Linear stress combination ductile fracture identification method and device considering hydrostatic stress reinforcement, computer storage medium and equipment

Abstract

The invention discloses a linear stress combination ductile fracture identification method considering hydrostatic stress reinforcement. The method comprises the following steps: calculating local principal stress of a ductile fracture body to be forecasted; respectively calculating stress invariants and Mises equivalent stress of the ductile fracture body to be forecasted based on the local principal stress; calculating stress state parameters of the ductile fracture body to be forecasted based on the stress invariants; based on Mises equivalent stress and stress state parameters, converting local principal stress into a stress state parameter space; a hydrostatic stress strengthening item is added to the Mohr-Coulomb model; and the Mohr-Coulomb model with the reinforced hydrostatic stress is converted into a stress-stress state parameter space, and a linear stress combination ductile fracture recognition model considering the reinforced hydrostatic stress is obtained. According to the method, the application range of the Mohr-Coulomb model is expanded, and the ductile fracture of the alloy can be predicted more accurately and stably compared with the Mohr-Coulomb model.

Description

Technical Field

[0001] The present invention relates to the technical field of ductile fracture identification, and more particularly to a method, apparatus, computer storage medium and device for identifying ductile fracture of stress linear combination considering hydrostatic stress reinforcement. Background Art

[0002] Ductile alloy materials are widely used in civil engineering, aerospace, and nuclear power. Accurately predicting the ductile fracture of alloy materials is a key issue related to the ultimate limit state of components and structures. The Mohr-Coulomb model is widely used for brittle alloy materials, and it has certain effectiveness for some ductile alloy materials. The Mohr-Coulomb model assumes that the material fails when the linear combination of the maximum shear stress and the normal stress on its shear stress plane reaches a critical value. The mathematical form in the principal stress space is as follows:

[0003] (σ1-σ3)+c(σ1+σ3)=b

[0004] Where σ1 and σ3 are the first and third principal stresses; c and b are material parameters.

[0005] However, studies have shown that the Mohr-Coulomb model has large errors in predicting ductile fracture in the high stress triaxiality range. Summary of the Invention

[0006] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides a linear stress combination ductile fracture identification method that considers hydrostatic stress enhancement. This method aims to improve the adaptability of the Mohr-Coulomb model and address the large error in ductile fracture prediction using the Mohr-Coulomb model in high stress triaxiality ranges.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for identifying linear stress combination ductile fracture considering hydrostatic stress enhancement, comprising the following steps:

[0009] Calculate the local principal stress of the body to be predicted for ductile fracture;

[0010] Calculating the stress invariant of the ductile fracture body to be predicted based on the local principal stress of the ductile fracture body to be predicted;

[0011] Based on the local principal stress of the ductile fracture body to be predicted, the Mises equivalent stress of the ductile fracture body to be predicted is calculated:

[0012] Calculating stress state parameters of the ductile fracture body to be predicted based on stress invariants of the ductile fracture body to be predicted;

[0013] Based on the Mises equivalent stress and stress state parameters of the ductile fracture body to be predicted, the local principal stress of the ductile fracture body to be predicted is converted into the stress state parameter space;

[0014] Add hydrostatic stress enhancement term to the Mohr-Coulomb model to establish the hydrostatic stress enhanced Mohr-Coulomb model;

[0015] Based on the local principal stresses of the ductile fracture body to be predicted converted to the stress state parameter space, the Mohr-Coulomb model enhanced by hydrostatic stress is converted to the stress-stress state parameter space, and a linear stress combination ductile fracture identification model considering hydrostatic stress enhancement is obtained, which can predict the fracture trajectory of the ductile fracture body to be predicted.

[0016] Preferably, the stress invariant of the body to be predicted for ductile fracture is calculated by the following formula:

[0017] I1=σ1+σ2+σ3

[0018]

[0019] where Ix, J2, and J3 are the first, second, and third stress invariants of the ductile fracture body to be predicted, respectively; σ1, σ2, and σ3 are the first, second, and third local principal stresses of the ductile fracture body to be predicted, respectively.

[0020] Preferably, the Mises equivalent stress of the body to be predicted for ductile fracture is calculated by the following formula:

[0021]

[0022] Where, σ eq is the Mises equivalent stress of the ductile fracture body to be predicted.

[0023] Preferably, the stress state parameters of the body to be predicted for ductile fracture include stress triaxiality and Rhodes angle parameters, which are calculated by the following formula:

[0024]

[0025] Where η is the stress triaxiality and ξ is the Rhodes angle parameter.

[0026] Preferably, the expression after converting the local principal stress of the body to be predicted for ductile fracture into the stress state parameter space is as follows:

[0027] σ1=σ eq (η+f1)

[0028] σ2=σ eq (η+f2)

[0029] σ3=σ eq (η+f3)

[0030] in,

[0031]

[0032] Where f1, f2 and f3 are intermediate parameters.

[0033] As an example: the hydrostatic stress-enhanced Mohr-Coulomb model:

[0034] (σ1-σ3)+c1(σ1+σ3)+c2<η-η0>=c3

[0035] Where c1, c2 and c3 are material constants; η0 is the reference stress triaxiality; <x>is a piecewise function. When x≥0, <x>=x, otherwise <x>=0.

[0036] Preferably, the linear stress combination ductile fracture identification model considering hydrostatic stress enhancement is expressed as follows:

[0037]

[0038] Where, σ eq is the Mises equivalent stress of the ductile fracture body to be predicted.

[0039] In a second aspect, the present invention provides a linear stress combination ductile fracture identification device considering hydrostatic stress enhancement, comprising:

[0040] The first processing unit is used to calculate the local principal stress of the ductile fracture body to be predicted;

[0041] The second processing unit is configured to calculate the stress invariant of the ductile fracture body to be predicted based on the local principal stress of the ductile fracture body to be predicted;

[0042] The third processing unit is used to calculate the Mises equivalent stress of the ductile fracture body to be predicted based on the local principal stress of the ductile fracture body to be predicted:

[0043] a fourth processing unit, configured to calculate stress state parameters of the ductile fracture body to be predicted based on stress invariants of the ductile fracture body to be predicted;

[0044] a fifth processing unit, configured to convert the local principal stress of the ductile fracture body to be predicted into a stress state parameter space based on the Mises equivalent stress and stress state parameters of the ductile fracture body to be predicted;

[0045] a sixth processing unit, configured to add a hydrostatic stress enhancement term to the Mohr-Coulomb model to establish a hydrostatic stress enhanced Mohr-Coulomb model;

[0046] The seventh processing unit is used to convert the hydrostatic stress-enhanced Mohr-Coulomb model into the stress-stress state parameter space based on the local principal stress of the ductile fracture body to be predicted converted into the stress state parameter space, thereby obtaining a linear stress combination ductile fracture identification model considering the hydrostatic stress enhancement, thereby predicting the fracture trajectory of the ductile fracture body to be predicted.

[0047] In a third aspect, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is executed by a processor to control the device where the processor is located to implement the steps of the linear stress combination ductile fracture identification method described in the first aspect of the present invention.

[0048] In a fourth aspect, the present invention provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the linear stress combination ductile fracture identification method described in the first aspect of the present invention are implemented.

[0049] The present invention has the following advantages due to the adoption of the above technical solution:

[0050] The ductile fracture identification model proposed in this invention reduces the average absolute value of the relative error by up to 3% compared to the Mohr-Coulomb model. Furthermore, the absolute value of the maximum relative error is reduced by at least 5% compared to the Mohr-Coulomb model, effectively reducing the fracture prediction error in high-stress triaxiality stress states.

[0051] In summary, the ductile fracture identification model proposed in the present invention expands the applicable scope of the Mohr-Coulomb model and can predict the ductile fracture of alloys more accurately and stably than the Mohr-Coulomb model. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0053] Figure 1 This is a flow chart of a stress linear combination ductile fracture identification method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] To make the objectives, technical solutions, and advantages of the present invention more apparent, specific embodiments of the present invention are further described below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0055] The present invention provides a linear stress combination ductile fracture identification method that considers hydrostatic stress enhancement, comprising: calculating the local principal stresses of the body to be predicted for ductile fracture; calculating the stress invariant and Mises equivalent stress of the body to be predicted for ductile fracture based on the local principal stresses; calculating the stress state parameters of the body to be predicted for ductile fracture based on the stress invariants; converting the local principal stresses to a stress state parameter space based on the Mises equivalent stress and stress state parameters; adding a hydrostatic stress enhancement term to the Mohr-Coulomb model; and converting the hydrostatic stress-enhanced Mohr-Coulomb model to a stress-stress state parameter space to obtain a linear stress combination ductile fracture identification model that considers hydrostatic stress enhancement. The present invention expands the scope of application of the Mohr-Coulomb model and can more accurately and stably predict alloy ductile fracture than the Mohr-Coulomb model.

[0056] Hereinafter, a linear stress combination ductile fracture identification method and apparatus considering hydrostatic stress enhancement provided by an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0057] See also Figure 1 This embodiment provides a linear stress combination ductile fracture identification method considering hydrostatic stress enhancement, comprising the following steps:

[0058] S1. Calculate the local principal stresses of the body to be predicted for ductile fracture. The local principal stresses of the body to be predicted for ductile fracture of simple components and structures can be solved by analytical methods, while the local principal stresses of the body to be predicted for ductile fracture of complex components and structures can be solved by the finite element method. Since both methods are common knowledge to those skilled in the art, they will not be described in detail.

[0059] S2. Based on the local principal stress of the ductile fracture body to be predicted obtained in step S1, the stress invariant of the ductile fracture body to be predicted is calculated by the following formula:

[0060] I1=σ1+σ2+σ3

[0061]

[0062] Where I1, J2 and J3 are the first, second and third stress invariants of the ductile fracture body to be predicted, respectively; σ1, σ2 and σ3 are the first, second and third local principal stresses of the ductile fracture body to be predicted, respectively.

[0063] S3. Calculate the Mises equivalent stress of the ductile fracture body to be predicted according to the local principal stress of the ductile fracture body to be predicted using the following formula:

[0064]

[0065] Where, σ eq is the Mises equivalent stress of the ductile fracture body to be predicted.

[0066] S4. Based on the stress invariant of the ductile fracture body to be predicted, the stress state parameters of the ductile fracture body to be predicted, including stress triaxiality and Rhodes angle parameters, are calculated using the following formula:

[0067]

[0068] Where η is the stress triaxiality and ξ is the Rhodes angle parameter.

[0069] S5. Based on the Mises equivalent stress of the ductile fracture body to be predicted obtained in step S3 and the stress state parameter obtained in step S4, the local principal stress of the ductile fracture body to be predicted is converted into the stress state parameter space:

[0070] σ1=σ eq (η+f1)

[0071] σ2=σ eq (η+f2)

[0072] σ3=σ eq (η+f3)

[0073] in,

[0074]

[0075]

[0076] S6. Add a hydrostatic stress enhancement term to the Mohr-Coulomb model to establish the following hydrostatic stress enhanced Mohr-Coulomb model:

[0077] (σ1-σ3)+c1(σ1+σ3)+c2<η-η0>=c3

[0078] Where c1, c2 and c3 are material constants; η0 is the reference stress triaxiality, also a material constant; <x>is a piecewise function. When x≥0, <x>=x, otherwise <x>=0.

[0079] S7. Based on the local principal stresses of the ductile fracture body to be predicted converted to the stress state parameter space, the hydrostatic stress-enhanced Mohr-Coulomb model is converted to the stress-stress state parameter space to obtain a linear stress combination ductile fracture identification model considering the hydrostatic stress enhancement. The fracture trajectory of the ductile fracture body to be predicted can be predicted. The expression of the linear stress combination ductile fracture identification model is as follows:

[0080]

[0081] To demonstrate the effectiveness of the present method, we used fracture test data from A12024-T351 aluminum alloy and X80 pipeline steel to verify the validity of the present ductile fracture criterion. The data are listed in Tables 1 and 2, respectively. Due to the sufficient amount of test data, the least squares method was used to minimize the average value of the absolute relative error. The model calibration results are shown in Table 3. The absolute relative error is defined as follows:

[0082]

[0083] Where, and are the predicted and experimental Mises equivalent stresses, respectively; N is the number of experimental samples.

[0084] Table 1 Fracture test data of Al 2024-T351 aluminum alloy

[0085]

[0086]

[0087] Table 2 Ductile fracture test data of X80 pipeline steel

[0088]

[0089] Table 3 Model parameters and maximum relative error

[0090]

[0091] From the comparison results, it can be seen that the average value of the absolute value of the relative error of the ductile fracture identification model proposed by the present invention is reduced by up to 3% compared with the Mohr-Coulomb model. Moreover, the absolute value of the maximum relative error of the present invention is reduced by no less than 5% compared with the Mohr-Coulomb model. Most importantly, it can be seen from Tables 1 and 2 that the present invention can effectively reduce the fracture prediction error of high stress triaxiality stress state. In summary, the ductile fracture identification model proposed by the present invention expands the scope of application of the Mohr-Coulomb model and can predict alloy ductile fracture more accurately and stably than the Mohr-Coulomb model.

[0092] Example 2:

[0093] The above-mentioned embodiment 1 provides a linear stress combination ductile fracture identification method, and correspondingly, this embodiment provides a linear stress combination ductile fracture identification device. The linear stress combination ductile fracture identification device provided in this embodiment can implement the linear stress combination ductile fracture identification method of embodiment 1. The linear stress combination ductile fracture identification device can be implemented by software, hardware, or a combination of software and hardware. For example, the linear stress combination ductile fracture identification device can include integrated or separate functional modules or functional units to perform the corresponding steps in each method of embodiment 1. Since the linear stress combination ductile fracture identification device of this embodiment is basically similar to the method embodiment, the description process of this embodiment is relatively simple. For relevant points, please refer to the partial description of embodiment 1. The linear stress combination ductile fracture identification device of this embodiment is merely illustrative.

[0094] The linear stress combination ductile fracture identification device provided in this embodiment includes:

[0095] The first processing unit is used to calculate the local principal stress of the ductile fracture body to be predicted;

[0096] The second processing unit is used to calculate the stress invariant of the ductile fracture body to be predicted based on the local principal stress of the ductile fracture body to be predicted.

[0097] The third processing unit is used to calculate the Mises equivalent stress of the ductile fracture body to be predicted based on the stress invariant of the ductile fracture body to be predicted.

[0098] A fourth processing unit is configured to calculate stress state parameters based on the local principal stress of the ductile fracture body to be predicted;

[0099] a fifth processing unit, configured to convert the local principal stress of the ductile fracture body to be predicted into a stress state parameter space based on the Mises equivalent stress and stress state parameters of the ductile fracture body to be predicted;

[0100] The sixth processing unit is used to add a hydrostatic stress reinforcement term to the Mohr-Coulomb model to establish a hydrostatic stress-enhanced Mohr-Coulomb model.

[0101] The seventh processing unit is used to convert the Mohr-Coulomb model based on hydrostatic stress enhancement into stress-stress state parameter space to obtain a linear stress combination ductile fracture identification model considering hydrostatic stress enhancement.

[0102] Example 3:

[0103] This embodiment provides a processing device for implementing the linear stress combination ductile fracture identification method provided in this embodiment 1. The processing device can be a processing device for a client, such as a mobile phone, laptop computer, tablet computer, desktop computer, etc., to execute the method of embodiment 1.

[0104] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to facilitate communication between them. The memory stores a computer program executable on the processor. When the processor executes the computer program, it executes the linear stress combination ductile fracture identification method provided in Example 1.

[0105] Preferably, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory.

[0106] Preferably, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited here.

[0107] Example 4:

[0108] The linear stress combination ductile fracture identification method of this embodiment 1 can be specifically implemented as a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for executing the method described in this embodiment 1.

[0109] Computer readable storage media can be tangible devices that hold and store instructions used by instruction execution devices. Computer readable storage media can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any combination thereof.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.< / x> < / x> < / x> < / x> < / x> < / x>

Claims

1. A linear stress combination ductile fracture identification method considering hydrostatic stress enhancement, characterized in that: The following steps are involved: Calculate the local principal stress of the body to be predicted for ductile fracture; Based on the local principal stress of the ductile fracture body to be predicted, the stress invariant of the ductile fracture body to be predicted is calculated; Based on the local principal stress of the ductile fracture body to be predicted, the Mises equivalent stress of the ductile fracture body to be predicted is calculated: Calculating stress state parameters of the ductile fracture body to be predicted based on stress invariants of the ductile fracture body to be predicted; Based on the Mises equivalent stress and stress state parameters of the ductile fracture body to be predicted, the local principal stress of the ductile fracture body to be predicted is converted into the stress state parameter space; Add hydrostatic stress enhancement term to the Mohr-Coulomb model to establish the hydrostatic stress enhanced Mohr-Coulomb model; Based on the local principal stress of the ductile fracture body to be predicted converted to the stress state parameter space, the Mohr-Coulomb model enhanced by hydrostatic stress is converted to the stress-stress state parameter space, and a linear stress combination ductile fracture identification model considering hydrostatic stress enhancement is obtained, which can predict the fracture trajectory of the ductile fracture body to be predicted.

2. The linear stress combination ductile fracture identification method according to claim 1, characterized in that: The stress invariant of the ductile fracture body to be predicted is calculated by the following formula: I1=σ1+σ2+σ3 Where I1, J2 and J3 are the first, second and third stress invariants of the ductile fracture body to be predicted, respectively; σ1, σ2 and σ3 are the first, second and third local principal stresses of the ductile fracture body to be predicted, respectively.

3. The linear stress combination ductile fracture identification method according to claim 2, characterized in that: The Mises equivalent stress of the ductile fracture body to be predicted is calculated by the following formula: In the formula, σ eq is the Mises equivalent stress of the ductile fracture body to be predicted.

4. The linear stress combination ductile fracture identification method according to claim 3, characterized in that: The stress state parameters of the ductile fracture body to be predicted include stress triaxiality and Rhodes angle parameters, which are calculated by the following formula: Where η is the stress triaxiality and ξ is the Rhodes angle parameter.

5. The linear stress combination ductile fracture identification method according to claim 4, characterized in that: The expression after converting the local principal stress of the ductile fracture body to be predicted into the stress state parameter space is as follows: σ1=σ eq (n+f1) σ2=σ eq (n+f2) σ3= σ eq (n+f3) in, Where f1, f2 and f3 are all intermediate parameters.

6. The linear stress combination ductile fracture identification method according to claim 5, characterized in that: The Mohr-Coulomb model of hydrostatic stress enhancement: (σ1-σ3)+c1(σ1+σ3)+c2<η-η0>=c3 Where c1, c2 and c3 are material constants; η0 is the reference stress triaxiality; <x>is a piecewise function. When x ≥ 0, <x>= x, otherwise <x> ＝0。< / x> < / x> < / x> 7. The linear stress combination ductile fracture identification method according to claim 6, characterized in that: The expression of the linear stress combination ductile fracture identification model considering hydrostatic stress enhancement is as follows: In the formula, σ eq is the Mises equivalent stress of the ductile fracture body to be predicted.

8. A linear stress combination ductile fracture identification device considering hydrostatic stress enhancement, characterized in that: include: The first processing unit is used to calculate the local principal stress of the ductile fracture body to be predicted; A second processing unit is used to calculate the stress invariant of the ductile fracture body to be predicted based on the local principal stress of the ductile fracture body to be predicted; The third processing unit is used to calculate the Mises equivalent stress of the ductile fracture body to be predicted based on the local principal stress of the ductile fracture body to be predicted: A fourth processing unit is used to calculate stress state parameters of the ductile fracture body to be predicted based on the stress invariant of the ductile fracture body to be predicted; A fifth processing unit is used to convert the local principal stress of the ductile fracture body to be predicted into a stress state parameter space based on the Mises equivalent stress and stress state parameter of the ductile fracture body to be predicted; A sixth processing unit is used to add a hydrostatic stress enhancement term to the Mohr-Coulomb model to establish a hydrostatic stress enhanced Mohr-Coulomb model; The seventh processing unit is used to convert the hydrostatic stress-enhanced Mohr-Coulomb model into the stress-stress state parameter space based on the local principal stress of the ductile fracture body to be predicted converted into the stress state parameter space, and obtain a linear stress combination ductile fracture identification model considering the hydrostatic stress enhancement, so as to predict the fracture trajectory of the ductile fracture body to be predicted.

9. A computer-readable storage medium, characterized in that: A computer program is stored, and the computer program is executed by a processor to control the device where the processor is located to implement the steps of the linear stress combination ductile fracture identification method according to any one of claims 1 to 7.

10. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the linear stress combination ductile fracture identification method according to any one of claims 1 to 7 are implemented.

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