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991.
DYNAMIC STRESS FIELD AROUND THE MODE Ⅲ CRACK TIP IN AN ORTHOTROPIC FUNCTIONALLY GRADED MATERIAL 总被引:2,自引:0,他引:2
IntroductionInrecentyears,greatattentionshavebeenpaidtotheresearchofFunctionallyGradedMaterials(FGM).Fromtheviewpointsofappliedmechanics,FGMarenon_homogeneoussolids.Thenon_homogeneityofFGMhasagreatinfluenceontheirmechanicalbehavior,especiallywhenthecomp… 相似文献
992.
各向异性压电材料平面裂纹的耦合场分析 总被引:4,自引:1,他引:3
用Stroh方法分析了各向异性压电材料电导通型裂纹问题的耦合场。结果表明,裂纹面上的切向电场强度和法向电位移均为常数,在裂纹尖端有由弹性场的耦事作用产生的奇异电导通裂纹模型中的静电场对裂纹尖端扩展的能量释放率不作贡献。 相似文献
993.
Discrete dipoles located near the crack tip play an important role in nonlinear electric field induced fracture of piezoelectric
ceramics. A physico-mathematical model of dipole is constructed of two generalized concentrated piezoelectric forces with
equal density and opposite sign. The interaction between crack and electric dipole in piezoelectricity is analyzed. The closed
form solutions, including those for stress and electric displacement, crack opening displacement and electric potential, are
obtained. The function of piezoelectric anisotropic direction,p
a
(θ)=cosθ+p
a
sinθ, can be used to express the influence of a dipole's direction. In the case that a dipole locates near crack tip, the
piezoelectric stress intensity factor is a power function with −3/2 index of the distance between dipole and crack tip.
Supported by National Natural Science Foundation of China(No. 10072033) 相似文献
994.
995.
The mode competition is significant in laser physics and applications. A priority frequency will suppress, in competition, a potential frequency within gain profile, and this becomes more obvious with greatly decreasing the spacing of the two frequencies. The small spacing is produced by splitting one mode into two orthogonally polarized frequencies in a 0. 6328 μm He-Ne laser with a short cavity length (150 mm long). By tuning the cavity length, the intensities of the two frequencies (e-mode and o-mode) under a ariety of frequency spacings is measured. The suppression bandwidth for the potential mode is up to several hundreds of MHz and changes with the frequency spacing of the pair of frequencies. The intensities for the two frequencies are vary oppositely. 相似文献
996.
复合物邻二甲苯…NH3(ND3)分子间的振动 总被引:2,自引:0,他引:2
Resonant two photon ionization spectra of S1←S0 transition in complex o xylene…NH3(ND3) in supersonic molecular beam are observed using resonant two photon ionization,together with time of flight mass spectrometry.
The spectra exhibit rich information on the complex intermolecular vdW vibrational modes.We have tentatively assigned all the observed spectral features.By analyzing the spectra,the stretching vibrational frequencies and two bending vibrational frequencies of the the complex are obtained.The structure of the complex has been obtained by ab initio computation method. 相似文献
997.
In this paper, the isotropic and anisotropic photoelastic experimental hybrid methods for fracture mechanics are developed.
Using the photoelastic experimental hybrid method, it is demonstrated that one can precisely obtain stress intensity factors
and separate the stress components of isotropic and anisotropic plate problems from the only isochromatics. 相似文献
998.
双材料反平面问题界面端奇异应力场分析 总被引:4,自引:0,他引:4
利用位移函数的级数展开,对任意角度的反平面问题界面端的应力场进行了分析研究,得到了全场解。研究一阶场后发现,奇异规律与一般平面问题界面端有显著区别,在界面端关于界面对称的情况下,平角界面端(θ1 = θ2 = θ = 90°) 应力场没有奇异性,其它形状的界面端随着角度θ 从90°到180°,奇异指数也从0到0.5。当界面端是非对称时,平角界面端(θ1 θ2 = 180°)、直角界面端(θ1 = 90°,θ2 = 180°)以及其它形状界面端的奇异指数是一个与两相材料常数比Γ有关的常数。以上两种情况下的应力强度因子完全类似单相材料中裂纹尖端附近应力强度因子,故可根据定义得到 相似文献
999.
Dynamic load is applied to a functionally graded material with penny-shaped cracks. The materials are also transversely isotropic depending only on the axial coordinate z. The elastic region may be regarded to consist of many thin layers such that properties are constants within each layer, but they may vary from layer to layer. Laplace and Hankel transform are used in conjunction with the stiffness matrix approach. The Dual integral equations are then obtained by application of appropriate boundary and interface conditions. Stress intensity factors are then determined in the Laplace transform domain. Inversion yields the results in the time domain. Numerical examples show that multiple crack configurations in functionally graded materials can be treated where the continuously varied material properties can be divided into a finite number of layers with different properties. 相似文献
1000.
The transient response of two coplanar cracks in a piezoelectric ceramic under antiplane mechanical and inplane electric impacting
loads is investigated in the present paper. Laplace and Fourier transforms are used to reduce the mixed boundary value problems
to Cauchy-type singular integral equations in Laplace transform domain, which are solved numerically. The dynamic stress and
electric displacement factors are obtained as the functions of time and geometry parameters. The present study shows that
the presence of the dynamic electric field will impede or enhance the propagation of the crack in piezoelectric ceramics at
different stages of the dynamic electromechanical load. Moreover, the electromechanical response is greatly affected by the
ratio of the space of the cracks and the crack length. 相似文献