铝蜂窝夹层板动力学建模仿真与试验验证

卫星结构中含有大量的铝蜂窝夹层板,振动主要在蜂窝板之中传递.通过构建铝蜂窝夹层板有限元模型,可计算得到其响应特性,进而建立准确的卫星结构有限元模型,为微振动响应分析提供基础.文中基于Y单元,考虑应力作用下的剪切变形,将蜂窝壁视作Timoshenko梁,推导出等壁厚正六边形蜂窝芯层的等效参数.建立了蜂窝夹层板的等效模型,考虑预埋件与胶粘层质量的影响,并计算其固有频率、振型及频响曲线.蜂窝板模型前4阶固有频率与试验结果最大误差为2.29％,振型一致,且频响曲线近似,表明了蜂窝夹层板有限元模型的准确性.     

考虑结构因素的蜂窝纸板等效模型适用性研究

为提高蜂窝纸板的数值计算精度、适用不同规格蜂窝纸板等效模型选择，分析了不同等效模型对不同结构蜂窝纸板固有频率的对应等效精度。首先，对Reissner等效模型、Ekavall等效模型和三明治夹芯板模型分别进行有限元建模；其次，将等效板的模态分析与实验结果进行对比，分析不同胞元边长、厚度与芯纸克重对等效模型的精度影响；最后，总结这3个变量对不同模型计算精度的影响规律，在此基础上得到蜂窝纸板固有频率解析方程。结果表明：Reissner理论模型适用于厚度小于等于20 mm的蜂窝纸板；Ekavall等效模型整体精度最高，误差基本低于10%；三明治夹芯板模型在蜂窝纸板胞元边长为10 mm时精度最高；在胞元边长与厚度相同的情况下，芯纸克重对计算精度影响较小；所得解析方程的解析结果与实验结果对比误差在12.43%以内。该结论为蜂窝纸板的模型选取提供依据。     

过载条件下铝蜂窝天线结构静动态响应研究

采用正交各向异性蜂窝夹层板的一种高精度等效分析方法,在MSC-PATRAN平台下建立某铝蜂窝夹层板天线结构有限元模型。重点分析了蜂窝夹层板尺寸对天线板极限承载能力的影响,并用大质量法分析其受冲击载荷的响应结果,得出了适合实际发射要求的结构设计参数,为天线结构优化设计提供工程依据。     

基于轻量化与强度的短纤维复合材料蜂窝三明治板结构多目标优化设计

蜂窝三明治板在结构轻量化中得到了广泛应用,采用具有良好材料性能的短纤维复合材料替换铝蜂窝,能进一步满足轻量化需求.为了短纤维复合材料更好地应用,针对增大蜂窝三明治板抗拉强度要求,提出了一种增大面板与蜂窝粘接面积的结构设计方案.在有限元软件ABAQUS中建立了考虑损伤退化的短纤维复合材料蜂窝三明治板有限元计算模型,验证了设计方案的可行性.为了兼顾力学性能和减重要求,采用基于代理模型和多岛遗传算法的优化方法对蜂窝结构参数进行了多目标优化.分析结果表明,所建立的精细化有限元模型能够模拟三明治板的性能突降行为,基于代理模型高效准确的优化流程,优化后三明治板的面密度相比于优化前降低了30％,强度满足要求.     

基于轻量化与强度的短纤维复合材料蜂窝三明治板结构多目标优化设计

蜂窝三明治板在结构轻量化中得到了广泛应用,采用具有良好材料性能的短纤维复合材料替换铝蜂窝,能进一步满足轻量化需求.为了短纤维复合材料更好地应用,针对增大蜂窝三明治板抗拉强度要求,提出了一种增大面板与蜂窝粘接面积的结构设计方案.在有限元软件ABAQUS中建立了考虑损伤退化的短纤维复合材料蜂窝三明治板有限元计算模型,验证了设计方案的可行性.为了兼顾力学性能和减重要求,采用基于代理模型和多岛遗传算法的优化方法对蜂窝结构参数进行了多目标优化.分析结果表明,所建立的精细化有限元模型能够模拟三明治板的性能突降行为,基于代理模型高效准确的优化流程,优化后三明治板的面密度相比于优化前降低了30％,强度满足要求.     

移动荷载作用下夹层板的动力学响应仿真分析

应用层合板理论将夹层板等效为一个正交各向异性板,分别计算出了实体金属夹芯、金属泡沫夹芯、正六边形蜂窝夹芯、金属波纹板夹芯四种夹层板的等效刚度,再应用正交各向异性板理论和模态叠加原理分析了这四种夹层板在移动荷载作用下的动力学响应,并对此做了比较分析,得出移动荷载作用下正六边形蜂窝夹层板相对于其它三种夹层板更具有优越性,而实体金属夹层板是这四种夹层板中承载能力最差的.所得结果对桥梁,公路的建设具有一定的指导意义.     

四边简支条件下对称蜂窝夹层板的弯曲振动分析

应用经典叠层板理论、一阶剪切板理论和三阶剪切板理论分析了四边简支条件下对称蜂窝夹层板的弯曲振动.将蜂窝芯层等效为一正交异性层,等效弹性参数由修正后的GIBSON公式得出.具体算例表明,经典叠层板理论和一阶剪切板理论不适合用于蜂窝夹层板的振动分析.应用三阶剪切板理论研究了蜂窝夹层板板厚、芯层板厚及胞元角度对弯曲振动频率的影响,并绘出相应的曲线图,该曲线图对蜂窝夹层板的工程应用具有指导意义.     

一种面向动态分析的PCB板等效建模方法

有限元分析是PCB板动态分析的一种常用方法.由于PCB板上元器件结构复杂、材料众多,因而仿真建模复杂或无法建模.为此,提出了一种面向动态性能分析的PCB板等效建模方法,将PCB板等效为和原PCB板主尺寸相同的均质等厚板,采用质量相等原则获得等效板密度,并基于振动理论和有限元理论推导了等效刚度的计算方法.在此基础上,分析了元器件的刚度、质量和分布等因素对等效刚度的影响.最后对某服务器机箱PCB进行了等效实例分析,结果表明了该等效方法的有效性.     

类蜂窝夹层结构振动特性分析及应用研究

对新型类蜂窝夹层结构进行了振动特性研究,运用Hoff理论对类蜂窝夹层结构进行振动特性分析,计算类蜂窝夹层结构在四边简支边界条件下的振动固有频率方程解.并用有限元软件ABAQUS进行振动模态分析与理论值进行对比,结果表明误差保持在10％以内,吻合度较好,检验了理论公式的可行性.在此基础上研究类蜂窝夹芯壁厚和面板与夹层板厚...     

手风琴式蜂窝材料等效弯曲和扭转刚度分析

手风琴式蜂窝材料因其零泊松比和大应变特性,日益受到航空界的关注。将手风琴蜂窝材料等效为均质正交各向异性薄板,提出了基于能量等效原理的手风琴蜂窝材料等效弯曲刚度和等效扭转刚度的理论分析方法,得到了等效刚度系数的解析表达式,并分析了其对胞元结构参数的敏感性。建立了手风琴蜂窝板的参数化模型,并运用数值仿真反演技术,得到了手风琴蜂窝材料的等效刚度系数。通过对比等效刚度系数的理论解与反演解,表明了该理论分析方法的可行性和正确性。     

复合材料起落架舱门结构优化设计

基于有限元软件ANSYS建立复合材料起落架舱门参数化有限元模型,基于三明治夹芯板理论将蜂窝芯层等效为均质的厚度不变的层板,以蜂窝夹芯高度与复合材料面板各铺层厚度为设计变量,以铺层板、蜂窝夹芯的强度,结构稳定性以及结构刚度为约束函数,以结构质量最轻为目标函数,基于ANSYS优化模块首先选择零阶法进行优化得到粗略解,其次选择一阶梯度优化法进一步对夹层结构进行优化设计,得到最优蜂窝芯子厚度、蒙皮各铺层厚度.     

Studies on buckling behavior of honeycomb sandwich panel

In the present work, an avant-garde study on Buckling of honeycomb sandwich panel of hexagonal cell has been carried out by considering simply supported boundary constraints explicitly. A novel theoretical formulation has been developed for the buckling of honeycomb panel as per Mil Standard (MIL-HDBK-23A). The laminate element type has been considered for linear static analysis using Lanczos Method (finite element method (FEM)). The buckling analysis carried out by FEM has been compared and validated with theoretical and experimental investigation for different panel aspect ratio under static load.     

复合材料蜂窝夹层板低速冲击损伤模拟及实验研究

复合材料蜂窝夹层板因其良好的力学特性及质量轻等优点在工程中得到了广泛应用,但其抗冲击能力较差。本文研究了复合材料蜂窝夹层板受低速冲击后的变形和损伤情况,采用光滑粒子动力学结合有限元数值模拟方法分析了复合材料蜂窝夹层板受不同能量冲击后的响应,并通过试验和模拟计算结果对比分析,给出了不同冲击能量下复合材料蜂窝夹层板的位移和损伤。研究结果表明:给出的复合材料蜂窝夹层板冲击数值模型能够合理的模拟低速冲击行为,能为工程中复合材料蜂窝夹层板结构受冲击损伤的测定提供参考依据。     

激光干涉在蜂窝夹心层板振动模态测量中的应用

采用激光电子散斑干涉测量技术(electronic speckle pattern interferometry,简称ESPI)对悬臂矩形损伤蜂窝夹心复合板稳态振动下的振型进行了实验研究。通过完整试样的振型测量结果与有限元模拟均匀悬臂金属板结构振型的类比,验证了有关蜂窝夹心复合材料具有横观各向同性假设的观点,获得了悬臂矩形蜂窝夹心复合层板前14阶离面振动模态的振型图。实验结果表明,结构的损伤导致其局部刚度改变,使得共振频率减少,损伤对其高阶振型的形状改变较为明显,有时甚至是模态跃迁。     

约束层阻尼板的有限元建模研究

粘弹性材料（VEM）的本构关系随频率和温度的变化而变化，对粘弹结构难以进行动特性分析及控制研究。基于Hamilton原理，给出了一种建立约束层阻尼（CLD）板动力学方程的新建模方法，建模时，考虑到VEM的纵向位移影响，并引入虚拟自由度，导出了标准二阶定常线性系统模型，从而避免因粘弹性材料导致的高阶非线性方程。采用GHM方法描述VEM的本构关系，它能直接与有限元法融合。算例分析了夹芯层为ZN—1型粘弹性材料的CLD悬臂板的动态特性，并与相关文献中的计算及试验结果进行比较，计算结果更加准确，表明新建模方法是准确的。     

A finite element formulation based on an enhanced first order shear deformation theory for composite and sandwich structures

A finite element formulation based on an enhanced first order shear deformation theory is developed to accurately and efficiently predict the behavior of laminated composite and sandwich structures. An enhanced first order shear deformation theory is systematically derived by minimizing the least-squared energy error between the first order shear deformable plate theory and a higher order shear deformable plate theory. In this way, the strain energy of a higher order theory is transformed to that of the Reissner-Mindlin plate theory. This minimization procedure yields a relationship between them that is also used to improve the accuracy of predicted stresses and displacements. The key feature of the proposed theory is in that it can be implemented to commercial FEM packages by simply changing the input, and the results obtained can be also enhanced by post-processing them via a differential quadrature method. Thus, a proposed finite element formulation can be widely used in various application problems. Through numerical examples, the accuracy and robustness of the present formulation are demonstrated.     

A study on the crashworthiness and rollover characteristics of low-floor bus made of sandwich composites

This paper describes the results of the numerical evaluation on crashworthiness and rollover characteristics of a lowfloor bus vehicle made of sandwich composites. The sandwich composite used for the vehicle structures was composed of aluminum honeycomb core and WR580/NF4000 glass-fabric/epoxy laminate facesheets. Material tests were conducted to determine the input parameters of the composite laminate facesheet model and the effective equivalent damage model for the orthotropic honeycomb core material. Crashworthiness and rollover analysis of the low-floor bus was conducted using the explicit finite element method (FEM) analysis code LS-DYNA3D with the lapse of time. The crash condition of the low-floor bus was a frontal accident with a speed of 60 km/h. Rollover analysis was done according to the safety rules of the European standards (ECE-R66). The angular and translation velocity and its angle with the ground just before impact for rollover were calculated using the dynamic analysis program. The results showed that the survival spaces for the driver and passengers were secured against frontal crashworthiness and rollover of the low-floor bus. In addition, the modified Chang-Chang failure criterion is recommended to predict the failure modes of the composite structures for crashworthiness and rollover analysis.     

Buckling of laminated sandwich plates subjected to partial edge compression

The buckling characteristics of sandwich plates having laminated stiff layers are studied for different types of partial edge loadings using a refined plate theory. With this plate theory, the through thickness variation of transverse shear stresses is represented by piecewise parabolic functions where the continuity of these stresses is satisfied at the layer interfaces by taking jumps in the transverse shear strains at the interfaces. The transverse shear stresses free condition at the plate top and bottom surfaces is also satisfied. It is quite interesting to note that this plate model having all these refined features requires unknown parameters only at the reference plane. To have a generality in the present analysis, finite element technique is adopted and it is carried out with newly developed triangular element, as existing finite elements cannot accommodate this plate model. So far, no solution exists in the literature for the problem of sandwich plate subjected to partial edge loading. The present analysis is first validated for the case of an isotropic plate subjected to partial edge compression and then it is extended to analyze sandwich plates. Few results are presented.     

蜂窝夹芯板参数化建模与优化设计

在蜂窝夹芯板的有限元分析过程中,为提高结构的建模和分析效率,基于有限元软件开发参数化建模与分析模块,可以完整地进行蜂窝结构的建模、分析、校核与后处理,使蜂窝结构的有限元分析过程流程化、高效化.在此基础上,以质量轻量化为目标,以结构强度为约束条件,基于MATLAB使用遗传算法、罚函数法、模式搜索法对蜂窝结构进行尺寸参数优...     

FINITE STRIP DYNAMIC ANALYSIS OF CYLINDRICAL SHELL SANDWICH STRUCTURES

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