Three-dimensional Reynolds-averaged Navier-Stokes simulations have been performed to explore the aerodynamic characteristics of ramjet projectiles. The turbulence model used is the RNG k-ε model. The numerical algorithms termed total variational diminishing (TVD) was adopted. The complex wave structures of ramjet projectiles with different architecture at different inflow Mach number were achieved by numerical simulation. The influence of inflow Mach number on aerodynamic characteristics and pressure center of ramjet projectiles were analyzed. Results show that lift coefficient and pressure center increase with the argument of inflow Mach number. Ramjet projectiles with different architecture have different drag coefficient trend.

In order to study the effect of the fraction of PVA fiber on the axial compressive strength and flexural properties of high performance concrete, a series of tests have been conducted in this study. The middle span deflection was measured by a micrometer with dial indicator, and six different concrete mixes have been chosen. Flexural properties include flexural strength and flexural modulus of elasticity. The mechanism of PVA fiber acting on axial compressive strength, flexural strength and flexural modulus of elasticity has been analyzed in details. The results indicate that there is a tendency of increase in the axial compressive strength and flexural strength when the fiber volume fraction is below 0.08%, and the flexural modulus of elasticity of high-performance concrete decrease gradually with the increase of fiber volume fraction.

Due to influence by many factors like soil classification, viscosity property and vibration frequency, there is no common view yet about the effect of frequency on dynamic pore pressure and characteristics. In order to study the development of pore pressure, strain and dynamic strength of Hangzhou Bay undisturbed structural silty clay under different vibration frequencies, cyclic triaxial tests were performed. The test results indicate that the frequency has little influence on pore pressure and strain when they didn’t reach the threshold values, but once they exceeded the threshold values the frequency will has strong influence. There is critical cyclic stress ratio when the cyclic stress ratio has not reached that value, the frequency has no influence on dynamic strength. For the given cycles, the higher the frequency is, the bigger the dynamic strength is. And with the increment of frequency, the influence on dynamic is decreased eventually.