Dynamic stress field generation method for bolt fault state of annular mechanical structure

Abstract

The invention discloses a dynamic stress field generation method of an annular mechanical structure bolt fault state, and belongs to the technical field of mechanical health monitoring. The technical problem of mathematical modeling of a nonlinear stress wave propagation path in an annular mechanical structure bolt is solved. The method comprises the steps of initializing parameters of bolts of the annular mechanical structure, and generating a loosening parameter data set; constructing a bidirectional stress field model; bidirectional stress calculation is carried out on each node bolt in the annular mechanical structure bolts, the forward stress component is a stress component of each layer calculated in the circumferential speed increasing direction, and the reverse stress component is a seam attenuation component calculated in the circumferential speed reducing direction; then calculating the total stress of each node bolt in the bolts of the annular mechanical structure to construct an adaptive measuring point network of the bolts of the annular mechanical structure, adjusting the positions of the measuring points according to a dynamic phase deviation matching formula, and optimizing the layout of the measuring points; simulation noise conforming to N (0, sigma2) normal distribution is overlaid on each measuring point of the annular mechanical structure bolt, and a standard characteristic waveform library is generated.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical health monitoring, and in particular relates to a method for generating a dynamic stress field of a bolt fault state in an annular mechanical structure. Background Art

[0002] Bolts are critical connectors in complex equipment, and loosening poses a significant risk to structural safety. Current technologies for detecting bolt connection status primarily include manual retesting, sensor implantation, and acoustic emission. Manual retesting relies on downtime for maintenance, resulting in low efficiency and the inability to provide online early warning. While sensor implantation offers real-time performance, it is costly and sensitive to complex electromagnetic environments. While acoustic emission offers some responsiveness, it suffers from high false alarm rates and poor positioning accuracy.

[0003] Existing detection methods for annular mechanical structures have significant modeling limitations. Due to their circumferential continuity, traditional linear propagation models struggle to accurately characterize the multipath reflection and interference behavior of stress waves within the annular path, leading to signal aliasing and large fault location errors. Furthermore, typical models fail to fully account for wave reflection and coupling effects at bolted joints, resulting in incomplete dynamic responses and loosening criterion deviations exceeding 30%. Furthermore, in the presence of high noise, existing algorithms struggle to effectively extract weak fault signatures from multi-source superposition signals.

[0004] In summary, bolted joint condition monitoring faces three core bottlenecks in the application of annular structures: (1) the lack of a dynamic modeling method for stress propagation in annular structures; (2) the coupling of responses from multiple loosening points leads to the annihilation of characteristic signals; and (3) the lack of systematic optimization of measurement point layout and sampling strategy, which limits monitoring efficiency and accuracy. Therefore, it is urgent to build a dynamic stress field generation mechanism for annular structure characteristics to provide a high-resolution and robust physical field perception foundation for loosening identification. Summary of the Invention

[0005] The problem to be solved by the present invention is the technical difficulty of mathematical modeling of the nonlinear stress wave propagation path in the annular mechanical structure bolt, and a method for generating a dynamic stress field of the fault state of the annular mechanical structure bolt is proposed.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure comprises the following steps:

[0008] S1. Initialize the parameters of the annular mechanical structure bolt, including the number of circumferential groups P, the number of radial levels M, and the maximum number of loose groups K;

[0009] S2. Randomly select the initial loose groups with the fault interval factor Q times the spacing through discrete Fourier phase, and determine the loose boundary parameters (R0, R z ), where R0 is the loosening starting position, R z For the loosening extension length, a loosening parameter data set is generated;

[0010] S3. Construct a bidirectional stress field model and perform bidirectional stress calculations on each node bolt in the annular mechanical structure. The positive stress component is calculated along the circumferential acceleration direction for each layer, while the negative stress component is calculated along the circumferential deceleration direction for the attenuation component at the joint. The total stress at each node bolt in the annular mechanical structure is then calculated.

[0011] S4 based on the loose parameter data set obtained in step S2, build a ring mechanical structure bolt adaptive measuring point network, adjust the measuring point position according to the dynamic phase deviation matching formula, optimize the measuring point layout;

[0012] S5. Superimpose each measuring point of the ring mechanical structure bolt in accordance with N(0, σ 2 ) Normally distributed simulated noise to generate a library of standard characteristic waveforms.

[0013] Furthermore, the calculation method of each group of loose boundary parameters in step S2 is:

[0014]

[0015] Where G represents the circumferential group number, G∈[1, P / Q], L represents the radial position offset, L∈[1, M], and Q represents the fault interval factor;

[0016]

[0017] Where λ is the fault diffusion coefficient, T is the system operation time, K a Indicates the maximum number of loose bolts per group; R z Obeys modified exponential distribution.

[0018] Furthermore, the specific implementation method of step S3 includes the following steps:

[0019] S3.1. Set the normal stress component to calculate the stress component of each layer along the circumferential acceleration direction. The calculation formula is:

[0020]

[0021] Among them, α, β, and γ are the first attenuation parameter of the bolt material, the second attenuation parameter of the bolt material, and the third attenuation parameter of the bolt material, respectively; i is the target point, j is the fault source, represents the normal stress influence component of the j-th bolt on the i-th bolt, represents the normal stress component of the target point, c k Indicates the looseness index of each set of bolts;

[0022]

[0023] Where N is the total number of bolts, mod represents the remainder sign;

[0024] S3.2. Set the reverse stress component to calculate the attenuation component at the joint along the circumferential deceleration direction. The calculation formula is:

[0025]

[0026] in, represents the reverse stress component at the target point, represents the negative stress influence component of the j-th bolt on the i-th bolt;

[0027]

[0028] Wherein, Δ is the seam compensation amount;

[0029] S3.3. Calculate the total stress at each node bolt in a ring of mechanical structure bolts , the calculation formula is:

[0030] .

[0031] Furthermore, the calculation formulas for the first attenuation parameter of the bolt material, the second attenuation parameter of the bolt material, and the third attenuation parameter of the bolt material in step S3.1 are:

[0032]

[0033]

[0034] Where E is the elastic modulus and ρ is the material density;

[0035]

[0036] Among them, K is the maximum number of loose groups.

[0037] Furthermore, the specific implementation method of step S4 includes the following steps: S4.1. Construct a dynamic phase deviation matching formula, which is expressed as:

[0038]

[0039] Among them, R ref is the reference looseness dimension, Δ pTo dynamically correct the phase difference, fix is ​​the rounding symbol;

[0040] S4.2. Construct the base measurement points of the adaptive measurement point network for the bolt configuration of the annular mechanical structure. The expression is:

[0041]

[0042] Where k is the number of loose bolt groups, The bolt number of the measuring point;

[0043] S4.3. Construct a redundant measurement point set for the adaptive measurement point network of the ring-shaped mechanical structure bolt configuration. The expression is:

[0044] ;

[0045] S4.4. Based on the redundant measurement point set, perform multi-channel signal synthesis, expressed as:

[0046] .

[0047] Furthermore, in step S5, a frequency band noise adding technique is used to add noise to the signal frequency band B=[f low , f high ] Divide into three levels of sub-bands:

[0048] B1=[ f low , 0.5f c ]:Injected noise amplitude A1=0.2A max ;

[0049] B2=(0.5f c , 0.8 f c ]:Injected noise amplitude A2=0.5A max ;

[0050] B2=(0.8f c , f high ]:Injected noise amplitude A3=0.1A max ;

[0051] Among them, B1 is the first-level sub-band, B2 is the second-level sub-band, B3 is the third-level sub-band, f low is the subband lower limit, f high is the upper limit of the subband, A1 is the noise amplitude injected into the first subband, A2 is the noise amplitude injected into the second subband, A3 is the noise amplitude injected into the third subband, f c is the structural characteristic frequency, A max is the maximum amplitude of the signal.

[0052] Beneficial effects of the present invention:

[0053] The method described in this paper for generating dynamic stress fields for bolt failures in annular mechanical structures significantly improves the detection accuracy and location resolution of loose bolt faults by constructing a bidirectional dynamic stress vector synthesis model and incorporating phase difference correction and adaptive measurement point placement algorithms. This method effectively suppresses errors caused by structural node interference and achieves high-fidelity reconstruction of stress propagation characteristics.

[0054] The method described in this paper for generating dynamic stress fields for bolt faults in an annular mechanical structure significantly reduces the number of sensor locations and data storage requirements through a non-uniform phase correction mechanism, improving the economic efficiency of system deployment and data processing efficiency. Furthermore, multimodal fault identification and frequency-band noise reduction enhance the system's diagnostic robustness under complex operating conditions, providing excellent anti-interference capabilities.

[0055] The method for generating a dynamic stress field for a bolt failure state in an annular mechanical structure described in the present invention, and the proposed material parameter adaptation model and parallel stress field calculation framework have good structural and material compatibility, are applicable to a variety of large-scale annular connection structures, and have excellent versatility and engineering promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a flow chart of a method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure according to the present invention. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the specific embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the specific embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0058] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected specific embodiments of the present invention. All other specific embodiments obtained by those skilled in the art based on the specific embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0059] In order to further understand the content, features and effects of the present invention, the following specific embodiments are given as examples, and the attached Figure 1 The detailed instructions are as follows:

[0060] Example 1:

[0061] A method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure comprises the following steps:

[0062] S1. Initialize the parameters of the annular mechanical structure bolt, including the number of circumferential groups P, the number of radial levels M, and the maximum number of loose groups K;

[0063] S2. Randomly select the initial loose groups with the fault interval factor Q times the spacing through discrete Fourier phase, and determine the loose boundary parameters (R0, R z ), where R0 is the loosening starting position, R z For the loosening extension length, a loosening parameter data set is generated;

[0064] Furthermore, the calculation method of each group of loose boundary parameters in step S2 is:

[0065]

[0066] Where G represents the circumferential group number, G∈[1, P / Q], L represents the radial position offset, L∈[1, M], and Q represents the fault interval factor;

[0067]

[0068] Where λ is the fault diffusion coefficient, T is the system operation time, K a Indicates the maximum number of loose bolts per group; R z Obeys modified exponential distribution.

[0069] Furthermore, a method was proposed to generate an initial loosening group and construct a loosening characteristic parameter set by randomly selecting discrete Fourier transform phases and controlling the spacing factor. This method combines the circumferential group sequence and radial offset of the structure to accurately model the loosening starting location and extension range. The loosening length was modeled using a modified exponential distribution, fully accounting for the influence of fault propagation characteristics and system operating time, thereby improving the physical rationality and adaptability of the parameter modeling.

[0070] S3. Construct a bidirectional stress field model and perform bidirectional stress calculations on each node bolt in the annular mechanical structure bolt system. The positive stress component is the stress component calculated for each layer along the circumferential acceleration direction, and the negative stress component is the attenuation component calculated at the joint along the circumferential deceleration direction. The total stress at each node bolt in the annular mechanical structure bolt system is then calculated.

[0071] Furthermore, the specific implementation method of step S3 includes the following steps:

[0072] S3.1. Set the normal stress component to calculate the stress component of each layer along the circumferential acceleration direction. The calculation formula is:

[0073]

[0074] Among them, α, β, and γ are the first attenuation parameter of the bolt material, the second attenuation parameter of the bolt material, and the third attenuation parameter of the bolt material, respectively; i is the target point, j is the fault source, represents the normal stress influence component of the j-th bolt on the i-th bolt, represents the normal stress component of the target point, c k Indicates the looseness index of each set of bolts;

[0075]

[0076] Where N is the total number of bolts, mod represents the remainder sign;

[0077] Furthermore, the calculation formulas for the first attenuation parameter of the bolt material, the second attenuation parameter of the bolt material, and the third attenuation parameter of the bolt material in step S3.1 are:

[0078]

[0079]

[0080] Where E is the elastic modulus and ρ is the material density;

[0081]

[0082] Among them, K is the maximum number of loose groups.

[0083] S3.2. Set the reverse stress component to calculate the attenuation component at the joint along the circumferential deceleration direction. The calculation formula is:

[0084]

[0085] in, represents the reverse stress component at the target point, represents the negative stress influence component of the j-th bolt on the i-th bolt;

[0086]

[0087] Wherein, Δ is the seam compensation amount;

[0088] S3.3. Calculate the total stress at each node bolt in the annular mechanical structure bolt system using the following formula:

[0089] .

[0090] Furthermore, the model introduces material attenuation parameters and structural compensation, comprehensively considering the effects of elastic modulus, density, and loose group distribution on stress transfer, achieving high-precision estimation of the composite stress at each node, effectively improving the resolution and physical consistency of fault characterization;

[0091] S4 based on the loose parameter data set obtained in step S2, build a ring mechanical structure bolt adaptive measuring point network, adjust the measuring point position according to the dynamic phase deviation matching formula, optimize the measuring point layout;

[0092] Furthermore, the specific implementation method of step S4 includes the following steps: S4.1. Construct a dynamic phase deviation matching formula, which is expressed as:

[0093]

[0094] Among them, R ref is the reference looseness dimension, Δ p To dynamically correct the phase difference, fix is ​​the rounding symbol;

[0095] S4.2. Construct the base measurement points of the adaptive measurement point network for the bolt configuration of the annular mechanical structure. The expression is:

[0096]

[0097] Where k is the number of loose bolt groups, The bolt number of the measuring point;

[0098] S4.3. Construct a redundant measurement point set for the adaptive measurement point network of the ring-shaped mechanical structure bolt configuration. The expression is:

[0099] ;

[0100] S4.4. Based on the redundant measurement point set, perform multi-channel signal synthesis, expressed as:

[0101] .

[0102] Furthermore, an adaptive measurement point network is constructed, using a dynamic phase deviation matching strategy to adjust sampling locations, ensuring that measurement points avoid structural vibration nodes. Base measurement points are determined by a fixed formula, and phase deviations are dynamically corrected based on looseness characteristics, improving sampling sensitivity to fault signatures. A redundant measurement point set is also introduced, and multi-channel signal synthesis enhances the system's anti-interference capability and fault identification robustness.

[0103] S5. Superimpose each measuring point of the ring mechanical structure bolt in accordance with N(0, σ 2 ) Normally distributed simulated noise to generate a library of standard characteristic waveforms.

[0104] Furthermore, in step S5, a frequency band noise adding technique is used to add noise to the signal frequency band B=[f low , f high ] Divide into three levels of sub-bands:

[0105] B1=[ f low , 0.5f c ]:Injected noise amplitude A1=0.2A max ;

[0106] B2=(0.5f c , 0.8 f c ]:Injected noise amplitude A2=0.5A max ;

[0107] B2=(0.8f c , f high ]:Injected noise amplitude A3=0.1A max ;

[0108] Among them, B1 is the first-level sub-band, B2 is the second-level sub-band, B3 is the third-level sub-band, f low is the subband lower limit, f high is the upper limit of the subband, A1 is the noise amplitude injected into the first subband, A2 is the noise amplitude injected into the second subband, A3 is the noise amplitude injected into the third subband, f c is the structural characteristic frequency, A max is the maximum amplitude of the signal.

[0109] Furthermore, a standard feature waveform library is constructed by superimposing simulated noise that follows a normal distribution to improve the diversity of data samples. A frequency-band noise addition strategy is adopted to divide the signal frequency band into three sub-bands, and noise with different amplitudes is injected into each sub-band to enhance the anti-interference ability of the feature signal in different frequency domains. This method helps to improve the generalization performance of model training and the robustness of fault identification.

[0110] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0111] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, as long as there are no structural conflicts, the various features of the embodiments disclosed herein may be combined with each other in any manner, and the omission of an exhaustive description of these combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure, characterized in that: The steps include: S1. Initialize the parameters of the annular mechanical structure bolt, including the number of circumferential groups P, the number of radial levels M, and the maximum number of loose groups K; S2. Randomly select the initial loose groups with the fault interval factor Q times the spacing through discrete Fourier phase, and determine the loose boundary parameters (R0, R z ), where R0 is the loosening starting position, R z For the loosening extension length, a loosening parameter data set is generated; S3. Construct a bidirectional stress field model and perform bidirectional stress calculations on each node bolt in the annular mechanical structure. The positive stress component is calculated along the circumferential acceleration direction for each layer, while the negative stress component is calculated along the circumferential deceleration direction for the attenuation component at the joint. The total stress at each node bolt in the annular mechanical structure is then calculated. S4 based on the loose parameter data set obtained in step S2, build a ring mechanical structure bolt adaptive measuring point network, adjust the measuring point position according to the dynamic phase deviation matching formula, optimize the measuring point layout; S5. Superimpose each measuring point of the ring mechanical structure bolt in accordance with N(0, σ 2 ) Normally distributed simulated noise to generate a library of standard characteristic waveforms.

2. The method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure according to claim 1, characterized in that: The calculation method of each group of loose boundary parameters in step S2 is: Where G represents the circumferential group number, G∈[1, P / Q], L represents the radial position offset, L∈[1, M], and Q represents the fault interval factor; Where λ is the fault diffusion coefficient, T is the system operation time, K a Indicates the maximum number of loose bolts per group; R z Obeys modified exponential distribution.

3. A method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure according to claim 1 or 2, characterized in that: The specific implementation method of step S3 includes the following steps: S3.

1. Set the normal stress component to calculate the stress component of each layer along the circumferential acceleration direction. The calculation formula is: Among them, α, β, and γ are the first attenuation parameter of the bolt material, the second attenuation parameter of the bolt material, and the third attenuation parameter of the bolt material, respectively; i is the target point, j is the fault source, represents the normal stress influence component of the j-th bolt on the i-th bolt, represents the normal stress component of the target point, c k Indicates the looseness index of each set of bolts; Where N is the total number of bolts, mod represents the remainder sign; S3.

2. Set the reverse stress component to calculate the attenuation component at the joint along the circumferential deceleration direction. The calculation formula is: in, represents the reverse stress component at the target point, represents the negative stress influence component of the j-th bolt on the i-th bolt; Wherein, Δ is the seam compensation amount; S3.

3. Calculate the total stress at each node bolt in a ring of mechanical structure bolts , the calculation formula is: 。 4. The method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure according to claim 3, characterized in that: The calculation formulas for the first attenuation parameter, the second attenuation parameter, and the third attenuation parameter of the bolt material in step S3.1 are: Where E is the elastic modulus and ρ is the material density; Among them, K is the maximum number of loose groups.

5. The method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure according to claim 4, characterized in that: The specific implementation method of step S4 includes the following steps: S4.

1. Construct a dynamic phase deviation matching formula, which is expressed as: Among them, R ref is the reference looseness dimension, Δ p To dynamically correct the phase difference, fix is ​​the rounding symbol; S4.

2. Construct the base measurement points of the adaptive measurement point network for the bolt configuration of the annular mechanical structure. The expression is: Where k is the number of loose bolt groups, The bolt number of the measuring point; S4.

3. Construct a redundant measurement point set for the adaptive measurement point network of the ring-shaped mechanical structure bolt configuration. The expression is: ； S4.

4. Based on the redundant measurement point set, perform multi-channel signal synthesis, expressed as: 。 6. The method for generating a dynamic stress field of a bolt failure state in an annular mechanical structure according to claim 5, characterized in that: In step S5, the frequency band noise adding technology is used to add noise to the signal frequency band B=[f low , f high ] Divide into three levels of sub-bands: B1=[ f low , 0.5f c ]:Injected noise amplitude A1=0.2A max ; B2=(0.5f c , 0.8 f c ]:Injected noise amplitude A2=0.5A max ; B2=(0.8f c , f high ]:Injected noise amplitude A3=0.1A max ; Among them, B1 is the first-level sub-band, B2 is the second-level sub-band, B3 is the third-level sub-band, f low is the subband lower limit, f high is the upper limit of the subband, A1 is the noise amplitude injected into the first subband, A2 is the noise amplitude injected into the second subband, A3 is the noise amplitude injected into the third subband, f c is the structural characteristic frequency, A max is the maximum amplitude of the signal.

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