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夹芯圆柱壳稳定性优化 总被引:5,自引:0,他引:5
研究了在轴压载荷作用下圆柱壳结构的失稳模态和结构承载效率,分析了空心圆柱壳厚度对失稳模态和承载效率的影响,以及圆柱壳填充轻质芯体对提高承载效率的作用;研究了圆柱壳结构的基于参数化建模、稳定性分析以及承载效率优化设计的一体化方法,并基于商用软件PATRAN的PCL语言予以实现。针对特定夹芯圆柱壳结构的稳定性分析和优化表明,空心薄壁圆柱壳结构在轴压载荷作用下容易失稳,结构承载效率低。适当增加壳体厚度,不但提高抗屈曲能力,而且也提高了结构承载效率。但厚度增加到一定限度后,进一步增加壳体厚度会提高结构的失稳荷载,但承载效率下降。利用泡沫状材料填充薄壁圆柱壳结构可以提高圆柱壳的结构抗屈曲承载能力和承载效率。通过优化壳体壁厚和芯体材料的相对密度,可有效地提高结构的承载能力和承载效率。 相似文献
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对完整复合材料圆柱壳轴向压缩性能进行了试验研究,得到了圆柱壳结构的破坏载荷和各测量点的载荷-应变曲线,通过分析得出结构的破坏形式为屈曲破坏。利用ANSYS有限元软件建立了模型,对复合材料圆柱壳进行屈曲分析,将有限元计算的结构变形和屈曲载荷与试验结果进行对比,计算结果与试验结果一致,验证了模型的有效性。利用建立的有限元模型,分析了开口尺寸和铺层角度对含矩形开口的复合材料圆柱壳屈曲载荷的影响。在开口处加装复合材料口盖对结构进行补强,补强后的柱壳结构满足强度设计要求。 相似文献
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为提高双层圆柱壳结构在水下爆炸载荷作用下的抗冲击性能,基于双层圆柱壳结构的特殊性,提出适用于双层圆柱壳的圆管型舷间加筋结构,即采用圆管来代替传统的T型加筋。首先开展带圆管型和T型加筋的双层圆柱壳远场水下爆炸试验,同时运用数值仿真方法分析圆管型加筋的抗冲击性能,试验和数值仿真结果吻合良好。结果表明:相对于T型加筋,圆管型加筋在水下爆炸作用下表现出不同的变形模式,即圆管的逐渐扁化;带圆管型加筋的双层圆柱壳结构加速度冲击响应峰值降幅达到40 %以上;圆管型加筋能够通过自身的变形在水下爆炸过程中吸收更多冲击能,同时使轻外壳和耐压壳的内能有所降低。因此,圆管型加筋比传统T型加筋具有更优的缓冲效果,可用于双层圆柱壳结构的缓冲和防护设计。 相似文献
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以加筋圆柱壳模型为分析对象,应用MSC—DYTRAN非线性瞬态有限元分析软件建立水下爆炸载荷作用下流固耦合数值分析模型,对冲击因子为1.1的典型试验工况进行数值模拟,分析了加筋圆柱壳在爆炸载荷作用下的破坏机理,并将数值计算结果与试验结果进行对比,验证了数值模拟方法的正确性和有效性,进一步通过大量数值试验,分析了爆炸攻角、模型浸深对加筋圆柱壳弹塑性响应的影响,最后对气泡脉动载荷的二次毁伤效应进行了探讨。数值结果表明:同等当量炸药在相同爆距、相同浸深下,90°攻角总是最危险的爆炸角度,0°攻角与其他攻角相比,毁伤效果总是最小;模型浸深对结构的响应影响显著,模型浸深愈深,毁伤程度愈严重;当考虑气泡脉动载荷后,对于结构具有二次破坏作用,在相同药量相同爆距下、不同浸深下的二次破坏效果并不相同,呈现出浸深愈大,二次破坏效果愈显著的现象。 相似文献
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无序非周期结构振动在通频带会产生局域化效应。基于该思想,对质量无序配置加筋圆柱壳开展了振动局域化研究。为定量预报无序配置加筋圆柱壳的局域化因子,将加筋圆柱壳振动等效为耦合振子链的振动,利用耦合振子链的无序局域化因子公式预报质量无序配置加筋圆柱壳的局域化因子。以加筋圆柱壳有限元分析的振动结果为输入,使用结合波数分析的参数辨识技术给出了等效振子固有频率参数和耦合参数。等效无序度参数使用了参考模型辨识的技术。针对两个质量无序配置加筋圆柱壳开展的振动局域化分析结果表明,质量配置无序度参数是影响局域化因子的重要参数,它与质量配置参数相关;当无序质量配置的平均值超过结构重量的15%时,可以观察到较为显著的振动局域化效果。 相似文献
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本文分析了筋和壳的儿何参数及壳的铺层对纵向或环向密加筋的复合材料层合圆柱壳在轴压和侧压下的稳定性和初始后屈曲性能的影响。初始后屈曲分析基于Koiter理论。对几种不同几何参数、壳体铺层和载荷情况的加筋壳的计算表明:在所有情况下,外加筋比内加筋更有效地提高了屈曲载荷;复合材料壳的加筋效率一般都高于各向同性材料加筋壳;壳体的铺层对屈曲和初始后屈曲性能有很大影响。 相似文献
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为研究全频段加筋圆柱壳声辐射特性,基于VA-ONE建立FE-BEM混合法、FE-SEA混合法及SEA法低中高全频段的计算模型,并进行加筋圆柱壳辐射声功率的计算,从结构固有模态角度研究了各阶模态的声辐射效率。结果表明,加筋能够减小圆柱壳结构的总体辐射声功率,尤其可以减小低频段的辐射声功率;在中低频区,各阶模态的模态辐射效率具有较大差异,在中高频区,则相差不大。进一步研究了激励位置、壳厚、材质及辐射介质对加筋圆柱壳声辐射特性的影响。为减小加筋圆柱壳对外场点的辐射声功率,基于NCT模块及Design Optimization模块进行声学优化设计,结果表明,将GA算法与SQP算法或MMA算法组合使用不仅可以减少运算时间,而且可以获得较好的优化方案。 相似文献
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采用高分子高弹性材料Mylar薄膜制作衬壳,其外侧的刚性限制为钢制圆柱筒壳,两端用加强环压紧以模拟边界条件。用气压加载模拟圆柱壳受周向均匀压力,观察衬壳的屈曲过程,同时测量衬壳的临界载荷。实验测量结果与有限元计算的结果符合较好。另外还通过人为制造不同初始缺陷和变换不同壳体长度,研究了限制失稳临界载荷与初始缺陷及不同长度的关系。结果表明圆柱薄衬壳受侧向外压的限制失稳临界载荷比自由失稳临界载荷有很大提高。 相似文献
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A thermal buckling analysis is presented for laminated cylindrical shells with surface mounted piezoelectric actuators under combined action of thermal and electrical loads. Derivations of the equations are based on the classical laminated shell theory, using the Sanders nonlinear kinematic relations. The analysis uses the Galerkin method to obtain closed form solutions for the buckling loads of shallow and nonshallow piezolaminated cylindrical shells. Temperature dependency of material properties is taken into account. Illustrative examples are presented to verify the accuracy of the proposed formulation. The effects of the various design parameters on thermal buckling loads are investigated. 相似文献
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Buckling is usually initiated from a local region near the cutout for cylindrical stiffened shells under axial compression, and then the evolution of buckling waves is governed by the combined effects of local and global stiffness, which limit the load-carrying capacity. Therefore, a simultaneous buckling pattern is crucial for improving the structural efficiency. In this study, a multi-step optimization strategy for the integrated design of near and far fields away from cutouts is proposed, and the convergence criterion of buckling optimization is improved as a deformation-based index. The numerical implementation of the asymptotic homogenization method is utilized to construct an efficient finite element model for post-buckling analysis. A 5?m diameter stiffened shell in a launch vehicle demonstrates that the proposed framework can provide a simultaneous buckling design with high structural efficiency in an efficient manner. Both the buckling deformations and stress of the optimum design are more uniform compared to other optimum designs. 相似文献
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The problem of optimal design for elastic buckling loads of composite plates under uncertain loading conditions is considered. It is observed that this is a multicriterion optimization problem whose solution is time consuming. Thus, an alternative minimax formulation is proposed and demonstrated. The buckling load is maximized with respect to the structural parameters and minimized with respect to variations in the load parameters. The mechanical loads applied to the rectangular plates are a combination of normal compression and shear. Moreover, the admissible loading configurations belong to a convex hull which significantly enhances the optimization procedure. The consideration of an uncertainty degree in the mechanical loads leads to optimal designs which are inherently insensitive to perturbations and/or randomness in the applied loads. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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This paper describes an optimum structural design of a CFRP isogrid cylindrical shell using a genetic algorithm (GA). When the CFRP isogrid cylindrical shell receives a prescribed uniaxial compressive load, an objective is to minimize weight of the CFRP isogrid cylindrical shell subjected to the constraint conditions of no buckling and no material failure. The buckling and material failure loads were approximated by a response surface method combined with partitioning of design spaces and these approximated values were used in the process of GA instead of FEM calculations in order to reduce the computational time. Furthermore, the differences from the constraint conditions of the linear or the non-linear (local) buckling loads were also calculated and their results were compared with each other. 相似文献
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针对船用复合材料螺旋桨叶片,分别采用壳单元赋予不同截面参数和实体单元赋予不同等效材料参数两种建模方法进行了有限元分析,对比了壳单元和实体单元模型的模态、均布压力载荷下的响应以及均匀温度场中的热变形。结果表明:对于从桨根到桨尖各位置铺层不同的叶片来说,两种建模方法在建模时间和铺层调整便捷性方面各有利弊;模态分析中两种模型的固有频率和振型计算结果存在一定差异,它们均可在一定条件下用于复合材料螺旋桨叶片模态计算;两种模型中,模拟均布压力载荷下的响应时应采用壳单元模型,而分析叶片在均匀温度场中结构的热变形应采用实体单元模型。 相似文献
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This paper presents experimental studies on buckling of cylindrical shell models under axial and transverse shear loads. Tests
are carried out using an experimental facility specially designed, fabricated and installed, with provision forin-situ measurement of the initial geometric imperfections. The shell models are made by rolling and seam welding process and hence
are expected to have imperfections more or less of a kind similar to that of real shell structures. The present work thus
differs from most of the earlier investigations. The measured maximum imperfections δmax are of the order of ±3t (t = thickness). The buckling loads obtained experimentally are compared with the numerical buckling values obtained through
finite element method (FEM). In the case of axial buckling, the imperfect geometry is obtained in four ways and in the case
of transverse shear buckling, the FE modelling of imperfect geometry is done in two ways. The initial geometric imperfections
affect the load carrying capacity. The load reduction is considerable in the case of axial compression and is marginal in
the case of transverse shear buckling. Comparisons between experimental buckling loads under axial compression, reveal that
the extent of imperfection, rather than its maximum value, in a specimen influences the failure load. Buckling tests under
transverse shear are conducted with and without axial constraints. While differences in experimental loads are seen to exist
between the two conditions, the numerical values are almost equal. The buckling modes are different, and the experimentally
observed and numerically predicted values are in complete disagreement. 相似文献