Self-vibration frequency calculation method and device, electronic equipment and storage medium

Abstract

This invention relates to the field of hydraulic structure technology, and discloses a method, apparatus, electronic device, and storage medium for calculating natural frequencies. The invention selects a first local structure and a second local structure in a created three-dimensional model of a hydraulic structure, and assigns values ​​to the material properties of the first and second local structures respectively. The three-dimensional model of the hydraulic structure is composed of the first and second local structures. A first preset algorithm is used to calculate the initial natural frequency of the first local structure after the assignment. Based on the initial natural frequency, target nodes and target elements are determined, and the material properties of the target elements are assigned values. The target nodes are extracted from the second local structure. Based on the assigned target elements and the second preset algorithm, the target natural frequency of the first local structure is calculated, thereby improving the accuracy of solving for the natural frequency of the local structure.

Description

Technical Field

[0001] This invention relates to the field of hydraulic structures technology, specifically to a method, apparatus, electronic device, and storage medium for calculating natural frequencies. Background Technology

[0002] Large hydraulic structures (such as underground powerhouses of pumped storage power stations) have highly complex spatial structural systems. Their structures include irregularly shaped components such as piers, wind tunnels, staircases, slabs, beams, and columns, and there are complex mechanical coupling relationships between these components. Due to the high complexity of the construction of hydraulic structures, the natural frequencies of various local structures (such as piers, columns, and floor slabs) often overlap and are cross-coupled. It is difficult to distinguish the natural vibration characteristics and corresponding mode shapes of each local structure from the overall natural vibration characteristics, resulting in insufficient accuracy of traditional overall calculation methods in solving the natural vibration characteristics of local structures. Summary of the Invention

[0003] This invention provides a method for calculating natural frequencies to solve the problem of insufficient accuracy in solving the natural vibration characteristics of local structures using traditional overall calculation methods.

[0004] In a first aspect, the present invention provides a method for calculating the natural frequency, the method comprising: In the created three-dimensional model of the hydraulic structure, a first local structure and a second local structure are selected, and the material properties of the first local structure and the second local structure are assigned values ​​respectively. The three-dimensional model of the hydraulic structure is composed of the first local structure and the second local structure. The initial natural frequency of the first local structure after assignment is calculated using a first preset algorithm; Based on the initial natural frequency, target nodes and target elements are determined, and the material properties of the target elements are assigned values. The target nodes are extracted from the second local structure. The target natural frequency of the first local structure is calculated based on the assigned target unit and the second preset algorithm.

[0005] In this embodiment of the invention, on the one hand, the target elements and target nodes are accurately selected by using the initial natural frequency, and then the target elements of the second local structure are oriented and parameterized a second time, gradually eliminating the mass and stiffness interference of non-critical structures, thereby improving the accuracy of calculating the natural frequency of the local structure. On the other hand, by assigning values ​​to the material properties of the first and second local structures respectively, the natural frequencies and independent mode shapes of the local structures in the overall structure can be effectively separated, reducing the possibility of overall mode confusion.

[0006] In one optional implementation, the material properties include at least: density value, Poisson's ratio, and elastic modulus; the assignment of values ​​to the material properties of the first local structure and the second local structure includes: The density, Poisson's ratio, and elastic modulus of the first local structure and the second local structure are assigned values ​​according to preset actual parameters, respectively. The method further includes: The density value of the second local structure is set to 0.

[0007] In this embodiment of the invention, by assigning different values ​​to the material properties of the first local structure and the second local structure, the dynamic interaction between the components of the complex hydraulic structure can be effectively decoupled, reducing the possible frequency overlap and mode mixing problems, accurately obtaining the true natural vibration characteristics of the local structure, and improving the calculation accuracy.

[0008] In one optional implementation, determining the target node and target element based on the initial natural frequency includes: Based on the initial natural frequency, the first-order natural frequency of the oscillator is determined in the first direction, the second direction, and the third direction, respectively. The first direction represents the horizontal direction, the second direction represents the direction perpendicular to the first direction, and the third direction represents the direction perpendicular to the first direction and the second direction, respectively. Determine the rotation angle threshold based on the frequencies of each first-order self-oscillator; Based on the corner threshold, the target node and the target unit are determined.

[0009] In this embodiment of the invention, on the one hand, by determining the first-order natural frequency of the oscillator in each direction, the vibration characteristics of the first local structure in different directions can be understood in more detail. On the other hand, by determining the rotation angle threshold based on the first-order natural frequency, regions (i.e., target nodes and target elements) that have a greater impact on structural vibration can be accurately screened, providing a basis for subsequent assignment of differentiated material properties, thereby further improving the calculation accuracy of the natural frequency of the first local structure.

[0010] In one optional implementation, determining the rotation angle threshold based on the frequencies of each of the first-order self-oscillators includes: The first local structure is divided into a first unit, and the second local structure is divided into a second unit. The first unit represents all units within the first local structure, and the second unit represents all units within the second local structure. The target natural frequency is determined in each of the first-order natural frequencies using a preset rule, and the target modal parameters corresponding to the target natural frequency are obtained. Based on the target modal parameters, the first rotation angle value of the first node in the first unit and the second rotation angle value of the second node in the second unit are determined. The first node represents all nodes in the first unit, and the second node represents all nodes in the second unit. The corner threshold is determined by multiplying the absolute value of the first corner value by a preset corner threshold coefficient.

[0011] In this embodiment of the invention, on the one hand, by determining the target modal parameters corresponding to the target natural frequency, the subsequent rotation angle calculation is based on the actual vibration modal characteristics of the structure, thereby improving the objectivity and rationality of the judgment criteria. On the other hand, the rotation angle threshold is calculated by combining the maximum absolute value of the rotation angle of the first local structural node with a fixed threshold coefficient. This threshold is used to set a level that closely matches the actual dynamic response of the structure, further increasing the calculation accuracy of the target natural frequency of the first local structure.

[0012] In one optional implementation, determining the target node and the target unit based on the corner threshold includes: Determine a target angle value that is greater than the angle threshold from the absolute value of the second angle value, and obtain the target node corresponding to the target angle value from the second node; The target unit corresponding to the target node is obtained in the second node.

[0013] In this embodiment of the invention, on the one hand, by using a determined corner threshold as a criterion to filter the corner values ​​of each node in the second local structure, target nodes and target units are selected, thereby improving the accuracy of the selection. On the other hand, by accurately selecting target nodes and corresponding target units, clear processing objects are provided for subsequent assignment of differentiated materials, further reducing vibration interference in non-target areas and significantly improving the calculation accuracy of the target natural frequency of the first local structure.

[0014] In one optional implementation, assigning values ​​to the material properties of the target unit includes: assigning values ​​to the density value of the target unit according to preset actual parameters.

[0015] In this embodiment of the invention, the target unit is modified by assigning a density value to the target unit, thereby accurately restoring the inertial coupling effect of the surrounding structure on the local dynamic characteristics, and thus improving the accuracy of the natural frequency calculation.

[0016] In an alternative implementation, the method further includes applying boundary conditions to the three-dimensional model of the hydraulic structure, the boundary conditions including at least a spring stiffness coefficient and a damping coefficient.

[0017] In this embodiment of the invention, by applying boundary conditions including spring stiffness coefficient and damping coefficient to the three-dimensional model of the hydraulic structure, the actual elastic constraint effect of the surrounding rock, surrounding rock mass and constraint structure of the underground powerhouse can be accurately simulated, so that the boundary conditions of the model are more in line with the actual site, further reducing numerical simulation error and ensuring that the calculation results of the target natural frequency of the first local structure are accurate and reliable.

[0018] In a second aspect, the present invention provides a device for calculating natural frequency, the device comprising: The assignment module is used to select a first local structure and a second local structure in the created three-dimensional model of the hydraulic structure, and assign material properties to the first local structure and the second local structure respectively. The three-dimensional model of the hydraulic structure is composed of the first local structure and the second local structure. The first calculation module is used to calculate the initial natural frequency of the first local structure after assignment using a first preset algorithm; The determination module is used to determine the target node and target element based on the initial natural frequency, and to assign values ​​to the material properties of the target element. The target node is extracted from the second local structure. The second calculation module is used to calculate the target natural frequency of the first local structure based on the assigned target unit and the second preset algorithm.

[0019] Thirdly, the present invention provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the natural frequency calculation method of the first aspect or any corresponding embodiment described above.

[0020] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the natural frequency calculation method of the first aspect or any corresponding embodiment thereof. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific 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 from these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart of the first method for calculating the natural frequency according to an embodiment of the present invention; Figure 2This is a schematic diagram of a three-dimensional model of a hydraulic structure according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the second process of the natural frequency calculation method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a partial structure according to an embodiment of the present invention; Figure 5 This is a structural block diagram of a natural frequency calculation device according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] Large hydraulic structures are complex in overall design. For example, the underground powerhouse structure of a pumped-storage power station typically has intricate structural forms, including piers, wind tunnels, staircases, slabs, beams, and columns. Analysis of the overall natural vibration characteristics of the underground powerhouse structure of a large hydropower station shows that due to the complexity of the main powerhouse structure, the frequencies of various local structures overlap and intersect, making it difficult to distinguish the natural vibration characteristics and mode shapes of each local structure from the overall natural vibration characteristics. Based on current observations of pumped-storage power stations in China that have experienced severe vibrations, the areas of intense vibration in the powerhouse generally occur only in local structures rather than the overall structure.

[0027] However, the calculation schemes for the natural frequencies of local structures in related technologies generally have the following problems: 1. The calculation method based on the overall structural stiffness matrix and mass matrix is ​​simple to calculate, but due to the complexity of the factory structure, it is difficult to identify which local structure's natural frequency a certain frequency belongs to from the mode shape.

[0028] 2. The method of independently modeling and solving local structures can focus on local characteristics, but the calculation deviation is large because the constraint stiffness and modal participation mass do not match the actual situation.

[0029] To address the aforementioned problems, this invention proposes a method for calculating natural frequencies, thereby effectively improving the accuracy of calculating the natural frequencies of local structures.

[0030] According to an embodiment of the present invention, a method for calculating natural frequency is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0031] This embodiment provides a method for calculating the natural frequency, which can be used in the aforementioned electronic equipment. Figure 1 This is a schematic flowchart of the first method for calculating the natural frequency according to an embodiment of the present invention, as shown below. Figure 1 As shown, the process includes the following steps: Step S101: Select the first local structure and the second local structure in the created three-dimensional model of the hydraulic structure, and assign material properties to the first local structure and the second local structure respectively. The three-dimensional model of the hydraulic structure is composed of the first local structure and the second local structure.

[0032] Here, professional 3D modeling software (such as ANSYS, ABAQUS, Revit, etc.) is used to construct a complete 3D model of the hydraulic structure based on the design drawings, actual dimensions, and geometric shapes. This 3D model should include local structures such as the tailrace pipe, spiral casing and surrounding concrete, machine piers, wind tunnel hood, floor slabs, powerhouse sidewalls, and structural columns, and also simulate the stairs and some openings at full size. The concrete structure is almost entirely constructed using hexahedral block elements, effectively simulating the true stiffness of the actual floor slabs and beams.

[0033] like Figure 2 As shown, Figure 2 This is a schematic diagram of a 3D model of a hydraulic structure. Taking the structure of a pumped storage power station as an example, assume that the dimensions of a column are 1.0m × 1.5m, the dimensions of the main beam are 1.0m × 1.6m, and the thickness of the slab is 0.6m.

[0034] The first and second local structures can be selected in any suitable manner. For example, each local structure can be numbered, and the local structure corresponding to the selected target number can be used as the first local structure. Alternatively, the local structure at the target location in the model can be directly selected as the first local structure. This invention does not impose any limitations on this method.

[0035] It should be noted that after determining the first local structure, other local structures besides the first local structure are regarded as the second local structure.

[0036] Here, material properties mainly include density, elastic modulus, and Poisson's ratio. These material properties determine the mechanical behavior of a material under stress. For example, density affects the inertial force of a local structure, elastic modulus reflects the stiffness of a local structure, and Poisson's ratio characterizes the lateral deformation characteristics of a local structure under stress.

[0037] In some implementations, appropriate material properties can be specified for the first and second local structures respectively in the material property setting module of the modeling software. For example, if the first local structure is a concrete column, it can be assigned the material properties of concrete, such as a density of 2400 kg / m³, an elastic modulus of 30 GPa, and a Poisson's ratio of 0.2. Similarly, if the second local structure is a steel floor slab, it can be assigned the material properties of steel, such as a density of 7850 kg / m³, an elastic modulus of 206 GPa, and a Poisson's ratio of 0.3. It should be noted that material properties can be assigned values ​​according to actual conditions, and this method does not impose any limitations on this.

[0038] Step S102: The initial natural frequency of the first local structure after assignment is calculated using the first preset algorithm.

[0039] Here, the first preset algorithm can refer to a pre-defined calculation method used to calculate the initial natural frequency of the first local structure. Examples include the finite element method, subspace iteration method, and Lanzos algorithm. This method does not limit the first preset algorithm.

[0040] The initial natural frequency refers to the natural vibration frequency of the first local structure in its initial state, calculated by the first preset algorithm after the material properties of the first local structure are assigned. It characterizes the speed of vibration of the first local structure during free vibration and is related to factors such as the mass and stiffness of the first local structure.

[0041] In some implementations, the natural frequencies and mode shapes can be obtained by discretizing the continuous structure into a finite number of elements, assembling the elements into an overall stiffness matrix and mass matrix using their mechanical properties, and then solving the eigenvalue problem.

[0042] In some implementations, a correspondence between the initial natural frequency of the first local structure and the material properties of the first local structure can be established in advance. Based on this correspondence, an initial natural frequency that matches the material properties of the first local structure can be obtained.

[0043] In some implementations, the material properties of the first local structure can be input into a pre-established frequency calculation model to obtain the initial natural frequency of the first local structure. This frequency calculation model can be any suitable neural network model capable of performing this function.

[0044] Specifically, the target natural frequency can be calculated using the following formula:

[0045] in, This is the mass matrix, representing the mass distribution of the local structure; This is a time-varying vector, representing the deformation state of the local structure at different times; is the stiffness matrix, which characterizes the stiffness properties of the local structure; It is a displacement vector that represents the displacement of the local structure.

[0046] By displacement vector Assuming it is in the form of simple harmonic motion, the following characteristic formula is obtained:

[0047] in, Angular frequency, This is the mode shape vector.

[0048] Furthermore, based on the obtained angular frequency, according to This yields the specific value of the natural frequency f.

[0049] Step S103: Based on the initial natural frequency, determine the target node and target element, and assign values ​​to the material properties of the target element. The target node is extracted from the second local structure.

[0050] Here, the initial natural frequency can refer to the natural frequency of the structure under undamped free vibration state, calculated by assigning material properties to the first local structure and using a first preset algorithm (such as the finite element method). This reflects the dynamic characteristics of the first local structure itself. For example, in hydraulic engineering, for a column structure, the initial natural frequency is 10Hz, obtained through finite element analysis, which characterizes the vibration characteristics of the column under the current material properties and boundary conditions.

[0051] Step S104: Calculate the target natural frequency of the first local structure based on the assigned target unit and the second preset algorithm.

[0052] Here, the second preset algorithm can be the same as or different from the first preset algorithm. The second preset algorithm can refer to a pre-set calculation method used when calculating the target natural frequency of the first local structure. The solution method for the target natural frequency can be shown in step S102, and will not be elaborated here.

[0053] In some implementations, after obtaining the target natural frequency of the first local structure, the first direction (e.g., X), the second direction (e.g., Y), and the third direction (e.g., z) are determined by analyzing the degree of freedom of the target natural frequency, and the target natural frequency of the first local structure in each direction is calculated based on the target natural frequency.

[0054] As shown in Table 1, when the first local structure is a busbar column, the first-order precise natural frequency of the busbar column in the horizontal X direction is 87.5Hz and the first-order precise natural frequency in the Y direction is 114.2Hz.

[0055] At this point, the target sub-natural frequencies of the busbar columns in the X and Y directions are obtained using Method 1 and Method 2, respectively. Method 1 solves the column structure in conjunction with the overall structure, but only selects the column itself as the solution area. Method 2 considers the actual participating mass of the local structural mode shape when solving for the natural frequencies, and solves for the natural frequencies of the local structure through multiple iterative cycles.

[0056] Furthermore, by obtaining the relative error between the target oscillator frequency and the test value obtained from the field test, the accuracy of each method in obtaining the target oscillator frequency is characterized; that is, the smaller the relative error, the more accurate the target oscillator frequency.

[0057] The formula for relative error is as follows:

[0058] in, For the target oscillator frequency, Here, r represents the test value, and r represents the relative error.

[0059] The details are shown in Table 1:

[0060] It should be noted that, compared with the field test results, the natural frequencies calculated by Method 1 have a relatively large error, with a relative error of 14.24% in the X-direction and 11.59% in the Y-direction. Both Method 2 and this method can accurately solve for the natural frequencies of the local structure, with relative errors of less than 10%, indicating that the calculation results accurately reflect the natural frequencies of the local structure.

[0061] Furthermore, Method 2 requires continuously selecting grid cells adjacent to the local structure during the iterative process, typically requiring at least 2 to 3 iterations, and the stability of the calculation results is easily affected by the grid cell scale. In contrast, this invention only requires 2 calculations, improving computational efficiency by more than 50%, with a more significant improvement in large-scale computations, and it has no strict requirements on grid scale.

[0062] In this embodiment of the invention, on the one hand, the target elements and target nodes are accurately selected by using the initial natural frequency, and then the target elements of the second local structure are oriented and parameterized a second time, gradually eliminating the mass and stiffness interference of non-critical structures, thereby improving the accuracy of calculating the natural frequency of the local structure. On the other hand, by assigning values ​​to the material properties of the first and second local structures respectively, the natural frequencies and independent mode shapes of the local structures in the overall structure can be effectively separated, reducing the possibility of overall mode confusion.

[0063] In some optional implementations, step S101 above further includes: Step a1 involves assigning values ​​to the density, Poisson's ratio, and elastic modulus of the first and second local structures according to preset actual parameters. For details, please refer to [link to relevant documentation]. Figure 1 Step S101 of the illustrated embodiment will not be described again here.

[0064] Step a1 also includes: step a2, setting the density value of the second local structure to 0.

[0065] It should be noted that due to the complex interactions between the various local structures in hydraulic engineering, the mass of the second local structure may interfere with the analysis of the dynamic characteristics such as the natural frequency of the first local structure, making it difficult to accurately separate the inherent characteristics of the target structure. By setting the density of the second local structure to zero, the influence of its mass can be eliminated, allowing the analysis to focus more on the first local structure.

[0066] In this embodiment of the invention, by assigning different values ​​to the material properties of the first local structure and the second local structure, the dynamic interaction between the components of the complex hydraulic structure can be effectively decoupled, reducing the possible frequency overlap and mode mixing problems, accurately obtaining the true natural vibration characteristics of the local structure, and improving the calculation accuracy.

[0067] This embodiment provides a method for calculating the natural frequency, which can be used in the aforementioned electronic equipment. Figure 3 This is a second flowchart of the natural frequency calculation method according to an embodiment of the present invention, as shown below. Figure 3 As shown, the process includes the following steps S1031 to S1033: Step S1031: Based on the initial natural frequency, determine the first-order natural frequency of the oscillator in the first, second, and third directions, respectively. Step S1032: Based on each first-order natural frequency, determine the rotation angle threshold. Step S1033: Based on the rotation angle threshold, determine the target node and target element.

[0068] Here, the first direction represents the horizontal direction, the second direction represents the direction perpendicular to the first direction, and the third direction represents the direction perpendicular to the first and second directions respectively.

[0069] In some implementations, taking the busbar column as an example, it is assumed that the column has a rectangular cross-section and different dimensions in the X and Y directions, resulting in different moments of inertia in the two directions, and thus different stiffness in the two directions.

[0070] In some implementations, by selecting the busbar layer column as the first local structure and the other parts as the second local structure, modal analysis is performed to obtain the first natural frequency in the X direction. In this case, the obtained first natural frequency of the column in the X direction is 101.9 Hz, indicating that the column is prone to resonance when subjected to excitation of a similar frequency in the X direction.

[0071] In some implementations, the busbar layer column is selected as the first local structure, and other parts are selected as the second local structure. Modal analysis is then performed to obtain the first natural frequency in the Y direction. In this case, the obtained first natural frequency in the Y direction is 121.3 Hz, indicating that the column is prone to resonance when excited by a similar frequency in the Y direction.

[0072] In this embodiment of the invention, on the one hand, by determining the first-order natural frequency of the oscillator in each direction, the vibration characteristics of the first local structure in different directions can be understood in more detail. On the other hand, by determining the rotation angle threshold based on the first-order natural frequency, regions (i.e., target nodes and target elements) that have a greater impact on structural vibration can be accurately screened, providing a basis for subsequent assignment of differentiated material properties, thereby further improving the calculation accuracy of the natural frequency of the first local structure.

[0073] Specifically, step S1032 includes: Step b1: Divide the first local structure into a first unit and the second local structure into a second unit. The first unit represents all units within the first local structure, and the second unit represents all units within the second local structure.

[0074] like Figure 4 As shown, Figure 4 This is a schematic diagram of a partial structure. Taking the busbar column of the pumped storage power station building as the first partial structure, the first unit of this column is selected and assigned an actual density. kg / m3, Poisson's ratio And the elastic modulus E = 30 GPa. The second element of the second local structure is selected, and its actual Poisson's ratio is assigned. The elastic modulus is E=30GPa, and the density value of the second element is set to 0. The horizontal dimension of the divided mesh is approximately 0.25m, and the vertical dimension is approximately 0.2m.

[0075] Finite element meshes can be generated in various ways, such as manually generating them according to the actual situation, or using software (such as ANSYS, HyperMesh, etc.) to generate structured meshes. This application does not limit the methods used.

[0076] Step b2: Determine the target natural frequency of each first-order natural frequency using preset rules, and obtain the target modal parameters corresponding to the target natural frequency.

[0077] Here, the preset rule can be any suitable rule for determining the target natural frequency of the natural frequency in each first-order natural frequency, and this application does not limit it.

[0078] In some implementations, a target sub-frequency can be selected from the natural sub-frequency in each direction according to actual needs.

[0079] In some implementations, the minimum first-order natural frequency in each direction can be used as the target natural frequency.

[0080] Step b3: Based on the target modal parameters, determine the first rotation angle value of the first node in the first unit and the second rotation angle value of the second node in the second unit. The first node represents all nodes in the first unit, and the second node represents all nodes in the second unit.

[0081] Here, target modal parameters refer to the parameters corresponding to a specific mode (usually a mode of interest) in modal analysis. Modal analysis is a method for studying the dynamic characteristics of a structure, and it can obtain information such as the structure's natural frequencies and mode shapes. Target modal parameters include parameters such as mode shape vectors and rotation angles.

[0082] In some implementations, modal analysis can be used to obtain target modal parameters corresponding to the determined target natural frequency.

[0083] Step b4: Determine the corner threshold based on the product of the absolute value of the first corner value and the preset corner threshold coefficient.

[0084] Here, the corner threshold coefficient can be any suitable value in the range of 0.1 to 0.3, such as 0.1, 0.21, etc., and this method does not impose any restrictions on it.

[0085] The first turning value can refer to the turning value corresponding to each node.

[0086] In some implementations, by obtaining the corner values ​​of all nodes, determining the absolute value of the maximum corner value among the absolute values ​​of each corner value, and multiplying the absolute value of the maximum corner value by a preset corner threshold coefficient, the product is determined as the corner threshold.

[0087] For example, if the corner threshold coefficient is set to 0.1, the absolute value of the maximum corner value is 0.007, and the corner threshold is 0.0007.

[0088] The method for determining the maximum turning angle can be any suitable method, and this method does not impose any restrictions on it.

[0089] In this embodiment of the invention, on the one hand, by determining the target modal parameters corresponding to the target natural frequency, the subsequent rotation angle calculation is based on the actual vibration modal characteristics of the structure, thereby improving the objectivity and rationality of the judgment criteria. On the other hand, the rotation angle threshold is calculated by combining the maximum absolute value of the rotation angle of the first local structural node with a fixed threshold coefficient. This threshold is used to set a level that closely matches the actual dynamic response of the structure, further increasing the calculation accuracy of the target natural frequency of the first local structure.

[0090] In some optional implementations, step S1033 above includes: Step c1: Determine the target angle value that is greater than the angle threshold from the absolute value of the second angle value, and obtain the target node corresponding to the target angle value in the second node. Step c2: Obtain the target unit corresponding to the target node in the second node.

[0091] Here, the second rotation angle value refers to the rotation angle value of the second node in the second local structure under a specific mode, which characterizes the degree of rotation of each node in the second local structure during the vibration process.

[0092] It should be noted that by determining the target node corresponding to the target rotation value greater than the rotation threshold, the node with a large rotation amplitude during the local structural vibration is determined. At the same time, based on the obtained target node, the target unit associated with the target node in the second unit (i.e. all units in the second local structure) is further determined.

[0093] To further clarify, in the finite element model, each node is a component of an element, and each node connects to multiple elements. The elements connected to a target node can be found through that target node; these elements are the target elements.

[0094] In this embodiment of the invention, on the one hand, by using a determined corner threshold as a criterion to filter the corner values ​​of each node in the second local structure, target nodes and target units are selected, thereby improving the accuracy of the selection. On the other hand, by accurately selecting target nodes and corresponding target units, clear processing objects are provided for subsequent assignment of differentiated materials, further reducing vibration interference in non-target areas and significantly improving the calculation accuracy of the target natural frequency of the first local structure.

[0095] In some optional implementations, step S1033 above includes: Step d1: Assign density values ​​to the target cells according to preset actual parameters.

[0096] It should be noted that considering the complete mass of all structures during structural dynamics analysis will significantly increase the size of the mass matrix. Secondary local structures (such as surrounding ancillary structures, floor slabs, etc.) are often complex and have a large number of elements. Therefore, when solving for the natural frequencies of the first local structure for the first time, the density value of the second local structure is set to 0. This significantly reduces the number of non-zero elements in the mass matrix, thus reducing computational load and memory requirements.

[0097] Although the density of the second local structure was initially set to 0 to simplify calculations, the mass of certain regions actually has a significant impact on the dynamic characteristics of the overall structure. Therefore, by selecting target elements in step S103 and assigning density values ​​to them, these real-world physical scenarios can be simulated more accurately, making the analysis results more consistent with reality.

[0098] In this embodiment of the invention, the target unit is modified by assigning a density value to the target unit, thereby accurately restoring the inertial coupling effect of the surrounding structure on the local dynamic characteristics, and thus improving the accuracy of the natural frequency calculation.

[0099] In some optional implementations, the above method further includes the following steps: Step e1: Apply boundary conditions to the three-dimensional model of the hydraulic structure. The boundary conditions include at least the spring stiffness coefficient and the damping coefficient.

[0100] Here, boundary conditions are used to define the mechanical behavior of the model at the boundaries and characterize the interaction between the model and the external environment.

[0101] In some implementations, simulating the radiation damping effect of rock mass, the normal and tangential spring stiffness coefficients and damping coefficients per unit area on the artificial boundary are:

[0102] In the formula, and These are the normal and tangential spring stiffness coefficients, respectively; , These are the damping coefficients in the normal and tangential directions, respectively; The distance from the wave source to the artificial boundary point; and These are the P-wave and S-wave velocities of the medium, respectively. This is the shear modulus of the medium.

[0103] It should be noted that the spring stiffness coefficient represents the force required for a spring to produce a unit deformation. In hydraulic engineering models, it characterizes the elastic constraint effect of the boundary on the structure. For example, when the structure undergoes displacement, the spring generates an elastic force in the opposite direction of the displacement to resist it. A larger spring stiffness coefficient means stronger boundary constraints on the structure, resulting in smaller displacements at the boundaries.

[0104] Damping refers to the ability of a structure to dissipate energy during vibration due to various reasons (such as internal friction of materials, resistance of the medium, etc.). The damping coefficient is an indicator of this energy dissipation ability. In hydraulic engineering models, damping can reduce the vibration amplitude of the structure, allowing it to reach a stable state more quickly.

[0105] The rock mass radiation damping effect refers to the phenomenon where, as seismic waves propagate through rock, some of their energy radiates outwards to infinity; this energy dissipation is the rock mass radiation damping effect. In finite element models, because the model's scope is limited, appropriate boundary conditions need to be set to simulate this radiation damping effect in order to more accurately reflect the structure's response under seismic loading.

[0106] To further explain, in order to simulate the effects of rock masses in an infinite domain, artificial boundaries are typically set on the boundaries of the finite element model. Springs and dampers on these artificial boundaries can simulate the elasticity and energy dissipation characteristics of the rock mass.

[0107] On artificial boundaries, the spring stiffness coefficient and damping coefficient need to be considered separately in the normal (perpendicular to the boundary direction) and tangential (parallel to the boundary direction) directions. The spring stiffness coefficient and damping coefficient per unit area represent the mechanical properties of the springs and dampers per unit area. For example, the normal spring stiffness coefficient per unit area reflects the elastic constraint capacity of the boundary on the structure in the normal direction, while the tangential spring stiffness coefficient per unit area reflects the elastic constraint capacity of the boundary in the tangential direction; the normal and tangential damping coefficients per unit area reflect the energy dissipation capacity of the boundary in the normal and tangential directions, respectively.

[0108] In this embodiment of the invention, by applying boundary conditions including spring stiffness coefficient and damping coefficient to the three-dimensional model of the hydraulic structure, the actual elastic constraint effect of the surrounding rock, surrounding rock mass and constraint structure of the underground powerhouse can be accurately simulated, so that the boundary conditions of the model are more in line with the actual site, further reducing numerical simulation error and ensuring that the calculation results of the target natural frequency of the first local structure are accurate and reliable.

[0109] In this embodiment of the invention, the specific process of the natural frequency calculation method is as follows: First, create a three-dimensional finite element model of the factory structure. Second, assign material properties to the first local structure and the second local structure. Third, apply viscoelastic boundary conditions to the three-dimensional finite element model. Fourth, calculate the initial natural frequency of the first local structure for the first time. Fifth, set a rotation angle threshold, determine the target node based on the rotation angle threshold, and assign the actual density of the target element corresponding to the target node. Sixth, calculate the target natural frequency of the first local structure again.

[0110] This embodiment also provides a natural frequency calculation device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0111] This embodiment provides a device for calculating natural frequency, such as... Figure 5 As shown, it includes: The assignment module 501 is used to select a first local structure and a second local structure in the created three-dimensional model of hydraulic structure, and to assign values ​​to the material properties of the first local structure and the second local structure respectively. The three-dimensional model of hydraulic structure is composed of the first local structure and the second local structure. The first calculation module 502 is used to calculate the initial natural frequency of the first local structure after assignment using a first preset algorithm; The determination module 503 is used to determine the target node and target element based on the initial natural frequency, and to assign values ​​to the material properties of the target element. The target node is extracted from the second local structure. The second calculation module 504 is used to calculate the target natural frequency of the first local structure based on the assigned target unit and the second preset algorithm.

[0112] In some alternative implementations, the assignment module 501 includes: The first assignment unit is used to assign values ​​to the density, Poisson's ratio, and elastic modulus of the first local structure and the second local structure according to preset actual parameters.

[0113] The second assignment unit is used to assign the density value of the second local structure to 0.

[0114] In some alternative implementations, the determining module 503 includes: The first determining unit is used to determine the first-order natural oscillator frequencies in the first direction, the second direction, and the third direction based on the initial natural frequency. The first direction represents the horizontal direction, the second direction represents the direction perpendicular to the first direction, and the third direction represents the direction perpendicular to the first direction and the second direction, respectively.

[0115] The second determining unit is used to determine the rotation angle threshold based on the frequency of each first-order self-oscillator.

[0116] The third determining unit is used to determine the target node and target unit based on the corner threshold.

[0117] In some optional implementations, the first determining unit includes: The sub-unit is used to divide the first local structure into a first unit and the second local structure into a second unit. The first unit represents all units within the first local structure, and the second unit represents all units within the second local structure.

[0118] The first acquisition subunit is used to determine the target natural frequency of the natural frequency in each first-order natural frequency using preset rules, and to acquire the target modal parameters corresponding to the target natural frequency.

[0119] The first determining sub-unit is used to determine the first rotation angle value of the first node in the first unit and the second rotation angle value of the second node in the second unit based on the target modal parameters. The first node represents all nodes in the first unit, and the second node represents all nodes in the second unit.

[0120] The second determining subunit is used to determine the turning threshold based on the product of the absolute value of the first turning angle and the preset turning threshold coefficient.

[0121] In some optional implementations, the second determining unit includes: The third determining subunit is used to determine the target angle value that is greater than the angle threshold from the absolute value of the second angle value, and to obtain the target node corresponding to the target angle value in the second node.

[0122] The second acquisition sub-unit is used to acquire the target unit corresponding to the target node in the second node.

[0123] In some alternative implementations, the determining module 503 further includes: The third assignment unit is used to assign density values ​​to the target unit according to preset actual parameters.

[0124] In some alternative implementations, the natural frequency calculation further includes: The application module is used to apply boundary conditions to the 3D model of hydraulic structures. The boundary conditions include at least the spring stiffness coefficient and the damping coefficient.

[0125] The natural frequency calculation device provided in this embodiment of the invention can execute the natural frequency calculation method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0126] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0127] The following is a detailed reference. Figure 6 This diagram illustrates a suitable structural design for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 601, which can perform various appropriate actions and processes based on a program stored in read-only memory (ROM) 602 or a program loaded from memory 608 into random access memory (RAM) 603. RAM 603 also stores various programs and data required for the operation of the electronic device. The processor 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0128] Typically, the following devices can be connected to I / O interface 605: input devices 606 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 607 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 608 including, for example, magnetic tapes, hard disks, etc.; and communication devices 609. Communication device 609 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 6 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0129] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 609, or installed from a memory 608, or installed from a ROM 602. When the computer program is executed by the processor 601, it performs the functions defined in the natural frequency calculation method of the embodiments of the present invention.

[0130] Figure 6 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0131] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the natural frequency calculation method shown in the above embodiments is implemented.

[0132] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0133] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A method for calculating natural frequency, characterized in that, The method includes: In the created three-dimensional model of the hydraulic structure, a first local structure and a second local structure are selected, and the material properties of the first local structure and the second local structure are assigned values ​​respectively. The three-dimensional model of the hydraulic structure is composed of the first local structure and the second local structure. The initial natural frequency of the first local structure after assignment is calculated using a first preset algorithm; Based on the initial natural frequency, target nodes and target elements are determined, and the material properties of the target elements are assigned values. The target nodes are extracted from the second local structure. The target natural frequency of the first local structure is calculated based on the assigned target unit and the second preset algorithm.

2. The method according to claim 1, characterized in that, The material properties include at least: density value, Poisson's ratio, and elastic modulus; the assignment of values ​​to the material properties of the first local structure and the second local structure includes: The density, Poisson's ratio, and elastic modulus of the first local structure and the second local structure are assigned values ​​according to preset actual parameters, respectively. The method further includes: The density value of the second local structure is set to 0.

3. The method according to claim 1, characterized in that, The determination of target nodes and target elements based on the initial natural frequency includes: Based on the initial natural frequency, the first-order natural frequency of the oscillator is determined in the first direction, the second direction, and the third direction, respectively. The first direction represents the horizontal direction, the second direction represents the direction perpendicular to the first direction, and the third direction represents the direction perpendicular to the first direction and the second direction, respectively. Determine the rotation angle threshold based on the frequencies of each first-order self-oscillator; Based on the corner threshold, the target node and the target unit are determined.

4. The method according to claim 3, characterized in that, The determination of the rotation angle threshold based on the frequencies of each of the first-order self-oscillators includes: The first local structure is divided into a first unit, and the second local structure is divided into a second unit. The first unit represents all units within the first local structure, and the second unit represents all units within the second local structure. The target natural frequency is determined in each of the first-order natural frequencies using a preset rule, and the target modal parameters corresponding to the target natural frequency are obtained. Based on the target modal parameters, the first rotation angle value of the first node in the first unit and the second rotation angle value of the second node in the second unit are determined. The first node represents all nodes in the first unit, and the second node represents all nodes in the second unit. The corner threshold is determined by multiplying the absolute value of the first corner value by a preset corner threshold coefficient.

5. The method according to claim 4, characterized in that, The step of determining the target node and the target unit based on the corner threshold includes: Determine a target angle value that is greater than the angle threshold from the absolute value of the second angle value, and obtain the target node corresponding to the target angle value from the second node; The target unit corresponding to the target node is obtained in the second node.

6. The method according to claim 2, characterized in that, Assigning values ​​to the material properties of the target unit includes: The density value of the target unit is assigned according to the preset actual parameters.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: Boundary conditions are applied to the three-dimensional model of the hydraulic structure, and the boundary conditions include at least the spring stiffness coefficient and the damping coefficient.

8. A device for calculating natural frequency, characterized in that, The device includes: The assignment module is used to select a first local structure and a second local structure in the created three-dimensional model of the hydraulic structure, and assign material properties to the first local structure and the second local structure respectively. The three-dimensional model of the hydraulic structure is composed of the first local structure and the second local structure. The first calculation module is used to calculate the initial natural frequency of the first local structure after assignment using a first preset algorithm; The determination module is used to determine the target node and target element based on the initial natural frequency, and to assign values ​​to the material properties of the target element. The target node is extracted from the second local structure. The second calculation module is used to calculate the target natural frequency of the first local structure based on the assigned target unit and the second preset algorithm.

9. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the natural frequency calculation method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to execute the natural frequency calculation method according to any one of claims 1 to 7.

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