共查询到18条相似文献,搜索用时 140 毫秒
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以层合板结构的临界屈曲载荷系数最大化为优化目标,基于改进型模拟退火算法对层合板结构铺设角度和铺层顺序进行优化。由于层合板结构的铺层角度是离散变量,模拟退火算法适合求解离散变量的优化问题。利用模拟退火算法优化层合板铺层,在算法内采用并行计算、引入记忆功能同时设置双阈值终止准则,有效地提高了优化过程的收敛速度,同时避免优化过程中出现局部最优解。以临界屈曲载荷系数作为目标函数,选取复合材料层合板的铺设角度顺序为设计变量,采用改进的模拟退火算法得出复合材料层合板的最优铺设角度以及铺层顺序。 相似文献
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本文讨论了双向增强层合板在横向载荷作用下的铺层优化分析。文中首先证明了具有最高固有频率及最小挠度的最优结构必定是对称铺设结构,进一步还说明了上述优化问题可化为单设计变量优化问题,本中导出了相应的极其简单的计算公式。 相似文献
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本文给出了对称铺设的复合材料层合板的结构反应(静载下结构的柔韧性*、自振频率及屈曲载荷)对各层纤级铺设角的灵敏度,并给出了最优铺设角应满足的准则。对最优化准则的分析表明,在很一般的条件下,任一最优层合板最多只有四个不同的铺设角度。本文还对静载下矩形板的柔韧性作了大量数值计算,结果有明柔韧性是铺设角的非凸函数;最后本文建议了将数学规划法和准则法结合的一混合优化方法。用它对铺设角进行优化,数值例子说明这种方法是成功的。 相似文献
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采用广义微分求积(GDQ)法开展了不同边界条件下承受面内线性变化载荷作用复合材料层合板振动与屈曲的分析与优化。针对GDQ法求解面内线性变化载荷工况复合材料层合板屈曲问题存在计算振荡、不收敛现象,提出载荷扰动策略实现了GDQ法对复合材料层合板屈曲问题的稳定高效求解。基于基础圆频率和临界屈曲载荷系数的归一化指标,分析了铺层角度对复合材料层合板综合性能的影响,并结合直接搜索模拟退火算法开展了复合材料层合板的铺层顺序优化。结果表明:铺层角度变化对屈曲性能的影响明显强于频率特性;面内线性变化载荷中,以弯曲载荷作用下复合材料层合板的优化综合性能受边界条件变化的影响最小,而优化铺层角度受边界条件变化的影响最大。研究结果为复杂载荷作用下复合材料层合板的设计提供了参考。 相似文献
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连续丝束剪切(CTS)作为一种新的丝束变角度(VAT)铺放技术,能克服传统的自动铺丝技术(AFP)的诸多缺陷。鉴于此,分别采用CTS和AFP这2种技术铺设而成的VAF层合板为研究对象,对其屈曲性能进行了有限元分析;在施加相同端部轴向位移的条件下,以铺层顺序[90±<0|75>]4s为例,对比分析了2种层合板的内力分布;最后,讨论了丝束最小转弯半径对2种铺放技术的影响。结果表明:CTS层合板因其变厚度的特性,其屈曲性能优于AFP层合板;与AFP技术受制于最小转弯半径,导致其在小尺寸结构中的应用受到限制相比,CTS技术适用于各种尺寸的层合板。 相似文献
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在面内纯剪切载荷作用下, 采用试验与有限元模拟方法研究了结构中心设置椭圆形大开口的正方形复合材料层合板的应力/应变集中现象及屈曲、 后屈曲行为, 通过测试结果对试验件失效模式进行了评估。研究结果表明: 层合板开口附近应力/应变集中程度很高; 大尺寸开口使结构稳定性显著降低, 且开口层合板具有较好的后屈曲承载能力; 由于弯曲产生高水平的层间应力, 导致局部分层损伤并伴有基纤剪切破坏; 随着横向挠度的增加, 各应力集中区域的纤维发生拉伸断裂, 导致整体结构瞬间发生脆性失效。有限元模拟结果与试验结果符合较好。 相似文献
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A shear deformable laminated theory is used to study the optimal design of rectangular plates under biaxial compressive loads. Such loads lead to plate failure by buckling or material failure which corresponds to the violation of the selected strength criterion. The minimum of the two loads (buckling load or material failure load) determines the critical failure load for a given set of problem parameters. At the optimum values of the ply angles, buckling or both failure criteria may be operational depending on the laminate thickness. The present study investigates the effect of laminate thickness on the optimal design and gives numerical results for symmetrically laminated angle-ply plates. 相似文献
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Yu Xie Mukherjee Zhicheng Xie Anthony R. Ingraffea 《International journal for numerical methods in engineering》1991,32(6):1321-1337
The subject of this paper is the buckling of laminated plates, with a pre-existing delamination, subjected to in-plane loading. Each laminate is modelled as an orthotropic Mindlin plate. The analysis is carried out by a combination of the finite element and asymptotic expansion methods. By applying the finite element method, plates with general delamination regions can be studied. The asymptotic expansion method reduces the number of unknown variables of the eigenvalue equation to that of the equation for a single Kirchhoff plate. Numerical results for the critical buckling load are presented for several examples. The effects of the shape, size and position of the delamination on the buckling load are studied through these examples. 相似文献
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A shear deformable finite element is developed for the buckling analysis of laminated composite plates. The finite element formulation is based on Mindlin's theory in which shear correction factors are derived from the exact expressions for orthotropic materials. A variety of problems on uniaxial and shear bucklings of laminated composite plates are solved. The effects of material properties, plate aspect ratio, length-to-thickness ratio, number of layers and lamination angle on the buckling loads of symmetrically and antisymmetrically laminated composite plates are investigated. Optimal lamination arrangements of layers for maximizing the buckling loads of the plates are determined. 相似文献
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船体板材不可避免地存在不同形式的开孔,开孔破坏了结构的连续性,对结构的强度、稳定性具有重要影响,因此研究船体板开孔结构的屈曲特性对保证船舶安全十分重要。在面内载荷作用下,通过画框型剪切夹具、3D全场变形测量-分析系统等对两种不同形式的船体开孔薄板进行剪切屈曲试验,获得了圆形开孔板和方形开孔板的临界屈曲载荷、全场位移/应变信息和拉力-伸长率曲线等;考虑试验夹具的影响,基于Abaqus对不同形式的开孔板进行数值仿真,通过对开孔板进行特征值屈曲分析和非线性屈曲分析,获得了两种不同形式船用开孔薄板的屈曲、后屈曲力学响应信息。通过数值仿真与试验结果的对比研究,验证了数值仿真方法的有效性、准确性。在此基础上,重点剖析载荷-伸长率关系、典型时刻板面全场位移、临界屈曲载荷以及开孔边缘的应力分布响应特征,明确了面积等效情况下圆孔和倒圆角方孔对方形薄板剪切稳定性的影响。为船用薄板面内剪切稳定性的试验和仿真研究以及大型船体结构的设计优化、力学性能评估等提供有益参考。 相似文献
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A semi-analytical extended Kantorovich approach for the buckling analysis of symmetrically laminated rectangular plates with general boundary conditions is presented. The solution is derived as a multi-function expansion that allows the analysis of laminated plates characterized by a non-separable solution. Among these, the cases of buckling of angle-ply laminates under inplane compression and shear buckling of any type of plate are the most common ones. The formulation is based on the variational principal of total energy minimization and the iterative extended Kantorovich method. The exact element method is adopted for the solution of the resulting differential eigenvalue problem. The capabilities of the proposed approach and its applicability to buckling analysis of composite laminated plates that cannot be analyzed using the classical single-term extended Kantorovich method are demonstrated numerically. The results are compared with exact solutions (where available), and with approximate results from other numerical methods. The accuracy and convergence of the proposed approach are also discussed. 相似文献
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Study of interaction curves for composite laminate subjected to in-plane uniaxial and shear loadings
In this study an attempt has been made to incorporate the effect of transverse shear on the stability of moderately thick/very thick composite laminated plates under in-plane compressive and shear loading using a Simple Higher Order Shear Deformation Theory based on four unknown displacement functions (u0,v0,wb,ws) instead of five which is commonly used in most of the higher order theories. The finite element method is employed to study the initial buckling load of laminated plates. The change in initial buckling response of thick rectangular antisymmetric laminates with respect to the fibre orientation angle has been studied. The interaction curves (between Nx and Nxy for different parameters of the laminates) are studied in detail. 相似文献
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研究了复合材料加筋板翼面结构稳定性问题,分析了加筋板在压缩和剪切等载荷作用下的稳定性安全裕度。利用计算复合材料加筋板屈曲及后屈曲承载能力的方法,验证复杂受载情况下结构的稳定性。验证对象是一个优化后的满足强度、刚度和工艺制造要求的复合材料机翼。该机翼在各种载荷工况下的内力分布情况由MSC.NASTRAN分析得到,通过本文提出的方法得到每块蒙皮的稳定性承载能力。然后给出复合材料层合板在复杂载荷下的屈曲及后屈曲安全裕度的计算准则,验证优化后的机翼加筋板是否满足稳定性设计要求。该方法可作为约束集成到结构优化系统平台中。 相似文献