For the fracture failure phenomena occurred in random vibration experiment of the isolation clamp cylinder on the aerospace vehicles, the NX NASTRAN was used to make the finite element modeling for the overall structure of cylinder and analyze the random vibration response. The simulation results show that the maximum RMS stress of the clamp was 96 MPa at the test load conditions. The position of the maximum RMS stress is consistent with the one where fracture happens during vibration test. According to finite element analysis results, the original structure has been modified. The maximum RMS stress of modified structure is only 21.8 MPa.

The zirconium silicate can be deposited as functional coatings which will be used at high temperature because of its high melting point and low thermal conductivity. It can also prevent the oxygen of the environment through the coatings and react with the substrate. In this paper, plasma spraying technology was selected to prepare the coatings of zirconium silicate. The orthogonal design method was used to optimize the parameter of plasma spraying process. The content of zirconium silicate in the coatings was checked by XRD because of the decomposition of the zirconium silicate at 1711K.The bond strength and porosity of the coatings were also measured after the optimizing of the plasma spraying parameters in this paper. According the impact on the porosity, the factors of the process can be ordered as follows: spraying distance, current, primary gases and secondary gases. And the order of spraying factors according the impact on the content of zirconium silicate in the coatings was showed as follows: spraying distance, secondary gas, primary gas and current.

Based on the random vibration theory and numerical analysis method, the paper presents a process of carrying out the fatigue life prediction for pipeline of a rocket engine under random excitation. The numerical analysis adopt the power spectrum density of acceleration as random loads. The material parameters of the simulation contains two straight lines in double logarithmic coordinate. The location of danger points is found and the root mean square stress, fatigue life of it is acquired in different excitation directions. The results show that the root of the ball head is the location of danger points, whose fatigue life is 3763 seconds. Furthermore, the location of danger points and its fatigue life obtained from numerical analysis are consistent with the test.