Based On Ansys Vehicle Failure Mode Analysis Of Liquefied Natural Gas Cylinders

In recent years, as an energy-conservation and environmental-protection model liquefied natural gas (LNG) vehicle has been developing rapidly. LNG cylinder is one of the key components of the model. As a new product and with the lack of domestic research, LNG cylinder is still in trail operation. Therefore, we need to do further research to improve its safety performance.This paper modeled the LNG cylinder by adopting ANSYS software and the up-to-down method, and carried on statics analysis, thermal analysis, motion analysis, constraint failure mode analysis, impact failure mode analysis and corrosion failure mode analysis on the working pressure of1.6MPa and design pressure of3.2MPa. And then checked the calculation results, the conclusions are as follows:1. The conclusions of numerical simulation analysis in the normal working condition:Through the statics analysis, thermal analysis, motion analysis, the gas cylinder was in accord with the demands of strength and also safe in the working pressure. But in the design pressure, the gas cylinder was not in accord with the demands of strength in some weak positions, such as the junction of the inner cylinder head and lip, the junction of the inner cylinder head and body.2. The conclusions of failure mode analysis:(1) Imposing axial and hoop constraints on the inner cylinder, in the working pressure the gas cylinder was not in accord with the demands of strength in the inner cylinder body, the junction of the outer cylinder head and lip, the junction of the inner cylinder body and connecting rings; in the design pressure not only the above mentioned parts was not in accord with the demands of strength but also in the junction of the inner cylinder head and body, the inner cylinder head, the junction of the inner cylinder head and lip.(2) Imposing radial and hoop constraints on the inner cylinder, in the working pressure the gas cylinder was not in accord with the demands of strength in the inner cylinder body, the junction of the inner cylinder head and body, the junction of the outer cylinder head and lip, the junction of the inner cylinder body and connecting rings; in the design pressure the parts are the same with the axial and hoop constraints failure mode analysis.(3) Imposing full constraints on the inner cylinder, in the working pressure the gas cylinder was not in accord with the demands of strength in the inner cylinder body, the junction of the inner cylinder head and body, the junction of the inner cylinder body and connecting rings; in the design pressure the parts are the same with the radial and hoop constraints failure mode analysis.(4) Carrying on impact failure mode analysis to the cylinder, in the working pressure the gas cylinder was not in accord with the demands of strength in the junction of the outer cylinder head and body; in the design pressure the gas cylinder was not in accord with the demands of strength in the inner cylinder body, the junction of the inner cylinder head and body, the inner cylinder body head, the junction of the inner cylinder head and lip, the junction of the outer cylinder head and body.(5) Carrying on corrosion failure mode analysis to the cylinder, in the working pressure the gas cylinder was not in accord with the demands of strength in the inner cylinder body, the junction of the inner cylinder head and body, the inner cylinder head, the junction of the inner cylinder head and lip; in the design pressure the inner cylinder body, the junction of the inner cylinder head and body, the inner cylinder head, the junction of the inner cylinder head and lip.(6) According to different operating conditions this paper calculated the time of vaporization. When the LNG cylinder is in the fire environment, the insulation layer fails, the time of vaporization is0.22h and0.3h; when the LNG cylinder is in the normal environment, the insulation layer fails, the time of vaporization is1.04h and1.41h.Then, this paper simulated the accident consequences of LNG cylinder by ALOHA software, and concluded the accident harm degree and damage range.