Damage smear method(DSM)is adopted to study trans-scale progressive rock failure process,based on statistical meso-damage model and finite element solver.The statistical approach is utilized to reflect the mesoscopic ...Damage smear method(DSM)is adopted to study trans-scale progressive rock failure process,based on statistical meso-damage model and finite element solver.The statistical approach is utilized to reflect the mesoscopic rock heterogeneity.The constitutive law of representative volume element(RVE)is established according to continuum damage mechanics in which double-damage criterion is considered.The damage evolution and accumulation of RVEs are used to reveal the macroscopic rock failure characteristics.Each single RVE will be represented by one unique element.The initiation,propagation and coalescence of meso-to macro-cracks are captured by smearing failed elements.The above ideas are formulated into the framework of the DSM and programed into self-developed rock failure process analysis(RFPA)software.Two laboratory-scale examples are conducted and the well-known engineering-scale tests,i.e.Atomic Energy of Canada Limited’s(AECL’s)Underground Research Laboratory(URL)tests,are used for verification.It shows that the simulation results match with other experimental results and field observations.展开更多
提出求解环肋圆柱壳固有振动特性的辛解析方法。首先,采用“刚度平摊”法,将环肋等效为圆柱壳重量的增加,并选取合适的状态向量,通过Hamilton函数将环肋圆柱壳的自由振动问题导入辛对偶体系,环肋圆柱壳的固有振动问题被归结为辛本征值...提出求解环肋圆柱壳固有振动特性的辛解析方法。首先,采用“刚度平摊”法,将环肋等效为圆柱壳重量的增加,并选取合适的状态向量,通过Hamilton函数将环肋圆柱壳的自由振动问题导入辛对偶体系,环肋圆柱壳的固有振动问题被归结为辛本征值和辛本征解问题,原高阶控制微分方程被转化为一组低阶常微分方程组。然后,即可利用分离变量法求解环肋圆柱壳的固有频率和相应振型。通过数值算例将其与其他文献、有限元方法(Finite Element Method,FEM)所得的固有频率进行对比,验证了该方法的正确性和高精度。随后研究环肋数量和环肋截面尺寸对环肋圆柱壳固有频率的影响。展开更多
Anisogrid composite lattice conical shells, which exhibit varying stiffness along their cone generators, are widely used as interstage structures in aerospace applications. Buckling under axial compression represents ...Anisogrid composite lattice conical shells, which exhibit varying stiffness along their cone generators, are widely used as interstage structures in aerospace applications. Buckling under axial compression represents one of the most hazardous failure modes for such structures. In this paper, the smeared stiffness method, which incorporates the effect of component torsion, is used to obtain the equivalent stiffness coefficients for composite lattice conical shells with triangular and hexagonal patterns. A unified framework based on the variational differential quadrature (VDQ) method is established, leveraging its suitability for asymptotic expansion to determine the critical buckling loads and the b-imperfection sensitivity parameter of lattice conical shells with axially varying stiffness due to rib layout. The influence of pre-buckling deformation is taken into account to enhance the accuracy of predictions on the linear buckling loads. The feasibility of the present equivalent continuum model is verified, and the differences in buckling behaviors for composite lattice conical shells with both triangular and hexagonal unit cells are numerically evaluated through the finite element (FE) simulations and the VDQ method.展开更多
基金supported in part by the National Natural Science Foundation of China (Grant Nos.51679028 and 51879034)Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology (Grant No. SKLGDUEK1804)the Fundamental Research Funds for the Central Universities (Grant No.DUT18JC10)
文摘Damage smear method(DSM)is adopted to study trans-scale progressive rock failure process,based on statistical meso-damage model and finite element solver.The statistical approach is utilized to reflect the mesoscopic rock heterogeneity.The constitutive law of representative volume element(RVE)is established according to continuum damage mechanics in which double-damage criterion is considered.The damage evolution and accumulation of RVEs are used to reveal the macroscopic rock failure characteristics.Each single RVE will be represented by one unique element.The initiation,propagation and coalescence of meso-to macro-cracks are captured by smearing failed elements.The above ideas are formulated into the framework of the DSM and programed into self-developed rock failure process analysis(RFPA)software.Two laboratory-scale examples are conducted and the well-known engineering-scale tests,i.e.Atomic Energy of Canada Limited’s(AECL’s)Underground Research Laboratory(URL)tests,are used for verification.It shows that the simulation results match with other experimental results and field observations.
文摘提出求解环肋圆柱壳固有振动特性的辛解析方法。首先,采用“刚度平摊”法,将环肋等效为圆柱壳重量的增加,并选取合适的状态向量,通过Hamilton函数将环肋圆柱壳的自由振动问题导入辛对偶体系,环肋圆柱壳的固有振动问题被归结为辛本征值和辛本征解问题,原高阶控制微分方程被转化为一组低阶常微分方程组。然后,即可利用分离变量法求解环肋圆柱壳的固有频率和相应振型。通过数值算例将其与其他文献、有限元方法(Finite Element Method,FEM)所得的固有频率进行对比,验证了该方法的正确性和高精度。随后研究环肋数量和环肋截面尺寸对环肋圆柱壳固有频率的影响。
基金Project supported by the Shanghai Aerospace Science and Technology Innovation Foundation(No.SAST2021048)。
文摘Anisogrid composite lattice conical shells, which exhibit varying stiffness along their cone generators, are widely used as interstage structures in aerospace applications. Buckling under axial compression represents one of the most hazardous failure modes for such structures. In this paper, the smeared stiffness method, which incorporates the effect of component torsion, is used to obtain the equivalent stiffness coefficients for composite lattice conical shells with triangular and hexagonal patterns. A unified framework based on the variational differential quadrature (VDQ) method is established, leveraging its suitability for asymptotic expansion to determine the critical buckling loads and the b-imperfection sensitivity parameter of lattice conical shells with axially varying stiffness due to rib layout. The influence of pre-buckling deformation is taken into account to enhance the accuracy of predictions on the linear buckling loads. The feasibility of the present equivalent continuum model is verified, and the differences in buckling behaviors for composite lattice conical shells with both triangular and hexagonal unit cells are numerically evaluated through the finite element (FE) simulations and the VDQ method.
