| This project comes from the National Natural Science Foundation of China(51705037;51605046);six peak projects of Jiangsu Province(gdzb-061);Science and technology project of Jiangsu special equipment safety supervision and Inspection Institute(KJ(Y)2016001).Due to the hyperelasticity and shape memory properties,NiTi alloy has good recovery performance and fine anti-creep property.Therefore,it can be used as the framework material of sealing gasket.The hyperelasticity can make the gasket have good resilience,and the shape memory property can make the gasket have shape memory effect at high temperature,which can make up for the lack of pre-tightening force caused by the bolt after a lone time work for reduce the leakage channels and enhance the sealing property.In this paper,the compressibility and resilience test and creep test of NiTi alloy are carried out.The corrugation sealing gasket and self sealing gasket of NiTi alloy framework are designed.The compression rebound performance and sealing characteristics of NiTi alloy sealing gasket are analyzed by using the finite element software ANSYS.The leakage rate of NiTi alloy corrugation sealing gasket is studied through the leakage test bench.The main contents of this paper are as follows:(1)Compressibility and resilience test and creep test(room temperature,100℃ and 200℃)were carried out were carried out on NiTi alloy(Ni51.9Ti49.1).The material parameter of NiTi alloy for ANSYS finite element analysis are obtained by compressibility and resilience test.The Norton creep constitutive model of NiTi alloy is fitted by creep test and Norton creep model.(2)A new type of NiTi alloy corrugated sealing gasket was designed,with internal and external diameters of 149mm and 105mm respectively.ANSYS is used to simulate the compression resilience of NiTi alloy corrugated gasket.Compared with stainless steel corrugated gasket,the resilience of NiTi alloy gasket is much better than that of stainless steel corrugated gasket,and the compression performance is slightly lower.According to the characteristics of NiTi alloy and a self-sealing characteristic of bimetal self sealing gasket,a self sealing gasket is designed.The parameters of ripple number(N),ripple amplitude(h)and framework thickness(T)were optimized.Through the finite element analysis and comparison of the sealing characteristics of self sealing gasket and corrugated sealing gasket,it can be seen that with the increase of medium pressure,the sealing performance of self sealing gasket is better and better than that of corrugated sealing gasket.With the increase of medium pressure,it can be seen through the finite element analysis and comparison of the sealing characteristics of self sealing gasket and corrugated sealing gasket,that the sealing performance of self sealing gasket is better and better than that of corrugated sealing gasket.(3)The thermal analysis,thermal structure coupling analysis and creep analysis of NiTi alloy corrugated gasket in flange temperature field were carried out.The results show that the temperature of the flange decreases linearly from the inside to the outside,and the pressure stress on the gasket surface can meet the initial sealing pressure of the gasket under pre-tightening;with the increase of creep time,the pressure stress of the gasket decreases gradually.After 10000 h,the pressure stress on the gasket surface can still meet the sealing specific pressure under the operating condition.It shows that the sealing gaskets meet the sealing requirements.(4)The leakage rate test of the processed NiTi alloy corrugated sealing gasket was carried out.The sealing performance of the gasket at the same temperature level(22℃,100℃,200℃),different medium pressure(0～5 MPa)and different pre tightening stress(40 MPa,45 MPa and 50 MPa)was measured.The results show that the sealing performance increases with the increase of medium pressure,and decreases with the increase of preload stress and temperature. |
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