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《舰船科学技术》2021,43(13)
加筋板单元的载荷-端缩曲线是影响Smith法计算精度的重要因素,而目前HCSR规定的载荷-端缩曲线尚未考虑侧向载荷的作用。为了计入侧向载荷对加筋板单元载荷-端缩曲线的影响,拓宽Smith法的适用范围,采用非线性有限元法,计算192个具有梁柱屈曲破坏模式的T型加筋板单元,在纵向压缩载荷和侧向载荷作用下的极限强度。通过回归分析,得出在侧向载荷和纵向压缩载荷联合作用下,T型加筋板单元在梁柱屈曲模式下的载荷-端缩曲线修正公式。对8个T型加筋板模型分别采用修正公式和非线性有限元法计算结构的临界应力和临界应变,2种计算方法结果相对误差小于10%,验证了修正公式的有效性。 相似文献
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船体是一个由加筋板格组成的箱形结构,加筋板格的强度计算对于船体结构的强度分析极为重要。最近几年计多作者提出了采用简化方法来计算加筋板格的极限强度。但是,绝大部分采用这种方法进行研究的文章均只讨论了纵向受压一种情况。对于实际的船体加筋板格来说,最一般的载荷工况是纵向应力、横向应力、剪应力和垂向压力的组合载荷,但纵向应力占主导地位,本文将简化方法推广到解决组合载荷的情况。通过本文的计算表明,本简化方法 相似文献
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《舰船科学技术》2017,(9)
舰船长期服役,甲板结构易产生初始挠度变形,这会对甲板承载能力带来不利影响。加筋板作为船体甲板结构的主要构成单元,研究初始挠度变形对其极限承载力的影响具有重要意义。为了确定初始挠度变形对加筋板极限承载力的影响作用,根据实际情况假设初始挠度为双三角级数形式,利用Ansys计算分析了整体初始挠度的幅值与半波数对极限载荷的影响和典型位置的应力特性,并得到初始挠度对加筋板极限载荷的影响因子计算方法。计算结果分析表明,随着初始挠度的幅值和半波数的增加,加筋板极限承载力逐渐减小;对于含有某种初始挠度的加筋板,其影响因子主要受加筋板的长宽比、厚度和加强筋间距等因素的影响。 相似文献
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舰船长期服役,甲板结构易产生初始挠度变形,这会对甲板承载能力带来不利影响.加筋板作为船体甲板结构的主要构成单元,研究初始挠度变形对其极限承载力的影响具有重要意义.为了确定初始挠度变形对加筋板极限承载力的影响作用,根据实际情况假设初始挠度为双三角级数形式,利用Ansys计算分析了整体初始挠度的幅值与半波数对极限载荷的影响和典型位置的应力特性,并得到初始挠度对加筋板极限载荷的影响因子计算方法.计算结果分析表明,随着初始挠度的幅值和半波数的增加,加筋板极限承载力逐渐减小;对于含有某种初始挠度的加筋板,其影响因子主要受加筋板的长宽比、厚度和加强筋间距等因素的影响. 相似文献
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金属夹层板以优异的力学性能已应用于实船。本文根据与加筋板重量相当原则,设计一种金属折叠式夹层板结构,考虑其应用于舰船甲板的受力特性,采用非线性有限元方法,研究夹层板结构在不同组合载荷作用下的非线性后屈曲极限强度。首先通过与经验公式及相关结果对比验证了本文数值仿真方法和技术的可行性和准确性;然后建立双向面内受压和垂向载荷作用下的金属折叠式夹层板结构数值模型,基于屈曲特征值确定屈曲极限强度分析的初始缺陷;考虑结构初始缺陷,计算得到夹层板结构的后屈曲极限强度;对金属折叠式夹层板在不同组合载荷作用下的横向、纵向后屈曲极限承载能力进行计算分析;并与传统加筋结构对比,结果显示本文设计的金属折叠式夹层板结构具有更优异的稳定性和极限承载力,结果对金属夹层板的应用与强度设计提供参考。 相似文献
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无筋板格是波浪中航行船舶的基本结构单元,精确评估无筋板格极限强度对保证船舶结构安全性具有重要意义.本文基于弹性大挠度理论分析和刚塑性分析,给出了复杂应力状态下无筋板格极限强度计算方法;定性的研究了各参数对无筋板格极限强度的影响;比较了剪应力与其它应力作用的合成分析方法和分离分析方法,验证了分离分析方法的可行性和高效性;开展了本文方法与经验公式及ABS规范公式的比较研究. 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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目前,对加筋板稳定性的研究多采用有限元法,缺乏理论指导。本文忽略材料非线性的影响,利用理论方法求解四边简支加筋板的整体屈曲临界应力。对有单根加强筋的加筋板,首先假设板的挠曲函数,接着将其代入板和加强筋的边界方程和协调方程,最后解线性方程组的特征方程得到加筋板的临界应力计算公式。为了验证该公式正确与否,选取多个算例,利用有限元软件Abaqus和Nastran进行数值仿真,与理论解比较后得出本文推导的公式是正确的,并得出临界应力随γ和δ的变化趋势。 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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《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
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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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复合材料加筋板复杂的破坏过程与失效形式增加了应用难度。以面外均布载荷与面内压缩联合作用下的夹芯复合材料帽型加筋板为研究对象,在通过试验结果验证非线性有限元方法准确性的基础上,基于复合材料的hashin准则与胶层界面的最大应力准则展开渐进破坏分析,讨论了极限载荷、破坏模式及失效机理。采用有限元子模型技术对中段破坏区域建模,基于Shokrieh-Hashin准则进行局部破坏分析,讨论蒙皮的铺层损伤规律。结果表明:加筋板呈整体一阶屈曲破坏,极限载荷为316.8 kN;壁板下蒙皮的纤维压缩失效是导致加筋板整体破坏的原因;各铺层的面内失效规律基本相同,蒙皮的纤维压缩失效从外层逐渐向内层扩展,且扩展速率逐渐降低。 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