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运用斜拉桥的近似分析方法,将漂浮体系的斜拉桥结构简化成两端简支且中间离散弹性支撑梁、变地基系数梁和均匀地基系数地基梁三种模型。建立了移动载荷作用下斜拉桥结构的动力学方程,用四阶龙格库塔法对动力学方程进行了计算,对三种模型的固有频率和三种模型在相同移动载荷作用下的动态响应进行了比较,并对移动载荷移动速度、垂直振动的刚度和阻尼对桥梁动态响应的影响进行分析。结果表明,当拉索等效弹性系数较小时,三种模型的固有频率和挠度曲线差别较小,当拉索等效弹性系数较大时,三种模型的固有频率和挠度曲线差别明显;桥梁动态响应的频谱由桥梁的固有频率和移动载荷的自振频率组成;移动载荷垂直振动的刚度越大,阻尼越小,桥梁振动的响应越大。 相似文献
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计算粘弹结构动力学参数的新模态应变能方法 总被引:1,自引:0,他引:1
粘弹结构在噪声与振动控制领域已得到广泛应用,然而准确地计算粘弹结构的动力学参数一直存在困难,模态应变能法及其修正方法常用作近似计算。在分析模态应变能方法和已有修正方法的原理及其相互关系的基础上,提出一种基于损耗因子幅值的新模态应变能方法,用于计算粘弹结构的损耗因子与固有频率。新方法的修正因子随粘弹结构对应模态阶次损耗因子幅值变化。取可等价为粘弹性夹层梁/板的四参数原型系统和新型高阻尼航天载荷隔振器为算例,通过与已有方法的对比分析了新方法的准确性。 相似文献
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针对鱼洗的喷水现象,进行了较详细的动力学理论分析和实验研究。首先,对鱼洗进行了充水和无水下双耳悬挂实验模态分析,完整地得到了鱼洗的前十一阶模态频率,振型和阻尼比;其次,进行了鱼洗的手搓喷水实验,通过工况模态分析理论和算法实现,得到了喷水状态的模态参数。与实验模态分析结果的对比,得到了鱼洗喷水态的动力学特征与模态参数一致的结论;第三,进行了激振器共振实验,用激振器对盆-水系统进行固定频率的稳态激励,得到了各阶模态频率下的共振喷水现象,说明鱼洗在共振激励下可以喷水,且喷水态动力学参数也与模态参数相一致。 相似文献
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为研究敷设覆盖层圆板水下爆炸响应,提出一种理论计算方法。敷设覆盖层对圆板水下爆炸响应影响包括两方面:一为对冲击载荷的影响,二为在冲击载荷作用下对响应的影响。该理论计算方法运用波在多层介质传播理论得到湿表面压力,并积分得到冲量,运用等效均一化理论得到覆盖层与钢板整体结构的等效参数,根据圆板振动理论得到圆板真空振动方程,通过考虑水附加质量的影响修正圆板振动频率,最后根据初始条件得到圆板的响应。将理论方法的结果与有限元结果通过实例进行对比,证明该理论计算方法可以很好地预测圆板振动的位移响应。 相似文献
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小孔缺陷对受力平板试件的承栽能力有着重要的影响。本文采用应力函数法和叠加原理,推导出了单向拉伸平板试件孔边应力场;利用该应力场公式、主应力公式和Mises屈服方程推导出了孔边塑性区方程,利用Mathematica软件求解出孔边塑性区尺寸-r和θ,并绘出了无限大单向拉伸平板试件的孔边塑性区。采用退火态SUS304—2B不锈钢和热轧态LC52铝舍金两种材料的带孔平板试件进行单向拉伸实验,通过实验结果与上述孔边应力集中理论的分析比较发现,由于塑性钝化使得单向拉伸带孔平板试件的实际承载能力与理论计算存在一定差别。 相似文献
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A simple analytical impact damage model for preliminary design analysis is developed on the basis of experimental findings observed from quasi-static lateral load and low velocity impact tests. The analytical model uses a non-linear approximation method (Rayleigh–Ritz) and the large deflection plate theory to predict the number of failed plies and damage area in a quasi-isotropic composite circular plate (axisymmetric problem) due to a point load at its centre. It is assumed that the deformation due to a static transverse load is similar to that occurred in a low velocity impact. It is found that the model, despite its simplicity, is in good agreement with finite element (FE) predictions and experimental data for the deflection of the composite plate and gives a good estimate of the number of failed plies due to fibre breakage. The predicted damage zone could be used with a fracture model developed by the second investigator to estimate the compression after impact strength of such laminates. This approach could save significant running time when compared to FE numerical solutions.
Corresponding author. 相似文献
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Sabir Rizwan Khan Abid Ali Hasham Hassan Junaid Khan Irfan Ali 《Journal of Failure Analysis and Prevention》2018,18(3):647-658
Journal of Failure Analysis and Prevention - Iso-grid structures provide high strength with reduced weights, which is an essential requirement for aerospace applications. Buckling of Ortho-grid... 相似文献
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Andreas P. Christoforou Ahmet S. Yigit Wesley J. Cantwell Fanjing Yang 《Applied Composite Materials》2010,17(5):463-472
This paper presents an experimental study for the normalized low-velocity impact response of composite plates. It is demonstrated
that a characterization diagram that shows the relationship of three non-dimensional parameters with the normalized maximum
impact force can be used to fully characterize the response. With the governing non-dimensional parameters obtained experimentally,
it is shown that impact tests having the same non-dimensional parameters, have dynamic similarity and the same non-dimensional
response. Furthermore, the experiments can be placed in appropriate dynamic regions in which simplified dynamic models can
be used to predict the response. 相似文献
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Six flat total-pressure tubes with a slot receiving aperture are calibrated for use when measuring surface friction. The readings of the tubes as a function of the relative width of the receiving cross section are established. 相似文献
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A. Riccio M. Damiano M. Zarrelli M. Giordano F. Scaramuzzino 《Applied Composite Materials》2014,21(3):511-524
The present paper introduces a numerical study on the fire behavior of composites during exposure to a heating source at high incident power. A novel numerical model is proposed which is able to simulate the behavior of composite materials in fire environment providing the composites mass loss rate and heat release rate during heating source application. Two commercial software have been selected as platforms for the implementation of the proposed numerical model COMSOL and ANSYS. In COMSOL the model has been implemented by introducing proper field equations, while a macro, written in Ansys Parametric Design Language, has been used to allow the ANSYS FEM code to numerically simulate, by an incremental procedure, all the relevant physical phenomena related to fire. As an application, an experiment on thermal degradation over a laminated composite plate has been numerically simulated and the numerical model has been validated by comparing the COMSOL and Ansys numerical results to experimental literature data in terms of temperature profile over the panel thickness, Mass Loss Rate and Heat Release Rate. An excellent agreement has been found between the obtained numerical results and the experimental test data for both the adopted numerical platforms. However the ANSYS implementation, which showed to be the most effective in terms of accuracy of results and perspectives of applications to complex numerical models, led to the definition of a powerful tool able to assesses the fire performance of composite structures. 相似文献
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The paper addresses the problem of impact on layered fibre composites. The behaviour of composite laminates under impact loading is dependent not only on the velocity but also on the mass and geometry of the impactor. Using micromechanical Mori-Tanaka approach, mechanical properties of the laminate have been calculated utilizing the material constants of the fibre and matrix. General purpose FEM software ABAQUS has been modified by means of user written subroutines for modelling of composite laminate and rigid impactor. The kinematics of the impact has been simulated using transient dynamic analysis. Employing user defined multi point constraints, delamination zones have been modeled and visualised 相似文献
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本文用空间有限元、时间差分法分析了受冲击荷载的矩形固支板的动力响应。分析中考虑了大位移引起的几何非线性;塑性、应变强化及应变率效应引起的材料非线性的影响。 相似文献