Based on the analysis of complex terrains and current forest transportation equipment,a forest tracked vehicle prototype LY1352 JP was developed.The road model and the virtual prototype of the chassis were constructed...Based on the analysis of complex terrains and current forest transportation equipment,a forest tracked vehicle prototype LY1352 JP was developed.The road model and the virtual prototype of the chassis were constructed using dynamic simulation software RecurDyn.The optimal tension of the vehicle as well as its capabilities for crossing trenches,climbing vertical walls,uphill and downhill slopes were simulated.The simulation results showed that the optimum tension force of the chassis of the vehicle was 63 kN(kilonewton),accounting for 45%of the total vehicle weight.The maximum trench crossing width and vertical obstacle climbing height were 1.35 m and 0.45 m,respectively.The maximum uphill and downhill angles were 50°and 45°,respectively.Tests on the prototype capacity for crossing trenches,and uphill and downhill driving were carried out.The test results were in agreement with the simulation results.A cross-country performance of a fire truck based on the tracked vehicle chassis was conducted in an old-growth forest.Tests verified that the vehicle has a strong forest trafficability performance and can meet the needs for forest transportation.展开更多
Based upon a discussion on the merits and limitations of proportional navigation（PN）guidance law in which constant gravity compensation is included as a part,a counterpart having varying compensations,which changes ...Based upon a discussion on the merits and limitations of proportional navigation（PN）guidance law in which constant gravity compensation is included as a part,a counterpart having varying compensations,which changes with pitching angle and line-of-sight angle,is substituted.Flight trajectory simulation over a submissile model is conducted,resulting in increased impact angle,shorter miss distance,smaller maximum normal overload and narrower terminal angle of attack.展开更多
The formation mechanism of an EFP(explosively formed projectile)using a double curvature liner under the overpressure effect generated by a regular oblique reflection was investigated in this paper.Based on the detona...The formation mechanism of an EFP(explosively formed projectile)using a double curvature liner under the overpressure effect generated by a regular oblique reflection was investigated in this paper.Based on the detonation wave propagation theory,the change of the incident angle of the detonation wave collision at different positions and the distribution area of the overpressure on the surface of the liner were calculated.Three dimensional numerical simulations of the formation process of the EFP with tail.as well as the ability to penetrate 45#steel were performed using LS-DYNA software,and the EFP ve locity,the penetration ability,and the forming were assessed via experiments and x_ray photographs.The experimental results coincides with those of the simulations.Results indicate that the collision of the detonation wave was controlled to be a regular oblique reflection acting on the liner by setting the di-mensions of the unit charge and maintai ning the pressure at the collision point region at more than 2.4 times the CJ detonation when the incident angle approached the cnitical angle.The distance from the liner midline to the boundary of the area within which the pressure ratio of the regular oblique reflection pressure to the qJ detonation pressure was greater than 2.5,2,and 15was approximately 0.66 mm,132 mm,and 3.3 mm,respectively.Itis noted that pressure gradient caused the liner to turn inside out in the middle to form the head of the EFP and close the two tails of the EFP at approximately 120μs.The penetration depth of the EFP into a 45#steel target exceeded 30 mm,and there was radial expansion between the head and tail of the EFP,increasing the penetration resistance of the EFP.Therefore,the structural size of the unit charge and the liner can be further optimized to reduce resist ance to increase the penetration ability of the EFP.展开更多
基金funded by the Fundamental Research Funds for the Central Universities(No.2572019BL02)the National Key Research and Development Program of China(No.2018YFD0600205)。
文摘Based on the analysis of complex terrains and current forest transportation equipment,a forest tracked vehicle prototype LY1352 JP was developed.The road model and the virtual prototype of the chassis were constructed using dynamic simulation software RecurDyn.The optimal tension of the vehicle as well as its capabilities for crossing trenches,climbing vertical walls,uphill and downhill slopes were simulated.The simulation results showed that the optimum tension force of the chassis of the vehicle was 63 kN(kilonewton),accounting for 45%of the total vehicle weight.The maximum trench crossing width and vertical obstacle climbing height were 1.35 m and 0.45 m,respectively.The maximum uphill and downhill angles were 50°and 45°,respectively.Tests on the prototype capacity for crossing trenches,and uphill and downhill driving were carried out.The test results were in agreement with the simulation results.A cross-country performance of a fire truck based on the tracked vehicle chassis was conducted in an old-growth forest.Tests verified that the vehicle has a strong forest trafficability performance and can meet the needs for forest transportation.
文摘Based upon a discussion on the merits and limitations of proportional navigation（PN）guidance law in which constant gravity compensation is included as a part,a counterpart having varying compensations,which changes with pitching angle and line-of-sight angle,is substituted.Flight trajectory simulation over a submissile model is conducted,resulting in increased impact angle,shorter miss distance,smaller maximum normal overload and narrower terminal angle of attack.
基金The work presented in this paper has been supported by the science foundation(YT20-01-02)of Nanjing Vocational University of Industry Technology and the National Science Foundation of China under NO.11802141.
文摘The formation mechanism of an EFP(explosively formed projectile)using a double curvature liner under the overpressure effect generated by a regular oblique reflection was investigated in this paper.Based on the detonation wave propagation theory,the change of the incident angle of the detonation wave collision at different positions and the distribution area of the overpressure on the surface of the liner were calculated.Three dimensional numerical simulations of the formation process of the EFP with tail.as well as the ability to penetrate 45#steel were performed using LS-DYNA software,and the EFP ve locity,the penetration ability,and the forming were assessed via experiments and x_ray photographs.The experimental results coincides with those of the simulations.Results indicate that the collision of the detonation wave was controlled to be a regular oblique reflection acting on the liner by setting the di-mensions of the unit charge and maintai ning the pressure at the collision point region at more than 2.4 times the CJ detonation when the incident angle approached the cnitical angle.The distance from the liner midline to the boundary of the area within which the pressure ratio of the regular oblique reflection pressure to the qJ detonation pressure was greater than 2.5,2,and 15was approximately 0.66 mm,132 mm,and 3.3 mm,respectively.Itis noted that pressure gradient caused the liner to turn inside out in the middle to form the head of the EFP and close the two tails of the EFP at approximately 120μs.The penetration depth of the EFP into a 45#steel target exceeded 30 mm,and there was radial expansion between the head and tail of the EFP,increasing the penetration resistance of the EFP.Therefore,the structural size of the unit charge and the liner can be further optimized to reduce resist ance to increase the penetration ability of the EFP.
