A ship vibration isolation device vibration isolation calculation method based on vibration isolator type spectrum data

Abstract

This application discloses a method for calculating the vibration isolation of ship vibration isolation devices based on isolator type spectrum data, relating to the field of ship vibration isolation design. The method includes: acquiring the type spectrum data and impedance test data of the target isolator; determining the stiffness and damping parameters of the target isolator based on the type spectrum data and impedance test data; constructing a finite element model of the ship vibration isolation device; inputting the stiffness and damping parameters of the target isolator into the finite element model for calculation, and obtaining the vibration isolation calculation results of the target isolator. This method can efficiently utilize isolator type spectrum data to conduct vibration isolation calculation and evaluation of ship vibration isolation devices during the ship design phase, avoiding resonance between the natural frequency of the vibration isolation device and the excitation frequency of the equipment, and improving the vibration isolation effect.

Description

Technical Field

[0001] This application relates to the field of ship vibration isolation design, and in particular to a method for calculating the vibration isolation of ship vibration isolation devices based on vibration isolator type spectrum data. Background Technology

[0002] Vibration isolation calculation and evaluation of ship vibration isolation devices is a crucial step in vibration isolation design, providing important guidance for vibration isolation optimization and the selection of ship vibration isolation devices. Vibration isolators are the core components of ship vibration isolation systems, and their simulation is key to transferring calculations in ship floating raft vibration isolation calculations. However, due to the fact that vibration isolators typically use rubber elements, coupled with the influence of their internal rubber vulcanization structure, direct calculation using finite element modeling is difficult.

[0003] Vibration isolation calculations are generally performed using a hybrid numerical testing method combining finite element modeling and experimental testing. Finite element calculations require the performance parameters of the isolator as input data. Traditional methods often rely on human experience to select these parameters, which is highly unpredictable and prone to significant errors. To meet the needs of designers for understanding and quickly selecting the vibration reduction, noise reduction, and shock resistance performance of isolators, standard documents for marine vibration isolator series have been published both domestically and internationally. These documents contain dynamic and static performance parameters for numerous isolator models. How to efficiently utilize these parameters in the specifications for rapid vibration isolation calculations is a key focus for vibration isolation designers. However, due to the inherent material properties of the isolators, their dynamic characteristics are difficult to express precisely. Therefore, a standard vibration isolation calculation method has not yet been established for shipboard vibration isolation devices in practical marine engineering. Summary of the Invention

[0004] This application addresses the aforementioned problems and technical needs by proposing a vibration isolation calculation method for ship vibration isolation devices based on vibration isolator type spectrum data. The technical solution of this application is as follows:

[0005] A method for calculating the vibration isolation of ship vibration isolation devices based on isolator type spectrum data includes the following steps: Acquire the type spectrum data and impedance test data of the target vibration isolator, which is then installed in the ship's vibration isolation device; A finite element model of the ship vibration isolation device was constructed, and the stiffness and damping parameters of the target vibration isolator were determined based on the type spectrum data and impedance test data. The stiffness and damping parameters of the target vibration isolator are input into the finite element model. Excitation loads are applied to the finite element model using finite element software, and the vibration response of the finite element model is extracted to obtain the vibration isolation calculation results of the target vibration isolation device.

[0006] The further technical solution involves determining the stiffness and damping parameters of the target vibration isolator, including: Based on the spectrum data and impedance test data, and combined with the finite element model of the ship vibration isolation device, the candidate stiffness parameters and candidate damping parameters of the target vibration isolator are determined. Based on candidate stiffness parameters and candidate damping parameters, multiple sets of preset parameter combinations are constructed. Finite element vibration isolation calculations are performed on each set of parameter combinations. The candidate stiffness parameter corresponding to the parameter combination with the optimal vibration isolation calculation result is determined as the stiffness parameter of the target vibration isolator, and the candidate damping parameter corresponding to the parameter combination with the optimal vibration isolation calculation result is determined as the damping parameter of the target vibration isolator.

[0007] The further technical solution is that the candidate stiffness parameters include candidate static stiffness parameters and candidate dynamic stiffness parameters; the candidate stiffness parameters and candidate damping parameters for determining the target vibration isolator include: When the finite element model of the constructed ship vibration isolation device includes a spring-damping element model for simulating the vibration isolator, the candidate static stiffness parameters of the target vibration isolator are determined based on the type spectrum data, the candidate dynamic stiffness parameters of the target vibration isolator are determined based on the type spectrum data, and the candidate damping parameters of the target vibration isolator are determined based on the type spectrum data and impedance test data. When the finite element model of the constructed ship vibration isolation device includes a line element model for simulating the vibration isolator, the candidate dynamic stiffness parameters of the target vibration isolator are determined based on the impedance test data, and the candidate damping parameters of the target vibration isolator are determined based on the impedance test data.

[0008] The further technical solution is as follows: the model spectrum data includes static stiffness parameters, dynamic stiffness parameters, damping ratio coefficient, and rated load; the static stiffness parameters in the model spectrum data are used as candidate static stiffness parameters, and the dynamic stiffness parameters in the model spectrum data are used as candidate dynamic stiffness parameters; based on the damping ratio coefficient, rated load, and static stiffness parameters in the model spectrum data, the candidate damping parameters of the target vibration isolator are calculated using the damping ratio formula for a single degree of freedom system, and / or, the admittance circle is plotted based on the impedance test data, and the candidate damping parameters of the target vibration isolator are fitted to obtain the damping parameters.

[0009] A further technical solution is to convert the imaginary part of the impedance test data into the candidate dynamic stiffness parameter of the target vibration isolator based on the conversion relationship between mechanical impedance and displacement impedance, and to use the real part of the impedance test data as the candidate damping parameter of the target vibration isolator.

[0010] The further technical solution is as follows: the impedance test data includes the origin impedance test data and the cross-point impedance test data; the static stiffness parameters include the static stiffness parameters in the length direction, the static stiffness parameters in the width direction, and the static stiffness parameters in the load direction; the dynamic stiffness parameters include the dynamic stiffness parameters in the length direction, the dynamic stiffness parameters in the width direction, and the dynamic stiffness parameters in the load direction; and the damping parameters include the damping parameters in the length direction, the damping parameters in the width direction, and the damping parameters in the load direction. When the finite element model of the constructed ship vibration isolation device includes a spring-damping element model for simulating the vibration isolator, the preset parameter combinations include the combination of candidate static stiffness parameters in the load-bearing direction, the combination of candidate static stiffness parameters in the load-bearing direction plus candidate damping parameters in the load-bearing direction, candidate static stiffness parameters in the length direction, candidate static stiffness parameters in the width direction, candidate static stiffness parameters in the load-bearing direction plus candidate damping parameters in the length direction, candidate damping parameters in the width direction, the combination of candidate damping parameters in the load-bearing direction, and the combination of candidate dynamic stiffness parameters in the load-bearing direction plus candidate damping parameters in the load-bearing direction. When the finite element model of the constructed ship vibration isolation device includes a line element model for simulating the vibration isolator, the preset parameter combination includes the candidate dynamic stiffness parameters in the length direction, the candidate dynamic stiffness parameters in the width direction, and the candidate dynamic stiffness parameters in the load-bearing direction obtained from the original impedance test data, plus the candidate damping parameters in the length direction, the candidate damping parameters in the width direction, and the candidate damping parameters in the load-bearing direction, and the combination of candidate dynamic stiffness parameters in the length direction, the candidate dynamic stiffness parameters in the width direction, and the candidate damping parameters in the load-bearing direction obtained from the cross-point impedance test data.

[0011] Further technical solutions include: the vibration isolation calculation method for ship vibration isolation devices also includes: Based on the rated load in the model data, several candidate vibration isolators that meet the load-bearing weight requirements of ship vibration isolation devices are identified. Vibration isolation calculations are performed on each candidate vibration isolator to obtain the vibration isolation calculation results for each candidate vibration isolator. Based on the vibration isolation calculation results of each candidate vibration isolator, a vibration isolator that meets the vibration isolation requirements is selected.

[0012] The further technical solution is that the vibration isolation calculation result includes the vibration isolation amount; when the vibration isolation amount corresponding to any vibration isolator is greater than or equal to the vibration isolation amount threshold, it is determined that the vibration isolator meets the vibration isolation requirements.

[0013] The beneficial technical effects of this application are: This application discloses a vibration isolation calculation method for ship vibration isolation devices based on vibration isolator type spectrum data. This method can be used to conduct vibration isolation calculation and evaluation of ship vibration isolation devices during the ship design phase, thereby avoiding resonance between the natural frequency of the vibration isolation device and the excitation frequency of the equipment and improving the vibration isolation effect.

[0014] This method directly utilizes standardized pattern data, avoiding finite element modeling of the complex vulcanized structure of vibration isolators, simplifying the calculation process and lowering the design threshold. Furthermore, this method is applicable to different types of vibration isolator finite element models. Through targeted parameter determination methods and preset parameter combination strategies, it can flexibly address different modeling needs and engineering scenarios, further enhancing the method's applicability and practicality. For spring-damped element models, it can fully utilize parameters such as static stiffness, dynamic stiffness, and damping ratio from the pattern data, supplemented and verified by impedance test data, thereby achieving accurate simulation of the static stiffness and damping parameters of the vibration isolator in different directions. For line element models, by converting impedance test data, the stiffness and damping parameters of the vibration isolator are obtained, ensuring the accuracy of the input parameters to the finite element model. Meanwhile, this method constructs multiple sets of preset parameter combinations and performs finite element vibration isolation calculations respectively. By comparing the vibration isolation calculation results under different combinations, the optimal parameter combination is selected, which further improves the accuracy of the simulation of the dynamic characteristics of the vibration isolator, realizes the efficient use of the spectrum data, provides data support for the refined design of ship vibration isolation devices, and can significantly improve the reliability and efficiency of vibration isolation calculation.

[0015] In addition, this method can also be used to guide the selection of vibration isolators. By performing batch vibration isolation calculations and evaluations on multiple candidate vibration isolators based on type spectrum data, the optimal vibration isolator that meets the vibration isolation requirements can be quickly screened out, avoiding the blindness of relying on experience for selection, effectively shortening the design cycle, reducing test costs, and providing strong technical support for the optimized design of ship vibration isolation systems. Attached Figure Description

[0016] Figure 1 This is a flowchart of the vibration isolation calculation method for ship vibration isolation devices.

[0017] Figure 2 This is a measured impedance diagram of a vibration isolator in an example.

[0018] Figure 3 It is an admittance circle in three directions.

[0019] Figure 4 This is a comparison diagram of the imaginary parts of the impedance at the origin and across the point in three directions.

[0020] Figure 5 This is a diagram showing the conversion of the impedance at the origin and span points in the load-bearing direction into dynamic stiffness.

[0021] Figure 6 This is a comparison diagram of the real parts of the impedance at the origin and across the point in three directions.

[0022] Figure 7 This is an assembly diagram of a typical floating raft vibration isolation device in an example.

[0023] Figure 8This is a finite element model diagram of a typical floating raft vibration isolation device.

[0024] Figure 9 This is a comparison chart showing the influence of damping parameters on the vibration response at three measuring points.

[0025] Figure 10 This is a comparison diagram showing the influence of static stiffness parameters in three directions on the vibration response at three measuring points.

[0026] Figure 11 This is a comparison diagram showing the influence of dynamic stiffness parameters and static stiffness parameters on the vibration response at three measuring points in the model spectrum.

[0027] Figure 12 This is a comparison chart showing the influence of dynamic stiffness parameters in the spectrum and the conversion of dynamic stiffness parameters from the original impedance test data on the vibration response at three measurement points.

[0028] Figure 13 This is a comparison chart showing the influence of dynamic stiffness parameters in the model spectrum and the converted dynamic stiffness parameters from the cross-point impedance test data on the vibration response at three measurement points.

[0029] Figure 14 This is a comparison chart of the calculated and experimental results of vibration isolation at the origin and diagonal span points on the raft frame of a single-layer vibration isolation device in an example.

[0030] Figure 15 This is a comparison chart of the vibration isolation calculation results and the test results at three measuring points in a single-layer vibration isolation device.

[0031] Figure 16 This is a comparison chart of the vibration isolation calculation results of different types of vibration isolators used in a single-layer vibration isolation device.

[0032] Figure 17 This is a finite element model diagram of a double-layer vibration isolation device in an example.

[0033] Figure 18 This is a comparison chart of the vibration isolation calculation results and the test results at each measuring point in the double-layer vibration isolation device. Detailed Implementation

[0034] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0035] This application discloses a method for calculating the vibration isolation of ship vibration isolation devices based on vibration isolator type spectrum data. Please refer to [reference needed]. Figure 1 The flowchart shown illustrates the specific steps of this method as follows: Step 1: Obtain the type spectrum data and impedance test data of the target vibration isolator.

[0036] The target vibration isolators are installed in the ship's vibration isolation system and are important components of the system. Their type range data was obtained by consulting publicly available vibration isolator type range manuals. These manuals include several models mainly produced by Chinese ship vibration isolator manufacturers, such as rubber vibration isolators (6JX, BE, BSH, etc.); polyurethane vibration isolators (PJX, PBE, CZ, etc.); airbag vibration isolators; wire rope vibration isolators; and flexible couplings, among others. Impedance test data is obtained beforehand based on impedance testing of the ship's vibration isolation system. The specific process of the impedance test can refer to conventional impedance testing methods. For example, excitation equipment can be used to apply excitation to the vibration isolator, and sensors can be used to collect the vibration response at different frequencies to obtain impedance test data.

[0037] This application uses the common rubber BE-120 vibration isolator as the target vibration isolator for description. By consulting the vibration isolator type manual, it is found that the structure of the BE vibration isolator consists of a core, a shell plate and a rubber body. Its total height, length, width, mounting hole spacing, number of mounting hole threads, upper and lower end connection dimensions, as well as the weight of the entire vibration isolator, static stiffness parameters, dynamic stiffness parameters, damping ratio coefficient and rated load can all be obtained from the type manual.

[0038] The impedance test data for the BE-120 vibration isolator includes the test frequency, origin impedance test data, and cross-point impedance test data. Both the origin and cross-point impedance test data include the real part, imaginary part, and magnitude. The impedance diagram of this vibration isolator as a function of frequency is shown below. Figure 2 As shown, Figure 2 (a) is the impedance diagram of the origin impedance test data. Figure 2 (b) shows the impedance diagram of the cross-point impedance test data. In the diagram, X, Y, and Z correspond to the length direction, width direction, and load-bearing direction, respectively. As can be seen from the diagram, in the origin impedance Z11, within the range of 10 to 300 Hz, the impedance in the X direction is consistent with the impedance in the Z direction. This explains why the static stiffness in the X and Z directions is consistent in the spectrum data. However, as the frequency changes, the origin impedances in the two directions differ. The origin impedance in the Y direction is higher than that in the other two directions within the range of 300 Hz. In the cross-point impedance Z12, within the frequency range of 10 to 200 Hz, the impedances in the X and Z directions basically overlap, and the impedance in the Y direction is greater than that in the other two directions.

[0039] Step 2: Construct a finite element model of the ship's vibration isolation device, and determine the stiffness and damping parameters of the target vibration isolator based on the type spectrum data and impedance test data.

[0040] In vibration isolation calculations, there are significant geometric and mass differences between the isolators and the upper raft frame and equipment in ship vibration isolation devices. Typically, spring-dashpots, which ignore the mass of the isolators themselves, can be used for simulation. For example, in Abaqus finite element modeling, the settings for spring-dashpots include information on the upper and lower connection nodes of the spring, its direction, stiffness parameters, and damping parameters. There are two modeling methods in Abaqus vibration isolation modeling calculations. One method is to create a spring-dashpot model simulating the isolator, which allows setting damping and stiffness values, but its drawback is that only a single stiffness or damping value can be input, and it cannot vary with frequency. The other method is to create a line element model in Abaqus where stiffness and damping vary with frequency. This model allows input of stiffness and damping values ​​that vary with frequency. Considering the differences between the two models, this application constructs two finite element models and designs appropriate parameter selection schemes for each model to improve the applicability of the vibration isolation calculation method.

[0041] However, regardless of the finite element model constructed, the stiffness and damping parameters of the vibration isolator are crucial input parameters in finite element vibration isolation calculations. The model spectrum contains data on the static stiffness, dynamic stiffness, and damping ratio of the vibration isolator. To more effectively utilize the model spectrum data to calculate the vibration isolation effect of the target vibration isolator, it is necessary to analyze and verify the data in the model spectrum to obtain the truly required stiffness and damping parameters for finite element vibration isolation calculations.

[0042] In one embodiment, determining the stiffness and damping parameters of the target vibration isolator includes: (1) Based on the spectrum data and impedance test data, and combined with the finite element model of the ship vibration isolation device, determine the candidate stiffness parameters and candidate damping parameters of the target vibration isolator.

[0043] Because different finite element models require different stiffness and damping parameters, and the parameter types contained in spectrum data and impedance test data are also different, it is necessary to analyze the influence of different parameters on the vibration response of ship vibration isolation devices for different finite element models in order to achieve accurate vibration isolation calculations for the target vibration isolator. Specifically, candidate stiffness parameters include candidate static stiffness parameters and candidate dynamic stiffness parameters. Determining the candidate stiffness and candidate damping parameters of the target vibration isolator includes: When the finite element model of the constructed ship vibration isolation device includes a spring-damping element model for simulating the vibration isolator, the candidate static stiffness parameters of the target vibration isolator are determined based on the type spectrum data, the candidate dynamic stiffness parameters of the target vibration isolator are determined based on the type spectrum data, and the candidate damping parameters of the target vibration isolator are determined based on the type spectrum data and impedance test data.

[0044] If the finite element model used to simulate the vibration isolator is a spring-damped element model, the input stiffness and damping parameters need to be fixed values. Therefore, candidate static and dynamic stiffness parameters can be determined based on the type spectrum data. The type spectrum data includes static stiffness parameters, dynamic stiffness parameters, damping ratio coefficient, and rated load. The static stiffness parameters in the type spectrum data are used as candidate static stiffness parameters, and the dynamic stiffness parameters are used as candidate dynamic stiffness parameters. By querying the type spectrum data of the BE-120 vibration isolator, the candidate static stiffness parameters in three directions can be determined as follows: 290 N / mm in both the X and Z directions, and 900 N / mm in the Y direction; the dynamic stiffness parameter in the Z direction is 480 N / mm.

[0045] For fixed candidate damping parameters, the candidate damping parameters of the target vibration isolator are calculated using the damping ratio coefficient, rated load, and static stiffness parameters in the spectrum data, and / or the candidate damping parameters of the target vibration isolator are obtained by plotting the admittance circle based on the impedance test data and fitting it.

[0046] The first method involves calculating the damping parameters using the damping ratio given in the model manual, based on the damping ratio formula for a single-degree-of-freedom system: (1) in, c The damping parameter is determined by consulting the vibration isolator type catalog for the BE-120 vibration isolator. =0.05, rated load is m =120kg, static stiffness in the bearing direction is k =290N / mm, the calculated damping parameter is: c =590N / m / s.

[0047] The second method uses the admittance circle. According to the book *Mechanical Impedance Methods and Applications*, "The Nyquist plot of velocity admittance is a true circle. The center of this circle (1 / 2c, 0) is on the real axis (along the positive direction), and its diameter is equal to 1 / c." Based on the vibration isolator impedance test data, the admittance circles in the three directions are as follows... Figure 3 As shown. Figure 3 (a) is the admittance circle in the X direction. Figure 3 (b) is the admittance circle in the Y direction. Figure 3 (c) is the admittance circle in the Z direction. The horizontal axis in the figure is the frequency, and the vertical axis is the dimensionless damping ratio coefficient.

[0048] When the finite element model of the constructed ship vibration isolation device includes a line element model for simulating the vibration isolator, the candidate dynamic stiffness parameters of the target vibration isolator are determined based on the impedance test data, and the candidate damping parameters of the target vibration isolator are determined based on the impedance test data.

[0049] If a linear model is used to simulate the vibration isolator in the constructed finite element model, the input stiffness and damping parameters need to be values ​​that vary with frequency. Therefore, candidate dynamic stiffness and candidate damping parameters need to be determined based on impedance test data. Specifically, according to the conversion relationship between mechanical impedance and displacement impedance, the imaginary part of the impedance test data is converted to obtain the candidate dynamic stiffness parameters of the target vibration isolator, and the real part of the impedance test data is used as the candidate damping parameters of the target vibration isolator.

[0050] According to the mechanical impedance expression in formula (2), the mechanical impedance consists of two parts: the real part and the imaginary part. Therefore, the real part of the impedance test data is related to the damping of the vibration isolator, and the imaginary part is related to the stiffness of the vibration isolator. Figure 4 The figure shows the imaginary parts of the origin and cross-point impedances of the vibration isolator in three directions, which are the stiffness terms of the vibration isolator. As can be seen from the figure, the stiffness parameters of the vibration isolator change with frequency. The stiffness in the impedance direction, Zz, is almost linear in the range of 100 to 1000 Hz, and no resonance peak of the vibration isolator itself appears.

[0051] (2) in, z It is impedance. k It's stiffness. j It is the imaginary unit. It's the angular frequency. Based on the relationship between velocity and position... jw The mechanical impedance can be converted into the displacement impedance of the vibration isolator, i.e., the dynamic stiffness of the vibration isolator. The converted dynamic stiffness values ​​of the vibration isolator at the origin Z11 and the span Z12 are as follows: Figure 5 As shown. From Figure 5 As can be seen, the dynamic stiffness range of the origin Z11 is in the range of 10–100 Hz, while the dynamic stiffness range of the cross point Z12 is in the range of 10–300 Hz. With increasing frequency, the influence of the vibration isolator mass range on the square of the frequency increases. The dynamic stiffness of the origin calculated using the vibration isolator is 680 N / m, corresponding to… Figure 5 The horizontal region (i.e., the stiffness region) of the dynamic stiffness curve.

[0052] The real part of the impedance test data of the vibration isolator is substituted into the real part of the formula (2). Figure 6 Let Z11 be the real part of the origin impedance Z11 and the cross-point impedance Z12 of the vibration isolator. The figure shows that the damping is smallest in the Z direction, and the damping fluctuations at the origin and cross-point are relatively small in this direction. However, there are obvious resonance peaks and anti-resonance peaks in the X and Y directions, and the resonance peak frequency in the X direction is lower than that in the Y direction. According to... Figure 6 According to the data conversion, the damping of the origin Z11 fluctuates with frequency between -170 and 170 N / m / s, and the damping of the cross point Z12 fluctuates with frequency between -150 and 50 N / m / s.

[0053] (2) Based on the candidate stiffness parameters and candidate damping parameters, construct multiple sets of preset parameter combinations, perform finite element vibration isolation calculations on each set of parameter combinations, determine the candidate stiffness parameters corresponding to the parameter combination with the best vibration isolation calculation results as the stiffness parameters of the target vibration isolator, and determine the candidate damping parameters corresponding to the parameter combination with the best vibration isolation calculation results as the damping parameters of the target vibration isolator.

[0054] Since the parameter values ​​obtained by different methods are not the same—for example, the dynamic stiffness parameter obtained by converting impedance test data is 680 N / m, while the dynamic stiffness on the model spectrum is 480 N / m—further selection of optimal parameters is needed to obtain the most accurate vibration isolation calculation results. Considering that the impedance test data includes origin impedance test data and cross-point impedance test data; static stiffness parameters include length direction static stiffness parameters, width direction static stiffness parameters, and load-bearing direction static stiffness parameters; dynamic stiffness parameters include load-bearing direction dynamic stiffness parameters; and damping parameters include length direction damping parameters, width direction damping parameters, and load-bearing direction damping parameters—this application constructs different parameter combinations to analyze the vibration isolation effect under different calculation conditions.

[0055] Specifically, depending on the different input parameters required for the constructed finite element model, there are two main cases: When the finite element model of the constructed ship vibration isolation device includes a spring-damping element model for simulating the vibration isolator, the preset parameter combinations include the combination of candidate static stiffness parameters in the load-bearing direction, the combination of candidate static stiffness parameters in the load-bearing direction plus candidate damping parameters in the load-bearing direction, the combination of candidate static stiffness parameters in the length direction, candidate static stiffness parameters in the width direction, the combination of candidate static stiffness parameters in the load-bearing direction plus candidate damping parameters in the length direction, candidate damping parameters in the width direction, and candidate damping parameters in the load-bearing direction, the combination of candidate dynamic stiffness parameters in the load-bearing direction plus candidate damping parameters in the load-bearing direction, and the combination of candidate dynamic stiffness parameters in the load-bearing direction plus candidate damping parameters. When the finite element model of the constructed ship vibration isolation device includes a line element model for simulating the vibration isolator, the preset parameter combination includes the candidate dynamic stiffness parameters in the length direction, the candidate dynamic stiffness parameters in the width direction, and the candidate dynamic stiffness parameters in the load-bearing direction obtained from the original impedance test data, plus the candidate damping parameters in the length direction, the candidate damping parameters in the width direction, and the candidate damping parameters in the load-bearing direction, and the combination of candidate dynamic stiffness parameters in the length direction, the candidate dynamic stiffness parameters in the width direction, and the candidate damping parameters in the load-bearing direction obtained from the cross-point impedance test data.

[0056] The two finite element models above correspond to a total of 6 calculation conditions, as shown in the table below: Table 1. Parametric Calculation Conditions

[0057] The calculation and analysis example in this application uses a typical raft structure mounted on a base to form a typical floating raft vibration isolation device. The raft is 1.6 meters long, 1 meter wide, and 0.15 meters high, with an overall plate thickness of 14 millimeters, and an additional 10 millimeters at the mounting points. The base is 0.5 meters high, and its length and width are matched to the raft structure. It uses four BE-120 vibration isolators, and the vibration isolation device uses a single electromagnetic vibrator as the excitation source. The assembly drawing of this floating raft vibration isolation device is shown below. Figure 7 As shown, the finite element model of the floating raft vibration isolation device was constructed in Abaqus finite element software as follows. Figure 8 As shown, the entire vibration isolation device structure in the finite element model uses a quadrilateral structured mesh with a mesh size of 0.01m and a total of 73,500 shell elements. The entire base plate adopts a fixed boundary condition.

[0058] A unit excitation force was applied to the geometric center of the upper surface of the raft frame, and the vibration response under the corresponding calculation conditions for each set of parameters was calculated. The vibration response accelerations of a total of 9 measuring points were extracted, including the origin (geometric center of the upper surface of the raft frame), the contact position between the raft frame and the vibration isolator, and the contact position between the vibration isolator and the base panel.

[0059] The difference between calculation case 1 and calculation case 2 lies in the setting of the damping parameters. Therefore, the influence of damping on the vibration response can be analyzed. The comparison diagram of the influence of the damping parameters in the bearing direction on the vibration response at the three measuring points at the origin, on the raft, and on the base is shown in the figure. Figure 9 As shown, Figure 9 (a) is a comparison diagram showing the influence of damping parameters on the vibration response at the origin. Figure 9 (b) is a comparison diagram showing the influence of damping parameters on the vibration response on the raft. Figure 9 (c) is a comparison diagram of the influence of damping parameters on the vibration response on the base. As can be seen from the figure, the vibration response curves on the raft basically overlap with and without damping, but the amplitudes at the resonance and anti-resonance peaks are attenuated. For example, at the 42Hz anti-resonance position in the origin response, the amplitude is 34.12dB in the undamped state and 47.18dB in the damped state, a decrease of 13dB. Therefore, the damping parameter of the vibration isolator cannot be ignored in the entire calculation method and is one of the important input parameters. It should be noted that because damping changes the vibration transmission path, without damping, the vibration energy is mainly concentrated on the raft; with damping, some energy is transferred to the base panel through the damping term, but the total vibration energy of the overall system is still reduced due to damping dissipation. Moreover, in engineering, more attention is paid to the vibration control of the equipment (raft), and the increase in local vibration of the base panel does not affect the damping's vibration isolation effect on the core area.

[0060] The difference between calculation case 2 and calculation case 3 lies in the direction setting. Therefore, the influence of direction on vibration response can be analyzed. The comparison diagram of the influence of the three-dimensional static stiffness parameters on the vibration response at the three measuring points at the origin, on the raft, and on the base is shown in the figure. Figure 10 As shown, Figure 10 (a) is a comparison diagram showing the influence of triaxial static stiffness parameters on the vibration response at the origin. Figure 10 (b) is a comparison diagram showing the influence of triaxial static stiffness parameters on the vibration response on the raft. Figure 10 (c) is a comparison diagram of the influence of triaxial static stiffness parameters on the vibration response on the base. As can be seen from the figure, the responses at the three locations are basically overlapping when using triaxial and uniaxial stiffness in the vibration isolator. This is because in the above example, the load application direction is consistent with the bearing direction, and there is no difference in vibration response under triaxial and uniaxial stiffness. However, the individual raft frame and the vibration isolator are decoupled, with no coupling. Therefore, it is necessary to consider whether there is coupling in the direction of the excitation force. However, in actual vibration isolation calculations, the equipment is often connected to the raft frame via machine feet, inevitably resulting in rotational excitation other than translational motion. The influence of the rotational (bending) impedance of the vibration isolator itself on the vibration isolation effect depends on the correspondence between the vibration isolator's geometric dimensions and the raft frame's dimensions. When the raft frame's geometric dimensions are much larger than the vibration isolator's dimensions, the bending impedance in the vibration isolator can be ignored. However, the raft frame dimensions of actual ship vibration isolation devices are often much larger than the vibration isolator's dimensions, and the rotational stiffness and damping are small quantities, so they can be ignored in the calculation process.

[0061] The difference between calculation case 2 and calculation case 4 lies in the setting of dynamic and static stiffness. Therefore, the influence of static and dynamic stiffness on vibration response can be analyzed. The comparison diagram of the influence of dynamic and static stiffness parameters on the vibration response at the three measuring points at the origin, on the raft, and on the base is shown in the figure. Figure 11 As shown, the dynamic and static stiffness values ​​here are obtained based on the type spectrum data. Figure 11 (a) is a comparison diagram of the influence of dynamic and static stiffness parameters on the vibration response at the origin. Figure 11 (b) is a comparison diagram of the influence of dynamic and static stiffness parameters on the vibration response on the raft frame. Figure 11 (c) is a comparison diagram of the influence of dynamic and static stiffness parameters on the vibration response on the base. As can be seen from the figure, the use of dynamic or static stiffness has little effect on the vibration response at the origin, but has an effect on the vibration of the base panel and raft in the low-frequency range of 10-100Hz, and no effect on other frequency ranges.

[0062] The difference between calculation case 4 and calculation case 5 or 6 lies in the setting of dynamic stiffness. Therefore, the influence of dynamic stiffness parameters from different sources on the vibration response can be analyzed. The comparison diagram of the influence of dynamic stiffness parameters on the vibration response at the three measuring points at the origin, on the raft, and on the base is shown in the figure. Figure 12 , Figure 13 As shown, Figure 12 and Figure 13The dynamic stiffness represented by the solid blue line is obtained based on the type spectrum data. Figure 12 The dynamic stiffness parameter represented by the red dashed line is obtained based on the original impedance test data. Figure 13 The dynamic stiffness parameter represented by the red dashed line is obtained by converting the cross-point impedance test data. Figure 12 (a) is a comparison of the influence of dynamic stiffness parameters obtained from the conversion of origin impedance test data on the vibration response at the origin. Figure 12 (b) is a comparison graph showing the influence of dynamic stiffness parameters obtained from the conversion of the original impedance test data on the vibration response on the raft. Figure 12 (c) is a comparison of the influence of the dynamic stiffness parameters obtained from the conversion of the original impedance test data on the vibration response on the base. Figure 13 (a) is a comparison of the influence of dynamic stiffness parameters obtained from the conversion of cross-point impedance test data on the vibration response at the origin. Figure 13 (b) is a comparison graph showing the influence of dynamic stiffness parameters obtained from the conversion of cross-point impedance test data on the vibration response on the raft. Figure 13 (c) is a comparison of the influence of the dynamic stiffness parameters obtained from the cross-point impedance test data on the vibration response on the base. Comparing the above 6 figures, it can be seen that the two dynamic stiffness conversion calculation methods have little effect on the origin on the raft and the upper end of the vibration isolator, but there is a significant difference in the vibration response on the base under the vibration isolator: the calculation results of Z11 basically coincide with the dynamic stiffness calculation results of the type spectrum at high frequencies, while the calculation results of Z12 are smaller than the dynamic stiffness values ​​calculated in the type spectrum in the entire 10-1000Hz range.

[0063] Based on the comparative analysis of the various calculation conditions mentioned above, and considering that the dynamic stiffness parameter in the model spectrum data has only one value, while the impedance test data has multiple sets of data (including impedance test data under different static pressures), making it more applicable, the optimal parameter combination in vibration isolation calculation is the dynamic stiffness parameter and damping parameter converted from the measured origin impedance test data of the vibration isolator. The next best is the dynamic stiffness parameter and damping parameter from the model spectrum data, and the least desirable is the static stiffness parameter and damping parameter from the model spectrum data.

[0064] Step 3: Input the stiffness and damping parameters of the target vibration isolator into the finite element model, apply excitation load to the finite element model using finite element software, and extract the vibration response of the finite element model to obtain the vibration isolation calculation results of the target vibration isolation device.

[0065] After determining the stiffness and damping parameters of the target vibration isolator, they can be input into the finite element model. Finite element software can then be used to calculate the vibration response at each measuring point in the finite element model, and the vibration response can be used to calculate the vibration isolation result. The raft admittance is one of the important parameters in the vibration isolation calculation result. The upper surface of the raft is connected to the equipment via an interface, the lower surface is connected to the upper end of the vibration isolator, and the lower surface of the vibration isolator is connected to the base panel. The raft, vibration isolator, and base constitute a single-layer vibration isolation device. The entire raft vibration isolation structure in the single-layer vibration isolation device can be regarded as a multi-input multi-output structure. On the other hand, considering the elasticity of the raft itself, the finite element model of the entire raft can be condensed based on the interface between the upper and lower surfaces of the raft. The vibration isolation calculation of the finite element model of this application is performed using the method of this application, and the vibration isolation calculation results are compared with the test results of the raft admittance to verify the effectiveness of the method of this application.

[0066] In the raft admittance test, the entire raft was suspended by slings, and a hammer impact method was used to strike the four ends of the raft. Simultaneously, vibration sensors were used to measure the origin admittance and cross-point admittance at the four ends of the raft. The origin admittance measurement involved applying excitation (hammer impact) to the same end and measuring the vibration response to obtain the origin admittance (transfer function) at that point. The cross-point admittance measurement involved applying excitation to one end and measuring the vibration response at the other end to obtain the cross-point admittance (transfer function) between the two points. The transfer function, i.e., the admittance, is obtained by calculating the ratio of the acquired force signal to the response signal. The experimentally measured origin admittance and the calculated origin admittance of the raft are shown below. Figure 14 As shown in (a), the experimentally measured raft span admittance and the calculated raft span admittance are as follows: Figure 14 As shown in (b), the calculated and experimental results of the raft admittance are basically consistent within the 400Hz range, indicating that the finite element model can accurately simulate the first five resonant frequencies of the raft.

[0067] Furthermore, the effectiveness of the proposed method is verified by comparing the experimental test results with the vibration isolation calculation results at various measuring points of the single-layer vibration isolation device. A single-layer vibration isolation device was constructed in the laboratory. Four vibration isolators were arranged between the raft frame and the base of the single-layer vibration isolation device. The base was rigidly connected to the ground via anchor bolts. An exciter was installed at the geometric center (origin) of the raft frame and suspended by an elastic rope. A total of nine accelerometers and one force sensor were installed throughout the experiment. The force sensor was connected to the geometric center of the raft frame, and the accelerometer was connected to the upper and lower surfaces of each vibration isolator. The transfer function of the experimental results was normalized. In this example, the dynamic stiffness parameter of the vibration isolator in the finite element model for vibration isolation calculation is 480 N / mm, and the damping parameter is 1155 N / m / s. The vibration isolation calculations and experimental results at various measuring points are compared as follows: Figure 15 As shown, Figure 15 (a) Comparison of calculated and experimental results of the excitation position origin on the raft. Figure 15 (b) Comparison of calculated and experimental results on the upper raft frame of the vibration isolator. Figure 15 (c) shows the comparison between the calculated and experimental results on the base panel.

[0068] As can be seen from the three comparison figures above, the results for the excitation origin on the raft and the upper end of the isolator are better than those for the base panel. This is because the base panel has greater rigidity, and the differences at different locations are more obvious. For example, in practice, the BE isolator is generally connected to the base panel by 2-4 bolts. However, in the modeling calculation, the simplified mechanical model and the isolator impedance test both reduce the isolator to a two-port interface, which will introduce some errors. However, the calculation results using the method of this application are basically consistent with the experimental test results in terms of magnitude, natural frequency, and trend, and can meet the accuracy requirements of vibration isolation design calculation in marine engineering. Therefore, the calculation results in this application can be used for equipment vibration isolation evaluation calculation in marine engineering.

[0069] In addition, this calculation method can also be used to evaluate the vibration isolation effect of a single-layer vibration isolation device. However, there are multiple models of vibration isolators with the same rated load in the model range, and the method in this application can be used for rapid prediction. Specifically, the vibration isolation calculation method for ship vibration isolation devices also includes: Based on the rated load in the model data, multiple candidate vibration isolators that meet the load-bearing weight requirements of the ship vibration isolation device are determined. The vibration isolation calculation of the ship vibration isolation device is performed on each candidate vibration isolator to obtain the vibration isolation calculation results corresponding to each candidate vibration isolator. Based on the vibration isolation calculation results of each candidate vibration isolator, a vibration isolator that meets the vibration isolation requirements is selected.

[0070] In one embodiment, the vibration isolation calculation result includes the vibration isolation amount; when the vibration isolation amount corresponding to any vibration isolator is greater than or equal to the vibration isolation amount threshold, it is determined that the vibration isolator meets the vibration isolation requirements, wherein the vibration isolation amount threshold is customized according to actual application requirements and experience.

[0071] For example, in this case study, the weight of the upper raft is 362.5 kg. By consulting the model manual, there are five types of rubber vibration isolators that meet the load-bearing requirements. Different vibration isolators have different rubber formulations and load-bearing structures, so their dynamic stiffness, damping parameters and natural frequencies are also different.

[0072] Table 2 Rubber Vibration Isolators Meeting Load-Bearing Capacity Requirements

[0073] Using the calculation method described in this application, a vibration isolation evaluation model can be quickly established for the above five types of vibration isolators, and the evaluation results... Figure 16As shown (average value measured from the excitation point to the base panel), the E120 model has the worst vibration isolation effect, while the JQ120 and 6JX100 models have the best. The BE120 and AP120 models have comparable vibration isolation values. It should be noted that, in addition to evaluating the vibration isolation amount, the selection of vibration isolators in actual engineering projects should also consider factors such as the isolator's size and installation frequency, taking a comprehensive approach.

[0074] In practical shipbuilding engineering, both double-layer and single-layer vibration isolation are common vibration isolation devices, and the vibration isolation performance of double-layer devices is often superior to that of single-layer devices. Another example further verifies the effectiveness of the vibration isolation calculation method proposed in this application for a double-layer vibration isolation device. The double-layer vibration isolation device includes isolators arranged between the equipment and the raft frame, and between the raft frame and the base. The calculation model and measurement point distribution are as follows: Figure 17 As shown, point A2 is located at the excitation origin of the vibrator (on the equipment mounting panel), point A3 is on the upper vibration isolator (on the equipment mounting panel), point B1 is below the upper vibration isolator (on the raft), point C1 is on the lower vibration isolator (on the raft), and point D1 is below the lower vibration isolator (on the base panel).

[0075] The results of vibration isolation calculations and experimental tests at each measuring point are as follows: Figure 18 As shown, Figure 18 (a) shows the comparison between the calculated and experimental results for point A2. Figure 18 (b) shows the comparison between the calculated and experimental results for point A3. Figure 18 (c) shows the comparison between the calculated and experimental results for point B1. Figure 18 (d) shows the comparison between the calculated and experimental results for point C1. Figure 18 (e) shows the comparison results of calculation and experiment at point D1. As can be seen from the comparison results at each measuring point, the calculation results and the experimental results at each measuring point are consistent in magnitude, natural frequency and trend, which can meet the accuracy requirements of vibration isolation design calculation in marine engineering. Therefore, the method of this application can also effectively calculate the vibration isolation effect of double-layer vibration isolation device.

[0076] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A method for calculating the vibration isolation of ship vibration isolation devices based on vibration isolator type spectrum data, characterized in that, The vibration isolation calculation method for the ship vibration isolation device includes: Acquire the type spectrum data and impedance test data of the target vibration isolator, which is installed in the ship's vibration isolation device; A finite element model of the ship vibration isolation device was constructed, and the stiffness and damping parameters of the target vibration isolator were determined based on the type spectrum data and impedance test data. The stiffness and damping parameters of the target vibration isolator are input into the finite element model. Excitation loads are applied to the finite element model using finite element software, and the vibration response of the finite element model is extracted to obtain the vibration isolation calculation results of the target vibration isolation device.

2. The vibration isolation calculation method for ship vibration isolation devices according to claim 1, characterized in that, Determining the stiffness and damping parameters of the target vibration isolator includes: Based on the spectrum data and impedance test data, and combined with the finite element model of the ship vibration isolation device, the candidate stiffness parameters and candidate damping parameters of the target vibration isolator are determined. Based on candidate stiffness parameters and candidate damping parameters, multiple sets of preset parameter combinations are constructed. Finite element vibration isolation calculations are performed on each set of parameter combinations. The candidate stiffness parameter corresponding to the parameter combination with the optimal vibration isolation calculation result is determined as the stiffness parameter of the target vibration isolator, and the candidate damping parameter corresponding to the parameter combination with the optimal vibration isolation calculation result is determined as the damping parameter of the target vibration isolator.

3. The vibration isolation calculation method for ship vibration isolation devices according to claim 2, characterized in that, Candidate stiffness parameters include candidate static stiffness parameters and candidate dynamic stiffness parameters; The candidate stiffness and candidate damping parameters for the target vibration isolator are determined by: When the finite element model of the constructed ship vibration isolation device includes a spring-damping element model for simulating the vibration isolator, the candidate static stiffness parameters of the target vibration isolator are determined based on the type spectrum data, the candidate dynamic stiffness parameters of the target vibration isolator are determined based on the type spectrum data, and the candidate damping parameters of the target vibration isolator are determined based on the type spectrum data and impedance test data. When the finite element model of the constructed ship vibration isolation device includes a line element model for simulating the vibration isolator, the candidate dynamic stiffness parameters of the target vibration isolator are determined based on the impedance test data, and the candidate damping parameters of the target vibration isolator are determined based on the impedance test data.

4. The vibration isolation calculation method for ship vibration isolation devices according to claim 3, characterized in that, The model data includes static stiffness parameters, dynamic stiffness parameters, damping ratio coefficients, and rated loads; the static stiffness parameters in the model data are used as candidate static stiffness parameters, and the dynamic stiffness parameters in the model data are used as candidate dynamic stiffness parameters. Based on the damping ratio coefficient, rated load, and static stiffness parameters in the spectrum data, the candidate damping parameters of the target vibration isolator are calculated using the damping ratio formula for a single degree of freedom system, and / or, the admittance circle is plotted based on the impedance test data, and the candidate damping parameters of the target vibration isolator are obtained by fitting.

5. The vibration isolation calculation method for ship vibration isolation devices according to claim 3, characterized in that, Based on the conversion relationship between mechanical impedance and displacement impedance, the imaginary part of the impedance test data is converted to obtain the candidate dynamic stiffness parameter of the target vibration isolator, and the real part of the impedance test data is used as the candidate damping parameter of the target vibration isolator.

6. The vibration isolation calculation method for ship vibration isolation devices according to claim 4 or 5, characterized in that, The impedance test data includes origin impedance test data and cross-point impedance test data; the static stiffness parameters include static stiffness parameters in the length direction, static stiffness parameters in the width direction, and static stiffness parameters in the load direction; the dynamic stiffness parameters include dynamic stiffness parameters in the length direction, dynamic stiffness parameters in the width direction, and dynamic stiffness parameters in the load direction; and the damping parameters include damping parameters in the length direction, damping parameters in the width direction, and damping parameters in the load direction. When the finite element model of the constructed ship vibration isolation device includes a spring-damping element model for simulating the vibration isolator, the preset parameter combinations include the combination of candidate static stiffness parameters in the load-bearing direction, the combination of candidate static stiffness parameters in the load-bearing direction plus candidate damping parameters in the load-bearing direction, candidate static stiffness parameters in the length direction, candidate static stiffness parameters in the width direction, candidate static stiffness parameters in the load-bearing direction plus candidate damping parameters in the length direction, candidate damping parameters in the width direction, the combination of candidate damping parameters in the load-bearing direction, and the combination of candidate dynamic stiffness parameters in the load-bearing direction plus candidate damping parameters in the load-bearing direction. When the finite element model of the constructed ship vibration isolation device includes a line element model for simulating the vibration isolator, the preset parameter combination includes the candidate dynamic stiffness parameters in the length direction, the candidate dynamic stiffness parameters in the width direction, and the candidate dynamic stiffness parameters in the load-bearing direction obtained from the original impedance test data, plus the candidate damping parameters in the length direction, the candidate damping parameters in the width direction, and the candidate damping parameters in the load-bearing direction, and the combination of candidate dynamic stiffness parameters in the length direction, the candidate dynamic stiffness parameters in the width direction, and the candidate damping parameters in the load-bearing direction obtained from the cross-point impedance test data.

7. The vibration isolation calculation method for ship vibration isolation devices according to claim 1, characterized in that, The vibration isolation calculation method for the ship vibration isolation device also includes: Based on the rated load in the model data, multiple candidate vibration isolators that meet the load-bearing weight requirements of the ship vibration isolation device are determined. The vibration isolation calculation of the ship vibration isolation device is performed on each candidate vibration isolator to obtain the vibration isolation calculation results corresponding to each candidate vibration isolator. Based on the vibration isolation calculation results of each candidate vibration isolator, a vibration isolator that meets the vibration isolation requirements is selected.

8. The vibration isolation calculation method for ship vibration isolation devices according to claim 7, characterized in that, The vibration isolation calculation results include the vibration isolation amount; when the vibration isolation amount corresponding to any vibration isolator is greater than or equal to the vibration isolation amount threshold, it is determined that the vibration isolator meets the vibration isolation requirements.

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