Finite Element Analysis On The Operation Of Submarine Move-in-soil Robot Based On CEL Algorithm

The common method for salvaging sunken ships is with salvage pontoons.In the salvage operation,divers are essential to manually attack a small tunnel underwater and lead the wire go through the tunnel.It is so danger and difficult for divers to operate in the deep ocean and the polluted gulf or channel.Thus,it is necessary to design an automatic move-in-soil robot to lead the wire go through the soil instead of divers.To accomplish this operation,when the parameters of soil meet the working conditions of the robot,we must gain the motion parameters to design the trajectory of robot in a specific soil and prepare to write a program for the robot moving automatically.It is known well that move-in-soil robot moves forward under the interaction between the support force of the feet and the resistance of the head.And the movement parameters could be determined by the support force and the resistance.Consequently,the mainly purpose of this thesis is to research the influence of the soil properties on the movement parameters,the working conditions and the movement mechanism of the robot.The motion consists of many punching units.And as the robot moves forward,in every movement phase,large deformations and even failure will take place continuously in the soil.In this thesis,the Coupled Eulerian-Lagrangian Method(CEL),which can deal with large deformation problems in three-dimension space,was applied to simulate the straight and rotary motion of the move-in-soil robot in saturated marine clay.The soil is considered as a perfect elasto-plastic material,in according with the Tresca criteria and the associated flow rule.The phenomenon,the large deformations and failure of the soil,and the interaction between the robot and the soil could be simulated and described by CEL method.Through the connector element in ABAQUS,the motion of piston could be simulated.According to the calculation results,as to a specific move-in-soil robot,its working conditions are related to the undrained shear strength and the soil stiffness.The average velocity and acceleration of the robot is convenient to design the motion trajectory.The load conditions in the restoring step have an important effect on the movement velocity.The end support force and the lateral support force acting on the foot-A play an important role on the motion.