Two types of sensitivities are proposed for stat- ically stable sailcrafts. One type is the sensitivities of solar-radiation-pressure force with respect to position of the center of mass, and the other type is the sen...Two types of sensitivities are proposed for stat- ically stable sailcrafts. One type is the sensitivities of solar-radiation-pressure force with respect to position of the center of mass, and the other type is the sensitivities of solar-radiation-pressure force with respect to attitude. The two types of sensitivities represent how the solar-radiation- pressure force changes with the position of mass center and the attitude. Sailcrafts with larger sensitivities undergo larger error of the solar-radiation-pressure force, leading to larger orbit error, as demonstrated by simulation. Then as a case study, detailed formulas are derived to calculate the sensi- tivities for sailcrafts with four triangular sails. According to these formulas, in order to reduce both types of sensitivities, the angle between opposed sails should not be too large, and the center of mass should be as close to the axis of symmetry of the four sails as possible and as far away from the center of pressure of the sailcraft as possible.展开更多
In order to evaluate the vibration characteristics of non-rigid airship with suspended curtain,we introduce vibration characteristic analysis method of the inflatable membrane structure.Modal numerical method of the i...In order to evaluate the vibration characteristics of non-rigid airship with suspended curtain,we introduce vibration characteristic analysis method of the inflatable membrane structure.Modal numerical method of the inflatable membrane structure under the pressure difference is validated by the model testing of the inflatable cantilever tube.The finite element model of 75 m airships is established to simulate the vibration characteristics subjected to only pressure difference and the resultant force of weight and buoyancy.The nonlinear static deformation and stress analysis are investigated for two kinds of equilibrated configurations with various pressure differences,as well as the vibration characteristics.The structural efficiency of the suspended curtain is investigated through the force transfer ratio at the assumed equilibrated point.The effects of manufacture error of the suspended cable length on the structural behavior are analyzed.The results indicate that the local area of airship envelope connected to the suspended cable is a weak part.Various pressures and pressure gradients have significant effects on the global airship structure and the suspended curtain.The suspended curtain is effective to transfer the equilibrated force from the bottom to the top of airship envelope.Manufacture error of the suspended cable length could result in obvious deformation of local airship envelope.The presented work is valuable to the structural engineering design of stratospheric airship.展开更多
基金supported by the National Natural Science Foundation of China (10832004)China Postdoctoral Science Foundation (023200006)
文摘Two types of sensitivities are proposed for stat- ically stable sailcrafts. One type is the sensitivities of solar-radiation-pressure force with respect to position of the center of mass, and the other type is the sensitivities of solar-radiation-pressure force with respect to attitude. The two types of sensitivities represent how the solar-radiation- pressure force changes with the position of mass center and the attitude. Sailcrafts with larger sensitivities undergo larger error of the solar-radiation-pressure force, leading to larger orbit error, as demonstrated by simulation. Then as a case study, detailed formulas are derived to calculate the sensi- tivities for sailcrafts with four triangular sails. According to these formulas, in order to reduce both types of sensitivities, the angle between opposed sails should not be too large, and the center of mass should be as close to the axis of symmetry of the four sails as possible and as far away from the center of pressure of the sailcraft as possible.
基金the National Natural Science Foundation of China(No.51278299)
文摘In order to evaluate the vibration characteristics of non-rigid airship with suspended curtain,we introduce vibration characteristic analysis method of the inflatable membrane structure.Modal numerical method of the inflatable membrane structure under the pressure difference is validated by the model testing of the inflatable cantilever tube.The finite element model of 75 m airships is established to simulate the vibration characteristics subjected to only pressure difference and the resultant force of weight and buoyancy.The nonlinear static deformation and stress analysis are investigated for two kinds of equilibrated configurations with various pressure differences,as well as the vibration characteristics.The structural efficiency of the suspended curtain is investigated through the force transfer ratio at the assumed equilibrated point.The effects of manufacture error of the suspended cable length on the structural behavior are analyzed.The results indicate that the local area of airship envelope connected to the suspended cable is a weak part.Various pressures and pressure gradients have significant effects on the global airship structure and the suspended curtain.The suspended curtain is effective to transfer the equilibrated force from the bottom to the top of airship envelope.Manufacture error of the suspended cable length could result in obvious deformation of local airship envelope.The presented work is valuable to the structural engineering design of stratospheric airship.
