Container shipping vibration simulation method, simulation device and simulation system

Abstract

The invention belongs to the technical field related to energy storage safety, and particularly relates to a simulation method, a simulation device and a simulation system for container shipping vibration. A sea wave spectrum model and a cargo ship model are obtained, and a time domain signal is obtained according to the sea wave spectrum model; defining the time domain signal as fluid excitation, and obtaining a first response signal of a preset acquisition point of the cargo ship model according to the fluid excitation; acquiring a frequency domain sequence according to the first response signal, and calculating and acquiring power spectral density according to the frequency domain sequence; obtaining a container model, and calculating and obtaining a second response signal of the container model according to the power spectral density; whether the container of the current cargo ship meets the safety requirement or not is judged according to the second response signal. Safety simulation is carried out on the energy storage container body during marine transportation, so that mechanical damage caused by design problems during marine transportation of the designed energy storage container is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage safety related, and particularly relates to a simulation method, a simulation device and a simulation system for container sea transportation vibration. BACKGROUND

[0002] With the global energy structure accelerating the transformation to low carbon, as the core carrier of distributed energy storage, energy storage containers are applied in scenarios such as renewable energy consumption, grid peak regulation and off-grid power supply.

[0003] In the prior art, as the main transportation mode of cross-border logistics, low-frequency large-amplitude vibration (typical frequency range 0.1-5Hz, acceleration amplitude up to 2-5g) caused by irregular sea waves in the process of sea transportation may be transmitted to the internal equipment through the container frame, resulting in safety hazards such as loose connection of battery modules, fatigue fracture of line interfaces, and even deformation of structural parts. However, in the existing test technology, although the existing sea transportation standard system (such as ISO container standards and ship classification society specifications) has clear specifications for the wind pressure resistance and impact resistance of the container shell, there are no special technical standards and test methods for the dynamic load bearing capacity of the internal core components of the energy storage container, including battery packs, BMS control systems, electrical connection devices and their fixed support structures.

[0004] Therefore, in the absence of a special safety simulation method for energy storage containers during sea transportation in the prior art, mechanical damage to energy storage containers may occur due to sea transportation, resulting in the inability of the structure of the energy storage container to adapt to sea transportation during design. SUMMARY

[0005] To solve the problem that in the absence of a special safety simulation method for energy storage containers during sea transportation in the prior art, mechanical damage to energy storage containers may occur due to sea transportation, resulting in the inability of the structure of the energy storage container to adapt to sea transportation during design. The present application proposes the following technical means to achieve the purpose of solving the above problems: In a first aspect, the present application proposes a simulation method for container sea transportation vibration, comprising: obtaining a sea wave spectrum model and a cargo ship model provided with a preset collection point, and obtaining a time domain signal according to the sea wave spectrum model; defining the time domain signal as a fluid excitation source, and obtaining a first response signal of the preset collection point according to the fluid excitation source; obtaining a frequency domain sequence according to the first response signal, and calculating a power spectral density according to the frequency domain sequence; obtaining a container model, and calculating a second response signal of the container model according to the power spectral density; According to the second response signal, it is judged whether the container of the current cargo ship meets the safety requirement.

[0006] By obtaining a sea wave spectrum model and a cargo ship model, a time domain signal is obtained according to the sea wave spectrum model; the time domain signal is defined as fluid excitation, and a first response signal of a preset acquisition point of the cargo ship model is obtained according to the fluid excitation; a frequency domain sequence is obtained according to the first response signal, and a power spectral density is calculated according to the frequency domain sequence; a container model is obtained, and a second response signal of the container model is calculated according to the power spectral density; and according to the second response signal, it is judged whether the container of the current cargo ship meets the safety requirement. The safety simulation of the energy storage container during sea transportation is carried out to avoid mechanical damage of the designed energy storage container due to design problems during sea transportation.

[0007] In some embodiments, the sea wave spectrum model and the cargo ship model are obtained, and the time domain signal is obtained according to the sea wave spectrum model, including: The sea wave spectrum model is obtained according to the JONSWAP sea wave spectrum; The cargo ship model is simulated and obtained according to the computational fluid dynamics method; The time domain signal is calculated according to the sea wave spectrum model.

[0008] In some embodiments, the cargo ship model is simulated and obtained according to the computational fluid dynamics method; and further comprising: Repairing the 3D digital model of the cargo ship, and defining the fluid domain according to the size of the cargo ship; Setting the fluid grid for the fluid domain, and setting the conditions of the model and the boundary.

[0009] In some embodiments, the time domain signal is defined as fluid excitation; including: Defining the boundary of the air domain and the water domain, and establishing a multiphase flow model; Defining the time domain signal as fluid excitation for the multiphase flow model to calculate the first response signal.

[0010] In some embodiments, the first response signal of the preset acquisition point is obtained according to the fluid excitation; including: At least one preset acquisition point is preset on the cargo ship model, the preset acquisition point and the fluid excitation are input into the multiphase flow model, and the first response signal corresponding to the preset acquisition point is calculated.

[0011] In some embodiments, the frequency domain sequence is obtained according to the first response signal, and the power spectral density is calculated according to the frequency domain sequence; including: Performing Fourier transform on the first response signal to obtain the frequency domain sequence; The frequency domain sequence is calculated by the average periodogram method to obtain the power spectral density.

[0012] In some embodiments, the container model is acquired, and a second response signal of the container model is calculated according to the power spectral density; comprising: According to the original three-dimensional geometric model of the container, the container model is acquired; According to the modal superposition method, the second response signal of the container model under the influence of the power spectral density is calculated.

[0013] In some embodiments, whether the container of the current cargo ship meets the safety requirement is judged according to the second response signal. Comprising: According to the second response signal, whether the container meets the safety requirement under the second response signal is judged by the three-sigma criterion.

[0014] In the second aspect, the application provides a simulation device, comprising: The first model establishing module is used for acquiring the sea wave spectrum model and the cargo ship model, and acquiring the time domain signal according to the sea wave spectrum model; The fluid response module is used for defining the time domain signal as a fluid excitation, and acquiring the first response signal of the preset acquisition point of the cargo ship model according to the fluid excitation; The frequency domain conversion module is used for acquiring the frequency domain sequence according to the first response signal, and calculating and acquiring the power spectral density according to the frequency domain sequence; The second model establishing module is used for acquiring the container model, and calculating and acquiring the second response signal of the container model according to the power spectral density; The safety judgment module is used for judging whether the container of the current cargo ship meets the safety requirement according to the second response signal.

[0015] In the third aspect, the application provides a simulation system, which in some embodiments comprises: a processor, a memory, a communication interface and a communication bus, the processor, the memory and the communication interface complete the communication among each other through the communication bus; The memory is used for storing at least one executable instruction, and the executable instruction makes the processor execute the operations of the simulation method of the container sea transportation vibration of any one of the first aspect.

[0016] The simulation method of the container sea transportation vibration, the simulation device and the simulation system of the application have the following beneficial effects: 1. The JONSWAP spectrum as the second generation sea wave spectrum model can accurately describe the concentration phenomenon of sea wave energy near the spectral peak under the condition of limited wind area by introducing the peak enhancement factor, and is more consistent with the actual sea condition than the traditional Pierson-Moskowitz spectrum.

[0017] 2. The complex interaction between the sea wave and the ship body is considered by the computational fluid dynamics calculation, including the nonlinear effect of the wave, the large amplitude motion response of the ship and the dynamic change of the fluid dynamic load, and is more accurate than the simplified potential flow theory.

[0018] 3. The original 3D geometric model of the container can consider the geometric details, material nonlinearity and connection characteristics of the container in detail, and the modal superposition method combined with the power spectral density excitation can accurately reflect the structural response characteristics under the random vibration environment.

[0019] 4. The research method covers a complete chain from the sea wave field (macro scale) to the ship motion (meso scale) to the container structural response (micro scale), and can capture the dynamic characteristics at different scales and their mutual influence.

[0020] 5. The two physical fields of fluid mechanics (CFD) and structural mechanics (FEA) are integrated, and the bidirectional coupling effect between fluid load and structural response is considered, which is closer to the real working condition than single-field analysis. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings: Figure 1 a flow chart of the simulation method of container sea transportation vibration according to the present application; Figure 2 a more specific flow chart of step S1 of the simulation method of container sea transportation vibration according to the present application; Figure 3 a more specific flow chart of step S12 of the simulation method of container sea transportation vibration according to the present application; Figure 4 a more specific flow chart of step S2 of the simulation method of container sea transportation vibration according to the present application; Figure 5 a more specific flow chart of step S3 of the simulation method of container sea transportation vibration according to the present application; Figure 6 a more specific flow chart of step S4 of the simulation method of container sea transportation vibration according to the present application; Figure 7 a frame diagram of the simulation device according to the present application; Figure 8 a frame diagram of the simulation system according to the present application. DETAILED DESCRIPTION

[0022] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. Although exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0023] Example 1: As Figures 1-6As shown, the embodiment proposes a simulation method for container sea transportation vibration, comprising: S1, obtaining a sea wave spectrum model and a cargo ship model provided with a preset collection point, and obtaining a time domain signal according to the sea wave spectrum model; Specifically, in order to more accurately represent the complexity of sea waves, a sea wave model is introduced before simulation. The conventional method uses sea wave spectrum as the research basis, which can include JONSWAP sea wave spectrum, Pierson-Moskowitz spectrum, NeumannSpectrum spectrum, etc., to establish a sea wave model. At the same time, a cargo ship model is established to simulate the actual sea transportation situation through the sea wave spectrum model and the cargo ship model. Further, the time domain signal obtained through the sea wave spectrum model is used as an excitation signal to simulate the influence of sea waves on the ship body. The preset collection point is provided on the cargo ship model, which is generally a standard position such as the bow, stern, and middle of the ship, or a preset position of the energy storage container.

[0024] S2, defining the time domain signal as a fluid excitation source, and obtaining a first response signal of the preset collection point of the cargo ship model according to the fluid excitation source; Specifically, according to the obtained time domain signal, the fluid excitation source is defined to excite the preset collection point, so as to simulate the first response signal of the preset collection point of the ship body during sea transportation, so as to analyze the influence of sea transportation on the preset collection point position through the first response signal (analyze the simulation results through the speed, displacement, etc. of the first response signal), and further design the structure of the energy storage container according to the simulation results. The advantage of this step is that the sea transportation result of the energy storage container is simulated in the fluid domain first, and then converted to frequency domain analysis. Compared with direct frequency domain analysis, this method makes the simulation result more realistic and close to the actual situation of the sea area.

[0025] S3, obtaining a frequency domain sequence according to the first response signal, and calculating a power spectral density according to the frequency domain sequence; Specifically, the first response signal is converted to frequency domain, i.e. the time domain signal in the fluid domain is converted to frequency domain signal, so as to calculate and obtain the power spectral density (hereinafter referred to as PSD) according to the frequency domain sequence, so as to convert the signal from time domain to frequency domain distribution map, and analyze the dynamic signal.

[0026] S4, obtaining a container model, and calculating a second response signal of the container model according to the power spectral density; Specifically, based on the original three-dimensional geometric model (3D CAD) of the container, necessary geometric repair (such as removing small features, filling holes, and stitching gaps) and engineering simplification (ignoring small detail features that have little effect on structural stiffness) are performed to retain the main load-bearing structure to obtain a geometric entity suitable for meshing. And calculate the second response signal of the container model according to the calculated power spectral density, so as to solve the second response signal of the container model under the PSD motion excitation when the ship is moving.

[0027] S5, judging whether the container of the current cargo ship meets the safety requirement according to the second response signal.

[0028] Specifically, to evaluate the reliability of the energy storage container structure in a random vibration environment, methods such as standard deviation criteria can be used to evaluate whether the dynamic strength and stiffness of the container structure under given sea state PSD excitation meet the safety requirements. Thus, the sea transportation safety simulation of the energy storage container is realized, thereby avoiding mechanical damage caused by design problems during the sea transportation of the designed energy storage container.

[0029] By obtaining a sea wave spectrum model and a cargo ship model, a time domain signal is obtained according to the sea wave spectrum model; the time domain signal is defined as a fluid excitation, and a first response signal of a preset acquisition point of the cargo ship model is obtained according to the fluid excitation; a frequency domain sequence is obtained according to the first response signal, and a power spectral density is calculated and obtained according to the frequency domain sequence; a container model is obtained, and a second response signal of the container model is calculated and obtained according to the power spectral density; and whether the container of the current cargo ship meets the safety requirement is judged according to the second response signal. To simulate the safety of the energy storage container during sea transportation, to avoid mechanical damage caused by design problems during the sea transportation of the designed energy storage container.

[0030] In some embodiments, the sea wave spectrum model and the cargo ship model are obtained, and the time domain signal is obtained according to the sea wave spectrum model, including the following steps: S11, obtaining a sea wave spectrum model according to a JONSWAP sea wave spectrum; Preferably, in order to more accurately characterize the complex characteristics of sea waves, the JONSWAP sea wave spectrum is selected to make the sea wave spectrum model. The JONSWAP spectrum can generate a sea wave frequency spectrum under the condition of limited wind area and limited wind time, and the peak shape parameter is introduced to better describe the frequency spectrum characteristics of actual sea waves and more accurately describe the energy distribution characteristics of sea waves in actual sea conditions. The mathematical expression is as follows: S(ω)= exp(- ) (1) Where S(ω) is the sea wave spectrum density, with units of , is the spectral peak elevation factor, usually taken as 0.0076 F is the fetch length, in meters, Hs is the significant wave height, in meters, g is the gravitational acceleration (9.81 m / s2), ω is the angular frequency, in rad / s f is the peak frequency, corresponding to the maximum value of the spectrum, γ is the peak enhancement factor, indicating the sharpness of the spectral peak; for wind waves, γ = 3.3; for swell, γ = 1.0-3.3; for extreme sea conditions, γ can be increased to 5-7 to enhance the probability of extreme waves, σ is the spectral width parameter, defined as:

[0031] The model can more accurately describe the concentration of sea wave energy near the spectral peak under the condition of limited fetch by introducing the peak enhancement factor γ.

[0032] S12, simulate and obtain a cargo ship model according to the computational fluid dynamics method; Specifically, since the time domain signal in subsequent data processing will be an important input parameter and will be applied to subsequent computational fluid dynamics (hereinafter referred to as CFD) numerical simulation, the corresponding 3D model of the cargo ship needs to be completely modeled by CFD so that the time domain signal can be numerically simulated with the 3D model of the cargo ship.

[0033] S13, calculating the time domain signal according to the sea wave spectrum model.

[0034] Specifically, the time domain signal is calculated according to the sea wave spectrum model, that is, the frequency domain signal is converted into the time domain signal. For example, inverse Fourier transform, wavelet inverse transform, Hilbert inverse transform and the like are used, which are conventional methods for those skilled in the art.

[0035] In some specific embodiments, the frequency domain signal S(ω) is converted into the time domain signal η(t) by the inverse discrete Fourier transform (IDFT) algorithm, and the mathematical expression is: η(t)=

[0036] wherein, η(t): represents the change of surface height with time, in meters (m), N: total number of discrete frequency points, A(i): amplitude of the i-th frequency component, in meters (m), calculated from the spectral density:

[0037] is the spectral density value at frequency Δω is the frequency interval. is the random phase angle of the i-th frequency component, uniformly distributed in The time-domain signal fully preserves the frequency components, phase relationships, and energy distribution characteristics of the ocean waves.

[0038] In some embodiments, a cargo ship model is obtained by simulation using computational fluid dynamics methods; the method further includes the following steps: S121. Repair the 3D digital model of the cargo ship and define the fluid domain according to the size of the cargo ship; Specifically, meticulous geometric repair is performed on the 3D model of the cargo ship, including addressing missing, overlapping, gaps, and non-manifold edges on opposite sides. This is to prevent defects from affecting the quality of mesh generation and the accuracy of calculation results, ensuring the geometric continuity and topological correctness of the model. This repair can be done using conventional geometric repair tools, which will not be elaborated upon here. Furthermore, to define an appropriate domain size and shape, the computational domain should be large enough to reduce the impact of boundary conditions on the flow field around the cargo ship. Simultaneously, the shape of the computational domain should be as regular as possible to improve mesh generation quality and computational efficiency. For example, a fluid domain three times the ship's length and twice the oscillation range can allow the flow to fully develop, while also considering the wake region.

[0039] S122. Set the fluid mesh for the fluid domain and set the conditions for the model and boundaries.

[0040] Specifically, an unstructured mesh is used to discretize the computational domain. A finer mesh is used on the cargo ship surface and at the fluid boundary layer to accurately capture the details of the flow field and boundary layer characteristics; a coarser mesh is used in areas far from the cargo ship to reduce computational load. After mesh generation, the mesh quality needs to be checked and optimized to ensure that the mesh orthogonality, aspect ratio, and other indicators meet the requirements of CFD calculations. Further, model and boundary conditions are set, mainly including: selecting a suitable turbulence model, such as the k-ω model, based on the characteristics of the cargo ship's hydrodynamic problem; and setting reasonable boundary conditions, such as inlet boundary conditions, outlet boundary conditions, and wall boundary conditions. The inlet boundary condition should be set as a velocity inlet according to the actual sea conditions; the outlet boundary condition is usually set as a pressure outlet; and the wall boundary conditions should be set as no-slip or slip boundary conditions according to the characteristics of the wall.

[0041] In some more specific embodiments, when no measured data is available, wind speed U and significant wave height can be combined. The relationship is based on the empirical formula:

[0042] For cases with limited wind areas, the Bretschneider-Darwin formula can be used:

[0043] Wherein U is the wind speed m / s, F is the length of the wind area m, and g is the acceleration of gravity.

[0044] In some embodiments, the time-domain signal is defined as a fluid excitation; comprising the following steps: S21, defining the air domain and water domain boundary, and establishing a multiphase flow model; Specifically, after the completion of the CFD model, the boundary of the air domain and the water domain needs to be defined first. According to the draft of the cargo ship and the fluctuation characteristics of the sea wave, the position of the interface between the air domain and the water domain is determined. At the interface, the surface tension coefficient needs to be set to accurately simulate the interaction between air and water. Further, a multiphase flow (hereinafter referred to as VOF, Volume of Fluid) model is established. In the establishment of the VOF model, the main phase is the air domain, and the secondary phase is the water domain. Appropriate surface tension model and interphase force model need to be set to accurately simulate the phenomena such as breaking and splashing of sea waves.

[0045] S22, defining the time-domain signal as a fluid excitation for calculating the first response signal of the multiphase flow model.

[0046] Specifically, in order to make the time-domain signal adapt to the VOF model calculation, it is necessary to convert or define the time-domain signal into a fluid excitation that can be used by the VOF model, that is, an excitation source. In some more specific embodiments, the time-domain signal is converted into a profile file and imported into the open channel flow module of the solving software (Fluent). The profile file is a CSV file containing the distribution information of physical quantities in a certain cross section or a certain region in the flow field. In Fluent, the time-domain signal can be loaded into the calculation domain through UDF (user-defined function) or profile file, so as to obtain the excitation source.

[0047] In some embodiments, the first response signal of the preset acquisition point is obtained according to the fluid excitation; comprising: At least one preset acquisition point is preset on the cargo ship model, the preset acquisition point and the fluid excitation are input into the multiphase flow model, and the first response signal corresponding to the preset acquisition point is calculated.

[0048] Specifically, in order to analyze the response characteristics of the cargo ship in the sea waves, signal acquisition points need to be set at key positions of the cargo ship, such as the bow, the stern, the middle of the ship, the deck and the like. These acquisition points will record the changes of physical quantities such as displacement, velocity, acceleration, pressure and the like of the cargo ship under the action of the sea waves. More specifically, it can be the position of the energy storage container. So as to obtain the first response signal of the preset acquisition point under the fluid excitation. Through the first response signal, the analysis of the vibration response of the energy storage container can be carried out, the motion performance and structural safety of the container and the key equipment inside the container in the sea waves can be evaluated, and a theoretical basis is provided for the design and optimization of the container.

[0049] In some embodiments, a frequency domain sequence is obtained according to the first response signal, and a power spectral density is calculated according to the frequency domain sequence; comprising: S31, Fourier transform is performed on the first response signal to obtain a frequency domain sequence; Specifically, in the CFD numerical simulation of step S2, the first response signal of the ship sailing in a specific sea state has been obtained, including key kinematic parameters such as linear velocity, angular velocity, linear acceleration, angular acceleration and displacement (translation and rotation) and the like. These parameters are usually output in the form of discrete time series, represented as x( ), wherein =nΔt (n=0,1,2,...,N-1), Δt is the sampling time interval. In order to represent the energy distribution characteristics of the ship response in the frequency domain and serve as the input excitation for subsequent structural analysis, the above discrete time domain signal x( ) needs to be preprocessed to eliminate noise and trend items. A high-pass filter is used to remove low-frequency drift, and the cutoff frequency is According to the signal characteristics, the filtered signal is windowed by a window function w( ) to reduce spectral leakage: ( )= w( ) Specifically, the commonly used Hann window expression is: w( )= , (n=0,1,2,...,N-1) The windowed signal is subjected to discrete Fourier transform (DFT) to obtain a frequency domain sequence :

[0050] Wherein, the frequency resolution is , and the corresponding frequency point is , is the sampling frequency. According to Nyquist theorem, the effective frequency range is ([0, / 2] ).

[0051] S32, calculate the frequency domain sequence by the average periodogram method to obtain the power spectral density.

[0052] Specifically, the signal is segmented and windowed, and then a plurality of periodograms are calculated and averaged by the average periodogram method (Welch method) to obtain the PSD, that is The average periodogram method (Welch method) is: (3) wherein L is the number of segments, the number of points in each segment, and the overlap rate is usually 50%.

[0053] In some embodiments, a container model is obtained, and a second response signal of the container model is obtained according to the power spectral density; comprising: S41, creating a container model according to the original three-dimensional geometric model of the container; Specifically, the original three-dimensional geometric model (3D CAD) of the container is geometrically repaired (such as removing small features, filling holes, and stitching gaps) and engineering simplified (ignoring small detail features that have little effect on structural stiffness), and the main load-bearing structure is retained to obtain a "clean" geometric entity suitable for meshing. Further, the thin-walled structure is simplified to a two-dimensional shell element by using a mid-surface extraction technique, the calculation efficiency is improved, the quadrilateral-dominated shell element is used for meshing, and the triangular element is used for transition in the key connection area. The mesh size is adaptively adjusted according to the stress gradient:

[0054] wherein L is the characteristic length, the number of elements, the maximum allowed mesh size (usually the minimum thickness of the structure ), and h is the mesh length.

[0055] Further, accurate material mechanical properties are given to each component (such as the steel plate of the box body, the frame structure, and the internal support) in the model, including the elastic modulus E, the Poisson's ratio v, the density p, etc. For analysis involving nonlinear or damping characteristics, the corresponding nonlinear constitutive model or structural damping coefficient also needs to be defined. This calculation of random vibration response does not involve nonlinear characteristics. According to the actual installation constraint conditions of the container on the ship (such as fixed connection with the ship deck through corner pieces), reasonable constraints (such as 6-degree-of-freedom fixed constraints or elastic supports) are applied to the corresponding nodes of the model to reflect the true boundary state.

[0056] S42, calculate the second response signal of the container model under the influence of the power spectral density according to the modal superposition method.

[0057] Specifically, the modal superposition method is used to solve the structural dynamic response of the container model under the excitation of the ship motion PSD in step S41. The core steps of the method include: S421, modal analysis, modal analysis is performed on the container model to solve the natural frequency and modal vector of the container under the constraint, the purpose of which is to decouple the dynamic equation of the structure in the modal space through the modal coordinate, and to convert the complex multi-degree-of-freedom system into a vibration problem of multiple independent single-degree-of-freedom systems. The decoupling equation in the modal coordinate (assuming the modal vector is ):

[0058] Among them: is the i-th modal coordinate; , , is the modal mass, damping, stiffness; is the modal force.

[0059] In a specific embodiment, the frequency response function of a single-degree-of-freedom system is assumed to be , and its output to the input excitation PSD (3) is:

[0060] Among them, the frequency response function is: (4) Among them, = is the i-th natural frequency, is the modal damping ratio.

[0061] S422, the modal coordinate response PSD is superimposed back to the physical space to obtain the PSD of the physical response quantity (such as stress component σ, displacement u) of the concerned position (such as the stress point and displacement point of the battery pack fixing frame in the container) as The response PSD in the physical coordinate is the superposition of the PSD of each mode, and the superposition formula is:

[0062] Among them, is the component of the i-th mode shape at the corresponding position. That is, the obtained is the second response signal.

[0063] In some embodiments, it is determined whether the current container of the cargo ship meets the safety requirement according to the second response signal. The determination includes: According to the second response signal, it is determined whether the container meets the safety requirement under the second response signal by a three-sigma rule (i.e., 3σ rule).

[0064] Specifically, to evaluate the reliability of the energy storage container structure under random vibration environment, the statistical characteristics of each concerned response quantity (such as stress component σ and displacement u) are calculated by using the PSD analysis results, the standard deviation of the response quantity, i.e., the root mean square value (MSV) of stress or displacement, is calculated, and the response PSD can be integrated to obtain the formula: (5) The root mean square value of the physical response is obtained by formula (5), and the PSD of the motion response (acceleration, displacement, etc.) of the ship under random sea wave excitation obtained after CFD simulation and signal processing describes a stationary random process. When the energy storage container is subjected to Gaussian random excitation (sea wave excitation can be approximately approximated as a Gaussian process), the dynamic response output (stress, displacement, etc.) thereof also obeys a Gaussian distribution (normal distribution), and the probability of the value falling within the range of is about 68.27%, the probability of the value falling within the range of is about 95.45%, and the probability of the value falling within the range of is about 99.73%, which means that among all possible instantaneous response values, more than 99.7% of the values fall within the range of Only less than 0.27% of the values fall outside the range, i.e., the probability of occurrence of “extreme value” is very small. Therefore, the value of is taken as the maximum probable extremum of the response quantity for the evaluation of the structure:

[0065] The physical meaning is that during the entire sea transportation voyage of the energy storage container (corresponding to a large number of response time history samples), the instantaneous value of the response quantity is almost impossible (probability <0.27%) to exceed . Therefore, is generally considered by the engineering field as the representative maximum value that the response quantity may encounter in actual operation. The calculated ​​The value is compared with the design criteria such as the allowable stress of the material, the allowable deformation of the structure, and the like, so that whether the dynamic strength and rigidity of the container structure under the given sea state PSD excitation meet the safety requirements can be evaluated. The first response signal is converted into the PSD, and the second response signal is obtained by using the modal superposition method, so as to meet the rigorous framework of the random vibration theory. The application of the 3σ criterion provides a structure safety evaluation method based on probability statistics, which is more reasonable than the traditional deterministic analysis. The random vibration analysis under the PSD excitation can more accurately simulate the fatigue load spectrum in the actual sea wave environment, and can realize more accurate fatigue life prediction in combination with the Miner criterion, so as to provide a scientific basis for the durability design of the container.

[0066] Embodiment 2 As shown in Figure 7 The embodiment provides a simulation device, which comprises: A first model establishing module 100 is configured to perform step S1 to obtain a sea wave spectrum model and a cargo ship model, obtain a time domain signal according to the sea wave spectrum model, and calculate the first response signal of the preset acquisition point according to the model established by the first model establishing module 100. A fluid response module 200 is configured to perform step S2 to define the time domain signal as a fluid excitation, obtain the first response signal of the preset acquisition point of the cargo ship model according to the fluid excitation, and calculate the first response signal of the preset acquisition point according to the model established by the first model establishing module 100. A frequency domain conversion module 300 is configured to perform step S3 to obtain a frequency domain sequence according to the first response signal, and calculate a power spectral density according to the frequency domain sequence, so as to obtain the frequency domain sequence and the power spectral density of the first response signal obtained by the fluid response module 200, and convert the signal from the time domain to the frequency domain.

[0067] A second model establishing module 400 is configured to perform step S4 to obtain a container model, and calculate the second response signal of the container model according to the power spectral density, so as to perform modal superposition on the power spectral density obtained by the frequency domain conversion module 300 and the container model, and obtain the second response signal.

[0068] A safety judgment module 500 is configured to perform step S5 to judge whether the container of the current cargo ship meets the safety requirement according to the second response signal, so as to perform safety evaluation on the second response signal obtained by the second model establishing module 400.

[0069] Embodiment 3 As shown in Figure 8 The embodiment provides a structure diagram of the embodiment of the simulation system of the application, and does not limit the specific implementation of the simulation system.

[0070] The simulation system can include a processor 602, a communications interface 604, a memory 606, and a communications bus 608.

[0071] The processor 602, the communications interface 604, and the memory 606 communicate with each other through the communications bus 608. The communications interface 604 is configured to communicate with network elements such as clients or other servers. The processor 602 is configured to execute the program 610, and specifically can execute the steps in the simulation method for container sea shipment vibration as described in Embodiment 1.

[0072] Specifically, the program 610 can include program codes including computer executable instructions.

[0073] The processor 602 can be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to perform the embodiments of the present application. The one or more processors of the simulation system can be the same type of processors, such as one or more CPUs; or can be different types of processors, such as one or more CPUs and one or more ASICs.

[0074] The memory 606 is configured to store the program 610. The memory 606 can include a high speed RAM memory, and can also include a non-volatile memory such as at least one disk memory. The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other apparatus. Furthermore, embodiments of the present application are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the embodiments of the present application.

[0075] In the description provided herein, a large number of specific details are illustrated. It is understood, however, that embodiments of the present application can be practiced without these specific details. Similarly, for the purpose of simplifying the present application and helping to understand one or more of the individual inventive aspects, in the above description of exemplary embodiments of the present application, individual features of the embodiments of the present application are sometimes grouped together in a single embodiment, figure, or description of a related aspect. The claims that follow this detailed description are hereby expressly incorporated into this detailed description, wherein each claim is separately and independently a separate embodiment of the present application.

[0076] It will be appreciated by those skilled in the art that modules in the apparatuses in the embodiments can be adapted and placed in one or more apparatuses other than that of the embodiments. Modules or units or components in the embodiments can be combined into one module or unit or component and furthermore can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and / or processes or units are mutually exclusive.

[0077] It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word 'comprising' does not exclude the presence of elements or steps other than those listed in a claim. The word 'a' or 'an' preceding an element does not exclude the presence of a plurality of such elements. The application can be implemented by means of both hardware and software, and any combination thereof. In a unit claim, any reference to 'composition' should not be construed as a limitation unless the composition is a product of manufacturing. The use of the word 'about' in relation to a numerical value preferably means ± 10 % of the value. The word 'first','second', 'third', etc. does not imply any order. The use of the terms 'first' and'second' are merely intended to differentiate between two distinct units. It is to be understood that the steps in the above-described embodiments can not be performed in the order described, unless specifically stated otherwise.

Claims

1. A method of simulating sea freight vibration of a container, characterized by, The method comprises the following steps: obtain a sea wave spectrum model and a cargo ship model provided with preset collection points, and obtain a time domain signal according to the sea wave spectrum model; define the time domain signal as a fluid excitation source, and obtain a first response signal of the preset collection points according to the fluid excitation source; obtain a frequency domain sequence according to the first response signal, and calculate a power spectral density according to the frequency domain sequence; obtain a container model, and calculate a second response signal of the container model according to the power spectral density; determine whether the container of the current cargo ship meets the safety requirement according to the second response signal.

2. The method of claim 1, wherein, The method for obtaining the sea wave spectrum model and the cargo ship model, and obtaining the time domain signal according to the sea wave spectrum model comprises the following steps: obtain the sea wave spectrum model according to a JONSWAP sea wave spectrum; simulate and obtain the cargo ship model according to a computational fluid dynamics method; calculate the time domain signal according to the sea wave spectrum model.

3. The method of claim 2, wherein, The method for simulating and obtaining the cargo ship model according to the computational fluid dynamics method further comprises the following steps: repair a 3D digital model of the cargo ship, and define a fluid domain according to the size of the cargo ship; set a fluid grid for the fluid domain, and set conditions for the model and the boundary.

4. The method of claim 1, wherein, The method for defining the time domain signal as the fluid excitation source comprises the following steps: define the boundary of an air domain and a water domain, and establish a multiphase flow model; define the time domain signal as the fluid excitation, and use the multiphase flow model to calculate the first response signal.

5. The method of claim 3, wherein, The method for obtaining the first response signal of the preset collection points according to the fluid excitation comprises the following steps: preset at least one preset collection point on the cargo ship model, input the preset collection points and the fluid excitation into the multiphase flow model, and calculate the first response signal corresponding to the preset collection points.

6. The method of claim 1, wherein, The method for obtaining the frequency domain sequence according to the first response signal, and calculating the power spectral density according to the frequency domain sequence comprises the following steps: perform Fourier transform on the first response signal to obtain the frequency domain sequence; calculate the frequency domain sequence by using an average periodogram method to obtain the power spectral density.

7. The method of claim 1, wherein, The method for obtaining the container model, and calculating the second response signal of the container model according to the power spectral density comprises the following steps: obtain the container model according to an original three-dimensional geometric model of the container; calculate the second response signal of the container model under the influence of the power spectral density according to a modal superposition method.

8. The method of claim 1, wherein, The method for determining whether the container of the current cargo ship meets the safety requirement according to the second response signal comprises the following steps: determine whether the container meets the safety requirement under the second response signal by using a three-sigma criterion according to the second response signal.

9. An emulation apparatus, characterized by, The method comprises the following steps: a first model establishment module is configured to obtain a sea wave spectrum model and a cargo ship model, and obtain a time domain signal according to the sea wave spectrum model; a fluid response module is configured to define the time domain signal as a fluid excitation, and obtain a first response signal of preset collection points of the cargo ship model according to the fluid excitation; a frequency domain conversion module is configured to obtain a frequency domain sequence according to the first response signal, and calculate a power spectral density according to the frequency domain sequence; A second model establishing module is configured to acquire a container model and calculate a second response signal of the container model according to the power spectral density; A safety judgment module is configured to judge whether the container of the current cargo ship meets the safety requirement according to the second response signal.

10. An emulation system, comprising: The method comprises the following steps: A processor, a memory, a communication interface and a communication bus, the processor, the memory and the communication interface complete mutual communication through the communication bus; The memory is used for storing at least one executable instruction, and the executable instruction enables the processor to execute the operation of the simulation method for container sea transportation vibration according to any one of claims 1-8.

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