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Quick Search     Adv Search 2019 Vol. 40, No. 6 Published: 2019-12-28 539 Meshless fracture analysis based on weight-function modification DOI: 10.19636/j.cnki.cjsm42-1250/o3.2019.025 In this paper, a meshless method based on discontinuous field weight-function modification is used to deal with finite length cracks in two-dimensional plane problems. Compared with the currently used crack discontinuity processing scheme, when the weight function is used to deal with the discontinuous field near the crack, only the original weight function needs to be modified, and the algorithm is simple and easy to implement. In this paper, the element-free Galerkin method (EFGM) based on the discontinuous weight-function modification is used to numerically analyze the oblique cracked plates with I-II mixed crack displacement fields on the boundary. The numerical accuracy of the crack tip displacement field, stress field, and stress intensity factors are compared with discontinuous criteria such as visibility criterion, diffraction method, and transparency method. In addition, the calculation efficiency of shape functions by the four discontinuous criterions is also analyzed and compared. 2019 Vol. 40 (6): 539-551 [Abstract] ( 193 ) HTML (1 KB)  PDF   (0 KB)  ( 185 ) 552 Research on Fractal Model of Thermal Contact Conductance between Two Cylinders’ Joint Surfaces DOI: 10.19636/j.cnki.cjsm42-1250/o3.2019.027 A fractal model of thermal contact conductance between two cylinders’ joint surfaces considering the elastic deformation, elastic-plastic deformation and plastic deformation was established using three-dimensional fractal theory. The influence of fractal dimensions, fractal scale parameters, cylinder curvature radius and contact type on thermal contact conductance is analyzed using numerical simulation. The results indicated that: The thermal contact conductance increases with the increase of the fractal dimensions and decreases with the increase of the fractal scale parameters; The thermal contact conductance of the internal contact is larger than that of the external contact with the same parameters; In addition, when the curvature radius of one cylinder is fixed, the thermal contact conductance increases with the increase of the curvature radius of the other cylinder. The model provides a theoretical basis for the research of thermal contact conductance of gears or other curved surfaces. 2019 Vol. 40 (6): 552-559 [Abstract] ( 188 ) HTML (1 KB)  PDF   (0 KB)  ( 178 ) 560 A Generalized Solution Procedure for Free Bending vibration of Anistropic Rectangular and Annular Sectorial Plates DOI: 10.19636/j.cnki.cjsm42-1250/o3.2019.026 A generalized solution procedure is presented for free bending vibration of anistropic rectangular and annular sectorial plates with elastic boundary conditions. For an anistropic annular sectorial plate, the basic theory is simplified through the introduction of a logarithmic radial coordinate. Unified s for the geometric parameters and potential energy for the two different shape are established. Based on improved Fourier series and Hamilton principle, a generalized solving procedure is realized. The generalized solution approach for free bending vibration of plates with both shapes has the advantage of generality, good precision and efficiency. The good convergence and precision of the presented method are attributed to the improve Fourier series of the displacement function, which can eliminate the potential discontinuity of the deflection function and their derivatives. These features of the generalized method are demonstrated by a few numerical examples. 2019 Vol. 40 (6): 560-570 [Abstract] ( 175 ) HTML (1 KB)  PDF   (0 KB)  ( 145 ) 571 Experimental study on mechanical and acoustic characteristics of high temperature granite after natural cooling and water cooling DOI: 10.19636/j.cnki.cjsm42-1250/o3.2019.032 Taking open granite in Songliao Basin as study object, uniaxial compression, uniaxial tensile and acoustic tests of the high temperature granite after natural cooling and water cooling are carried out. The relationship between granite temperature (100℃, 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, hereinafter referred to as 100℃-800℃) and superficial morphology, longitudinal and transverse wave velocity, elastic modulus, poisson's ratio, compressive strength and tensile strength after cooling in different ways is studied. Moreover, the relationship between longitudinal and transverse wave velocity and compressive strength and elastic modulus was established. Meanwhile, the influence of static setting process on the mechanical-acoustic properties of granite after water cooling is considered. Researches show that: (1) The mass and longitudinal wave velocity decreases mainly during the period of standing 0-2h, while the change rate after 6h is negligible. There is a linear relationship between the amount of free water loss and the amount of mechanical-acoustic characteristic loss. (2) With the increase of temperature, the longitudinal and transverse wave velocity, elastic modulus, compressive strength and tensile strength of granite decline linearly after natural cooling, while they descend in a concave pattern after water cooling. When the temperature is higher than 300℃, the mechanical-acoustic parameters of granite after natural cooling are all greater than that under water cooling, while the change rate of poisson's ratio is opposite. At 600℃, the influence of different cooling methods on the longitudinal and transverse wave velocity, elastic modulus and compressive strength of granite reached the maximum, and water-cooling was 33.33%, 31.88%, 53.33% and 31.74% lower than that of natural cooling, respectively. At 700℃-800℃, the influence of cooling method on the mechanical and acoustic characteristics of granite decreases. (3) With the increase of temperature, the relationships among longitudinal and transverse wave velocities, compressive strength and elastic modulus of granite demonstrate good correlations. The conclusions can improve the accuracy of measurement of mechanical-acoustic characteristics of granite, which will provide a feasible method for prediction of mechanical properties and provide basis for evaluation of safety and stability of geotechnical engineering. 2019 Vol. 40 (6): 571-582 [Abstract] ( 191 ) HTML (1 KB)  PDF   (0 KB)  ( 182 )

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