Fluid effect of the water-filled missile on impact force

• Numerical analysis of the wet missile impact tests was conducted.
• The analysis of the results was verified by comparing with test results.
• Impact forces were calculated using two different missile pipe failure mechanisms.
• The modified Riera function was proposed for the case of the wet missile impact.

The Riera function has been widely used in determining the force–time history of the missile impact on rigid targets. However, in certain cases, it is necessary to modify it by adding a coefficient to the second term of the function. This coefficient has been determined by experimental and numerical studies. In this paper, the force–time histories of soft missiles, with and without filled water, impacting the target wall were investigated using finite element analysis (FEA). The force plate tests, with a dry missile (test FP8) and a wet missile (test FP16) carried out by Technical Research Centre of Finland (VTT), were used. The numerical analysis results were verified by comparing with those of experiments. A parametric analysis with different missile velocities was also performed to investigate the force–time history and impulse of the missile impact on target plate. Based on a comparison with the Riera approach, the coefficients were proposed to modify the Riera function. The analysis results show that, in the case of the dry missile, the Riera function does not need to be modified. However, in the case of the wet missile, the coefficients α from 1.25 to 1.58 are recommended to be added to the second term of the Riera function in the case in which the impact velocity is in the range of 70 m/s to 200 m/s.