Study On The Restriction Effect Of Carbon Fiber Composite On Oil And Gas Pipe Lines Under Explosion

With the rapid development of China's economy and the promotion of urban integration,the scale of the city continues to expand,the original oil and gas pipeline far away from the city is gradually surrounded by new buildings,resulting in the lack of safety distance,which threatens the safety of people's property.With the increase of service life of oil and gas pipelines,if there is oil and gas leakage due to corrosion and other factors,there is a great possibility of continuous explosion in case of open fire.Under the action of explosion load,the crack develops continuously along the axial direction of the steel pipe,and the continuous explosion caused by it will bring serious casualties and economic losses.Therefore,how to effectively limit the continuous explosion of oil and gas pipelines is an important engineering problem to be solved.Carbon fiber reinforced composite has many advantages,such as light weight,high strength,corrosion resistance,fatigue resistance,fast construction speed and so on.It has been widely used in engineering structure reinforcement.If the carbon fiber reinforced composite explosion limiting ring(hereinafter referred to as the explosion limiting ring)is wound on the surface of oil and gas pipeline along a certain length,it is of great significance to block the continuous propagation of explosion load along the pipeline and reduce the loss caused by continuous explosion.In view of this,in this paper,the dynamic response of oil and gas pipelines under the action of internal explosion load and the influence of carbon fiber composite explosion limiting ring on the stress-strain field at the crack tip of the steel pipe surface are not studied,and the combination of internal explosion test and ANSYS / ly-dyna finite element simulation is adopted.The main work is as follows.(1)The propagation law of the blast wave in the closed steel tube is studied,and the explosion test in the steel tube is carried out with the explosive quantity as the variable.The overpressure time history curve,acceleration and strain data of the blast wave reaching the steel tube surface under different emulsion explosive mass are obtained.The mathematical calculation model of the blast wave propagation in the steel tube is obtained by analyzing the data.(2)The failure mechanism of steel tube under internal explosion load is studied,and the large amount of internal explosion test is carried out.According to the test conditions,the internal explosion of steel tube belongs to near-field explosion,and the main failure factors of steel tube are overpressure,impulse and temperature.Because the temperature propagation rate is far lower than the blast wave,it can be ignored.According to lame formula and impulse criterion,the failure criterion of steel tube under the coupling action ofshock wave overpressure and impulse is derived.(3)The stress-strain field at the crack tip of the tube under the restraint of the explosion limiting ring is studied.According to the feature of crack morphology,the crack of steel tube under internal explosion load is type I crack.In order to determine the stress intensity factor at the crack tip of type I crack under the restraint of the explosion limiting ring,through a series of explosion tests in the steel tube with the explosion limiting ring,the typical failure characteristics of the steel tube and the explosion limiting ring under the explosion load are obtained,the influence law of the explosion limiting ring on the stress-strain field at the crack tip is analyzed,and the crack propagation model considering the effect of the explosion limiting ring is established.(4)The overpressure time history curve and impulse of the steel tube under the internal explosion load with different explosive quantity are studied.The finite element simulation is carried out by ANSYS / ly-dyna to simulate the test conditions of the steel tube under different quality emulsion explosive.The overpressure and strain on the surface of the steel tube are analyzed and compared with the internal explosion test of the steel tube to verify the correctness of the numerical simulation Based on the data,the calculation model of steel tube failure under explosion load is further modified.