Research On The Effect Of Autofrettaged Treatment On The Crack Of Ultra-high Pressure Pump Head

At present,oil and gas etc energy becomes scarce,many fossil resources are more and more difficult to extract,and because of oil and natural gas extraction is carried out under high pressure environment,the equipment and related technical means requirements are gradually increased,in addition to increasing the relevant size The traditional method,more and more projects began to introduce self-enhanced processing technology,this technology is mainly in the equipment chamber to exert high pressure,so that the inner wall of the resulting residual stress,and stress generated by the stress overlap,reduce The overall stress level of the equipment,thereby extending the service life.And the component will be cracked due to processing or heat treatment means,so that the effect of self-reinforcing treatment will be affected,especially the stress distribution at the crack tip.Based on the fracture mechanics,the influence of the self-enhanced treatment on the stress distribution and the relevant fracture parameters of the cracked component is studied by means of numerical analysis.The propagation characteristics of the crack are evaluated by the method of numerical analysis.The field of research is of great importance.The study object is an ultrahigh pressure pump head with surface elliptical crack,but considering its complexity of cavity,and its core cavity is similar to thick wall tube,it is simplified to a certain thickness of the cylinder model,The expression of the residual stress and stress intensity factor of the cylinder including self-reinforced technique is deduced from the theoretical point of view.Based on the numerical analysis method,the influence of different crack size,the location and the stress distribution of the crack at the self-reinforced pressure is studied.It is found that the self-enhanced treatment has greatly reduced the stress of the crack front and has a positive effect on the crack initiation of the crack.After the quantitative analysis,the crack tip length is the same as the crack length decreases decreases;increases with increasing length of the shaft to reduce the proportion of the crack,taking a / c = 1.4 when the stress is minimized,and when the ratio is greater than 1,the suction cavity surface crack tip stress is large,is less than 1,The plunger cavity surface is more dangerous,and compared with the enhanced treatment on the distance from the cavity at the crack tip stress greater impact,which is related to the curvature of the crack;self-enhanced pressure,to prevent the crack tip expansion shear stress,but not the maximum crack tip stress variation;in stress crack front surface of the suction chamber with a / c decreases and increases,and the greater impact on the dimensional change of the maximum stress;stress crack intersecting line untreated The results of the intensity factor show that the I-type dominates and the stress intensity factor of the inhalation cavity is larger and easier to crack.The crack tip J value of the treated pump body in the pressure and crack size changes with the value of a / c increases,then decreases after Large,decreases with increasing process pressure,i.e.,the minimum value at the crack tip away from the luminal surface,since the enhancement processing is most effective for suppressing cracking.