结果与经验公式、有限元计算结果进行比较,验证了其适用性与可靠性,可用于工程分析计算。 相似文献
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The present study aims at applying structural reliability methods to assess the implicit safety levels of the buckling strength requirements for longitudinal stiffened panels implemented in the IACS Common Structural Rules (CSR) for double hull oil tankers. The buckling strength requirements considered are used in the initial stage of the hull girder scantlings’ design to control the buckling capacity of longitudinal stiffened panels subjected to the compressive loads induced by the hull girder vertical bending. The following buckling collapse failure modes are explicitly considered in the design formulation: uniaxial buckling of the plating between stiffeners, column buckling of stiffeners with attached plating and lateral-torsional buckling or tripping of stiffeners.The paper presents the procedure used to assess the implicit safety levels of the strength requirements for the three buckling collapse failure modes above mentioned, which includes the optimization of the scantlings of the plate panels and longitudinal stiffeners in order to reflect the minimum strength required by the formulation. A first order reliability formulation is adopted, and stochastic models proposed in the literature are used to quantify the uncertainty in the relevant design variables. A sample of five oil tankers representative of the range of application of the IACS-CSR design rules is considered. The effect of corrosion in the implicit safety levels is quantified based on the three corrosion levels of the Net Thickness Approach (NTA) adopted in the design rules. Sensitivity analyses are also performed to quantify the relative contribution or importance of each design random variable to the implicit safety levels. 相似文献
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Buckling and ultimate capability of plates and stiffened panels in axial compression 总被引:1,自引:0,他引:1
This paper presents extensive non-linear finite element (FE) analysis and formulation development work carried out on the ultimate compressive strength of plates and stiffened panels of ship structures. A review of contemporary designs for large ships was carried out. The existing formulae for plate ultimate compressive strength were reviewed and compared with non-linear FE analysis results. A semi-analytical formula for ultimate compressive strength assessments of stiffened panels was proposed and is described. The developed formula was verified against results using ABAQUS non-linear FE software for a series of 61 stiffened panels and a good agreement between the proposed formula and FE results were achieved. The method was verified against a large number of published FE results and was also compared with 58 experimental results. The developed method was also applied to the deck and bottom structures for a range of various sizes oil tankers and bulk carriers. 相似文献
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Five specimens are tested under axial compression until collapse to investigate the ultimate strength of wide stiffened panels with four stiffeners. To avoid the side bays collapse and reduce the influence of the clamped boundary condition on the collapse behaviour, the tests are made on panels with two half bays plus one full bay in the longitudinal direction with simply supported condition at the end edge of loading. Initial loading cycles are used to release the residual stresses of the stiffened panels and the gap between the stiffened panels and the supported steel block. Strain gauges are installed on the plates and the stiffeners to record the distribution of strain. This series of experiments is compared to a series of tests with narrow panels (two stiffeners), which allows analysing the effect of the width on the strength of stiffened panels. 相似文献
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The continued development of large high speed ships, often constructed from aluminium alloy, has raised important issues regarding the response of lightweight hull girders under primary hull girder bending. In particular, the response of lightly framed panels in compression may be influenced by overall panel buckling over several frame spaces. Therefore, to provide improved ultimate strength prediction for lightweight vessels, an extended progressive collapse methodology is proposed. The method has capabilities to predict the strength of a lightweight aluminium midship section including compartment level buckling modes. Nonlinear finite element analysis is used to validate the extended progressive collapse methodology. 相似文献
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用Fortran编写程序生成Patran的.ses文件,可将任意指定的初始挠度施加到要计算分析极限强度的光板和加筋板结构模型中去.具体分析6块光板和4块加筋板结构的极限强度,计算结果表明,该方法可以模拟任意复杂的变形形式,从而更加准确地计算和评估加筋板结构的极限强度. 相似文献