Characterization Method And Application Of Welding Joint Mechanical Properties Based On UMAT

To describe the distribution of inhomogeneous mechanical properties of welded joint materials accurately,the User-Defined Material(UMAT)subroutine in ABAQUS software is used to describe the problem of distribution of inhomogeneous mechanical properties of welded joint materials.It solves the problem of sudden changes in the mechanical properties of materials in the finite element simulation of "sandwich" welded joints,and provides a new finite element analysis method for the mechanical performance analysis and structural safety evaluation of welded joints.Taking the welding end of the nuclear power safety terminal as an example,the safety evaluation is carried out by using the established UMAT subroutine.The main work performed is as follows:(1)According to the distribution law of the mechanical properties of the welded joint materials,the UMAT subroutine is established to characterize the mechanical properties of the non-uniform materials of the welded joint.(2)Through the indentation test of the uneven material hardness,the hardness indentation test ABAQUS finite element inversion analysis and the UMAT subroutine numerical simulation of the hardness indentation test.Obtain the distribution law of the three hardness values,and obtain the distribution law of the yield strength according t.o the relationship between the hardness value and the yield strength to verify the accuracy of the subroutine.(3)Establish the finite element model of the "sandwich" welded joint with defects and the finite element model of the continuous transition welded joint respectively.Analyze the change law of crack tip mechanical field under the influence of different yield strength combinations of the two welded joint finite element models.(4)Taking the nuclear power welding joint as an example,the hardness indentation test is used to obtain the distribution law of the hardness value of the welded joint,and the distribution law of the yield strength is obtained according to the relationship between the hardness value and the yield strength.The UMAT subprogram was used to characterize the distribution law of the yield strength of the welded joints and to establish a finite element model of the welded joints,and to analyze the characteristics of the mechanical field distribution of the crack tip at different positions of the welded joints of the nuclear power safety end..