排序方式: 共有83条查询结果,搜索用时 15 毫秒
41.
双轴载荷作用下源于椭圆孔的分支裂纹的一种边界元分析 总被引:2,自引:1,他引:1
利用一种边界元方法来研究双轴载荷作用下无限大板中源于椭圆孔的分支裂纹.该边界元方法由Crouch与Starfied建立的常位移不连续单元和笔者提出的裂尖位移不连续单元构成.在该边界元方法的实施过程中,左、右裂尖位移不连续单元分别置于裂纹的左、右裂尖处,而常位移不连续单元则分布于除了裂尖位移不连续单元占据的位置之外的整个裂纹面及其它边界,文中算例说明本数值方法对计算平面弹性裂纹的应力强度因子是非常有效的。该文对双轴载荷作用下无限大板中源于椭圆孔的分支裂纹的数值结果进一步证实本数值方法对计算复杂裂纹的应力强度因子的有效性,同时该数值结果可以揭示双轴载荷及裂纹体几何对应力强度因子的影响。 相似文献
42.
Stress intensity factors for asymmetric branched cracks in plane extension by using crack-tip displacement discontinuity elements 总被引:3,自引:1,他引:3
Xiangqiao Yan 《Mechanics Research Communications》2005,32(4):375-384
Stress intensity factors are important in the analysis of cracked materials. They are directly related to the fracture propagation and fatigue crack growth criteria. Based on the analytical solution (Crouch, S.L., 1976. Solution of plane elasticity problems by displacement discontinuity method, Int. J. Numer. Methods Eng. 10, pp. 301–343; Crouch, S.L., Starfield, A.M., 1983. Boundary Element Method in Solid Mechanics, with Application in Rock Mechanics and Geological Mechanics, London, Geore Allon and Unwin, Bonton, Sydney) to the problem of a constant discontinuity in displacement over a finite line segment in the x, y plane of an infinite elastic solid, recently, the crack-tip displacement discontinuity element which can be classified as the left and right crack-tip displacement discontinuity elements are developed by the author Yan, X., (in press. A special crack-tip displacement discontinuity element, Mechanics Research Communications) to model the crack-tip fields to more accurately compute the stress intensity factors of cracks in general plane elasticity. In the boundary element implementation the left or the right crack-tip displacement discontinuity element is placed locally at the corresponding left or right crack tip on top of the ordinary non-singular displacement discontinuity elements that cover the entire crack surface and the other boundaries. To prove further the efficiency of the suggested approach and provide more results of the stress intensity factors, in this study, analysis of an asymmetric branched crack bifurcated from a main crack in plane extension is carried out. 相似文献
43.
Xiangqiao Yan 《Mechanics Research Communications》2004,31(2):263
In this paper, a numerical analysis of perpendicular cracks under general in-plane loading is performed by using a hybrid displacement discontinuity method which consists of the non-singular displacement discontinuity element presented by Crouch and Starfied and the crack tip displacement discontinuity elements by the author. In the boundary element implementation the left or the right crack tip displacement discontinuity element is placed locally at corresponding left or right crack tip on top of the ordinary non-singular displacement discontinuity elements that cover the entire crack surface and the other boundary. The present numerical results show that the numerical approach is simple, yet very accurate for calculating numerically stress intensity factors for perpendicular cracks under general in-plane loading. 相似文献
44.
界面裂纹非对称扩展模型 总被引:1,自引:0,他引:1
提出了一种新的复合材料结构中层间脱层裂纹扩展模型,该模型能够揭示裂纹扩展对裂纹左右尖端能量释放率的相对大小及界面材料性能的依赖性,能够比较真实地揭示复合材料结构层间脱层裂纹扩展复杂性的特点. 相似文献
45.
46.
In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly. 相似文献
47.
Xiangqiao Mao Fengping Yan Lin Wang Suchun Feng Jian Peng Shuisheng Jian 《Optics Communications》2009,282(1):93-2553
A stable, incorporate and switchable dual-wavelength fiber laser with two fiber Bragg gratings written in a photosensitive and polarization-maintaining erbium-doped fiber directly, that is, without splices in the laser cavity, is proposed and demonstrated. Simultaneous dual-wavelength oscillation is achieved at room temperature with a wavelength spacing of 0.343 nm. The power fluctuation and wavelength shift of single-wavelength oscillations are measured to be less than 0.24 dB and 0.013 nm over 2 h. The wavelength switchability between single- and dual-wavelength oscillations is realized by altering the voltage upon the electrostrictive ceramic actuator. 相似文献
48.
Suchun Feng Ou Xu Shaohua Lu Xiangqiao Mao Tigang Ning Shuisheng Jian 《Optics & Laser Technology》2009,41(3):264-267
A switchable erbium-doped fiber-ring laser providing dual-wavelength outputs with orthogonal polarizations when operating at room temperature is proposed. One polarization-maintaining fiber Bragg grating (PMFBG) in a Sagnac loop interferometer is used as the wavelength-selective filter. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The optical signal-to-noise ratio (OSNR) is over 42 dB. The amplitude variation over 90 min is less than 0.6 dB for both wavelengths. 相似文献
49.
This paper deals with such a kind of surface crack problem with an approximately same depth, which is called a liked-plane
crack problem. Based on the previous investigations on internal rectangular crack and surface rectangular crack in infinite
solid in tension and a hybrid displacement discontinuity method (a boundary element method) proposed recently by Yan, a numerical
approach for the liked-plane crack problem in hand is presented. Numerical examples are given to illustrate the numerical
approach is simple, yet accurate for calculating the SIFs of a liked-plane crack. Specifically, a pair of cracks emanating
from a surface elliptical hole in infinite body in tension are investigated in detail. 相似文献
50.
This paper deals with the rectangular tensile sheet with a center notch crack. Such a crack problem is called a center notch
crack problem for short. By using a hybrid displacement discontinuity method (a boundary element method) proposed recently
by Yan, two center notch models are analyzed in detail. By changing the geometrical forms and parameters of the center notch,
and by comparing the SIFs of the center notch crack problem with those of the center cracked plate tension specimen (CCT),
which is a model frequently used in fracture mechanics, the effect of the geometrical forms and parameters of the center notch
on the stress intensity factors (SIFs) of the center cracked plate tension specimen, is revealed. Some geometric characterestic
parameters are introduced here, which are used to formulate the notch length and the branch crack length, which are to be
determined in mechanical machining of the center cracked plate tension specimen. So we can say that the geometric characterestic
parameters and the formulae used to determine the notch length and the branch crack length presented in this paper perhaps
have some guidance role for mechanical machining of the center cracked plate tension specimen. In addition, the numerical
investigation proves that the conventional angular notched specimen is much less sensitive to the size of notch than is the
circular notched specimen. 相似文献