A method for predicting the life of a component with defects

Abstract

The application discloses a kind of defective component life prediction methods, including calculating stress at defect;Numerical model is established, initial crack length and crack critical final length are set, and crack tip grid is divided;The extension angle and local extension displacement of each node of crack tip in crack propagation process are calculated;Numerical model is updated, and the number of crack tip nodes is determined;The propagation distance of all crack tip nodes is weighted average smoothing processing, and crack propagation length is obtained;Whether crack propagation length is less than crack critical final length is judged;When crack propagation length reaches crack critical final length, crack propagation displacement and cycle number function relationship are constructed according to crack propagation length and cycle number of crack propagation process;The life of defective component is predicted according to crack propagation displacement and cycle number function relationship.The application improves the comprehensiveness and accuracy of life reliability evaluation, can effectively reduce the number of actual test, improves research efficiency.

Description

Technical Field

[0001] This invention relates to the field of crack propagation behavior monitoring technology for defective components, and specifically to a method for predicting the lifespan of defective components. Background Technology

[0002] When a material experiences ductile failure, crack propagation behavior directly determines its final service life. Crack propagation, due to its hidden and random nature, is easily influenced by loads and the material's microstructure. This makes it impossible to accurately quantify and characterize crack propagation, which in turn affects service life prediction and is one of the core issues restricting the reliability of materials in service.

[0003] Currently, there is no feasible and reliable method to test the crack propagation behavior of defective components, which greatly hinders life assessment research and makes it impossible to quickly respond to the service reliability requirements of defective components. Summary of the Invention

[0004] To address the aforementioned shortcomings in the prior art, this invention provides a method for predicting the lifespan of defective components.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0006] A method for predicting the life of a defective component includes the following steps:

[0007] S1. Calculate the stress and geometric coefficient of the defect at the defect point based on the geometric characteristics of the defect in the component with defects;

[0008] S2. Establish a numerical model based on the geometric characteristics of the defect, set the initial crack length and the critical final crack length, and draw the crack tip mesh;

[0009] S3. Calculate the propagation angle and local propagation displacement of each node at the crack tip during crack propagation based on the stress at the defect and the defect geometric coefficient.

[0010] S4. Update the numerical model based on the propagation angle and local propagation displacement of each node at the crack tip, and determine the number of nodes at the crack tip.

[0011] S5. Perform a weighted average smoothing process on the propagation distance of all crack tip nodes to obtain the crack propagation length;

[0012] S6. Determine whether the crack propagation length is less than the critical final crack length; if yes, proceed to step S3; otherwise, proceed to step S7.

[0013] S7. Generate a crack propagation length versus cycle number curve based on the crack propagation length and the number of cycles in the crack propagation process.

[0014] S8. Construct a prediction model for the life of defective components based on the crack propagation length and cycle count curves, and predict the life of defective components.

[0015] Optionally, step S1 specifically includes:

[0016] Define the defect geometry of the defective component, wherein the defect geometry includes the length and width of the defect;

[0017] Calculate the stress and geometric coefficient of the defect at the defect location based on the defect geometry characteristics of the defective component.

[0018] Optionally, the stress at the defect is calculated as follows:

[0019]

[0020] in, The stress at the defect is... For the applied load, a The length of the defect, b The width of the defect.

[0021] Optionally, the defect geometric coefficient is calculated as follows:

[0022]

[0023] in, r For the defect geometry coefficient, a The length of the defect, b The width of the defect.

[0024] Optionally, the propagation angle of each node at the crack tip in step S3 is calculated as follows:

[0025]

[0026] in, Indicates the first j The propagation angle of each crack tip node, K I , K II These represent the stress intensity factors for Type I and Type II cracks at the defect, respectively, and are calculated as follows:

[0027]

[0028]

[0029] in, These are the load conversion factors for Type I and Type II cracks. r For the defect geometry coefficient, a The length of the defect, This represents the stress at the defect.

[0030] Optionally, the local propagation displacement of each node at the crack tip in step S3 is calculated as follows:

[0031]

[0032] in, This represents the local propagation displacement at each node of the crack tip. This represents the stress intensity range at each node at the crack tip. M These are parameters related to defect geometry and material properties. , r For the defect geometry coefficient, For material constants, This refers to the cycle number.

[0033] Optionally, the life prediction model for defective components specifically includes:

[0034]

[0035] in, This represents the local propagation displacement at each node of the crack tip. , This represents the range of stress intensity at the defect location. This represents the stress intensity range at each node at the crack tip. , r For the defect geometry coefficient, For material constants, This refers to the range of cycle times.

[0036] The present invention has the following beneficial effects:

[0037] This invention targets defective components, first determining the defect geometry and stress concentration, then calculating the propagation direction and distance, defining the relationship between crack propagation displacement and cycle number, and ultimately achieving life prediction and assessment. This improves the comprehensiveness and accuracy of life reliability assessment, effectively reduces the number of actual tests, increases research efficiency, and obtains a life assessment model. It provides important theoretical guidance and technical support for the study of crack propagation, damage evolution, and life assessment in materials, and has significant scientific and engineering application value. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating a method for predicting the lifespan of a defective component according to an embodiment of the present invention. Detailed Implementation

[0039] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0040] like Figure 1 As shown, this embodiment of the invention provides a method for predicting the lifespan of a defective component, characterized by comprising the following steps S1 to S8:

[0041] S1. Calculate the stress and geometric coefficient of the defect at the defect point based on the geometric characteristics of the defect in the component with defects;

[0042] In an optional embodiment of the present invention, step S1 specifically includes:

[0043] Define the defect geometry of the defective component, wherein the defect geometry includes the length and width of the defect;

[0044] Calculate the stress and geometric coefficient of the defect at the defect location based on the defect geometry characteristics of the defective component.

[0045] Specifically, this invention defines the defect geometry of a defective component as a defect geometric feature, and the defect is a planar crack, with the defect geometry including length. a and width b .

[0046] The presence of defects causes stress discontinuity, leading to stress concentration and ultimately crack initiation and propagation. Therefore, this invention calculates the stress and defect geometric coefficient at the defect location based on the defect geometry of the defective component. The calculation method is as follows:

[0047]

[0048]

[0049] in, The stress at the defect is... For the applied load, a The length of the defect, b The width of the defect. r The defect geometry coefficient has a value range of (0,1).

[0050] S2. Establish a numerical model based on the geometric characteristics of the defect, set the initial crack length and the critical final crack length, and draw the crack tip mesh;

[0051] In an optional embodiment of the present invention, the present invention applies the finite element method based on fracture mechanics, establishes a numerical model according to the geometric characteristics of the defect, sets the initial crack length, and divides the crack tip mesh to determine the number of crack tips. The number of crack tip nodes is defined as follows: n The final crack propagation length is set as the calculation stopping condition.

[0052] The numerical model refers to the numerical model used for finite element calculation. Its establishment process is as follows: a CAD geometric model is established based on the appearance dimensions of the model, and then imported into the finite element calculation platform to generate a mesh and apply the boundary condition parameters of the loading process (including loading load, time, constraint conditions, etc.) to provide model and load boundary parameters for subsequent crack propagation calculation.

[0053] S3. Calculate the propagation angle and local propagation displacement of each node at the crack tip during crack propagation based on the stress at the defect and the defect geometric coefficient.

[0054] In an optional embodiment of the present invention, the number of crack tip nodes is determined based on the crack tip mesh, and the propagation angle of each node at the crack tip is calculated based on the maximum circumferential tensile stress strength theory. The calculation method is as follows:

[0055]

[0056] in, Indicates the first j The propagation angle of each crack tip node, ; K I , K II These represent the stress intensity factors for Type I and Type II cracks at the defect, respectively, and are calculated as follows:

[0057]

[0058]

[0059] in, The load conversion factor is used for Type I and Type II cracks, and its value ranges from 0.6 to 1.0. r For the defect geometry coefficient, a The length of the defect, This represents the stress at the defect.

[0060] This invention first determines the basic propagation parameters, namely C and m, of the crack propagation pair region of the material through crack propagation tests on standard CT specimens, providing material constitutive parameters for the next step of propagation calculation.

[0061] Then, the local propagation displacement at each node of the crack tip is calculated under the given load and number of cycles. The calculation method is as follows:

[0062]

[0063] in, This represents the local propagation displacement at each node of the crack tip. This represents the stress intensity range at each node at the crack tip. M These are parameters related to defect geometry and material properties. , r For the defect geometry coefficient, For material constants, This refers to the cycle number.

[0064] S4. Update the numerical model based on the propagation angle and local propagation displacement of each node at the crack tip, and determine the number of nodes at the crack tip.

[0065] In an optional embodiment of the present invention, the coordinates of the crack tip nodes in the new model are determined based on the calculated propagation distance and propagation angle of each node at the crack tip, and the numerical model is updated to complete the newly established propagation distance mesh. The number of new crack tip nodes is defined as follows: n It remains unchanged from before the expansion.

[0066] S5. Perform a weighted average smoothing process on the propagation distance of all crack tip nodes to obtain the crack propagation length;

[0067] In an optional embodiment of the present invention, the local propagation displacement of all nodes at the crack tip during crack propagation is extracted and subjected to weighted average smoothing. The calculation method is as follows:

[0068]

[0069] in, Indicates the first f Crack propagation length per cycle Indicates the first j Local propagation displacement of a crack tip node n This indicates the number of nodes at the crack tip.

[0070] S6. Determine whether the crack propagation length is less than the critical final crack length; if yes, proceed to step S3; otherwise, proceed to step S7.

[0071] In an optional embodiment of the present invention, the present invention compares the crack propagation length completed in step S5 with the set critical final crack length. If it is less than the critical final crack length, the crack continues to propagate, and the process jumps to step S3 to continue calculating the propagation angle and local propagation displacement of each node at the crack tip. If it is greater than the critical crack propagation length, the crack propagation stops, and the process jumps to step S7.

[0072] S7. Generate a crack propagation length versus cycle number curve based on the crack propagation length and the number of cycles in the crack propagation process.

[0073] In an optional embodiment of the invention, the invention is based on the calculated crack propagation length. Cycle number of times the crack propagation process Generate a crack propagation length versus cycle count curve to complete the crack propagation calculation for the specified number of cycles.

[0074] S8. Construct a prediction model for the life of defective components based on the crack propagation length and cycle count curves, and predict the life of defective components.

[0075] In an optional embodiment of the present invention, the establishment of the above crack propagation model and calculation method yields the crack propagation length versus cycle number curve, which can quantitatively obtain the functional relationship between the expected cycle number and the crack propagation amount under load and the cycle number, providing basic data and scientific basis for the construction of life prediction model.

[0076] This invention constructs a prediction model for the life of defective components by performing an integral transformation on the functional relationship between crack propagation length and number of cycles. Specifically:

[0077]

[0078] in, This represents the local propagation displacement at each node of the crack tip. , This represents the range of stress intensity at the defect location. This represents the stress intensity range at each node at the crack tip. , r For the defect geometry coefficient, For material constants, This refers to the range of cycle times. This is the predicted lifespan of the defective component.

[0079] This invention solves the problem of the inability to quantitatively and intuitively calculate the crack propagation behavior of defective components, and based on this, assesses their lifespan, providing a more comprehensive, accurate, and innovative calculation process and algorithm. The crack propagation and lifespan assessment model for defective components proposed in this invention is based on material testing results and has good compatibility and portability. Furthermore, the crack propagation calculation process constructed in this invention first determines the defect geometry and stress concentration, then calculates the propagation direction, obtains the propagation distance, defines the relationship between crack propagation displacement and cycle number function, and finally achieves lifespan prediction and assessment. This invention provides important theoretical guidance and technical support for the study of crack propagation and lifespan assessment of defective components, and has significant scientific and engineering application value.

[0080] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0081] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0082] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0083] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0084] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for predicting the lifespan of a defective component, characterized in that, Includes the following steps: S1. Calculate the stress and geometric coefficient of the defect at the defect point based on the geometric characteristics of the defect in the component with defects; S2. Establish a numerical model based on the geometric characteristics of the defect, set the initial crack length and the critical final crack length, and draw the crack tip mesh; S3. Calculate the propagation angle and local propagation displacement of each node at the crack tip during crack propagation based on the stress at the defect and the defect geometric coefficient. S4. Update the numerical model based on the propagation angle and local propagation displacement of each node at the crack tip, and determine the number of nodes at the crack tip. S5. Perform a weighted average smoothing process on the local propagation displacement of all crack tip nodes to obtain the crack propagation length; S6. Determine whether the crack propagation length is less than the critical final crack length; if yes, proceed to step S3; otherwise, proceed to step S7. S7. Generate a crack propagation length versus cycle number curve based on the crack propagation length and the number of cycles in the crack propagation process. S8. Construct a prediction model for the life of defective components based on the crack propagation length and cycle count curves, and predict the life of defective components. The calculation method for the local propagation displacement of each node at the crack tip in step S3 is as follows: in, This represents the local propagation displacement at each node of the crack tip. This represents the stress intensity range at each node at the crack tip. M These are parameters related to defect geometry and material properties. , r For the defect geometry coefficient, For material constants, For the cycle number; The specific life prediction model for defective components is as follows: in, This represents the local propagation displacement at each node of the crack tip. , This represents the range of stress intensity at the defect location. This represents the stress intensity range at each node at the crack tip. , r For the defect geometry coefficient, For material constants, The range is the number of cycles. This represents the crack propagation length.

2. The method for predicting the lifespan of a defective component according to claim 1, characterized in that, Step S1 specifically includes: Define the defect geometry of the defective component, wherein the defect geometry includes the length and width of the defect; Calculate the stress and geometric coefficient of the defect at the defect location based on the defect geometry characteristics of the defective component.

3. The method for predicting the lifespan of a defective component according to claim 2, characterized in that, The stress at the defect is calculated as follows: in, The stress at the defect is... For the applied load, a The length of the defect, b The width of the defect.

4. The method for predicting the lifespan of a defective component according to claim 2, characterized in that, The method for calculating the defect geometric coefficient is as follows: in, r For the defect geometry coefficient, a The length of the defect, b The width of the defect.

5. The method for predicting the lifespan of a defective component according to claim 1, characterized in that, The calculation method for the propagation angle of each node at the crack tip in step S3 is as follows: in, Indicates the first j The propagation angle of each crack tip node, K I , K II These represent the stress intensity factors for Type I and Type II cracks at the defect, respectively, and are calculated as follows: in, These are the load conversion factors for Type I and Type II cracks. r For the defect geometry coefficient, a The length of the defect, This represents the stress at the defect.

Images