48 results about "Statistical energy analysis" patented technology

The invention discloses an interior noise analysis and prediction method of a high speed train. The method comprises the following steps: establishing a train reconditioning train body model, a statistical energy analysis model of a body in white structure and an interior and exterior vocal cavity statistical energy analysis model, and carrying out simplification and subsystem division; obtaining the statistical energy analysis parameters of the train body structure and an interior vocal cavity model, and loading the statistical energy analysis parameters onto a train body structure model plate subsystem and a vocal cavity model subsystem; and obtaining exterior vocal excitation source energy borne on the train body, applying the exterior vocal excitation source energy onto the exterior vocal cavity statistical energy analysis model, causing the exterior vocal excitation source energy to reach an interior vocal cavity after the exterior vocal excitation source energy is attenuated by the sound insulation property of a structural plate in a body in white structure model so as to obtain structural noise energy radiated into the train by the reconditioning train body under the function of the two-line suspension force of a compartment, and then, carrying out interior noise analysis and prediction. The problem that the interior noise of the train is difficult in prediction and the problems of the upper limit boundedness of a frequency domain, complex calculation flow, incomplete motivation consideration in the traditional method are overcome, calculation efficiency and prediction accuracy are improved, and development and test cost is lowered.

The invention provides a statistical energy analysis parameter acquisition method based on a finite element method and a power input method. A finite element model of a structure is established according to a geometric model of the structure, boundary conditions are applied, the finite element model of the structure is subjected to mode analysis, a mode of a system and a rigidity matrix and a mass matrix of a subsystem are obtained, vibration energy of the subsystem and input power of the system are obtained through a power flow model, and statistical energy analysis parameters are obtained through calculation through the power input method. The finite element method and the power input method are combined to obtain the statistical energy analysis parameters of the structure, the calculated rigidity matrix, mass matrix, mode shape and inherent frequency are obtained through the finite element method, the input power and the vibration energy are obtained through calculation through the power flow model, and the input power and the vibration energy are substituted into the power input method for calculation to obtain the statistical energy analysis parameters. According to the method, statistical energy analysis can be carried out aiming at the problem of strong coupling between structures, the limitation about weak coupling assumption between the structures in existing statistical energy analysis is solved, and the method can be popularized to complex structures.

The invention provides a method for calculating the intermediate and high frequency dynamic response of an acoustic vibration system. The method comprises the following steps of: firstly dividing the acoustic vibration system to be researched into N subsystems; then, determining analysis frequency ranges to which a modal energy analysis method and a statistical energy analysis method are applicable; when the analysis frequency is in an intermediate frequency range, calculating the intermediate frequency dynamic response of the researched acoustic vibration system by adopting the modal energy analysis method; and when the analysis frequency is in a high frequency range, calculating the high frequency dynamic response of the researched acoustic vibration system by adopting the statistical energy analysis method, wherein the modal energy analysis method comprises the following steps of: firstly determining the number of resonance modes and resonance frequency values of all the subsystems in the intermediate frequency range, and then establishing a power flow balance relationship among the resonance modes of the N subsystems, and finally solving the modal energy of each mode of all the subsystems according to the power flow balance relationship, summing the modal energy of the modes of each subsystem in an analysis frequency band so as to obtain the energy response of each subsystem in the analysis frequency band.

The invention discloses a constrained damping layer structure vibration calculation method. Through starting from a constrained damping layer damping and noise reducing mechanism, utilizing damping loss factors in statistical energy analysis to reflect damping effects of constrained damping layers, combining a modal strain energy method and considering frequency-dependent shear modulus and material loss factors of frequency of the constrained damping layers, a vibration calculation method for large-scale constrained damping layer structures is established, so that the forecast evaluation and optimized analysis of the constrained damping layers applied to large-scale structure damping and noise reducing are realized. According to the method, the calculation efficiency is remarkably improved and the vibration simulated analysis of the large-scale constrained damping layer structures can be realized; and the frequency-dependent characteristics of material shear modulus and material loss factors of the damping layers are considered so that the precision of simulated analysis is improved. By utilizing the method, optimized analysis can be carried out on laying positions and structure parameters of the constrained damping layers, the damping and noise reducing effects of the constrained damping layers can be forecasted, and the constrained damping layers can be utilized to carry out vibration and noise control on engineering structures.

The invention provides a statistical energy analysis-based ship cabin noise forecasting method. The method comprises the steps of 1, preliminarily building a statistical energy analysis-based ship cabin noise forecasting model by utilizing ship drawing data; 2, performing local detail optimization on an emphatically assessed cabin and load region in the built model, and constructing an external auxiliary sound cavity; 3, determining a vibration acceleration load and a sound power load of equipment by utilizing an experimental test; 4, performing calculation by utilizing the experimental test or a formula to determine loss factors in a steel plate and the sound cavity; 5, building a microacoustic analysis model of an outfitting material structure by utilizing a transfer matrix method, and obtaining acoustic parameters of an outfitting material through sound absorption and insulation analysis; 6, setting frequency response analysis as a 1/3 octave frequency, and setting a calculation frequency to be 31.5Hz-8kHz; and 7, performing ship cabin noise forecasting analysis by applying statistical energy analysis. The efficiency and precision of ship cabin noise forecasting can be effectively improved; and the method can be applied to ocean platform and ship cabin noise forecasting and control.

The invention aims to provide a method for calculating mid-frequency transmission loss of subsystems and optimizing acoustic packages. According to the method, a model for calculating the transmission loss of the whole subsystems is established on the basis of Hypermesh software and VA One software, the transmission loss of the whole subsystems is obtained through calculation, the transmission loss of each subsystem and the transmission loss of the whole are compared, whether each subsystem belongs to a weak area or a non-weak area is determined, and the acoustic packages are optimized according to an optimization objective and a result whether each subsystem belongs to the weak area or the non-weak area. Compared with the prior art, the method adopts a hybrid FE-SEA (finite element-statistical energy analysis) method, a finite element model is divided into a plurality of FE subsystems, a comparison diagram of a mid-frequency transmission loss curve of each FE subsystem at the mid-frequency band and a transmission loss curve of the whole is obtained rapidly and accurately through calculation, whether each subsystem belongs to a weak area or a non-weak area is determined and the FE subsystems are subjected to different arrangement on the basis of the optimization objective, so that the purpose of effective optimization design of the acoustics packages can be achieved.

The invention relates to a vibration acoustic analysis method for a multi-layer CFRP structure flat plate, and the method comprises the following steps: S1, obtaining material parameters and structureparameters of the multi-layer CFRP structure flat plate, and building a finite element model; S2, setting a boundary condition and a frequency range of the finite element model, and solving the boundary condition and the frequency range by using a finite element solver to obtain a mode of the multi-layer CFRP structure flat plate; and S3, establishing a flat plate model with the same size as themulti-layer CFRP structure flat plate, endowing the flat plate model with CFRP material attributes, respectively establishing a sound source cavity and a receiving cavity at two sides of the flat plate model, generating a statistical energy analysis model, and obtaining the sound transmission loss of the multi-layer CFRP structure flat plate through statistical energy analysis. Compared with the prior art, the modal analysis and the sound transmission loss analysis are carried out by applying HyperMesh software and VAOne software, the simulation calculation is accurate and convenient, and theengineering practical value is high.

The method for obtaining the mechanical environment of a spacecraft under the action of combined random excitation, the steps are: (1) dividing the spacecraft subsystem according to the modal density; (2) solving the dynamic response of the random subsystem; (3) loading processing of the combined random excitation; (4) Dynamic response solution of deterministic subsystem. The method of the invention fully utilizes the advantages of the finite element-statistical energy hybrid analysis method for modeling, overcomes the shortcomings of the traditional finite element method and the traditional statistical energy analysis method in dealing with broadband dynamic problems, and realizes the external acoustic load of the spacecraft and the random The reasonable loading of the basic excitation load has established a set of engineering and practical means of predicting the mechanical environment of the spacecraft under the combined random excitation.

The invention discloses a ship overall scheme mechanical noise assessment method, and belongs to the technical field of ship vibration and noise reduction demonstration and assessment. The method comprises the steps of performing ship overall scheme design result analysis and structure modeling parameter sorting; establishing a ship geometric structure simulation model; establishing a ship statistical energy analysis model; evaluating the radiation noise of the ship single machine; and estimating ship navigation working condition mechanical noise. The method is reasonable and feasible, overcomes the uncertainty of a conclusion obtained by adopting a manual experience method in the mechanical noise assessment of the existing ship overall scheme, can realize quantitative simulation calculation of mechanical noise under the equipment single machine and navigation working conditions, and greatly improves the rationality and effectiveness of the mechanical noise assessment result of the ship overall scheme.

The invention relates to a method of analyzing the vibro-acoustic optimization potential of a structure of vibro-acoustically coupled subsystems having internal and coupling loss factors by means of statistical energy analysis (SEA). The invention further relates to a method of optimizing the vibro-acoustic behavior of such a structure. The inventive methods involve the steps of:

• • calculating the gradient of energy on the basis of a simplified SEA matrix in which all coupling loss factors θji with j>i have been substituted according to η_ijn_i=η_jin_j;
  • identifying the internal loss factors causing the M highest gradients as dominant internal loss factors and the coupling loss factors causing the N highest products, which each consist of a gradient times its coupling loss factor, as dominant coupling loss factors;
  • calculating an optimization potential for each of the dominant internal and coupling loss factors as the maximum sub-system energy change which can be achieved by varying said loss factor; and
  • identifying the dominant internal and coupling loss factors with the K highest optimization potentials as optimization loss factors for the further vibro-acoustic optimization of the structure.

The invention discloses a semi-infinite fluid based passenger car external noise analysis and predication method for overcoming the defects that passenger car external noise can not be analyzed and predicted accurately before the advanced development in the passenger car development and design. The semi-infinite fluid based passenger car external noise analysis and predication method comprises the steps of: establishing a car body structure SEA (Statistical Energy Analysis) model, establishing a passenger car external noise semi-infinite fluid predication model, determining car body structure subsystem SEA parameters, and determining external excitation energy applied to the car body and passenger car external noise analysis and predication. The establishment of the passenger car external noise semi-infinite fluid predication model comprises the steps of: establishing semi-infinite fluids at the left and right sides of the car body structure SEA model and connecting the semi-infinite fluids and all car body structure subsystems, wherein the semi-infinite fluids are positioned 7.5m away from a car body longitudinal symmetry plane and 1.2m away from ground and energy passes to the semi-infinite fluids from all the car body structure subsystems in the form of spherical wave.

The invention discloses a small sample data model verification method based on statistical analysis, relating to a small sample data model verification method. The invention aims to solve the problemsthat the scope of a conventional Bootstrap method for reproducing samples is limited to an original sample range, especially in the case of a small sample size, the distribution of the reproduced samples may deviate from the real distribution, the estimation results may be inaccurate, and certain risks exist. The method includes the following processes: step I, performing a normality test on a reference sample and a simulation sample, and if obeying the normal distribution, performing step II; and step II, when n is greater than or equal to 30, adopting a U test method; when n is greater than10 and less than 30, adopting a t or F test method; when n is greater than 3 and less than or equal to 10, adopting a formula 1 and a formula 2 (as shown in the original specification) to separatelyperform a single normal population parameter test on the simulation sample in the step I; determining whether the obtained mean value and variance of the reference sample and the simulation sample areconsistent; and when n is less than 3, not performing model verification. The scheme of the invention is applied to the field of simulation model verification.

The invention provides a full frequency-domain calculation method of vibration noise of a gear case, and relates to the technical field of calculation methods. The vibration noise of a low-frequency part in the gear case is determined by using a finite element-boundary element method; the vibration noise of a high-frequency part in the gear case is determined by using statistic energy analysis; and full frequency-domain calculation of the vibration noise is achieved by reasonably using a finite element and the statistic energy analysis according to the size relationship among an upper limit frequency calculated by the finite element, a lower limit frequency of the statistic energy analysis and a to-be-analyzed highest frequency. According to the full frequency-domain calculation method of the vibration noise of the gear case, full frequency-domain analysis of the vibration noise of the gear case can be effectively carried out according to respective characteristics of different frequency bands.

The invention discloses an online forecasting method for high-frequency mechanical noise of a structure, and belongs to the technical field of noise forecasting. The method comprises the following steps: building a reasonable and effective constraint and load statistical energy analysis model aiming at an engineering practice structure; obtaining quality data of various stimulated sub-systems by the built statistical energy analysis model; testing vibration response data of the stimulated sub-systems through a test; calculating energy data of the stimulated sub-systems by combining the quality data with the response data; obtaining radiated sound power energy mechanical mobility data corresponding to the stimulated sub-systems according to the model; and finally calculating the radiated sound power of the structure, and finishing online forecasting. The online forecasting method has the beneficial effects that rapid calculation from load to radiated sound power is achieved by the system transfer mobility invariability; the problem of relatively long elapsed time of the traditional algorithm is solved; and rapid forecasting of mechanical noise of the structure is achieved. The online forecasting method is considerable in accuracy and relatively short in elapsed time, can be applied to the online forecasting engineering practice, and has a wide application prospect.

The invention discloses a method for calculating the filling coefficient of a sound field of a fairing.The method is based on the statistical energy analysis theory, a calculation model for the filling coefficient of the sound field is established, a modal number correction term in the calculation model is established according to geometrical boundary parameters of the fairing and a spacecraft, then the filling ratio eta of the sound field in the fairing is calculated, finally a corrected modal number and the filling ratio are substituted into the calculation model for the filling coefficient, the filling coefficient of the sound field of the fairing is obtained, and a spacecraft noise test condition is corrected through the filling coefficient, obtained through calculation, of the sound field of the fairing.Compared with a calculation method in NASA 7001 applied to current engineering, the method has the advantages that the physical significance of the parameters is definite, geometrical characteristics of the spacecraft can be considered, and correction precision is high.

The invention discloses a ship cabin noise transmission path analysis method, which comprises the steps of establishing a statistical energy analysis model according to a ship drawing; setting attributes of each subsystem in the statistical energy analysis model according to drawings and data; calculating an internal loss factor of each subsystem and a coupling loss factor between the subsystems,and establishing a loss factor matrix of the whole system; converting the loss factor matrix into a path efficiency matrix, and establishing a path efficiency weighting graph for noise transmission path analysis; and solving the first k shortest paths of the weighted graph by using an algorithm of the shortest path problem, so as to obtain the first k noise energy transfer paths from the noise source to the target cabin. The cabin noise transmission path analysis work can be completed at the initial stage of ship design, the limitation that real ship test analysis can only be conducted after aship is built is overcome, guidance can be provided for subsequent noise reduction design, and the cabin noise transmission path analysis method has the obvious effects of saving cost and reducing space and weight occupation.

The invention provides a high-frequency local response indication method for a sound-solid coupling structure. A finite element method, a modal power flow equilibrium equation and a local energy indication theory are combined to indicate the high-frequency local response of the sound-solid coupling structure, the finite element method is used for obtaining the displacement modal vibration mode ofa structure subsystem on a coupling edge, the stress modal vibration mode of a sound cavity subsystem on the coupling edge and the inherent frequency and the modal quality of the subsystem, a modal coupling loss factor between subsystems is calculated, and the modal power flow equilibrium equation is established and solved to obtain the modal energy of the structure subsystem. Finally, the local energy indication theory is used for solving the local energy response of the structure subsystem, and a local stress/ strain response is solved through a relationship between the strain energy and thestress strain of an isotropy material. By use of the method, the high-frequency local response indication method for the sound-solid coupling structure can be accurately indicated, and the problems that discretization methods including a traditional finite element method, a boundary element method and the like are low in calculation efficiency and each hypothesis of a statistical energy analysismethod can not be completely satisfied usually in engineering application and is difficult to obtain the local energy of the subsystem can be solved.

The invention provides a transient statistical energy response prediction method considering an uncertain structure. Compared with a conventional transient statistical energy method which can only perform dynamic response prediction for a deterministic structure and does not take uncertain factors such as structure parameter randomness and measuring errors into account, the method characterizes the uncertainty of the structure through an interval method, the influence of uncertainty on the energy transfer and dissipation between structural subsystems is considered, a more precise transient energy expression of each subsystem of the structure is established based on an energy control equation, an expression of the subsystem transient energy is converted into a polynomial form suitable for interval calculation, so that the transient statistical energy analysis method is popularized and applied to the dynamic response analysis of the uncertain structure, the research scope of the currenttransient statistical energy analysis method is expanded, and the method has important engineering application value.

The invention discloses a method for predicting sound insulation factors of rectangular solid flat plates. The method is characterized by comprising steps of building statistic energy analysis models for predicting the sound insulation of the flat plates and quantifying uncertain parameters by triangular fuzzy numbers; determining order and Gauss integration points of optimal square approximation functions, related to each parameter, of sound insulation models of the flat plates; sampling fuzzy parameters in subspaces spanned by the Gauss integration points in fuzzy carried sets; acquiring sound insulation optimal square approximation functions of the flat plates by the aid of flat plate sound insulation response in discrete formats at sample point locations; acquiring extreme points of the carried sets and further acquiring maximum and minimum points of the carried sets; determining maximum and minimum points of alpha cut sets on the basis of the extreme points of the carried sets, acquiring flat plate sound insulation interval limit of the alpha cut sets on the basis of the maximum and minimum points of the alpha cut sets and ultimately predicting the sound insulation factors of the rectangular solid flat plates. The method has the advantages that frequency response distribution of the sound insulation fuzziness of the flat plates can be accurately predicted by the aid of fuzzy number models which are used as input, and the computation efficiency and the computation precision can be obviously improved by the aid of optimal square approximation theories.

The invention discloses an ocean platform piling bubble curtain noise reduction amount calculation and analysis method. Comprising three calculation methods, namely an air curtain layer noise reduction amount calculation method under normal sound wave incidence, an underwater air curtain bubble curtain low-frequency finite element fluid-solid coupling analysis calculation method and a full-band acoustic analysis calculation method based on a statistical energy analysis method. The influence of various parameters of the air curtain on the noise reduction amount and the noise reduction amount of the bubble curtain under low frequency and high frequency are quantitatively calculated, and the problems that in the prior art, a mode of measuring noise distribution through a detection device with a certain distance from a piling noise source is large in data acquisition difficulty, high in measurement cost, long in period, narrow in applicability and the like are solved. Meanwhile, the quantitative calculation method can also be used for guiding optimization design and analysis of a bubble curtain noise reduction system.