Nonlinear random vibration analysis on free standing grain of SRM

Paper number

IAC-11,C2,3,12,x9681

Author

Mr. Kuai He, Shanghai Academy of Spaceflight Technology, China

Coauthor

Dr. Chengli Mao, Shanghai Academy of Spaceflight Technology, China

Coauthor

Mr. Cheng Zhang, Shanghai Academy of Spaceflight Technology, China

Year

2011

Abstract

Free standing grain of solid rocket motor (SRM) has great backfill coefficient, so it plays an important role in many astronautic products. Comparing with case bonded grain, there is no structural integrity issue of free standing grain. However, the vibration state of the type of grain is complex under random vibration because of the gap between propellant and case and it leads to poor environmental adaptability of free standing grain. By nonlinear random vibration analysis, we get more insight into the mechanical response and vibration characteristics and it provides reference evidences for the improving of mechanic environmental adaptability.
The time domain data of acceleration is achieved by Monte Carlo method based on the Power Spectral Densities (PSD) in environmental test. The three dimensional model of free standing grain is established and the nonlinear factors which are contact and viscoelasticity are included in finite analysis with time domain numerical simulation. Due to the difficulty of data measuring to propellant in the motor, a sample is designed and tested on the vibration platform. The numerical simulation of sample is performed and comparisons of the results are made with calibration data. The reliability of the finite method is demonstrated.
The stress and strain distribution, contact pressure and the displacement, velocity and acceleration of propellant under vibration achieved. With the information, the key zones which cause failure easily come out and we could make a conclusion of security. The frequency domain characteristics are achieved via carrying out FFT to displacement and acceleration. Also, the evaluation of environmental adaptability to the grain is obtained.
The results show that the time domain numerical simulation is an efficient method to nonlinear random vibration analysis on free standing grain and it overcomes the shortcomings of frequency domain method. The all-around knowledge of propellant under vibration could be obtained and the precision is satisfying. According to the distribution o f stress and strain, the maximum of them is smaller than the limited characteristic and the strength failure will not happen under vibration .However, the fatigue failure in the end of grain appears with a higher probability. The master frequency of the grain is achieved by spectrum analysis.

Abstract document

IAC-11,C2,3,12,x9681.brief.pdf

Manuscript document

IAC-11,C2,3,12,x9681.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.