Safety estimation of high-pressure hydraulic cylinder using FSI method

Hydraulic cylinder is a primary component of the hydraulic valve systems.The numerical study of hydraulic cylinder to evaluate the stress analysis,the life assessment and the performance of operation characteristics in hydraulic cylinder were described.The calculation of safety factor,fatigue life,piston chamber pressure,rod chamber pressure and the change of velocity of piston with flow time after the beginning of hydraulic cylinder were incorporated.Numerical analysis was performed using the commercial CFD code,ANSYS with unsteady,dynamic mesh model,two-way FSI(fluid-structure interaction)method and k-εturbulent model.The internal pressure in hydraulic cylinder through stress analysis show higher than those of the yield strength.

Numerical simulation and experimental verification of a novel double-layered split die for high-pressure apparatus used for synthesizing superhard materials

Based on the principles of massive support and lateral support, a novel double-layered split die(DLSD) for high-pressure apparatus was designed to achieve a higher pressure-bearing capacity and larger sample cavity. The stress distributions of the DLSDs with different numbers of divided blocks were investigated by the finite element method and compared with the stress distributions of the conventional belt-type die(BTD). The results show that the cylinders and first-layer supporting rings of the DLSDs have dramatically smaller stresses than those of the BTD. In addition, increasing the number of divided blocks from 4 to 10 gradually increases the stress of the cylinder but has minimal influence on the stress of the supporting rings. The pressure-bearing capacities of the DLSDs with different numbers of divided blocks, especially with fewer blocks, are all remarkably higher than the pressure-bearing capacity of the BTD. The contrast experiments were also carried out to verify the simulated results. It is concluded that the pressure-bearing capacities of the DLSDs with 4 and 8 divided blocks are 1.58 and 1.45 times greater than that of the BTD. This work is rewarding for the commercial synthesis of high-quality, large-sized superhard materials using a double-layered split high-pressure die.

Seal contact performance analysis of soft seals on high-pressure hydrogen charge valves

The charge valve is an important element in the charging port of a high-pressure hydrogen storage cylinder(HP-HSC).It is normally closed after the HP-HSC is filled with hydrogen.If the seal of the charge valve is damaged,it will seriously affect the stable operation of the hydrogen supply system and may even cause safety problems.Therefore,the seal performance of the charge valve is important.In this paper,finite element analysis(FEA)is carried out to analyze the seal contact performance of hydrogenated nitrile rubber(HNBR)gaskets in the seal pair of a charge valve.The effects of different pre-compressions,seal widths,and hydrogen pressures on the seal contact performance of the charge valve are analyzed.The contact pressure on the seal surface increases with the increase of pre-compression.With a pre-compression of 2.5 mm,the maximum contact pressure without and with hydrogen pressure are 68.51 and 107.38 MPa,respectively.A contact gap appears in the inner ring of the seal surface with pre-compression below 0.15 mm.The contact gap occurs between the entire seal surface with a seal width of1 mm.The contact pressure on the seal surface and the width of the separation area between the seal surfaces increase with the increase of the seal width.The contact gap between the seal surfaces is zero with a width of 2.5 mm.The width of the separation area between the seal surfaces decreases with the decrease of the hydrogen pressure.The width of the separation area is reduced from 0.5 mm at 35 MPa to 0.17 mm at 15 MPa.This work can be useful for improvement of the seal performance and of the design of the charge valve used in the HP-HSC.