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复合材料故障诊断问题日益受到人们的重视。利用振动理论和实验技术进行故障诊断是一种很有吸引力和值得探索的方法。本文提出了一种复合材料层合板损伤的频响一能量诊断新方法,此方法选取对故障比较敏感,又能反映结构动力特性的频响函数作为诊断故障的参数,并引入阻尼耗散能计算本文定义的无损板在各阶模态下广义模态能量的分布,通过理论推导和计算得到了损伤前后频响函数在各阶共振峰处的变化,与无损板在给定模态下各单位的模态能量贡献之间的联系。从而得到一种分析小损伤位置和范围的新方法。此方法的一个重要结论是:在小损伤的前提下,对于同一单元或同一区域各阶广义模态能量贡献之间的比值,同假设这一单元或区域有损伤而得到的各阶频响函数在无损板峰值处的变化率之比基本相等。文中提供了能量贡献分布图等,可供分析之用。算例与实验的结果表明,本文提供的方法是有效,可行的。 相似文献
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复合材料故障诊断问题日益受到人们的重视。利用振动理论和实验技术进行故障诊断是一种很有吸引力和值得探索的方法。本文提出了一种复合材料层合板损伤的频响一能量诊断新方法,此方法选取对故障比较敏感,又能反映结构动力特性的频响函数作为诊断故障的参数,并引入阻尼耗散能计算本文定义的无损板在各阶模态下广义模态能量的分布,通过理论推导和计算得到了损伤前后频响函数在各阶共振峰处的变化,与无损板在给定模态下各单位的模态能量贡献之间的联系。从而得到一种分析小损伤位置和范围的新方法。此方法的一个重要结论是:在小损伤的前提下,对于同一单元或同一区域各阶广义模态能量贡献之间的比值,同假设这一单元或区域有损伤而得到的各阶频响函数在无损板峰值处的变化率之比基本相等。文中提供了能量贡献分布图等,可供分析之用。算例与实验的结果表明,本文提供的方法是有效,可行的。 相似文献
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提出了二阶子结构能量法以检测点阵结构损伤,称为SOSEM (second order substructure energy method)。对于复杂点阵板,在已知损伤位置条件下,该方法只需结构中存在“缺陷”构件的模态信息,就可以准确地得到构件损伤程度,而传统基于模态分析的方法必需整体结构完全的模态信息,新方法提高了检测效率,对实现快速(实时)点阵结构损伤检测具有重要的应用价值。为了验证本文方法的有效性,以点阵板为例,采用数值方法分析了几种典型损伤情况,结果表明,该方法能够准确地检测出点阵结构中一个或多个单元的损伤。 相似文献
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模态应变能在基于振动的结构损伤识别中得到了广泛的应用,其灵敏度分析成为了当前的一个重要问题。采用代数方法解析推导出了无阻尼线性系统单元模态应变能一阶和二阶灵敏度的解析表达式,该表达式简洁紧凑,便于编程,而且只需一阶模态信息,不存在模态截断引起的误差问题。通过数值模拟算例,对得到的单元模态应变能一阶灵敏度进行了参数分析,并着重考查了损伤及其噪声的影响。结果表明,低阶单元模态应变能比高阶模态能更好地反映出结构损伤,而且抗噪能力更好。 相似文献
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基于应变模态对损伤敏感、轨道板应变数据易于测量的特点,提出基于应变模态的无砟轨道轨道板裂缝与脱空识别方法。研究了轨道板的应变模态理论和应变模态分析方法。用数值仿真方法分析了损伤轨道板的应变模态特征,表明一阶应变模态振型在轨道板损伤区域有明显的弯曲,可作为损伤识别参数。提出了损伤识别的应变模态曲率差指标及其计算方法,研究了其对轨道板裂缝与脱空的识别能力和识别方法。应变模态曲率差对轨道板的开裂和脱空有很强的表征能力,应变模态曲率差矩阵的F范数可表征轨道板的开裂程度。 相似文献
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The present work focuses on vibration characteristics of damaged laminated composite plates. Damage is considered as a local reduction of anisotropic plate stiffness, and three damage factors (representing the damage severity, damage anisotropy, and damage location/area, respectively) are defined to describe damage status in the laminated composite plates. The analytical solutions are obtained by the perturbation method. A numerical analysis is conducted on the vibration of damaged laminated composited plates, and the effect of damage factors on the vibration characteristics is discussed. Results indicate that three damage factors have different influences on the vibration characteristics. Also, the modal curvatures and strain energy show higher damage sensitivity than the natural frequencies and displacement mode shapes. The perturbation-based vibration analysis developed in this study can be used to effectively evaluate the effect of damage on the vibration behavior of anisotropic plates and potentially identify the damage in the laminated plates. 相似文献
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The thermal postbuckling behavior of composite laminated plates subjected to a nonuniform temperature field is investigated by the finite element method. Based on the principle of minimum potential energy, the nonlinear stiffness matrix and geometry matrix are derived. The assumed displacement state over the middle surface of the plate element is expressed as a product of one-dimensional, first-order Hermitian polynomials. An iterative method is employed to determine the thermal postbuckling load. The results of the computations reveal that the thermal postbuckling behavior of composite laminated plates is influenced by lamination angle, plate aspect ratio, modulus ratio and the number of layers. 相似文献
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考虑芯层横向变形的粘弹性复合材料夹层板结构的声振特性分析 总被引:1,自引:0,他引:1
夹层板结构具有很高的比强度和比刚度。若芯层采用粘弹性阻尼材料,夹层板结构还具有良好的隔振和隔声特性,因此在工程结构中得到广泛应用。以往的夹层板理论大多忽略了芯层的横向正应变和横向正应力,在分析芯层较厚的夹层板或者夹层结构的高频振动问题时由于不能体现芯层的横向压缩变形,往往显得不够合理。针对这一不足,构造了一个复合材料夹层板单元:夹层板的上下面板采用基于一阶剪切变形理论的Mindlin假定以及层合板理论进行分析;采用文献[6,7]中提出的Timoshenko层合厚梁理论构造了单元每边的转角和剪应变场,消除了Mindlin板单元当板厚变小时的剪切锁死问题;假定芯层的位移沿厚度方向线性变化,并用上下面板的自由度表示,最终形成以上下面板自由度表示的系统总的运动方程。该单元不仅考虑了芯层的横向剪切变形,还考虑了芯层的横向压缩变形。数值计算结果表明:无论对于静力问题、动力问题还是声辐射等问题,考虑芯层的横向压缩变形是合理的,也是有必要的。 相似文献
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本文由线弹性压电结构有限元动力方程,推导了压电智能结构的振动控制方程。建立了准确模拟层合压电结构动力行为的有限元模型。基于主结构模态应变能分布提出了一种新的优化目标函数,将压电致动器/传感器位置编号作为优化变量,建立了离散变量表示的智能结构优化问题,并通过二进制编码的遗传算法(GA)求解了该最优问题。以四边固支复合层合压电智能板为数值算例,采用比例反馈控制, 研究了最优位置配置致动器/传感器智能结构目标模态的控制效果。数值结果表明基于模态应变能分布的遗传算法所得优化解具有较好的振动控制效果。 相似文献
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Considering geometric nonlinearity and damage evolution, the static response characteristics of laminated composite plates subjected to uniformly distributed loading are investigated using finite element approach based on the first-order shear deformation theory. The damage evolution is modeled employing generalized macroscopic continuum theory within the framework of irreversible thermodynamics. The governing nonlinear equations are solved using Newton–Raphson iterative technique. The resulting finite element-based continuum damage model enables to predict the progressive damage and failure load. A detailed parametric study is carried out to investigate the influences of damage evolution, boundary conditions, span-to-thickness ratio, and lamination scheme on the static response of laminated plates undergoing moderately large deformation. It is revealed that the in-plane stretching forces owing to geometric nonlinearity significantly influence the failure load, damage, and stress distribution for immovable thin laminates. 相似文献
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Sang-Youl Lee 《Inverse Problems in Science & Engineering》2019,27(8):1038-1056
This study deals with an identification of stiffness reduction and response predictions occurred by the delamination damage in laminated composite plates under impact loads. Combined bivariate Gamma function and microgenetic algorithms are developed to determine the crack region due to the delamination and predict future responses. The validity of the proposed method was verified using impact-induced data obtained from a two-dimensional delamination finite element model. Examples indicated that the proposed approach is a feasible and advantageous method through which future dynamic responses can be predicted and the distribution of the degraded stiffness of laminated composite structures can be inspected for different measuring locations and fibre angles. 相似文献