Analysis and modeling of the percussion coring of an innovative hydrostatic sediment corer

In order to optimize the utilization of the kinetic energy derived from the hydrostatic energy to collect more sediment core, the paper focus on the analysis and the modeling of the percussion coring of a hydrostatic seafloor sediment corer, including the modeling of the stress wave traveling along the tube and the construction of the dynamic model of the tube-sediment system. The hydrostatic corer is feature by using both the hydrostatic energy of the seawater and gravity potential energy to collect the sediment in a percussive way. The analysis results reveal the under-sampling phenomenon of the corer which was observed and confirmed by the sea trial. To weaken the under-sampling and improve the utilization of the hydrostatic energy, several effective factors have been studied through the dynamic model and the results shows that the large inner diameter of the tube and the high mechanical impedance of the cushion and the increase of the single percussion energy and the adequate area ratio of the tube can considerably weaken the under-sampling and improve the recovery ratio. The modeling method and analysis results can provide some instructive information for the design and improvement of the percussive seafloor sediment corer.