A method of augmenting an airborne vehicle for short-period dynamics and stability by passive means is presented in this study.A trajectoryphase disturbance rejection capability is achieved for an unguided fin-stabili...A method of augmenting an airborne vehicle for short-period dynamics and stability by passive means is presented in this study.A trajectoryphase disturbance rejection capability is achieved for an unguided fin-stabilized vehicle by flexible mounting of the fins to the vehicle body.The deflecting fins lag the body oscillation such that the harmonic oscillation can be quickly dampened.The amount of fin deflection may be chosen by a hinge-line location;among other things,the vehicle damping behaviour is largely determined by this choice.Linear theory is applied and 6-DOF simulations are carried out to demonstrate the approach suitability for the task.展开更多
Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering.Basalt fiber is a new kind of environment-friendly and highperfo...Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering.Basalt fiber is a new kind of environment-friendly and highperformance soil reinforcement material,and the mechanical properties of basalt fiber-reinforced soil have become a hot research topic.In this paper,we conducted monotonic triaxial and cyclic triaxial tests,and analyzed the influence of the fiber content,moisture content,and confining pressure on the shear characteristics,dynamic modulus,and damping ratio of basalt fiber-reinforced silty clay.The results illustrate that basalt fiber can enhance the shear strength of silty clay by increasing its cohesion.We find that the shear strength of reinforced silty clay reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%(optimum moisture content).Similarly,we also find that the dynamic modulus that corresponds to the same strain first increases then decreases with increasing fiber content and moisture content and reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%.The dynamic modulus is positively correlated with the confining pressure.However,the change in the damping ratio with fiber content,moisture content,and confining pressure is opposite to that of the dynamic modulus.It can be concluded that the optimum content of basalt fiber for use in silty clay is 0.2%.After our experiments,we used scanning electron microscope(SEM)to observe the microstructure of specimens with different fiber contents,and our results show that the gripping effect and binding effect are the main mechanisms of fiber reinforcement.展开更多
文摘A method of augmenting an airborne vehicle for short-period dynamics and stability by passive means is presented in this study.A trajectoryphase disturbance rejection capability is achieved for an unguided fin-stabilized vehicle by flexible mounting of the fins to the vehicle body.The deflecting fins lag the body oscillation such that the harmonic oscillation can be quickly dampened.The amount of fin deflection may be chosen by a hinge-line location;among other things,the vehicle damping behaviour is largely determined by this choice.Linear theory is applied and 6-DOF simulations are carried out to demonstrate the approach suitability for the task.
基金Project(51978674) supported by the National Natural Science Foundation of ChinaProject(2017G008-A) supported by the China Railway Corporation Science and the Technology Development Project。
文摘Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering.Basalt fiber is a new kind of environment-friendly and highperformance soil reinforcement material,and the mechanical properties of basalt fiber-reinforced soil have become a hot research topic.In this paper,we conducted monotonic triaxial and cyclic triaxial tests,and analyzed the influence of the fiber content,moisture content,and confining pressure on the shear characteristics,dynamic modulus,and damping ratio of basalt fiber-reinforced silty clay.The results illustrate that basalt fiber can enhance the shear strength of silty clay by increasing its cohesion.We find that the shear strength of reinforced silty clay reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%(optimum moisture content).Similarly,we also find that the dynamic modulus that corresponds to the same strain first increases then decreases with increasing fiber content and moisture content and reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%.The dynamic modulus is positively correlated with the confining pressure.However,the change in the damping ratio with fiber content,moisture content,and confining pressure is opposite to that of the dynamic modulus.It can be concluded that the optimum content of basalt fiber for use in silty clay is 0.2%.After our experiments,we used scanning electron microscope(SEM)to observe the microstructure of specimens with different fiber contents,and our results show that the gripping effect and binding effect are the main mechanisms of fiber reinforcement.
