| The shipborne tethered UAV system is attached to the ship,which mainly includes two parts: tethered cable and UAV platform.When the UAV moves greatly,the tethered cable may appear local relaxation and tension state,resulting in impact tension,and then fracture;similarly,the mutation tension of the cable will also affect the movement of the UAV platform,leading to the instability of the UAV,causing heavy losses.Therefore,it is necessary to study the impact response of Shipborne tethered UAV.In this paper,the stress wave method is used to study the shock response of Shipborne tethered UAV systemThe main research results of shock response of Shipborne tethered UAV are as follows(1)Considering the geometric nonlinearity,the tangential,normal and sub normal dynamic equations of Shipborne tethered UAV are derived by using Hamilton principle.Because the tangential and normal dynamic equations are coupled with each other,they are simplified under the assumption of small curvature,and the corresponding stress wave equations are obtained.(2)The characteristic method is used to analyze the wave equations.The results show that even if the tethered cable is a linear elastic constitutive relation,the propagation of stress wave in the tethered cable will still appear the phenomenon of geometric dispersion caused by geometric factors.The basis of the stress wave solution scheme is derived.Through numerical simulation,the dynamic responses of the shipborne tethered UAV under vertical excitation and lateral excitation are obtained.According to the calculation results of different working conditions,several methods to avoid excessive internal tension of Shipborne tethered UAV are proposed.(3)The dynamic response of the shipborne tethered UAV under the combined action of vertical excitation and lateral excitation is obtained by numerical simulation.Through dimensional analysis,the scale corresponding relationship between the model and the real object of the shipborne tethered UAV is obtained,and the experimental measurement devices and methods for different parameters of the tethered UAV are determined.The reason of birefringence phenomenon when fiber Bragg grating strain sensor measures the strain of slender composite cable is explored and improved.The theory is verified by model experiments and the results are in good agreement. |
