Mechanical simulation method for detecting a problem of a defect-containing structure

Abstract

This invention provides a mechanical simulation method for detecting defects in structures, comprising: applying a virtual excitation wave signal to a preset position of the model to be tested to obtain a simulated displacement cloud map; a signal source sending a real excitation wave signal at a specific position of the structure to be tested; a signal receiving sensor receiving feedback from the real excitation wave signal to obtain an actual displacement cloud map and a wave propagation curve; if the simulated displacement cloud map is different from the actual displacement cloud map, determining the actual defect position based on the wave propagation curve; repeating the calculation N times to obtain N actual defect positions; calculating the average value of the N actual defect positions, and determining the defect position of the model to be tested based on the average value, thereby making the simulation effect of the model to be tested closer to the defective structure to be tested, accurately simulating the wave propagation in the structure to be tested based on the model to be tested, and saving processing time.

Description

Technical Field

[0001] This invention relates to the field of mechanical model simulation technology, and more particularly to a mechanical simulation method for detecting defects in structures. Background Technology

[0002] Traditional continuum mechanics models are based on the continuity assumption, which leads to the problem of undefined derivatives at discontinuities. This makes it difficult to handle discontinuous displacement and strain fields, and often results in suboptimal handling of discontinuous problems.

[0003] Peri-field dynamics describes the mechanical behavior of matter by solving spatial integral equations. It is a nonlocal theory that does not require spatial derivatives and uses spatial integral equations for discontinuous bodies. Although peri-field dynamics can effectively handle discontinuous problems, it suffers from low computational efficiency and boundary effects due to the limitations of nonlocal theory.

[0004] However, in the simulation process of the near-field dynamics model, the phenomena of crack initiation, propagation, and bifurcation are generated naturally with the simulation process. Apart from adding a single bond fracture condition, there is no need for too many judgment conditions or special elements.

[0005] In view of this, the present invention combines near-field dynamics theory with isogeometric analysis to propose a mechanical simulation method for detecting defects in structures. Summary of the Invention

[0006] To address the aforementioned shortcomings, this invention provides a mechanical simulation method for detecting defects in structures. The invention primarily utilizes a combination of peri-field dynamics theory and isogeometric analysis to obtain a simulation model, thereby simulating wave propagation within the detected structure.

[0007] The technical means employed in this invention are as follows:

[0008] This invention provides a mechanical simulation method for detecting defects in structures, comprising:

[0009] S1: Establish an isogeometric analysis model using non-uniform rational B-splines, predict the location of defects in the isogeometric analysis model and set it as the near-field dynamic region to obtain an isogeometric analysis-near-field dynamic coupled model;

[0010] S2: The model to be tested is obtained by defining the boundary conditions and material parameters of the isogeometric analysis-peri-dynamic coupling model based on the structure to be tested;

[0011] S3: Apply a virtual excitation wave signal to the preset position of the model to be detected, and obtain the simulated displacement cloud map by using the explicit iteration method and the central difference method;

[0012] S4: The signal source sends a real excitation wave signal at a specific location on the structure to be detected, and the specific location corresponds to the preset location; the signal receiving sensor receives the feedback of the real excitation wave signal to obtain the actual displacement cloud map and wave propagation curve;

[0013] S5: If the simulated displacement cloud map is different from the actual displacement cloud map, the peak time of the real excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal are obtained according to the wave propagation curve. The actual defect location is determined according to the peak time of the real excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal.

[0014] S6: Repeat S3 to S5 N times to obtain N actual defect locations;

[0015] S7: Calculate the average value of the N actual defect locations, and determine the defect location of the model to be detected based on the average value.

[0016] Further, determining the actual defect location based on the peak time of the actual excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal includes:

[0017] Along the transmission direction of the real excitation wave signal, the distance between the signal receiving sensor and the defect location is set as the first distance, and the propagation distance of the transmitted wave formed by the real excitation wave signal through the defect location is set as the second distance.

[0018] The first distance and the second distance are calculated based on the peak time of the actual excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal;

[0019] The actual defect location is determined based on the first distance and the second distance.

[0020] Further, the first distance and the second distance are calculated as follows:

[0021]

[0022] Where L1 is the first distance, L2 is the second distance, t1 is the peak time of the actual excitation wave signal, t3 is the peak time of the end face echo signal, t5 is the peak time of the defect echo signal, and c g The group velocity is the propagation velocity of the signal wave.

[0023] Furthermore, S1 also includes:

[0024] The number of control points in the near-field dynamics is set, and there is a bond between two adjacent control points to divide the defects in the near-field dynamics region.

[0025] Furthermore, the minimum distance between two adjacent control points is X, the radius of the defect area is 3X, and the preset position coincides with the center of the defect area.

[0026] Furthermore, it also includes:

[0027] S8: Define a gap or hole at the defect location of the model to be inspected, and set the bond base passing through the gap or hole to be disconnected.

[0028] Furthermore, the material parameters include elastic modulus, material density, and Poisson's ratio.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The mechanical simulation method provided by this invention for detecting defects in structures obtains the model to be tested by defining the geometric analysis-near-field dynamic coupling model based on the boundary conditions and material parameters of the structure to be tested. A virtual excitation wave signal is applied to a preset position of the model to be tested, and a simulated displacement contour map is obtained using an explicit iteration method and a central difference method. A signal source sends a real excitation wave signal at a specific position of the structure to be tested, corresponding to a preset position. A signal receiving sensor receives the feedback of the real excitation wave signal to obtain the actual displacement contour map and wave propagation curve. If the simulated displacement contour map differs from the actual displacement contour map, [further steps are taken]. The peak times of the actual excitation wave signal, the end face echo signal, and the defect echo signal are obtained from the wave propagation curve. The actual defect location is determined based on these peak times. The calculation is repeated N times to obtain N actual defect locations. The average value of the N actual defect locations is calculated, and the defect location of the model to be tested is determined based on the average value. This makes the simulation effect of the model to be tested closer to the structure to be tested containing defects. The propagation of waves in the structure to be tested can be accurately simulated based on the model to be tested, and processing time can be saved. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1This is a schematic flowchart of a mechanical simulation method for detecting defects in structures provided by the present invention.

[0033] Figure 2 This is a comparison chart of simulated displacement contour maps and actual displacement contour maps.

[0034] Figure 3 This is another comparison diagram between simulated displacement contour plots and actual displacement contour plots.

[0035] Figure 4 This is another comparison chart between simulated displacement contour maps and actual displacement contour maps.

[0036] Figure 5 This is a schematic diagram of a signal source, a structure to be detected, and a signal receiving sensor.

[0037] Figure 6 This is a schematic diagram of a wave propagation curve.

[0038] Figure 7 This is a partial schematic diagram of a near-field dynamics model.

[0039] Figure 8 This is another local schematic diagram of the isogeometric analysis-peri-dynamic coupling model.

[0040] In the diagram: 1. Signal source; 2. Structure to be tested; 3. Signal receiving sensor. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 , Figure 1 This is a schematic flowchart of a mechanical simulation method for detecting defects in structures provided by the present invention. Figure 2 This is a comparison chart of simulated displacement contour maps and actual displacement contour maps. Figure 3 This is another comparison diagram between simulated displacement contour maps and actual displacement contour maps. Figure 4 This is another comparison chart between simulated displacement contour maps and actual displacement contour maps. Figure 5 This is a schematic diagram of a signal source, a structure to be detected, and a signal receiving sensor, illustrating a specific embodiment of the mechanical simulation method for detecting defects in a structure provided by the present invention, including:

[0044] S1: Establish an isogeometric analysis model using non-uniform rational B-splines, predict the location of defects using the isogeometric analysis model and set it as the near-field dynamic region to obtain the isogeometric analysis-near-field dynamic coupling model;

[0045] S2: The model to be tested is obtained based on the boundary conditions and material parameters of the geometric analysis-near-field dynamic coupling model defined for the structure to be tested 2;

[0046] S3: Apply a virtual excitation wave signal to the preset position of the model to be detected, and obtain the simulated displacement cloud map by using the explicit iteration method and the central difference method;

[0047] S4: Signal source 1 sends a real excitation wave signal at a specific position of the structure 2 to be detected, and the specific position corresponds to the preset position; signal receiving sensor 3 receives the feedback of the real excitation wave signal to obtain the actual displacement cloud map and wave propagation curve;

[0048] S5: If the simulated displacement cloud map is different from the actual displacement cloud map, obtain the peak time of the real excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal according to the wave propagation curve. Determine the actual defect location based on the peak time of the real excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal.

[0049] S6: Repeat S3 to S5 N times to obtain N actual defect locations;

[0050] S7: Calculate the average value of N actual defect locations, and determine the defect location of the model to be detected based on the average value.

[0051] Understandably, the virtual excitation wave signal is constructed by multiplying a sinusoidal carrier wave by a Gaussian function. (See reference...) Figures 2 to 4 , Figure 2 In this context, 'a' represents a simulated displacement contour plot. Figure 2 In this diagram, 'b' represents a type of actual displacement contour plot. Figure 3 a1 in the diagram represents another type of simulated displacement contour plot. Figure 3 b1 in the diagram represents another type of actual displacement contour plot; Figure 4 a2 in the diagram represents another type of simulated displacement contour plot. Figure 4 In the diagram, b2 represents another type of actual displacement contour map. If the simulated displacement contour map differs from the actual displacement contour map, it indicates that the structure 2 under test contains a defect. A corresponding defect needs to be added to the model under test to achieve accurate simulation. The actual excitation wave signal changes when passing through the defect. The signal receiving sensor 3 receives the defect echo and the end face echo, and calculates the end face echo rate and the defect echo rate to determine the actual defect location in the structure 2 under test. To further improve accuracy, steps S3 to S5 are repeated N times to obtain N actual defect locations. The average value of the N actual defect locations is calculated, and the defect location is determined in the model under test based on the position of the average value.

[0052] Compared with the prior art, the present invention has the following advantages:

[0053] The mechanical simulation method provided by this invention for detecting defects in structures obtains the test model 2 by defining the boundary conditions and material parameters of the geometric analysis-near-field dynamics coupled model. A virtual excitation wave signal is applied to a preset position of the test model, and a simulated displacement contour map is obtained using an explicit iteration method and a central difference method. A signal source 1 sends a real excitation wave signal at a specific position of the test structure 2, corresponding to a preset position. A signal receiving sensor 3 receives the feedback of the real excitation wave signal to obtain the actual displacement contour map and wave propagation curve. If the simulated displacement contour map differs from the actual displacement contour map, ... The peak times of the actual excitation wave signal, the end face echo signal, and the defect echo signal are obtained from the wave propagation curve. The actual defect location is determined based on these peak times. The calculation is repeated N times to obtain N actual defect locations. The average value of the N actual defect locations is calculated, and the defect location of the model to be tested is determined based on the average value. This makes the simulation effect of the model to be tested closer to the defective structure 2. The propagation of the wave in the structure 2 to be tested can be accurately simulated based on the model to be tested, and processing time can be saved.

[0054] In some alternative embodiments, refer to Figure 5 and Figure 6 , Figure 6 This is a schematic diagram of a wave propagation curve. The actual defect location is determined based on the peak times of the real excitation wave signal, the end-face echo signal, and the defect echo signal, including:

[0055] Along the transmission direction of the real excitation wave signal, the distance between the signal receiving sensor 3 and the defect location is set as the first distance, and the propagation distance of the transmitted wave formed by the real excitation wave signal through the defect location is set as the second distance.

[0056] The first distance and the second distance are calculated based on the peak time of the actual excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal.

[0057] The actual defect location is determined based on the first and second distances.

[0058] Understandably, in Figure 5 The diagram only illustrates one relative positional relationship between the signal source 1, the structure to be detected 2, and the signal receiving sensor 3. Of course, it is not limited to this; see also [reference needed]. Figure 5 Signal ① is the actual excitation wave signal, and the peak time of the actual excitation wave signal is t1. Signal ③ is the end face echo signal, and the peak time of the end face echo signal is t3. Signal ⑤ is the defect echo signal, and the peak time of the defect echo signal is t5. Record the peak values ​​and peak times of the actual excitation wave signal, the end face echo signal, and the defect echo signal, calculate the end face echo rate and the defect echo rate, and determine the specific location of the actual defect.

[0059] In some alternative embodiments, reference continues to be made to... Figure 5 and Figure 6 Calculate the first distance and the second distance as follows:

[0060]

[0061] Where L1 is the first distance, L2 is the second distance, t1 is the peak time of the actual excitation wave signal, t3 is the peak time of the end face echo signal, t5 is the peak time of the defect echo signal, and c g The group velocity is the propagation velocity of the signal wave.

[0062] In some alternative embodiments, refer to Figure 7 and Figure 8 , Figure 7 This is a partial schematic diagram of a near-field dynamics model. Figure 8 As another local schematic diagram of the isogeometric analysis-peri-dynamic coupling model, S1 also includes:

[0063] The number of control points in the near-field dynamics region is set, and there is a bond between two adjacent control points. Defects are then defined in the near-field dynamics region.

[0064] Understandably, in Figure 7In the diagram, the dotted line represents the control point, and the circular area enclosed by the dashed line represents the defect area. Figure 8 In this model, the defect area is a rectangular region. Based on experience, the defect is divided into near-field dynamic regions, which helps to quickly locate the defect and save time. Of course, the size and shape of the defect area can be adjusted according to the actual situation and are not limited to this.

[0065] In some alternative embodiments, reference continues to be made to... Figure 7 The minimum distance between two adjacent control points is X, the radius of the defect area is 3X, and the preset position coincides with the center of the defect area.

[0066] Understandably, this is a reasonable way to set up the defect area.

[0067] In some alternative embodiments, reference continues to be made to... Figure 7 The mechanical simulation method for detecting defects in structures provided in this embodiment also includes:

[0068] S8: Define a gap or hole at the defect location of the model to be inspected, and set the bond base passing through the gap or hole to be disconnected.

[0069] Understandable Figure 7 The diagram only illustrates the location of the defect as a crack. The defect location in the model to be tested is defined as a gap. In the calculation, any bond intersecting with the crack is considered broken, and bond breakage is defined by deleting family nodes. In the calculation, bond intersecting with the crack is set as broken; this method is simple and direct, requiring no remapping or modification of the computational model. The mechanical simulation method for detecting defects in structures provided in this embodiment can quickly simulate wave propagation in a medium and accurately obtain the location of defects such as cracks in the structure to be tested (2). It has high computational efficiency and can be applied to detect defects such as cracks and circular holes in structures.

[0070] In some alternative embodiments, material parameters include elastic modulus, material density, and Poisson's ratio.

[0071] It is understandable that the material parameters are the material parameters of the structure to be tested 2. The equivalent geometric analysis-peri-dynamic coupling model is defined based on the material parameters, so that the model to be tested corresponds to the structure to be tested 2, which facilitates simulation.

[0072] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0073] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mechanical simulation method for detecting defects in structures, characterized in that, include: S1: Establish an isogeometric analysis model using non-uniform rational B-splines, predict the location of defects in the isogeometric analysis model and set it as the near-field dynamic region to obtain an isogeometric analysis-near-field dynamic coupled model; S2: The model to be tested is obtained by defining the boundary conditions and material parameters of the isogeometric analysis-peri-dynamic coupling model based on the structure to be tested; S3: Apply a virtual excitation wave signal to the preset position of the model to be detected, and obtain the simulated displacement cloud map by using the explicit iteration method and the central difference method; S4: The signal source sends a real excitation wave signal at a specific location on the structure to be detected, and the specific location corresponds to the preset location; the signal receiving sensor receives the feedback of the real excitation wave signal to obtain the actual displacement cloud map and wave propagation curve; S5: If the simulated displacement cloud map is different from the actual displacement cloud map, the peak time of the real excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal are obtained according to the wave propagation curve. The actual defect location is determined based on the peak time of the real excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal, including: Along the transmission direction of the real excitation wave signal, the distance between the signal receiving sensor and the defect location is set as the first distance, and the propagation distance of the transmitted wave formed by the real excitation wave signal through the defect location is set as the second distance. The first distance and the second distance are calculated based on the peak time of the actual excitation wave signal, the peak time of the end face echo signal, and the peak time of the defect echo signal; The actual defect location is determined based on the first distance and the second distance; S6: Repeat S3 to S5 N times to obtain N actual defect locations; S7: Calculate the average value of the N actual defect locations, and determine the defect location of the model to be detected based on the average value.

2. The mechanical simulation method for detecting defects in structures according to claim 1, characterized in that, The first distance and the second distance are calculated as follows: ； Where L1 is the first distance, L2 is the second distance, t1 is the peak time of the actual excitation wave signal, t3 is the peak time of the end face echo signal, t5 is the peak time of the defect echo signal, and c g The group velocity is the propagation velocity of the signal wave.

3. The mechanical simulation method for detecting defects in structures according to claim 1, characterized in that, S1 also includes: The number of control points in the near-field dynamics region is set, and there is a bond between two adjacent control points to divide the defects in the near-field dynamics region.

4. The mechanical simulation method for detecting defects in structures according to claim 3, characterized in that, The minimum distance between two adjacent control points is X, the radius of the defect area is 3X, and the preset position coincides with the center of the defect area.

5. The mechanical simulation method for detecting defects in structures according to claim 3, characterized in that, Also includes: S8: Define a gap or hole at the defect location of the model to be inspected, and set the bond base passing through the gap or hole to be disconnected.

6. The mechanical simulation method for detecting defects in structures according to claim 1, characterized in that, The material parameters include elastic modulus, material density, and Poisson's ratio.

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