To understand the effect of attitude angle on helicopter water ditching,a finite element model(FEM)of helicopter water ditching was established via the nonlinear finite element method.Based on the LS-DYNA software,the...To understand the effect of attitude angle on helicopter water ditching,a finite element model(FEM)of helicopter water ditching was established via the nonlinear finite element method.Based on the LS-DYNA software,the finite element model of the helicopter was established.Different attitude of helicopter water ditching was simulated and analysed.Three pressure measuring points were arranged in the aircraft belly area.The pressure curves were provided seperately.Finally,the effects of attitude on helicopter water ditching was discussed,particularly the stability and the overload of helicopter.Through the contours of stress,it can be figured out that the maximum pressure locates at the position of aircraft belly where stiffness is larger.Then simulation and experimental results were compared.The difference of peak acceleration along the Z direction was small.Therefore,this method is feasible and helpful for the design of helicopter water ditching.展开更多
According to the annual variation of water discharge and water quality of Xidagou in Lingwu in Ningxia,combining local cropping system,the influence degree of ditch water recharge on soil and crop was studied,and the ...According to the annual variation of water discharge and water quality of Xidagou in Lingwu in Ningxia,combining local cropping system,the influence degree of ditch water recharge on soil and crop was studied,and the feasibility of ditch water recharge was analyzed in our paper,which could provide scientific basis for the utilization of ditch water recharge in local area.展开更多
基金funded by the International S&T Cooperation Program of China(No.2011DFR80210)the National Natural Science Foundation of China(No.11302105)
文摘To understand the effect of attitude angle on helicopter water ditching,a finite element model(FEM)of helicopter water ditching was established via the nonlinear finite element method.Based on the LS-DYNA software,the finite element model of the helicopter was established.Different attitude of helicopter water ditching was simulated and analysed.Three pressure measuring points were arranged in the aircraft belly area.The pressure curves were provided seperately.Finally,the effects of attitude on helicopter water ditching was discussed,particularly the stability and the overload of helicopter.Through the contours of stress,it can be figured out that the maximum pressure locates at the position of aircraft belly where stiffness is larger.Then simulation and experimental results were compared.The difference of peak acceleration along the Z direction was small.Therefore,this method is feasible and helpful for the design of helicopter water ditching.
基金Supported by National Science and Technology Major Program of Water Pollution Control and Management in China(2009ZX07212-004-2)~~
文摘According to the annual variation of water discharge and water quality of Xidagou in Lingwu in Ningxia,combining local cropping system,the influence degree of ditch water recharge on soil and crop was studied,and the feasibility of ditch water recharge was analyzed in our paper,which could provide scientific basis for the utilization of ditch water recharge in local area.
