A method for rapid calculation of residual strength loads of complex integral structures

Abstract

The present application provides a method for rapidly calculating the residual strength load of a complex integral structure, comprising: establishing a crack-free three-dimensional solid finite element model of the complex integral structure; embedding a crack tip singular element mesh containing a crack length; calculating the crack tip stress intensity factor under different external loads; obtaining a P-K curve showing the stress intensity factor changing with external load through data fitting; obtaining a plane strain fracture toughness value of the material used for the complex integral structure, and obtaining a preliminary residual strength load by interpolating the P-K curve; conducting a residual strength test on a complex integral structure containing a crack length a to obtain the residual strength load under the test; determining a correction coefficient for the plane strain fracture toughness value based on the preliminary residual strength load and the residual strength load under the test; and given an arbitrary crack length, repeating the above steps to obtain a family of P-K curves under the crack length, that is, obtaining the residual strength load of the complex integral structure under any crack length.

Claims

1. A method for rapidly calculating the residual strength load of a complex integral structure, characterized in that: The method comprises: Step S1: establishing a crack-free three-dimensional solid finite element model of the complex integral structure; Step S2: embedding a crack tip singular element mesh containing crack length a; Step S3: Calculate the crack tip stress intensity factor K under different external loads P; Step S4: Obtain the P-K curve of the stress intensity factor varying with the external load through data fitting. Among them, the obtained P-K curve of the stress intensity factor varying with the external load has a linear characteristic, and linear fitting is adopted: P = b×K + c, where P is the external load, K is the stress intensity factor value under a fixed-length crack, b is the slope, c is the intercept, P1 and P2 are different external loads, and P1 < P2; K1 and K2 are the stress intensity factors corresponding to the external loads P1 and P2, and K1 < K2; Step S5: obtaining the plane strain fracture toughness value of the material used for the complex integral structure, and obtaining a preliminary residual strength load P by interpolating the PK curve; Step S6: performing a residual strength test on a complex integral structure with a crack length a to obtain a residual strength load *P under the test; Step S7: Determine the plane strain fracture toughness value K based on the preliminary residual strength load and the residual strength load under the test 1C Correction coefficient ξ=*P / P; Step S8: Given any crack length, repeat steps S2 to S5 to obtain a family of PK curves at multiple crack lengths, where the plane strain fracture toughness value K used in the interpolation in step S5 is 1C is the corrected value, which is ξ×K 1C , that is, the residual strength load of the complex overall structure under any crack length is obtained.

2. The method for rapidly calculating the residual strength load of a complex integral structure according to claim 1, characterized in that: The three-dimensional solid finite element model of the complex overall structure is modeled using Abaqus.

3. The method for rapidly calculating the residual strength load of a complex integral structure according to claim 1, characterized in that: In the area where cracks need to be embedded, hexahedral mesh is used.

4. The method for rapidly calculating the residual strength load of a complex integral structure according to claim 1, characterized in that: The number of the external loads is not less than three.

5. The method for rapidly calculating the residual strength load of a complex integral structure according to claim 1, characterized in that: The calculation method of the stress intensity factor K is: Where K is the stress intensity factor, β J is the geometric configuration factor, β C is the load redistribution factor, for the whole panel β C =1, σ is the reference stress, and a is the crack length.

6. The method for rapidly calculating the residual strength load of a complex integral structure according to claim 1, characterized in that: There are multiple integration points along the thickness direction of the solid element at the crack tip. Under the same crack length and the same external load, multiple stress intensity factor values ​​K1, K2, K3…Kn are calculated. The required stress intensity factor K is calculated as follows: Where n is the number of integration points.

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