共查询到20条相似文献,搜索用时 593 毫秒
1.
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
2.
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
3.
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
4.
Results of eight tests on stiffened panels under axial compression until collapse and beyond are presented. The tests consider panels with different combinations of mechanical material properties and geometric configurations for the stiffeners including the use of ‘U’-shaped stiffeners. The specimens are three bay panels with associated plate made of high tensile steel S690. Four different configurations are considered for the stiffeners that are made of mild or high tensile steel for bar stiffeners and mild steel for ‘L’ and ‘U’ stiffeners. The influence of the stiffener's geometry on the ultimate strength of the stiffened panels under compression is analyzed. 相似文献
5.
6.
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
7.
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
8.
9.
《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
10.
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
11.
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
12.
13.
14.
为研究含裂纹加筋板的极限拉伸强度,本文建立一系列不同长细比、不同裂纹长度、不同裂纹位置的含裂纹加筋板有限元模型,并基于J积分理论对其在单轴拉伸载荷下的极限强度进行了计算。结果发现含裂纹加筋板极限拉伸强度随加筋板长细比的增大略有减小,但减小的程度并不明显;含裂纹加筋板极限拉伸强度随裂纹长度的增大而减小,且减小的幅度逐渐增大;加强筋上的裂纹对含裂纹加筋板极限强度的影响小于底板上的裂纹,而裂纹同时出现在底板和加强筋上时对含裂纹加筋板极限拉伸强度的影响最大。表明含贯穿型裂纹的加筋板在单轴拉伸载荷下的剩余强度对加筋板长细比不敏感,而对裂纹长度较为敏感。 相似文献
15.
Composite materials have been widely used in modern engineering fields such as aircraft, space and marine structures due to their high strength-to-weight and stiffness-to-weight ratios. However, structural efficiency gained through the adoption of composite materials can only be guaranteed by understanding the influence of production upon as-designed performance. In particular, topologies that are challenging to production including panels stiffened with pi or tophat stiffeners dominate many engineering applications and often observe complex loading. The design of stiffened composite panels against buckling is a key point of composite structures. While a growing number of studies are related to the reliability analysis of composites few of these relate to the local analysis of more complicated structures. Furthermore for the assessment of these structures in a design environment it is important to have models that allow the rapid assessment of the reliability of these local structures. This paper explores the use of a stochastic approach to the design of stiffened composite panels for which typical applications can be found in composite ship structures. A parametric study is conducted using Navier grillage theory and First-order Reliability Methods to investigate any detectable trend in the safety index with various design parameters. Finally, recommendations are made to provide guidance on applications. 相似文献
16.
17.
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
18.
Mohammad Reza Khedmati Zorareh Hadj Mohammad Esmaeil Nouri Karim Moradidohezari 《Journal of Marine Science and Technology》2012,17(1):68-93
This paper presents the results of an investigation into the post-buckling behaviour and ultimate strength of imperfect corroded
stiffened steel plates used in ships and other marine-related structures. A series of elastic–plastic large deflection finite
element analyses is performed on stiffened steel plates suffering general corrosion wastage with random distribution. General
corrosion is introduced into the finite element models using a random thickness surface model. The effects of corroded stiffened
plate parameters on the post-buckling and ultimate strengths are evaluated in detail. The stiffeners of different symmetrical
or unsymmetrical cross-sections are introduced into the models for analysis. Some distinctions are explored and highlighted
between the behaviours of steel plates suffering general corrosion in unstiffened and stiffened cases. Finally, a proposal
is given in order to simulate the average stress–average strain relationship of stiffened steel plates having both-surface
general corrosion wastage. 相似文献
19.
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
20.
《Marine Structures》2002,15(3):251-283
A new simplified model for collapse analysis of stiffened plates is developed in the framework of the idealized structural unit method (ISUM). By idealizing material and geometrical nonlinearities, larger structural units are defined as an element in ISUM than in conventional finite element analysis (FEA). The proposed stiffened plate model consists of ISUM plate elements and beam-column elements. The formulation of the plate element is performed by introducing accurate shape functions to simulate the buckling/plastic collapse behaviour of plate panels. Combining plate and beam-column elements allows for both local buckling of the plate panel and overall buckling of the stiffener.Fundamental collapse modes of plate panels and stiffened plates are investigated by conventional FEA. According to the observed characteristics, the new simplified model is formulated. Comparisons with FEA demonstrate the accuracy of the simplified model and its high applicability to typical stiffened plates in marine structures. 相似文献