Pressure wave propagation in pressurized thin-walled circular tubes under axial impact

Abstract

The pressurized thin-walled tubes are called as a member of adaptive energy absorbers of which energy absorbing performance can be controlled by variation of internal pressure. In this context, this study numerically investigates the axial impact performance of pressurized thin-walled circular tubes. For the realistic modeling of the compressed air, the ALE model was developed in LS-DYNA, which enabled an opportunity to investigate both pressure wave propagation in pressurized air and fluid-structure interaction effects between tube-wall and air. In addition, the models were run by taking into account both states, whether pressure regulator, which is an adjustable valve to control internal pressure value, was active. To validate the numerical models, the axial impact tests on Aluminum Aerosol cans were carried out using a light gas gun set-up. The results showed that at the onset of impact, a radial pressure wave, as well as an axial pressure one, simultaneously emerged. Whereas a radial pressure wave propagated towards the center from the tube-wall, the other one propagated along the centerline of the tube. Therefore, a complex pressure distribution and wave propagation occurred in the pressurized tubes. The pressure distribution obtained in the model with a pressure regulator revealed different behavior from the corresponding one obtained without pressure regulator. Also, the results showed that there is no distinct interaction between strain energy absorbed by tube-wall and pressure wave propagation although the total absorbed energy of pressurized tubes increases to some extent with the effects of wave propagation in the pressurized medium.