共查询到18条相似文献,搜索用时 78 毫秒
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为了测定汽车零部件用复合材料的性能参数,这里对纤维增强聚合物基复合材料进行了动态粘弹性能实验,实验结果可以看出,随着自振频率的升高,损耗因子有增大的趋势。当自振频率在400Hz和600Hz时,损耗因子分别达到最大值,分别为0.0625和0.0433。为减少振动中产生内耗热,在使用中应尽量避开这样的振动频率。为复合材料汽车零部件的结构设计优化、改善振动特性和降低噪声等方面提供了参考依据。 相似文献
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基于修补结构的本构关系,对一受损层合板的双面胶接修理问题进行分析。采用粘弹性和弹性有限元两种分析方法,并用相应的试验来验证两种方法所得的计算结果。通过分析得到了胶接参数对修补后的结构强度及胶层应力的影响,同时对比计算结果和试验结果,可以发现粘弹性分析比弹性分析更为准确。 相似文献
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均匀化理论在多孔板结构优化中的应用研究 总被引:3,自引:0,他引:3
多尺度均匀化理论自从上世纪 70年代产生以来 ,就被认为是确定复合材料当量性能的一种不可替代的方法。本文将多尺度均匀化方法应用于基于有限元分析的多孔板结构优化设计中 ,简述了求解当量板有效弹性常数的均匀化理论 ,在此基础上 ,建立了基于有限元分析的多孔板结构优化流程 ,编写了FORTRAN程序 ,并将其与AN SYS软件相连接 ,完成了一个多孔板结构的优化设计 ,所得结果表明 ,它能够满足工程应用的需要 ,并为多孔板结构设计提供了一种新思路 相似文献
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本文从粘弹力学基础出发,结合带式输送机输送带的具体结构和使用特点,建立输送带的粘弹性力学模型,为大运量、长距离、高带速带式输送机的动态分析的动态设计计算提供理论基础。以适应带式输送机发展的需要。 相似文献
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基于均匀化方法的柔顺机构的设计 总被引:4,自引:0,他引:4
应用均匀化方法,探讨以机械效率为优化目标的柔顺机构的设计方法。推导了基于弹簧模型的柔顺机构机械效率的计算表达式。引进等效弹性模量与投结构尺寸关系的函数来描述优化过程中的容许应力随着微结构尺寸的变化情况,初步解决了拓扑优化中不能处理应力约束的缺点。采用准则优化方法建立了柔顺机构的拓扑设计的数学模型。 相似文献
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超纯水隔膜阀具有结构简单、耐化学腐蚀、低离子析出等优点,多用于半导体行业,隔膜的疲劳破损是影响隔膜阀寿命和设备可靠性的关键性能指标。通过COMSOL模拟了隔膜启闭过程中的应力变化情况,并详细分析了隔膜工作时的受力特点。结果表明:隔膜启闭过程中受到的应力与阀口开度成线性关系,且阀口开度最大时出现峰值;对于小流量、低流速的超纯水隔膜阀,隔膜失效的主要因素是隔膜启闭过程中机械拉伸引起的疲劳损坏;优化后的隔膜在工作时的应力趋于均匀化,对进一步提高其工作寿命具有良好的工程指导意义。 相似文献
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Igor V. Andrianov Vladimir I. Bolshakov Vladyslav V. Danishevskyy Dieter Weichert 《International Journal of Mechanical Sciences》2007,49(12):1344-1354
An asymptotic approach for simulation of the imperfect interfacial bonding in composite materials is proposed. We introduce between the matrix and inclusions a flexible bond layer of a volume fraction c(3) and of a non-dimensional rigidity λ(3), derive a solution for such three-component structure, and then set c(3)→0, λ(3)→0. In the asymptotic limit depending on the ratio λ(3)/c(3) different degrees of the interface's response can be simulated. A problem of the axial shear of elastic fibre-reinforced composites with square and hexagonal arrays of cylindrical inclusions is considered. The performed analysis is based on the asymptotic homogenization method, the cell problem is solved using the underlying principles of the boundary shape perturbation technique. As a result, we obtain approximate analytical solutions for the effective shear modulus and for the stress field on micro level depending on the degree of the interfacial debonding. Developed solutions are valid for all values of the components’ volume fractions and properties. In particular, they work well in cases of rapid oscillations of local stresses (e.g., in the case of densely packed perfectly rigid inclusions), while many of other commonly used methods may face computational difficulties. 相似文献
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经验应力松弛模量与Maxwell模量的转换计算方法 总被引:3,自引:0,他引:3
基于MATLAB软件,利用单纯形法搜索最小误差范数,提出了一种针对粘弹材料的经验松弛函数KohlrauschWilliamWatts(KWW)方程与Maxwell模量转换的计算方法,实现了对粘弹材料的广义Maxwell模型的拟合。并以1050℃的粘弹光纤玻璃为例,给出了一组计算实例。 相似文献
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Forced vibration of composite cylindrical helical rods 总被引:2,自引:0,他引:2
Beytullah Temel Faruk Frat alm Naki Tütüncü 《International Journal of Mechanical Sciences》2005,47(7):998-1022
The dynamic behavior of composite cylindrical helical rods subjected to time-dependent loads is theoretically investigated in the Laplace domain. The governing equations for naturally twisted and curved spatial laminated rods obtained using Timoshenko beam theory are rewritten for cylindrical helical rods. The curvature of the rod axis, the anisotropy of the rod material, effect of the rotary inertia, axial and shear deformations are considered in the formulations. The material of the rod is assumed to be homogeneous, linear elastic and anisotropic. Ordinary differential equations in scalar form obtained in the Laplace domain are solved numerically using the complementary functions method to calculate the dynamic stiffness matrix of the problem accurately. The solutions obtained are transformed to the time domain using an appropriate numerical inverse Laplace transform method. The free vibration is then taken into account as a special case of forced vibration. The results obtained in this study are found to be in a good agreement with those available in the literature. 相似文献
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针对特殊情况下飞机座舱内部振动噪声过大的实际情况 ,本文对其进行了振动噪声被动控制实验研究。以某飞机座舱模型为研究对象 ,应用粘弹阻尼材料成功实现了一套飞机座舱模型振动噪声被动控制系统。同时利用比利时 L MS国际公司的 Cada- X L MS结构动力学分析系统建立了一套完整的振动噪声控制性能测试系统 ,可广泛应用于各种被动、主动控制系统的振动噪声控制性能测试。最后利用该测试系统对上述飞机座舱模型振动噪声被动控制系统进行了控制性能测试实验 ,结果表明控制效果良好 ,说明了此方法可以用于飞机座舱的振动噪声控制。 相似文献
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用共混烧结法制备了纳米TiO2 /聚四氟乙烯和纳米SiO2 /聚四氟乙烯两种复合材料 ,考察了纳米材料含量、载荷对复合材料的摩擦磨损性能和力学性能的影响 ,结果表明 ,两种复合材料的磨损量比纯聚四氟乙烯降低了 1~2个数量级 ,当纳米TiO2 含量为wt .15 %左右时 ,聚四氟乙烯复合物的综合性能最佳。 相似文献
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在瞬态声场质点振速的重建过程中,基于快速傅里叶变换(Fast Fourier transform,FFT)的重建公式在零频处存在奇异性,为此提出基于Laplace变换的瞬态声场质点振速重建方法。由于该方法重建公式中的分母为复数,而该复数的实部是一个不为零的常数,因此当频率为零时,分母并不为零,从而可从根本上解决零频处的奇异性问题。以固定在无限大障板上的圆形活塞为数值仿真对象,分别运用上述两种方法对活塞表面的法向质点振速进行重建。重建结果表明当质点振速信号在零频处的能量占信号总能量的比例较小时,运用基于FFT的方法进行重建可获得较满意的重建结果;但当质点振速信号在零频处的能量占信号总能量的比例较大时,运用基于FFT的方法进行重建会产生较大的重建误差,而由于基于Laplace变换的方法解决了零频处的奇异性问题,因此运用该方法进行重建可获得较好的重建结果。 相似文献
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The process of water jet cutting has advantages over laser beam cutting, especially in the case of temperature-sensitive materials. Together with the foam and cellulose material processing, the processing of composite materials of lightweight structures is becoming more and more important. In order to meet given requirements, these sandwich constructions can have various types of cover layers (defined by e.g., sheet thickness and material) and consist of core materials (differing e.g., in geometry or in structure).
Unlike simple sheets, multilayer structures have greater influence on the cutting result. When the process is planned, the CAD/CAM-systems must take all sheets of the composite material into account in order to avoid manufacturing problems. Due to the great variety of composite materials and desired contours, the necessary knowledge or experience must be efficiently represented. There is no universal system model for all these variations. This paper suggests a fuzzy-logic theory to build up a knowledge base for the water jet cutting of composite materials. The knowledge contained within the fuzzy-logic base proves to be efficient, due to the relatively high speed at which it can be acquired and due to the possibility to apply it to different structures. Development and structure of the necessary linguistic rule base are presented using sinusoidal composite material made of aluminium as an example. The expert system optimized according to the given design parameters determines the optimal cutting speed for the desired cutting contour. 相似文献
Unlike simple sheets, multilayer structures have greater influence on the cutting result. When the process is planned, the CAD/CAM-systems must take all sheets of the composite material into account in order to avoid manufacturing problems. Due to the great variety of composite materials and desired contours, the necessary knowledge or experience must be efficiently represented. There is no universal system model for all these variations. This paper suggests a fuzzy-logic theory to build up a knowledge base for the water jet cutting of composite materials. The knowledge contained within the fuzzy-logic base proves to be efficient, due to the relatively high speed at which it can be acquired and due to the possibility to apply it to different structures. Development and structure of the necessary linguistic rule base are presented using sinusoidal composite material made of aluminium as an example. The expert system optimized according to the given design parameters determines the optimal cutting speed for the desired cutting contour. 相似文献