In this paper, a set of variational formulas of solving nonlinear instability critical loads are established from the viewpoint of variational principle. The paper shows that it is very convenient to solve nonlinear i...In this paper, a set of variational formulas of solving nonlinear instability critical loads are established from the viewpoint of variational principle. The paper shows that it is very convenient to solve nonlinear instability critical load by using the variational formulas suggested in this paper.展开更多
A systematic experimental research work is done for the stability of sunken large diameter cylinder during construction period. It is the first research that gives the method for assessing the stability of the larger ...A systematic experimental research work is done for the stability of sunken large diameter cylinder during construction period. It is the first research that gives the method for assessing the stability of the larger diameter cylindrical structure, a set of values is derived also for the critical stability indices of the large diameter cylinder sunken to the sandy seabed.展开更多
The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equ...The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equilibrium points and the saddle node bifurcation point are computed through employing a variable step Runge Kutta method and the Poincaré map. Finally, numerical simulations are carried out for the stability of a high speed passenger car operating on straight and large radius curved tracks. The influences of the radius of curvature and the superelevation of the track on the stability of the vehicle system are investigated.展开更多
Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation (during loading) and vanishing (in unloading) of a high strain (martensite) domain. The two events...Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation (during loading) and vanishing (in unloading) of a high strain (martensite) domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales (the normalized tube length and normalized wall-thickness) and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model.展开更多
In this paper, the stability problem of Bingham fluids flowing down an inclinedplane is studied with respect to two dimensional disturbances. The crilical Reynolodsnumber is given in ihe case of long waves, and the e...In this paper, the stability problem of Bingham fluids flowing down an inclinedplane is studied with respect to two dimensional disturbances. The crilical Reynolodsnumber is given in ihe case of long waves, and the effect of yield stress on stability isanalysed.展开更多
The steady-state flow field characteristics have important effects on the stability of the throttled surge tank with the standpipe. This paper analyzes these effects on the basis of the numerical simulation of the flo...The steady-state flow field characteristics have important effects on the stability of the throttled surge tank with the standpipe. This paper analyzes these effects on the basis of the numerical simulation of the flow field by using the Computational Fluid Dynamics (CFD) method. It is shown that the anticlockwise recirculation zone is formed in the standpipe, which affects the local head loss at the junction of the standpipe with the pipeline. The variation of the head loss coefficient at the junction is linearly related with the diameter ratio of the standpipe to the pipeline. The dimensionless recirculation flow rate is proportional to the square of the diameter ratio. Considering the effects of the recirculation zone, an empirical expression of the critical stability area is obtained. Comparing with the Thoma critical area, the area obtained by the present method is smaller, and the reduction depends on the diameter ratio and the ratio of the velocity head to the head losses in the tunnel. words:展开更多
文摘In this paper, a set of variational formulas of solving nonlinear instability critical loads are established from the viewpoint of variational principle. The paper shows that it is very convenient to solve nonlinear instability critical load by using the variational formulas suggested in this paper.
文摘A systematic experimental research work is done for the stability of sunken large diameter cylinder during construction period. It is the first research that gives the method for assessing the stability of the larger diameter cylindrical structure, a set of values is derived also for the critical stability indices of the large diameter cylinder sunken to the sandy seabed.
文摘The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equilibrium points and the saddle node bifurcation point are computed through employing a variable step Runge Kutta method and the Poincaré map. Finally, numerical simulations are carried out for the stability of a high speed passenger car operating on straight and large radius curved tracks. The influences of the radius of curvature and the superelevation of the track on the stability of the vehicle system are investigated.
基金supported by the Hong Kong Research Grants Council (GRF619511)the National Natural Science Foundation of China (11128204)
文摘Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation (during loading) and vanishing (in unloading) of a high strain (martensite) domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales (the normalized tube length and normalized wall-thickness) and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model.
文摘In this paper, the stability problem of Bingham fluids flowing down an inclinedplane is studied with respect to two dimensional disturbances. The crilical Reynolodsnumber is given in ihe case of long waves, and the effect of yield stress on stability isanalysed.
基金supported by the National Natural Science Foundation of China(Grant No.51079050)the Doctoral Innovation Foundation in Jiangsu Province(Grant No.2017-B0803338)
文摘The steady-state flow field characteristics have important effects on the stability of the throttled surge tank with the standpipe. This paper analyzes these effects on the basis of the numerical simulation of the flow field by using the Computational Fluid Dynamics (CFD) method. It is shown that the anticlockwise recirculation zone is formed in the standpipe, which affects the local head loss at the junction of the standpipe with the pipeline. The variation of the head loss coefficient at the junction is linearly related with the diameter ratio of the standpipe to the pipeline. The dimensionless recirculation flow rate is proportional to the square of the diameter ratio. Considering the effects of the recirculation zone, an empirical expression of the critical stability area is obtained. Comparing with the Thoma critical area, the area obtained by the present method is smaller, and the reduction depends on the diameter ratio and the ratio of the velocity head to the head losses in the tunnel. words: