A heavy machinery equipment structural part fatigue calculation method, system, device and medium

Abstract

The application discloses a heavy machinery equipment structural member fatigue calculation method, system, equipment and medium, and the method comprises the steps of: selecting a plurality of characteristic loads of envelope time sequence loads according to the nonlinearity degree of the structure; segmenting the time sequence loads, and generating a load ratio file corresponding to each characteristic load; performing finite element loading calculation on the characteristic loads, and obtaining a stress result file for piecewise interpolation curve; obtaining the stress time sequence under each time sequence load by combining the load ratio file and the stress result file; performing rain flow counting on the stress time sequence to obtain the number of stress amplitudes and mean values, and then obtaining the fatigue damage of the structural member by combining an SN curve. Through the segmentation processing of the time sequence loads, finite element analysis is performed on each load step, the relationship between the nonlinearity degree of the structure and the stress response of the structure is considered, the stress time sequence and the fatigue damage of the structural member can be obtained with higher accuracy, and the occurrence of overdesign or excessively aggressive design and the like can be prevented.

Description

Technical Field

[0001] This invention relates to the technical field of fatigue analysis of nonlinear stress models of assembled structures, and in particular to a fatigue calculation method, system, equipment and medium for structural components of heavy machinery. Background Technology

[0002] Structural components in heavy machinery have specific mechanical performance requirements, namely, they must meet ultimate strength and fatigue strength requirements throughout their entire lifespan and be safe and reliable during use. Currently, fatigue calculations for structural components typically involve first determining a load value F0 using a time-series load, then performing finite element method (FEM) simulations to obtain the stress distribution under that load. Next, the fatigue time-series load is linearly interpolated with this fixed load F to obtain the time-series ratio k. This ratio k is then combined with the FEM results to obtain the stress time series. Finally, rainflow counting is performed on the stress time series, and combined with the SN curve, the fatigue damage of the structural component is determined.

[0003] Existing methods assume a linear relationship between structural stress and external load, neglecting the nonlinear effects of the structural system. Therefore, the magnitude of the load value F0 used in finite element analysis will significantly influence the final fatigue results. Figure 1 As shown. If the value of F0 is too small, the calculated damage will be underestimated, resulting in an overly aggressive outcome; if the value of F0 is too large, the calculated fatigue damage will be overestimated, resulting in an overly conservative outcome. The calculation results of this method have a large dispersion, which is not conducive to engineers' correct judgment of the calculation results, thus affecting the design and optimization of structural components. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a fatigue calculation method for heavy machinery structural components that takes into account the nonlinear effects of structural components and has high accuracy.

[0005] To address the aforementioned technical problems, this invention provides a fatigue calculation method for structural components of heavy machinery, comprising:

[0006] Based on the degree of structural nonlinearity, multiple characteristic loads of the envelope time-series load are selected;

[0007] The time-series loads are segmented, and a load ratio file is generated for each characteristic load.

[0008] Finite element method (FEM) calculations are performed on the characteristic loads to obtain stress result files for piecewise interpolation curves.

[0009] By combining the load ratio file and the stress result file, the stress time series under each time series load is obtained;

[0010] Rainflow counting is performed on the stress time series to obtain the number of stress amplitudes and averages, and then the fatigue damage of the structural components is obtained by combining the SN curve.

[0011] Furthermore, the time-series loads are segmented, and a load ratio file is generated for each characteristic load, including:

[0012] The time-series loads are split into two files according to their positive and negative values. The negative loads in the positive load file are replaced with 0, and the positive loads in the negative load file are replaced with 0.

[0013] The positive load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load.

[0014] The negative load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load.

[0015] Furthermore, the positive load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load; let the multiple characteristic loads of the envelope time series load be (-g,-e,-d,0,a,b,c);

[0016] In the load ratio file f1 for characteristic load a, loads between 0 and a are set as the ratio of load value Li to a, and load values ​​greater than a are set to 1.

[0017] In the load ratio file f2 of characteristic load b, load values ​​between 0 and a are set to 0, load values ​​Li between a and b are set to (Li-a) / (ba), and load values ​​greater than b are set to 1.

[0018] In the load ratio file f3 for characteristic load c, loads less than b are set to 0, and load values ​​Li located between b and c are set to (Li-b) / (cb).

[0019] Furthermore, finite element method (FEM) calculations are performed on the characteristic loads to obtain the corresponding stress result files for the piecewise interpolation curves, including:

[0020] Let the stress result file corresponding to characteristic load a be r1, the stress result file corresponding to characteristic load b be r2, the stress result file corresponding to characteristic load c be r3, the stress result file corresponding to characteristic load -d be r4, the stress result file corresponding to characteristic load -e be r5, and the stress result file corresponding to characteristic load -g be r6;

[0021] The stress result files corresponding to the piecewise interpolation curves are as follows: 0 to a segment is r1, a to b segment is r2-r1, b to c segment is r3-r2, 0 to -d segment is r4, -d to -e segment is r5-r4, and -e to -g segment is r6-r5, which are respectively denoted as R1, R2, R3, R4, R5, and R6.

[0022] Furthermore, by combining the load ratio file and the stress result file, the stress time series under each time series load is obtained, including:

[0023] The load ratio files f1, f2, ..., f6 are converted into .s3t format files using the Ncode fatigue analysis module, and then imported into the Ncode fatigue analysis module along with the stress result files R1, R2, ..., R6 for fatigue calculation, thereby obtaining the stress time series under each time-series load.

[0024] To address the aforementioned technical problems, this invention also provides a fatigue calculation system for structural components of heavy machinery, including a characteristic load selection module, a segmentation module, a finite element loading calculation module, an Ncode fatigue analysis module, and a fatigue damage calculation module.

[0025] The characteristic load selection module is used to select multiple characteristic loads of the envelope time-series load according to the degree of structural nonlinearity.

[0026] The segmentation module is used to segment the time-series loads and generate a load ratio file for each characteristic load.

[0027] The finite element loading calculation module is used to perform finite element loading calculations on the characteristic loads and obtain stress result files for piecewise interpolation curves.

[0028] The Ncode fatigue analysis module is used to combine the load ratio file and the stress result file to obtain the stress time series under each time series load;

[0029] The fatigue damage calculation module is used to count the number of stress amplitudes and averages by performing rainflow counting on the stress time series, and then combine it with the SN curve to obtain the fatigue damage of the structural component.

[0030] Furthermore, the Ncode fatigue analysis module employs Ncode fatigue analysis software.

[0031] To address the aforementioned technical problems, the present invention further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described fatigue calculation method for heavy machinery structural components.

[0032] To address the aforementioned technical problems, the present invention further provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the aforementioned fatigue calculation method for heavy machinery structural components.

[0033] The beneficial effects of implementing this invention are as follows:

[0034] This invention segments the time-series loads, performing finite element analysis on each load step to obtain the relationship between load and structural stress response considering structural nonlinearity. This allows for more accurate determination of stress timing and fatigue damage of structural components. It enables more precise calculation of structural component lifespan, preventing over-design or overly aggressive design, and largely overcomes the shortcomings of existing calculation methods. It is worthy of promotion in the field of heavy machinery and other industries. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating fatigue calculation using existing methods.

[0036] Figure 2 This is a schematic diagram illustrating fatigue calculation using the present invention;

[0037] Figure 3 This is a flowchart illustrating the principle of a fatigue calculation method for structural components of heavy machinery according to the present invention.

[0038] Figure 4 This is a schematic diagram of the finite element model for hub analysis (A is blade root 1, B is blade root 2, C is blade root 3, D is pitch bearing, E is hub, F is blade root connecting bolt, and G is wind turbine locking disc).

[0039] Figure 5 This is a connection block diagram of a fatigue calculation system for structural components of heavy machinery equipment according to the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.

[0041] like Figure 3 As shown, this embodiment provides a fatigue calculation method for structural components of heavy machinery equipment. The target object is a finite element analysis model of a wheel hub, which includes blade roots (blade root 1, blade root 2, blade root 3), blade root connecting bolts, pitch bearings, wheel hub, wind turbine locking disc, etc. Figure 4 As shown, this is a highly nonlinear structure.

[0042] Specifically, the steps include the following:

[0043] S1. Based on the degree of structural nonlinearity, select multiple characteristic loads of the envelope time-series load, including:

[0044] The maximum values ​​(envelope values) of each key load component are obtained by applying fatigue time-series loads to leaf root 1.

[0045] Mx_max = 9000kNm, My_max = 13000kNm, Mz_max = 300kNm and minimum values ​​Mx_min = -7000kNm, My_min = -6000kNm, Mz_min = -250kNm. The maximum and minimum values ​​are segmented. In this example, the maximum and minimum load values ​​are divided into three segments: Mx_max1 = 3000kNm, Mx_max2 = 6000kNm, Mx_max3 = 9000kNm, My_max1 = 4333kNm, My_max2 = 8667kNm, My... _max3=13000kNm, Mz_max1=100kNm, Mz_max2=200kNm, Mz_max3=300kNm, Mx_min1=-2333kNm, Mx_min2=-4667kNm, Mx_min3=-7 000kNm, My_min1=-2000kNm, My_min2=-4000kNm, My_min3=-6000kNm, Mz_min1=-83kNm, Mz_min2=-167kNm, Mz_min3=-250kNm;

[0046] S2. Segment the time-series loads and generate a load ratio file for each characteristic load, including:

[0047] The time-series loads are split into two files according to their positive and negative values. The negative loads in the positive load file are replaced with 0, and the positive loads in the negative load file are replaced with 0.

[0048] The positive load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load.

[0049] The negative load file is segmented by interpolation according to the value of the characteristic load (the principle is the same as that of segmenting the positive load file by interpolation according to the value of the characteristic load), and a load ratio file is generated for each corresponding characteristic load.

[0050] For example, if the time-series load values ​​(in kNm) of a segment of Mx are -5000, -3000, -1000, 2000, 5000, and 8000, then the load ratio file f1 corresponding to the positive segmented load Mx_max1 = 3000 is 0, 0, 0, 0.667, 1, 1; the load ratio file f2 corresponding to the positive segmented load Mx_max2 = 6000 is 0, 0, 0, 0, 0.667, 1; and the load ratio file f3 corresponding to the positive segmented load Mx_max3 = 9000 is 0, 0, 0, 0. 0, 0.667; the load ratio file f4 corresponding to the negative segmented load Mx_min1=-2333 is 1, 1, 0.428, 0, 0, 0; the load ratio file f5 corresponding to the negative segmented load Mx_min2=-4667 is 1, 0.286, 0, 0, 0, 0; the load ratio file f6 corresponding to the negative segmented load Mx_min3=-7000 is 0.143, 0, 0, 0, 0, 0; the other key component loads are obtained by analogy, resulting in the corresponding load ratio files f7, f8, ..., f17, f18.

[0051] S3. Perform finite element loading calculations on the segmented characteristic loads to obtain stress result files rst1, rst2, ..., rst17, rst18, a total of 18 stress result files; then perform a subtraction operation on the stress results to obtain stress result files R1, R2, ..., R17, R18 for the segmented interpolation curves.

[0052] S4. Repeat steps S1-S3 for the time-series loads on blade roots 2 and 3 to obtain load ratio files f19, f20, ..., f53, f54, which correspond to stress result files R19, R20, ..., R53, R54 for piecewise interpolation curves.

[0053] S5. Convert the load ratio files f1, f2, ..., f53, f54 into .s3t format files using Ncode fatigue analysis software, and import them together with the stress result files R1, R2, ..., R53, R54 into Ncode fatigue analysis software for fatigue calculation. The software calculates the stress time series under each time-series load, performs rainflow counting to obtain the number of stress amplitudes and average values, and then combines the SN curve to obtain the fatigue damage of the component.

[0054] Table 1 shows a comparison of fatigue damage at various hot spots in the wheel hub calculated using existing methods and the method of this invention:

[0055]

[0056] Table 1 Comparison of fatigue damage results

[0057] As shown in Table 1, the existing methods have different values ​​for the characteristic load F0, resulting in significant differences in fatigue damage values ​​at various hotspot locations, low accuracy, and large dispersion. In contrast, the method of this invention effectively improves the accuracy of fatigue interpolation calculations, fully considers the nonlinear effects of the structure, is closer to reality, and yields more reliable simulation results.

[0058] like Figure 5 As shown, this embodiment provides a fatigue calculation system for heavy machinery structural components, used to implement the above-mentioned fatigue calculation method for heavy machinery structural components. It includes: a characteristic load selection module, a segmentation module, a finite element loading calculation module, an Ncode fatigue analysis module, and a fatigue damage calculation module.

[0059] The characteristic load selection module is used to select multiple characteristic loads of the envelope time-series load according to the degree of structural nonlinearity.

[0060] The segmentation module is used to segment the time-series loads and generate a load ratio file for each characteristic load.

[0061] The finite element loading calculation module is used to perform finite element loading calculations on the characteristic loads and obtain stress result files for piecewise interpolation curves.

[0062] The Ncode fatigue analysis module is used to combine the load ratio file and the stress result file to obtain the stress time series under each time series load;

[0063] The fatigue damage calculation module is used to count the number of stress amplitudes and averages by performing rainflow counting on the stress time series, and then combine it with the SN curve to obtain the fatigue damage of the structural component.

[0064] In addition, this embodiment also provides a computer device and a computer-readable storage medium.

[0065] The computer device includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the fatigue calculation method for the structural components of the heavy machinery described above.

[0066] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described fatigue calculation method for structural components of heavy machinery.

[0067] This embodiment segments the time-series load, performing finite element analysis on each load step to obtain the relationship between load and structural stress response considering structural nonlinearity. This allows for more accurate determination of stress timing and structural fatigue damage. It enables more precise calculation of structural lifespan, preventing over-design or overly aggressive design, and largely overcomes the shortcomings of existing calculation methods. It is worthy of wider application in the field of heavy machinery and other industries.

[0068] Although the description of this disclosure has been quite detailed and particularly focused on several of the described embodiments, it is not intended to limit itself to any of these details or embodiments or any particular embodiment, but should be considered as providing a broad possible interpretation of the claims by referring to the appended claims and taking into account the prior art, thereby effectively covering the intended scope of this disclosure. Furthermore, the foregoing description of this disclosure with respect to embodiments foreseeable by the inventors is intended to provide a useful description, and non-substantial modifications to this disclosure that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A fatigue calculation method for structural components of heavy machinery, characterized in that, include: Based on the degree of structural nonlinearity, multiple characteristic loads of the envelope time-series load are selected; The time-series loads are segmented, and a load ratio file is generated for each characteristic load. Finite element method (FEM) calculations are performed on the characteristic loads to obtain stress result files for piecewise interpolation curves. By combining the load ratio file and the stress result file, the stress time series under each time series load is obtained; Rainflow counting is performed on the stress time series to obtain the number of stress amplitudes and averages, and then combined with the SN curve to obtain the fatigue damage of the structural components; The time-series loads are segmented, and a load ratio file is generated for each characteristic load, including: The time-series loads are split into two files according to their positive and negative values. The negative loads in the positive load file are replaced with 0, and the positive loads in the negative load file are replaced with 0. The positive load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load. The negative load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load. The positive load file is segmented by interpolation according to the value of the characteristic load, and a load ratio file is generated for each corresponding characteristic load; let the multiple characteristic loads of the envelope time series load be (-g, -e, -d, 0, a, b, c); In the load ratio file f1 for characteristic load a, loads between 0 and a are set as the ratio of load value Li to a, and load values ​​greater than a are set to 1. In the load ratio file f2 for characteristic load b, load values ​​between 0 and a are set to 0, load values ​​between a and b are set to (Li-a) / (ba), and load values ​​greater than b are set to 1. In the load ratio file f3 for characteristic load c, loads less than b are set to 0, and load values ​​between b and c are set to (Li-b) / (cb).

2. The fatigue calculation method for structural components of heavy machinery equipment according to claim 1, characterized in that, Finite element method (FEM) calculations are performed on the characteristic loads, resulting in stress result files used for piecewise interpolation curves. include: Let the stress result file corresponding to characteristic load a be r1, the stress result file corresponding to characteristic load b be r2, the stress result file corresponding to characteristic load c be r3, the stress result file corresponding to characteristic load -d be r4, the stress result file corresponding to characteristic load -e be r5, and the stress result file corresponding to characteristic load -g be r6; The stress result files corresponding to the piecewise interpolation curves are as follows: 0 to a segment is r1, a to b segment is r2-r1, b to c segment is r3-r2, 0 to -d segment is r4, -d to -e segment is r5-r4, and -e to -g segment is r6-r5, which are respectively denoted as R1, R2, R3, R4, R5, and R6.

3. The fatigue calculation method for structural components of heavy machinery equipment according to claim 2, characterized in that, By combining the load ratio file and the stress result file, the stress time series under each time series load is obtained, including: The load ratio files f1, f2, ..., f6 are converted into .s3t format files using the Ncode fatigue analysis module, and then imported into the Ncode fatigue analysis module along with the stress result files R1, R2, ..., R6 for fatigue calculation, thereby obtaining the stress time series under each time-series load.

4. A fatigue calculation system for structural components of heavy machinery, characterized in that, The method for fatigue calculation of heavy machinery equipment structural components according to any one of claims 1-3 includes: a characteristic load selection module, a segmentation module, a finite element loading calculation module, an Ncode fatigue analysis module, and a fatigue damage calculation module. The characteristic load selection module is used to select multiple characteristic loads of the envelope time-series load according to the degree of structural nonlinearity. The segmentation module is used to segment the time-series loads and generate a load ratio file for each characteristic load. The finite element loading calculation module is used to perform finite element loading calculations on the characteristic loads and obtain stress result files for piecewise interpolation curves. The Ncode fatigue analysis module is used to combine the load ratio file and the stress result file to obtain the stress time series under each time series load; The fatigue damage calculation module is used to count the number of stress amplitudes and averages by performing rainflow counting on the stress time series, and then combine it with the SN curve to obtain the fatigue damage of the structural component.

5. The fatigue calculation system for structural components of heavy machinery equipment according to claim 4, characterized in that, The Ncode fatigue analysis module uses Ncode fatigue analysis software.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the fatigue calculation method for heavy machinery structural components as described in any one of claims 1 to 3.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the fatigue calculation method for heavy machinery structural components as described in any one of claims 1 to 3.

Images