Design and Optimization of Multipoint Sampler for Seafloor Sediment Carried by a Deep-Sea Landing Vehicle

Abstract

The present study proposes a low-energy consumption multipoint sampler carried by a deep-sea landing vehicle (DSLV) to meet the requirements of time series sampling in local areas and location series sampling in wide areas, and an optimization method of sampling structure based on least-squares support-vector machine (LSSVM) surrogate model and a multi-objective particle swarm optimization (MOPSO) algorithm. First, the overall structure and core components, such as the multipoint sampler’s sampling structure, were designed. The optimization variables were the cone angle, sampling tube inner diameter, and sampling tube inner hole length, which were determined by considering the force with which the sampling structure penetrates the seafloor sediment. Then, the sampling process was simulated by the finite element method-smoothed particle hydrodynamics (FEM-SPH) method, while the accurate LSSVM model of force required for sampling and sampling tube volume was established. Finally, the MOPSO algorithm was used for multi-objective optimization of model parameters of sampling structure. The optimal model of sampling structure that can provide theoretical support for the optimal design of multipoint sampler effectively reduces energy consumption and improves sampling efficiency by force required for sampling 25.89% lower and sampling tube volume 34.81% higher than the original model.

Numerical simulation and experimental study on seafloor sampling of an anchor-type mud collector based on SPH-FEM coupling method

“…Guo et al 17 used ABAQUS software to study the soil–tube interaction during sampling using Euler–Lagrange coupling (CEL) and showed that at a penetration depth of 50 mm, the penetration resistance of the sampling tube was 599 N. The pressure-holding transfer process of the overburden water was simulated using the dynamic grid technique and FLUENT software, and the results showed that the pressure flux of the sample could be guaranteed to be no more than 0.03%. Gao et al 18 used the finite element-smooth particle hydrodynamics (FEM-SPH) method to numerically simulate the sampling process. He et al 19 used the volume of fluid (VOF) method to model soft viscous seafloor sediments as non-Newtonian Herschel–Bulkley viscoplastic fluids, established a numerical model for tubular sampling, and investigated the effects of the sampling tube diameter, drainage area rate, penetration velocity and the effects of sediment dynamic viscosity on coring rate and volume.…”