The micromechanical damage of a composite solid propellant was observed by in situ scanning electron microscopy. Based on the damage characteristics, a cohesive interfacial element was adopted to model the debonding processes along the particles and the binder interface. The effects of interfacial strength and microcracks in the binder on the debonding process of propellant were also examined. The results show that interfacial debonding is the propellant's main failure mode under tension. Finite element method analyses with a cohesive interfacial element could predict the heterogeneous strain and stress fields as well as the processes of the particles separated from the binder. Interfacial strength plays a significant role in macroscopic behaviors of the propellant. Microcracks in the binder significantly influence the debonding process. The numerical simulation results reasonably reflect the corresponding experimental results. These results provide the basis for the prediction of mechanical properties and the optimal design of the composite solid propellant.

No abstract

No abstract

In this paper, three controllers, which are the integer order PID(IOPID) controller, the fuzzy PID(FPID) controller and the fractional order PID(FOPID) controller for a class of high order systems, are designed. From the simulation, the three controllers designed work efficiently. Moreover, it is interesting to observe that the dynamic characteristic of the designed system based on the FOPID controller outperforms the other controllers.

In order to study the effects of shipboard environment on solid motor grain, the ambient temperature in multi-launch containers were monitored. The temperature and stress fields of solid propellant grain under different ambient temperature were obtained using three-dimensional viscoelastic finite element method. It is shown by the results that the changed trend of temperature, stress and strain of motors in multi-container is similar to the environment temperature. The stress and strain were largest at the star tip of grain, and the stress and strain were closer in the upper and bottom layer containers.