Study on Elastic-plastic Fracture of Pressure Vessel Based on Finite Element Method
The study on elastic-plastic fracture of the outer surface of pressure vessels is important to ensure the safe operation of the vessel and to extend the service life of vessels.Based on the finite element method and the elastic-plastic fracture theory,the three-dimensional J-integral method is used to solve the common problem of I-shaped elastic-plastic fracture of axial semi-elliptical cracks on the outer surface of pressure vessels.The results show that the three-dimensional J-integral increases with the increase of crack angle and decreases with the increase of integration region.When the internal pressure increases to 15 MPa,the calculation results of integral regions 1 and 2 with radius 0.2 a and 0.4 a(where a is the crack depth)show some fluctuations at the crack angle of 15°.At the same time,it can be seen that the results of different integral regions differ greatly in the locations with smaller crack angles and closer to the outer surface,while the results of different integral regions have little difference in the position with larger crack angles.This shows that three-dimensional J-integral method has good path independence,which provides a scientific basis for elastic-plastic fracture design,material selection,fracture prediction and repair of pressure vessels.
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