Effects of Suspension Rope on Modal Experiment of Rockets
TANG Bo;FAN Rui-xiang;PAN Zhong-wen;ZHANG Yong-liang;Beijing Institute of Astronautical System Engineering;China Academy of Launch Vehicle Technology;Beijing Institute of Structure & Environment;
The vibration equations and boundary conditions are established from the energy function of a beam system which is suspended with ropes; subsequently,the natural frequency characteristics equation is acquired. It is demonstrated that the free-free boundary model is the degenerated condition of the beam system. By solving this characteristics equation numerically,the natural frequency and modal relative to the length or density of the suspension rope is obtained. The appearance of the multiple first-order modals in a certain rocket's modal test is explained by using this method.