Icebreaker impact vibration noise test method and application

Abstract

The application relates to a method for testing the vibration and noise of ice-breaking impact of an icebreaker and application thereof, and belongs to the field of vibration and noise testing, in particular to the field of testing the vibration and noise of ice-breaking impact of an icebreaker. The method solves the problems of long testing time, difficulty in determining a suitable testing frequency range and large environmental influence on accuracy of existing electric testing methods. The method comprises the steps of obtaining vibration response data and noise response data of an icebreaker under ice-breaking conditions and non-ice-breaking conditions in an ice-breaking test, wherein the testing frequency and monitoring points are determined by using the monitoring point determination method for ice-breaking impact of an icebreaker. The method for testing the vibration and noise of ice-breaking impact of an icebreaker and application thereof are suitable for quantitatively evaluating the vibration response and noise response caused by ice-breaking impact of an icebreaker.

Description

Technical Field

[0001] This invention relates to the testing of vibration and noise, and more particularly to the testing of vibration and noise caused by icebreaking impacts of icebreakers. Background Technology

[0002] When ships navigate through ice-covered areas, they inevitably collide with surrounding ice floes. The ice-induced vibrations between the ice floes and the ship cause vibration and noise responses in the ship's structure.

[0003] Timely detection and evaluation of the vibration and noise responses of icebreakers under ice-breaking impacts help identify and address potential safety hazards, improving the safety of icebreakers. Furthermore, it is crucial for improving the design and performance of icebreakers, enhancing icebreaking efficiency and effectiveness. Therefore, to assess the impact of ice-induced vibrations, it is necessary to test and measure the vibration and noise responses.

[0004] For noise response testing, the common practice is to use a vibration noise testing system combined with sound pressure level measurement, and to test parameters such as sound pressure, sound intensity, and sound power of the device under test by means of a sampling point.

[0005] Vibration response testing, based on the physical properties involved in the testing process, currently mainly includes mechanical measurement methods, optical measurement methods, and electrical measurement methods:

[0006] (1) Mechanical measurement method, which involves testing the vibration quantities (such as displacement, acceleration, and velocity) and system characteristic parameters (such as natural frequency, damping, and mode shape) of a machine through experimental methods. Because mechanical structures have relatively large energy losses, the range of frequencies that can be measured is relatively small. Therefore, in ship vibration acceleration testing, the accuracy of vibration measurements using the mechanical measurement method is relatively low, and its application is limited.

[0007] (2) Optical measurement method: the vibration parameters are converted into optical signals, then amplified by an optical system, and converted into electrical signals by a photodetector. Technicians obtain the required vibration test results by measuring and analyzing the electrical signals.

[0008] (3) Electrical measurement method is to convert the vibration parameters of the components (such as displacement, velocity, acceleration) into electrical signals (such as current, voltage, etc.), then amplify them with the help of electronic system, and then convert the electrical signal value and the vibration physical quantity value to be measured into a function, thereby successfully completing the measurement and statistics.

[0009] Currently, electrical measurement methods have a more prominent application value compared to mechanical and optical measurement methods, with advantages in high measurement accuracy, good sensitivity, and fast response speed; however, electrical measurement methods still have the following problems:

[0010] (1) Electrical testing methods take a long time;

[0011] (2) It is difficult to determine a suitable test frequency range in electrical measurement methods;

[0012] (3) The accuracy of electrical testing is greatly affected by the environment. Summary of the Invention

[0013] The purpose of this invention is to solve the problems of long testing time, difficulty in determining a suitable testing frequency range, and high accuracy affected by the environment in existing electrical testing methods.

[0014] To achieve the above objectives, one aspect of the present invention provides a method for determining monitoring points of icebreaking impact by icebreakers, characterized by comprising the following steps:

[0015] Steps for establishing a numerical model of the impact vibration of an icebreaker to be tested;

[0016] The steps include performing modal analysis on the numerical model of impact vibration to obtain the characteristic frequencies and mode shapes of the icebreaker, and expanding the characteristic frequencies of the icebreaker into a given range to obtain the test frequencies.

[0017] In the numerical model of impact vibration, the shell portion of the icebreaker 1 meter above and below the waterline is selected, and the shell portion is regarded as a rigid body to obtain a simplified numerical model.

[0018] Based on the ice condition data from the icebreaking test and the simplified numerical model, the steps are as follows: using the finite element method to simulate the interaction between the icebreaker and the ice layer and the stress on the icebreaker under different ice conditions, and to obtain the simulation results of the icebreaker's impact vibration response and noise response.

[0019] The steps to obtain the hull vibration characteristics corresponding to different icebreaking speeds are: comparative analysis of the characteristic frequencies and mode shapes of icebreakers, as well as the simulation results of the impact vibration response and noise response of icebreakers.

[0020] Based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, the steps for determining the monitoring points for the icebreaking test are as follows.

[0021] Another aspect of the present invention is to provide a device for determining monitoring points of icebreaking impact of icebreakers, characterized in that it comprises the following modules:

[0022] A module for establishing a numerical model of the impact vibration of an icebreaker to be tested;

[0023] Modal analysis is performed on the numerical model of impact vibration to obtain the characteristic frequencies and mode shapes of the icebreaker, and the characteristic frequencies of the icebreaker are expanded to a given range to obtain the module of test frequencies.

[0024] In the numerical model of impact vibration, the shell portion of the icebreaker 1 meter above and below the waterline is selected, and the shell portion is regarded as a rigid body to obtain a simplified numerical model module.

[0025] Based on the ice condition data from the icebreaking test and the simplified numerical model, a module is used to simulate the interaction between the icebreaker and the ice layer and the stress on the icebreaker under different ice conditions using the finite element method, and to obtain the simulation results of the icebreaker's impact vibration response and noise response.

[0026] By comparing and analyzing the characteristic frequencies and mode shapes of icebreakers, as well as the simulation results of the impact vibration response and noise response of icebreakers, a module is obtained to obtain the hull vibration characteristics corresponding to different icebreaking speeds.

[0027] Based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, a module is used to determine the monitoring points for the icebreaking test.

[0028] Another aspect of the present invention is to provide a method for testing the vibration and noise of icebreaking impacts of icebreakers, characterized by comprising the following steps:

[0029] The steps for obtaining vibration response data and noise response data of icebreakers under icebreaking conditions and icebreaking conditions obtained in icebreaking tests, wherein the icebreaking test uses the above-mentioned method for determining monitoring points of icebreaking impact of icebreakers to determine the test frequency and monitoring points.

[0030] The steps involve comparing the vibration and noise response data of icebreakers under icebreaking conditions and icebreaking conditions, performing differential analysis of ice load, and obtaining the vibration and noise signals after removing interference noise.

[0031] The steps include dividing and truncating the vibration signal and noise signal after removing interference noise, and then performing mean removal processing on the divided and truncated vibration signal and noise signal.

[0032] The steps to process the mean-removed vibration signal to obtain the final vibration response of the icebreaker;

[0033] The steps involve processing the noise signal after mean removal to obtain the final noise response of the icebreaker.

[0034] Furthermore, a preferred embodiment is provided, wherein the step of processing the mean-reduced vibration signal to obtain the final vibration response result of the icebreaker includes the following steps:

[0035] The vibration signal after mean removal is analyzed using wavelet denoising and short-time Fourier transform methods to obtain the vibration acceleration amplitude spectrum as the final result of the icebreaker's vibration response.

[0036]

[0037] Among them, g ω,t (t)=g(t-τ)e -iωt Let e ​​be the integral kernel function. -iωt G is a frequency-limiting function, g(t-τ) is a time-limiting function, and G... x (ω,τ) represents the frequency component of the signal x(t) at time τ with frequency ω; x(t) is the objective function of the vibration signal after mean removal.

[0038] Furthermore, a preferred embodiment is provided, wherein the step of processing the mean-reduced noise signal to obtain the final noise response result of the icebreaker includes the following steps:

[0039] The short-time Fourier transform method was used to process the noise signal measured by the microphone in the noise signal after the mean was removed, and the sound pressure amplitude spectrum of each typical compartment was obtained.

[0040] The sound pressure amplitude spectrum of each typical chamber was converted to obtain the sound pressure values ​​at the center frequencies of each octave band from 31.5 to 8000 Hz:

[0041]

[0042] Among them, f 2i The upper limit of the frequency for each center frequency band, f 1i p represents the lower limit of the frequency for each center frequency band. i This represents the total sound pressure level within each center frequency band.

[0043] Obtain the sound pressure level at each center frequency in the octave band from 31.5 to 8000 Hz:

[0044]

[0045] Where, p0 = 2.0 × 10 -5 Pa and p0 are the reference sound pressure levels; A-weighting is performed on the sound pressure levels at the center frequencies of each octave band from 31.5 to 8000 Hz to obtain the A-weighted sound levels at each center frequency of each octave band from 31.5 to 8000 Hz.

[0046] L Ai =L Pi +Δ Ai dB(A);

[0047] Where, Δ Ai The adjusted value for weighting A;

[0048] For the noise signal measured by the sound level meter in the noise signal after mean removal processing, obtain its equivalent continuous A-weighted sound level:

[0049]

[0050] Where T is the measurement time, L A (t) represents the A-weighted sound level measured at each time point;

[0051] L Ai and L Aeq As the final result of the noise response of the icebreaker.

[0052] Furthermore, a preferred embodiment is provided, wherein the ice-breaking experiment is conducted using the following method:

[0053] Step 1: Determine the test frequency and monitoring points using the above-mentioned method for determining monitoring points of icebreaking impact by icebreakers;

[0054] Step 2: Install vibration acceleration sensors at monitoring points within the icebreaker's hull; deploy microphones and sound level meters in typical compartments of the icebreaker, wherein the vibration acceleration sensors are used to collect vibration response data; and the microphones and sound level meters are used to collect noise response data.

[0055] Step 3: Conduct vibration and noise tests in ice-free open areas to obtain vibration and noise response data of the icebreaker under icebreaking conditions.

[0056] Step 4: Conduct vibration and noise tests under icebreaking conditions according to the test frequency and given test conditions to obtain vibration response data and noise response data of the icebreaker under icebreaking conditions.

[0057] Another aspect of the present invention is to provide a vibration and noise testing device for icebreaking impact of an icebreaker, characterized in that it comprises the following modules:

[0058] A module for acquiring vibration response data and noise response data of icebreakers under icebreaking conditions and icebreaking conditions obtained in icebreaking tests, wherein the icebreaking test uses the above-mentioned method for determining monitoring points of icebreaking impact of icebreakers to determine the test frequency and monitoring points.

[0059] By comparing the vibration and noise response data of icebreakers under icebreaking conditions and icebreaking conditions, a differential analysis of ice load is performed to obtain the vibration and noise signals after removing interference noise.

[0060] A module that divides and truncates the vibration signal and noise signal after removing interference noise, and performs mean removal processing on the divided and truncated vibration signal and noise signal;

[0061] This module processes the mean-removed vibration signal to obtain the final vibration response of the icebreaker.

[0062] This module processes the noise signal after mean removal to obtain the final noise response of the icebreaker.

[0063] Another aspect of the present invention is to provide a computer program product, characterized in that it comprises: a processor and a memory, the memory being used to store executable instructions of the processor, the processor being configured to execute the above-described method for determining monitoring points of icebreaker icebreaking impact or the above-described method for testing vibration and noise of icebreaker icebreaking impact via executing the executable instructions.

[0064] Another aspect of the present invention is to provide a computer storage medium, characterized in that the storage medium stores a computer program, which, when executed, performs either the above-described method for determining monitoring points of icebreaking impact of an icebreaker or the above-described method for testing vibration and noise of icebreaking impact of an icebreaker.

[0065] Another aspect of the present invention is the application of a vibration and noise testing method for icebreaker icebreaking impact in the testing of vibration and noise of icebreaker icebreaking impact.

[0066] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0067] 1. The vibration and noise testing method for icebreakers under icebreaking impact described in this invention combines simulation analysis with actual icebreaking tests to numerically simulate and analyze the vibration and noise results of icebreakers under ice impact. The analysis results are then applied to actual icebreaking tests, which can quickly determine the test frequency and the placement of monitoring points.

[0068] 2. The vibration and noise testing method for icebreaking impact of an icebreaker described in this invention obtains the test frequency through modal analysis and the monitoring point location through the finite element method, which can greatly shorten the time required for icebreaking tests and thus reduce the test time for vibration and noise testing.

[0069] 3. The vibration and noise testing method for icebreaking impact of an icebreaker described in this invention obtains the test frequency through modal analysis and the monitoring point position through the finite element method, which can guide the icebreaking test to collect signals more accurately, thereby improving the accuracy of vibration and noise testing.

[0070] 4. The vibration and noise testing method for icebreaking impact of an icebreaker described in this invention obtains the vibration and noise signals after removing interference noise through difference analysis, which can eliminate environmental noise interference and thus significantly reduce the impact of the environment on vibration and noise testing.

[0071] 5. The vibration and noise testing method for icebreaker impact described in this invention uses actual icebreaking tests to closely simulate the actual operating environment, allowing the icebreaker to be driven and tested in a real ice surface environment, thereby obtaining the most realistic and reliable vibration and noise test results.

[0072] The present invention discloses a vibration and noise testing method and application for icebreaker icebreaking impact, which is applicable to the quantitative evaluation of the vibration and noise response caused by icebreaker icebreaking impact. Attached Figure Description

[0073] Figure 1 A flowchart illustrating the steps of a vibration and noise testing method for icebreaker icebreaking impact, as described in one embodiment of the present invention.

[0074] Figure 2 A schematic diagram of the common layout of the main compartments of existing icebreakers;

[0075] Figure 3 For based on Figure 2 The diagram shows the layout of monitoring points on the main deck of the icebreaker.

[0076] Figure 4 For based on Figure 2 The diagram shows the layout of monitoring points on the superstructure bridge deck of the icebreaker.

[0077] Figure 5 For based on Figure 2 The diagram shows the arrangement of the sound level meter and microphone on the icebreaker. Detailed Implementation

[0078] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0079] To make the technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail and completely below with reference to the accompanying drawings. The various embodiments described below are only some preferred embodiments of the present invention, and not all of them; the various embodiments described below are intended to explain the present invention and should not be construed as limiting the present invention; reasonable combinations of the technical features defined in the various embodiments of the present invention, as well as all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort, are all within the scope of protection of the present invention.

[0080] Implementation Method 1

[0081] Combination Figure 1 This embodiment describes a method for determining monitoring points for icebreaking impact by an icebreaker. The specific implementation details are as follows:

[0082] The method includes the following steps:

[0083] Steps for establishing a numerical model of the impact vibration of an icebreaker to be tested;

[0084] The steps include performing modal analysis on the numerical model of impact vibration to obtain the characteristic frequencies and mode shapes of the icebreaker, and expanding the characteristic frequencies of the icebreaker into a given range to obtain the test frequencies.

[0085] In the numerical model of impact vibration, the shell portion of the icebreaker 1 meter above and below the waterline is selected, and the shell portion is regarded as a rigid body to obtain a simplified numerical model.

[0086] Based on the ice condition data from the icebreaking test and the simplified numerical model, the steps are as follows: using the finite element method to simulate the interaction between the icebreaker and the ice layer and the stress on the icebreaker under different ice conditions, and to obtain the simulation results of the icebreaker's impact vibration response and noise response.

[0087] The steps to obtain the hull vibration characteristics corresponding to different icebreaking speeds are: comparative analysis of the characteristic frequencies and mode shapes of icebreakers, as well as the simulation results of the impact vibration response and noise response of icebreakers.

[0088] Based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, the steps for determining the monitoring points for the icebreaking test are as follows.

[0089] In this embodiment, the characteristic frequency represents the natural vibration frequency of the icebreaker in the absence of external interference; the mode shape represents the vibration pattern of the icebreaker at a specific frequency, specifically including the vibration mode and vibration amplitude of each point on the icebreaker.

[0090] In this embodiment, the simulation results of the icebreaker's impact vibration response obtained by finite element method are the simulation results of the icebreaker's vibration response under its own motion and external load (ice load impact).

[0091] In this embodiment, the ice condition data for the icebreaking test is data collected in advance.

[0092] The ice condition data refers to the ice condition data of the icebreaking test scenario, including the geometric parameters of the ice (ice thickness, ice area, etc.) and mechanical parameters (ice density, ice crystal structure, etc.), which can be obtained through actual collection; if the actual collection conditions do not permit (such as navigation in polar ice areas), the ice condition data can also be downloaded from the network.

[0093] In this embodiment, the icebreaking load model experienced by the icebreaker during actual icebreaking operations is related to factors such as ice conditions, the mechanical strength of the ice, the failure mode of the ice layer, and the speed of the icebreaker. To simplify the calculation, appropriate simplifications are made based on the actual situation: the difference between the thickness and mechanical strength of the ice layer in the icebreaking zone is ignored, and the buckling and shear failure of the ice layer are not considered.

[0094] Since the main area of ​​icebreaking load on the ship during icebreaking is the bow, the icebreaker can be simplified to the hull plating below the waterline, and the position 1 meter above the waterline can be considered to reduce the influence of the cut-off boundary. That is, the simplified numerical model obtained by simplifying the impact vibration numerical model mainly extracts the main area of ​​contact between the icebreaker and the ice load, which improves the simulation efficiency while ensuring the accuracy of the simulation results.

[0095] In this embodiment, based on the vibration simulation results, the hull vibration (characteristic) can be divided into total vibration (characteristic) and local vibration (characteristic):

[0096] Under total vibration conditions, monitoring points (or vibration monitoring points, vibration acceleration measuring points) are mainly arranged in key parts of the hull structure such as the longitudinal girder, strong beams and bottom keel;

[0097] Under localized vibration conditions, monitoring points are mainly arranged at locations where the hull structure experiences significant vibration and deformation, such as the center of the lattice, the mid-span of the crossbeam, and the intersection of the longitudinal girder and the crossbeam.

[0098] In this embodiment, the determination of the monitoring points is more specifically as follows:

[0099] Based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, the monitoring points for the icebreaking test were determined.

[0100] The vibration modes in the hull vibration characteristics are analyzed to determine the main vibration areas of the icebreaker structure. Based on the layout of the icebreaker structure and the difficulty of monitoring, monitoring points are determined from the main vibration areas (i.e., the monitoring points for measuring the vibration response on the actual icebreaker during the icebreaking test).

[0101] Implementation Method 2

[0102] Combination Figure 1 This embodiment describes a device for determining monitoring points of icebreaking impact by an icebreaker. The specific implementation details are as follows:

[0103] The device includes the following modules:

[0104] A module for establishing a numerical model of the impact vibration of an icebreaker to be tested;

[0105] Modal analysis is performed on the numerical model of impact vibration to obtain the characteristic frequencies and mode shapes of the icebreaker, and the characteristic frequencies of the icebreaker are expanded to a given range to obtain the module of test frequencies.

[0106] In the numerical model of impact vibration, the shell portion of the icebreaker 1 meter above and below the waterline is selected, and the shell portion is regarded as a rigid body to obtain a simplified numerical model module.

[0107] Based on the ice condition data from the icebreaking test and the simplified numerical model, a module is used to simulate the interaction between the icebreaker and the ice layer and the stress on the icebreaker under different ice conditions using the finite element method, and to obtain the simulation results of the icebreaker's impact vibration response and noise response.

[0108] By comparing and analyzing the characteristic frequencies and mode shapes of icebreakers, as well as the simulation results of the impact vibration response and noise response of icebreakers, a module is obtained to obtain the hull vibration characteristics corresponding to different icebreaking speeds.

[0109] Based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, a module is used to determine the monitoring points for the icebreaking test.

[0110] In this embodiment, the device for determining the monitoring point of icebreaking impact of an icebreaker is used to implement the method for determining the monitoring point of icebreaking impact of an icebreaker as described in the above embodiment.

[0111] Implementation Method 3

[0112] Combination Figure 1 This embodiment describes a method for testing the vibration and noise of an icebreaker during icebreaking impact. The specific implementation details are as follows:

[0113] The method includes the following steps:

[0114] The steps for obtaining vibration response data and noise response data of icebreakers under icebreaking conditions and icebreaking conditions obtained in icebreaking tests; wherein, the icebreaking test uses the above-mentioned method for determining monitoring points of icebreaking impact of icebreakers to determine the test frequency and monitoring points.

[0115] The steps involve comparing the vibration and noise response data of icebreakers under icebreaking conditions and icebreaking conditions, performing differential analysis of ice load, and obtaining the vibration and noise signals after removing interference noise.

[0116] The steps include dividing and truncating the vibration signal and noise signal after removing interference noise, and then performing mean removal processing on the divided and truncated vibration signal and noise signal.

[0117] The steps to process the mean-removed vibration signal to obtain the final vibration response of the icebreaker;

[0118] The steps involve processing the noise signal after mean removal to obtain the final noise response of the icebreaker.

[0119] In this embodiment, during actual operation, the icebreaker's generators, propellers, and other equipment, as well as the environment in which the icebreaker is located, will generate noise. This noise will affect the accuracy of the data obtained from the icebreaking test, and can be referred to as interference noise.

[0120] In this embodiment, the difference analysis refers to the process of subtracting the response data under different icebreaking speeds (i.e., under icebreaking conditions) from the response data under non-icebreaking conditions to eliminate the influence of equipment such as generators and propellers, as well as environmental noise (i.e., interference noise).

[0121] In this embodiment, during icebreaking operations, under intermittent or discontinuous icebreaking impact loads, the fluctuation amplitude of the time-domain signals of hull structure vibration and cabin noise response collected by each sensor is large, exhibiting obvious non-stationary characteristics. Reasonable segmentation and truncation of the signals can improve the accuracy of time-domain analysis.

[0122] In this embodiment, the signal is subjected to mean removal processing to reduce the offset and phase difference between signals, improve the clarity of the signal, and make the subsequent analysis results more accurate.

[0123] In this embodiment, the results of a vibration and noise testing method for icebreaker icebreaking impact can also be evaluated based on a method for determining monitoring points for icebreaker icebreaking impact described in the above embodiments. Specifically:

[0124] Using a method for determining monitoring points of icebreaker icebreaking impact in the above embodiments, simulation results of icebreaker impact vibration response and noise response are obtained.

[0125] The vibration and noise response of the icebreaker are obtained by using the vibration and noise test method of an icebreaker icebreaking impact according to the above embodiments.

[0126] Based on the simulation results of the icebreaker's impact vibration response and noise response, as well as the final results of the icebreaker's vibration response and noise response, the curve characteristics, spectral characteristics, and related indicators of the two are compared, and an error analysis is conducted.

[0127] The results of an icebreaker icebreaking impact vibration and noise test method are evaluated based on error analysis.

[0128] Implementation Method 4

[0129] Combination Figure 1 This embodiment further defines the vibration and noise testing method for icebreaker icebreaking impact described in Embodiment 3. The specific implementation details are as follows:

[0130] The step of processing the mean-removed vibration signal to obtain the final vibration response result of the icebreaker includes the following steps:

[0131] The vibration signal after mean removal is analyzed using wavelet denoising and short-time Fourier transform methods to obtain the vibration acceleration amplitude spectrum as the final result of the icebreaker's vibration response.

[0132]

[0133] Among them, g ω,t (t)=g(t-τ)e -iωt Let e ​​be the integral kernel function. -iωt G is a frequency-limiting function, g(t-τ) is a time-limiting function, and G... x (ω,τ) represents the frequency component of the signal x(t) at time τ with frequency ω; x(t) is the objective function of the vibration signal after mean removal.

[0134] Implementation Method 5

[0135] Combination Figure 1 This embodiment further defines the vibration and noise testing method for icebreaker icebreaking impact described in Embodiment 3. The specific implementation details are as follows:

[0136] The step of processing the mean-removed noise signal to obtain the final noise response result of the icebreaker includes the following steps:

[0137] The short-time Fourier transform method was used to process the noise signal measured by the microphone in the noise signal after the mean was removed, and the sound pressure amplitude spectrum of each typical compartment was obtained.

[0138] The sound pressure amplitude spectrum of each typical chamber was converted to obtain the sound pressure values ​​at the center frequencies of each octave band from 31.5 to 8000 Hz:

[0139]

[0140] Among them, f 2i The upper limit of the frequency for each center frequency band, f 1i p represents the lower limit of the frequency for each center frequency band. i This represents the total sound pressure level within each center frequency band.

[0141] Obtain the sound pressure level at each center frequency in the octave band from 31.5 to 8000 Hz:

[0142]

[0143] Where, p0 = 2.0 × 10-5 Pa and p0 are the reference sound pressure levels; A-weighting is performed on the sound pressure levels at the center frequencies of each octave band from 31.5 to 8000 Hz to obtain the A-weighted sound levels at each center frequency of each octave band from 31.5 to 8000 Hz.

[0144] L Ai =L Pi +Δ Ai dB(A);

[0145] Where, Δ Ai The adjusted value for weighting A;

[0146] For the noise signal measured by the sound level meter in the noise signal after mean removal processing, obtain its equivalent continuous A-weighted sound level:

[0147]

[0148] Where T is the measurement time, L A (t) represents the A-weighted sound level measured at each time point;

[0149] L Ai and L Aeq As the final result of the noise response of the icebreaker.

[0150] In this embodiment, the noise signal after mean removal processing includes the noise signal measured by the microphone after mean removal processing and the noise signal measured by the sound level meter after mean removal processing.

[0151] The noise signal measured by the sound level meter after the mean removal process is a non-steady-state noise signal.

[0152] Implementation Method Six

[0153] Combination Figure 1 This embodiment further defines the vibration and noise testing method for icebreaker icebreaking impact described in Embodiment 3. The specific implementation details are as follows:

[0154] The ice-breaking experiment was conducted using the following method:

[0155] Step 1: Determine the test frequency and monitoring points using the above-mentioned method for determining monitoring points of icebreaking impact by icebreakers;

[0156] Step 2: Install vibration acceleration sensors at monitoring points within the icebreaker's hull; deploy microphones and sound level meters in typical compartments of the icebreaker; wherein, the vibration acceleration sensors are used to collect vibration response data; and the microphones and sound level meters are used to collect noise response data.

[0157] Step 3: Conduct vibration and noise tests in ice-free open areas to obtain vibration and noise response data of the icebreaker under icebreaking conditions.

[0158] Step 4: Conduct vibration and noise tests under icebreaking conditions according to the test frequency and given test conditions to obtain vibration response data and noise response data of the icebreaker under icebreaking conditions.

[0159] In this embodiment, to eliminate the influence of excitation from other equipment, vibration and noise tests are first conducted in an ice-free open area.

[0160] In this embodiment, the typical cabins are those known based on the actual structure of the icebreaker and refer to the main cabins where the crew works and lives. The noise levels in these cabins are of particular importance.

[0161] In this embodiment, since the ice layer will significantly increase the resistance of the ship's forward movement during the icebreaking process, the speed of the icebreaker will be unstable and it will be difficult to maintain a constant speed. Therefore, the icebreaking speed of each icebreaking test condition is controlled within a small deviation range.

[0162] Meanwhile, since the magnitude and location of ice load impacts on icebreakers vary at different speeds (icebreaking speeds), the setting of monitoring points is closely related to the speed.

[0163] To better handle variations in icebreaking speed, icebreaking tests can be closely combined with finite element method simulations based on simplified numerical models.

[0164] First, during the actual measurement process of the ice-breaking test, a speedometer can be used to monitor the ice-breaking speed in real time;

[0165] Then, the icebreaking speed obtained from real-time monitoring can be used in a method for determining the monitoring point of icebreaking impact of an icebreaker in the above-described embodiment, that is, the icebreaking speed obtained from real-time monitoring can be used as an input parameter in the finite element method simulation, which can improve the accuracy and richness of the numerical model.

[0166] Finally, the icebreaker was rearranged based on the monitoring points obtained from the finite element method simulation, and the icebreaking test was carried out again using the previous icebreaking speed.

[0167] In this embodiment, to investigate the vibration impact of icebreaking impact on the local structures of the main living and working areas of the ship and the noise impact on key cabins, it is necessary to reasonably arrange monitoring points (also known as vibration acceleration measurement points) on the icebreaker for monitoring vibration response and noise measurement points (i.e., microphone and sound level meter placement points) for monitoring noise response in typical cabins on the icebreaker:

[0168] In this embodiment, in the step of determining the monitoring points for the icebreaking test based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, it is also necessary to consider the structure of the icebreaker, specifically:

[0169] According to the structural diagram of the bridge deck, the measuring points (monitoring points) are evenly arranged at the intersection of the longitudinal girder and the transverse beam, the mid-span of the transverse beam between the longitudinal girder, and the center of the local grid formed by the transverse beam and the longitudinal girder.

[0170] As attached Figure 3 As shown, monitoring points are set up on the floors of the dining room, lounge, and corridor in the main deck living area according to the layout diagram of the midship living area.

[0171] As attached Figure 4 As shown, based on the structural diagram of the main deck at the bow, the monitoring points are evenly distributed on the bow deck.

[0172] As attached Figure 5 As shown, microphones and sound level meters are arranged in typical compartments such as the midship main deck lounge, bridge, engine room, and bow equipment maintenance compartment of the icebreaker. The microphones are arranged in the center of each main test compartment.

[0173] In this embodiment, during each icebreaking test, the icebreaker is first reversed from the position reached in the previous icebreaking test back to the open water. Then, the icebreaking test is carried out on the complete ice layer at a certain speed. At the same time, the vibration acceleration response and noise response data of the icebreaker are measured until the icebreaker can no longer move on the ice. The icebreaking test ends and the next icebreaking test is prepared to begin.

[0174] In this embodiment, depending on the ice thickness, the icebreaker conducts icebreaking tests in two ways: ramming and continuous.

[0175] In this embodiment, when using the ramming icebreaking method for icebreaking operations (icebreaking test), the single icebreaking distance is 1 / 2L to 2 / 3L (L is the ship length). After each ramming operation, the icebreaker stops and reverses a certain distance before proceeding with a second ramming icebreaking operation. The reversing distance is generally 2L to 3L. During the second icebreaking operation, the icebreaking position is selected to the left (or right) of the first icebreaking position. During the third ramming icebreaking operation, the icebreaking position is on the opposite side of the first icebreaking position. This process is repeated, alternating between left and right, while maintaining a channel width of 1.5B to 2B (B is the ship width).

[0176] In this embodiment, when the ice layer is relatively thin, a continuous icebreaking method can be used for icebreaking operations. At this time, the icebreaker climbs onto the ice layer at different icebreaking speeds, relies on the weight of the bow to crush the ice layer, and then opens up a route, relying on the powerful thrust of the main engine to force its way through the ice layer.

[0177] Implementation Method Seven

[0178] Combination Figure 1 This embodiment describes a vibration and noise testing device for icebreaking impact of an icebreaker. The specific implementation details are as follows:

[0179] The device includes the following modules:

[0180] A module for acquiring vibration response data and noise response data of icebreakers under icebreaking conditions and icebreaking conditions obtained in icebreaking tests; wherein, the icebreaking test uses the above-mentioned method for determining monitoring points of icebreaking impact of icebreakers to determine the test frequency and monitoring points.

[0181] By comparing the vibration and noise response data of icebreakers under icebreaking conditions and icebreaking conditions, a differential analysis of ice load is performed to obtain the vibration and noise signals after removing interference noise.

[0182] A module that divides and truncates the vibration signal and noise signal after removing interference noise, and performs mean removal processing on the divided and truncated vibration signal and noise signal;

[0183] This module processes the mean-removed vibration signal to obtain the final vibration response of the icebreaker.

[0184] This module processes the noise signal after mean removal to obtain the final noise response of the icebreaker.

[0185] Implementation Method Eight

[0186] This embodiment provides a method for testing the vibration and noise of icebreaking impact in icebreakers, and its application in the testing of vibration and noise of icebreaking impact in icebreakers:

[0187] The vibration and noise testing method for icebreaking impact of icebreakers can be applied to the vibration and noise testing of icebreaking impact of various icebreakers.

[0188] The above description of several specific embodiments further details the technical solution provided by the present invention in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, reasonable combinations of embodiments, and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0189] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing vibration and noise from icebreaking impact of an icebreaker, characterized in that, Includes the following steps: The steps for obtaining vibration response data and noise response data of icebreakers under icebreaking conditions and icebreaking conditions obtained in icebreaking tests; wherein, the icebreaking test uses the method for determining the monitoring points of icebreaking impact of icebreakers to determine the test frequency and monitoring points. The steps involve comparing the vibration and noise response data of icebreakers under icebreaking conditions and icebreaking conditions, performing differential analysis of ice load, and obtaining the vibration and noise signals after removing interference noise. The steps include dividing and truncating the vibration signal and noise signal after removing interference noise, and then performing mean removal processing on the divided and truncated vibration signal and noise signal. The steps to process the mean-removed vibration signal to obtain the final vibration response of the icebreaker; The step of processing the noise signal after mean removal to obtain the final result of the icebreaker's noise response, wherein the method for determining the monitoring points of the icebreaker's icebreaking impact further includes the following steps: Steps for establishing a numerical model of the impact vibration of an icebreaker to be tested; The steps include performing modal analysis on the numerical model of the impact vibration to obtain the characteristic frequencies and mode shapes of the icebreaker, and expanding the characteristic frequencies of the icebreaker into a given range to obtain the test frequencies. In the numerical model of impact vibration, the shell portion of the icebreaker 1 meter above and below the waterline is selected, and the shell portion is regarded as a rigid body to obtain a simplified numerical model. Based on the ice condition data from the icebreaking test and the simplified numerical model, the steps are as follows: using the finite element method to simulate the interaction between the icebreaker and the ice layer and the stress on the icebreaker under different ice conditions, and to obtain the simulation results of the icebreaker's impact vibration response and noise response. The steps to obtain the hull vibration characteristics corresponding to different icebreaking speeds are: comparative analysis of the characteristic frequencies and mode shapes of icebreakers, as well as the simulation results of the impact vibration response and noise response of icebreakers. Based on the ship's vibration characteristics, combined with icebreaking conditions and icebreaking speed, the steps for determining the monitoring points for the icebreaking test are as follows.

2. The vibration and noise testing method for icebreaking impact of an icebreaker according to claim 1, characterized in that, The step of processing the mean-removed vibration signal to obtain the final vibration response result of the icebreaker includes the following steps: The vibration signal after mean removal is analyzed using wavelet denoising and short-time Fourier transform methods to obtain the vibration acceleration amplitude spectrum as the final result of the icebreaker's vibration response. ,in, For the integral kernel function, For frequency limiting function, It is a time-limited function. To reflect exist The frequency of time is The signal frequency components; The objective function is the vibration signal after mean removal processing.

3. The vibration and noise testing method for icebreaking impact of an icebreaker according to claim 1, characterized in that, The step of processing the mean-removed noise signal to obtain the final noise response result of the icebreaker includes the following steps: The short-time Fourier transform method was used to process the noise signal measured by the microphone in the noise signal after the mean was removed, and the sound pressure amplitude spectrum of each typical compartment was obtained. The sound pressure amplitude spectrum of each typical chamber was converted to obtain the sound pressure values ​​at the center frequencies of each octave band from 31.5 to 8000 Hz: ;in, The upper limit of the frequency for each center frequency band, These are the lower frequency limits for each center frequency band. This represents the total sound pressure level within the frequency band of each center frequency. Obtain the sound pressure level at each center frequency within the octave band of 31.5~8000Hz: ,in, , The reference sound pressure level is used; the sound pressure level at each center frequency of the octave band from 31.5 to 8000 Hz is A-weighted to obtain the A-weighted sound level at each center frequency of the octave band from 31.5 to 8000 Hz. ;in, The correction value for A-weighting; for the noise signal measured by the sound level meter in the noise signal after mean removal processing, obtain its equivalent continuous A-weighted sound level: ;in, To measure time, Let be the A-weighted sound level values ​​measured at various times; and As the final result of the noise response of the icebreaker.

4. The vibration and noise testing method for icebreaking impact of an icebreaker according to claim 1, characterized in that, The ice-breaking test was conducted using the following method: The testing frequency and monitoring points were determined using the method for determining monitoring points of icebreaking impact from icebreakers. Vibration acceleration sensors are installed at monitoring points within the icebreaker's hull; microphones and sound level meters are arranged in typical compartments of the icebreaker, wherein the vibration acceleration sensors are used to collect vibration response data; and the microphones and sound level meters are used to collect noise response data. Vibration and noise tests were conducted in ice-free open areas to obtain vibration and noise response data of the icebreaker under icebreaking conditions. Vibration and noise tests were conducted under icebreaking conditions based on the test frequency and given test conditions to obtain vibration and noise response data of the icebreaker under icebreaking conditions.

5. A vibration and noise testing device for icebreaking impact of an icebreaker, used to implement the vibration and noise testing method of claim 1, characterized in that, Includes the following modules: A module for acquiring vibration response data and noise response data of icebreakers under icebreaking conditions and icebreaking conditions obtained in icebreaking tests, wherein the icebreaking test uses the method of determining the monitoring points of icebreaking impact of icebreakers to determine the test frequency and monitoring points. By comparing the vibration and noise response data of icebreakers under icebreaking conditions and icebreaking conditions, a differential analysis of ice load is performed to obtain the vibration and noise signals after removing interference noise. A module that divides and truncates the vibration signal and noise signal after removing interference noise, and performs mean removal processing on the divided and truncated vibration signal and noise signal. This module processes the mean-removed vibration signal to obtain the final vibration response of the icebreaker. This module processes the noise signal after mean removal to obtain the final noise response of the icebreaker.

6. A computer program product, comprising: The processor and memory are characterized in that the memory is used to store executable instructions of the processor, the processor being configured to execute a vibration and noise testing method for icebreaking impact of an icebreaker as described in any one of claims 1-4.

7. A computer storage medium, characterized in that, The storage medium stores a computer program, which, when executed, performs a vibration and noise testing method for icebreaking impact of an icebreaker as described in any one of claims 1-4.

8. The application of the vibration and noise testing method for icebreaking impact of an icebreaker as described in claim 1 in the vibration and noise testing of icebreaking impact of an icebreaker.

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