A numerical code called RFPA-Dynamics was used to study the rockburst mechanism under dynamic load based on coupled static-dynamic analysis.The results show that dynamic disturbance has a very distinct triggering effe...A numerical code called RFPA-Dynamics was used to study the rockburst mechanism under dynamic load based on coupled static-dynamic analysis.The results show that dynamic disturbance has a very distinct triggering effect on rockburst.Under the dynamic load,rockburst is motivated by tensile stress formed by the overlapping of dynamic waves in the form of instantaneous open and cutting through of cracks in weak planes and pre-damaged areas.Meanwhile,the orientation of joint sets has an obvious leading effect on rockburst locations.Finally,a higher initial static stress state before dynamic loading can cause more pre-damaged area,thus leading to a larger rockburst scope.展开更多
A method for static aeroelastic trim analysis and flight loads computation of a flexible aircraft with large deformations has been presented in this paper,which considers the geometric nonlinearity of the structure an...A method for static aeroelastic trim analysis and flight loads computation of a flexible aircraft with large deformations has been presented in this paper,which considers the geometric nonlinearity of the structure and the nonplanar effects of aerodynamics.A nonplanar vortex lattice method is used to compute the nonplanar aerodynamics.The nonlinear finite element method is introduced to consider the structural geometric nonlinearity.Moreover,the surface spline method is used for structure/aerodynamics coupling.Finally,by combining the equilibrium equations of rigid motions of the deformed aircraft,the nonlinear trim problem of the flexible aircraft is solved by iterative method.For instance,the longitudinal trim analysis of a flexible aircraft with large-aspect-ratio wings is carried out by both the nonlinear method presented and the linear method of MSC Flightloads.Results obtained by these two methods are compared,and it is indicated that the results agree with each other when the deformation is small.However,because the linear method of static aeroelastic analysis does not consider the nonplanar aerodynamic effects or structural geometric nonlinearity,it is not applicable as the deformations increase.Whereas the nonlinear method presented could solve the trim problem accurately,even the deformations are large,which makes the nonlinear method suitable for rapid and efficient analysis in engineering practice.It could be used not only in the preliminary stage but also in the detail stage of aircraft design.展开更多
A novel method for the static analysis of structures with interval parameters under uncertain loads is proposed, which overcomes the inherent conservatism introduced by the conventional interval analysis due to ignori...A novel method for the static analysis of structures with interval parameters under uncertain loads is proposed, which overcomes the inherent conservatism introduced by the conventional interval analysis due to ignoring the dependency phenomenon. Instead of capturing the extremum of the structural static responses in the entire space spanned by uncertain parameters, their lower and upper bounds are calculated at the minimal and maximal point vectors obtained dimension by dimension with respect to uncertain parameters based on the Legend orthogonal polynomial approximation, overcoming the potential engineering insignificance caused by the optimization strategy. After performing its theoretical analysis, both the accuracy and applicability of the proposed method are verified.展开更多
基金Project(90401004)supported by the Fundamental Research Funds for the Central Universities of ChinaProjects(20100471465,201104572)supported by China Postdoctoral Science Foundation+1 种基金Project(20091029)supported by Postdoctoral Science Foundation of Liaoning Province,ChinaProjects(50934006,51111130206)supported by the National Natural Science Foundation of China
文摘A numerical code called RFPA-Dynamics was used to study the rockburst mechanism under dynamic load based on coupled static-dynamic analysis.The results show that dynamic disturbance has a very distinct triggering effect on rockburst.Under the dynamic load,rockburst is motivated by tensile stress formed by the overlapping of dynamic waves in the form of instantaneous open and cutting through of cracks in weak planes and pre-damaged areas.Meanwhile,the orientation of joint sets has an obvious leading effect on rockburst locations.Finally,a higher initial static stress state before dynamic loading can cause more pre-damaged area,thus leading to a larger rockburst scope.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11172025,91116005)the Research Fund for the Doctoral Program of Higher Education of China (Grant No.20091102110015)
文摘A method for static aeroelastic trim analysis and flight loads computation of a flexible aircraft with large deformations has been presented in this paper,which considers the geometric nonlinearity of the structure and the nonplanar effects of aerodynamics.A nonplanar vortex lattice method is used to compute the nonplanar aerodynamics.The nonlinear finite element method is introduced to consider the structural geometric nonlinearity.Moreover,the surface spline method is used for structure/aerodynamics coupling.Finally,by combining the equilibrium equations of rigid motions of the deformed aircraft,the nonlinear trim problem of the flexible aircraft is solved by iterative method.For instance,the longitudinal trim analysis of a flexible aircraft with large-aspect-ratio wings is carried out by both the nonlinear method presented and the linear method of MSC Flightloads.Results obtained by these two methods are compared,and it is indicated that the results agree with each other when the deformation is small.However,because the linear method of static aeroelastic analysis does not consider the nonplanar aerodynamic effects or structural geometric nonlinearity,it is not applicable as the deformations increase.Whereas the nonlinear method presented could solve the trim problem accurately,even the deformations are large,which makes the nonlinear method suitable for rapid and efficient analysis in engineering practice.It could be used not only in the preliminary stage but also in the detail stage of aircraft design.
基金supported by the Defense Industrial Technology Development Program(Grant Nos.A2120110001 and B2120110011)‘111’ Project(Grant No.B07009)the National Natural Science Foundation of China(Grant Nos.90816024 and 10876100)
文摘A novel method for the static analysis of structures with interval parameters under uncertain loads is proposed, which overcomes the inherent conservatism introduced by the conventional interval analysis due to ignoring the dependency phenomenon. Instead of capturing the extremum of the structural static responses in the entire space spanned by uncertain parameters, their lower and upper bounds are calculated at the minimal and maximal point vectors obtained dimension by dimension with respect to uncertain parameters based on the Legend orthogonal polynomial approximation, overcoming the potential engineering insignificance caused by the optimization strategy. After performing its theoretical analysis, both the accuracy and applicability of the proposed method are verified.
