Based on one type of practical Biot's equation and the dynamic-stiffness matrices ofa poroelastic soil layer and half-space, Green's functions were derived for unitformly distributed loads acting on an inclined line...Based on one type of practical Biot's equation and the dynamic-stiffness matrices ofa poroelastic soil layer and half-space, Green's functions were derived for unitformly distributed loads acting on an inclined line in a poroelastie layered site. This analysis overcomes significant problems in wave scattering due to local soil conditions and dynamic soil-structure interaction. The Green's functions can be reduced to the case of an elastic layered site developed by Wolf in 1985. Parametric studies are then carried out through two example problems.展开更多
An uncertainty analysis method is proposed for the assessment of the residual strength of a casing subjected to wear and non-uniform load in a deep well.The influence of casing residual stress,out-of-roundness and non...An uncertainty analysis method is proposed for the assessment of the residual strength of a casing subjected to wear and non-uniform load in a deep well.The influence of casing residual stress,out-of-roundness and non-uniform load is considered.The distribution of multi-source parameters related to the residual anti extrusion strength and residual anti internal pressure strength of the casing after wear are determined using the probability theory.Considering the technical casing of X101 well in Xinjiang Oilfield as an example,it is shown that the randomness of casing wear depth,formation elastic modulus and formation Poisson’s ratio are the main factors that affect the uncertainty of residual strength.The wider the confidence interval is,the greater the uncertainty range is.Compared with the calculations resulting from the proposed uncertainty analysis method,the residual strength obtained by means of traditional single value calculation method is either larger or smaller,which leads to the conclusion that the residual strength should be considered in terms of a range of probabilities rather than a single value.展开更多
The differential equations of the axisymmetric large amplitude free vibration for circular sandwich plates under static load are derived, and a set of nonlinearly coupled algebraic and differential eigenvalue equation...The differential equations of the axisymmetric large amplitude free vibration for circular sandwich plates under static load are derived, and a set of nonlinearly coupled algebraic and differential eigenvalue equations of the problem are formulated following an assumed time mode approach suggested. The analytic solutions are presented and a relation for amplitude frequency-load of the plates with edge clamped is derived by modified iteration method. The effects of static load on vibrations of plates are investigated.展开更多
According to the Mohr-Coulomb yield criterion, the stress field of the infinite slope is derived under a vertical uniform load q on the top of the slope. It is indicated that elastic and elasto-plastic states would oc...According to the Mohr-Coulomb yield criterion, the stress field of the infinite slope is derived under a vertical uniform load q on the top of the slope. It is indicated that elastic and elasto-plastic states would occur in the slope. When q is smaller than the critical load, q(p), the slope is in the elastic state. If q equals q(p), the slope is in the critical state, and the plastic deformation would occur along the critical angle. With the increase of q, the plastic zone would extend, and the slope is in the elasto-plastic State. If q equals limit load, the slope is in the limit equilibrium state. The slope may be divided into three zones. Some charts of the critical angle, the critical and limit load coefficients are presented in this paper.展开更多
In this paper, using of the superposition principle. the bending solution ofrectangular plate with one edge built-in and one corner point supported subjected touniform load is derived. The results indicate the method ...In this paper, using of the superposition principle. the bending solution ofrectangular plate with one edge built-in and one corner point supported subjected touniform load is derived. The results indicate the method has the advantages of rabidconvergence and high precision.展开更多
During the excavation of deep coal and rock mass, the radial stress of the free face changes from three-dimensional compression state to two-dimensional stress, bearing the combined action of dynamic disturbance and s...During the excavation of deep coal and rock mass, the radial stress of the free face changes from three-dimensional compression state to two-dimensional stress, bearing the combined action of dynamic disturbance and static load at the same time. With that, many mines suffer from dynamic disasters, such as coal and gas outburst, rock burst and rock caving during deep mining excavation, which is often accompanied by plate crack, spalling and other disasters, seriously affecting the stability of stope and roadway. Taking thin rectangular coal and rock mass as the research object, the dual equation of the free vibration was derived and the exact solution model of the free vibration was established with the use of Hamilton dual system. Based on the action characteristics of the uniform impact load, the effective mode of the forced vibration was obtained by using the Duhamel integral principle and the orthogonality of the mode function. Based on the third strength theory and the numerical simulation results, the dynamic damage process and development trend of coal and rock mass were analyzed under uniform impact load. It was concluded that the starting position of dynamic damage can be judged by the first order main mode, and the development direction and trend of the damage can be judged by the fifth and sixth order main modes. It was concluded that the vibration mode functions of coal and rock mass with four side fixed (C-C-C-C), the two sides fixed and simply supported on the other (S-C-S-C) are mainly composed of three modes that are the first order (dominant frequency), the fifth order and the sixth order, from which the dynamic damage mechanism is preliminarily studied.展开更多
In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell...In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs(BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element(FE) analysis.Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional(1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs.展开更多
According to the constitutive relationship in linear piezoceramics, elliptical crack problems in the impermeable case are reconsidered with the hypersingular integral equation method. Unknown displacement and electric...According to the constitutive relationship in linear piezoceramics, elliptical crack problems in the impermeable case are reconsidered with the hypersingular integral equation method. Unknown displacement and electric potential jumps in the integral equations are approximated with a product of the fundamental density function and polynomials, in which the fundamental density function reflects the singular behavior of electroelastic fields near the crack front and the polynomials can be reduced to a real constant under uniform loading. Ellipsoidal coordinates are cleverly introduced to solve the unknown displacement and electric potential jumps in the integral equations under uniform loading. With the help of these solutions and definitions of electroelastic field intensity factors, exact expressions for mode Ⅰ, mode Ⅱ and mode Ⅲ stress intensity factors as well as the mode Ⅳ electric displacement intensity factor are obtained. The present results under uniform normal loading are the same as the available exact solutions, but those under uniform shear loading have not been found in the literature as yet.展开更多
基金National Natural Science Foundation of China Under Grant No.50378063
文摘Based on one type of practical Biot's equation and the dynamic-stiffness matrices ofa poroelastic soil layer and half-space, Green's functions were derived for unitformly distributed loads acting on an inclined line in a poroelastie layered site. This analysis overcomes significant problems in wave scattering due to local soil conditions and dynamic soil-structure interaction. The Green's functions can be reduced to the case of an elastic layered site developed by Wolf in 1985. Parametric studies are then carried out through two example problems.
基金supported by the National Natural Science Foundation of China[51804061,51974052,51774063]the Academician Led Special Project of Chongqing Science and Technology Commission[cstc2017zdcy-yszxX0009]+1 种基金the Chongqing Research Program of Basic Research and Frontier Technology[cstc2019jcyj-msxmX0199,cstc2018jcyjAX0417]the Chongqing Education Committee foundation[KJQN201901544,KJZD-K201801501].
文摘An uncertainty analysis method is proposed for the assessment of the residual strength of a casing subjected to wear and non-uniform load in a deep well.The influence of casing residual stress,out-of-roundness and non-uniform load is considered.The distribution of multi-source parameters related to the residual anti extrusion strength and residual anti internal pressure strength of the casing after wear are determined using the probability theory.Considering the technical casing of X101 well in Xinjiang Oilfield as an example,it is shown that the randomness of casing wear depth,formation elastic modulus and formation Poisson’s ratio are the main factors that affect the uncertainty of residual strength.The wider the confidence interval is,the greater the uncertainty range is.Compared with the calculations resulting from the proposed uncertainty analysis method,the residual strength obtained by means of traditional single value calculation method is either larger or smaller,which leads to the conclusion that the residual strength should be considered in terms of a range of probabilities rather than a single value.
文摘The differential equations of the axisymmetric large amplitude free vibration for circular sandwich plates under static load are derived, and a set of nonlinearly coupled algebraic and differential eigenvalue equations of the problem are formulated following an assumed time mode approach suggested. The analytic solutions are presented and a relation for amplitude frequency-load of the plates with edge clamped is derived by modified iteration method. The effects of static load on vibrations of plates are investigated.
文摘According to the Mohr-Coulomb yield criterion, the stress field of the infinite slope is derived under a vertical uniform load q on the top of the slope. It is indicated that elastic and elasto-plastic states would occur in the slope. When q is smaller than the critical load, q(p), the slope is in the elastic state. If q equals q(p), the slope is in the critical state, and the plastic deformation would occur along the critical angle. With the increase of q, the plastic zone would extend, and the slope is in the elasto-plastic State. If q equals limit load, the slope is in the limit equilibrium state. The slope may be divided into three zones. Some charts of the critical angle, the critical and limit load coefficients are presented in this paper.
文摘In this paper, using of the superposition principle. the bending solution ofrectangular plate with one edge built-in and one corner point supported subjected touniform load is derived. The results indicate the method has the advantages of rabidconvergence and high precision.
文摘During the excavation of deep coal and rock mass, the radial stress of the free face changes from three-dimensional compression state to two-dimensional stress, bearing the combined action of dynamic disturbance and static load at the same time. With that, many mines suffer from dynamic disasters, such as coal and gas outburst, rock burst and rock caving during deep mining excavation, which is often accompanied by plate crack, spalling and other disasters, seriously affecting the stability of stope and roadway. Taking thin rectangular coal and rock mass as the research object, the dual equation of the free vibration was derived and the exact solution model of the free vibration was established with the use of Hamilton dual system. Based on the action characteristics of the uniform impact load, the effective mode of the forced vibration was obtained by using the Duhamel integral principle and the orthogonality of the mode function. Based on the third strength theory and the numerical simulation results, the dynamic damage process and development trend of coal and rock mass were analyzed under uniform impact load. It was concluded that the starting position of dynamic damage can be judged by the first order main mode, and the development direction and trend of the damage can be judged by the fifth and sixth order main modes. It was concluded that the vibration mode functions of coal and rock mass with four side fixed (C-C-C-C), the two sides fixed and simply supported on the other (S-C-S-C) are mainly composed of three modes that are the first order (dominant frequency), the fifth order and the sixth order, from which the dynamic damage mechanism is preliminarily studied.
基金the financial support provided by the Natural Science Foundation of Hebei Province of China [No. A2020502005]the Fundamental Research Funds for the Central Universities [No. 2020MS113]Science & Technology Program of Baoding [No. 1911ZG019]。
文摘In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs(BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element(FE) analysis.Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional(1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs.
基金Project supported by the Jiangxi Provincial Natural Science Foundation (No.0112001)the Japan Society for the Promotion of Science Postdoctoral Fellowship (No.P01205).
文摘According to the constitutive relationship in linear piezoceramics, elliptical crack problems in the impermeable case are reconsidered with the hypersingular integral equation method. Unknown displacement and electric potential jumps in the integral equations are approximated with a product of the fundamental density function and polynomials, in which the fundamental density function reflects the singular behavior of electroelastic fields near the crack front and the polynomials can be reduced to a real constant under uniform loading. Ellipsoidal coordinates are cleverly introduced to solve the unknown displacement and electric potential jumps in the integral equations under uniform loading. With the help of these solutions and definitions of electroelastic field intensity factors, exact expressions for mode Ⅰ, mode Ⅱ and mode Ⅲ stress intensity factors as well as the mode Ⅳ electric displacement intensity factor are obtained. The present results under uniform normal loading are the same as the available exact solutions, but those under uniform shear loading have not been found in the literature as yet.