Transfer Path Analysis Research Articles

Modeling and Contribution Analysis of Vibration Transfer Paths for a Dual-Rotor Aeroengine

Modeling and Contribution Analysis of Vibration Transfer Paths for a Dual-Rotor Aeroengine

Vibration source inversion-based fault diagnosis: approach and application

The gear transmission system of industrial equipment is characterized by a highly integrated structure, non-stationary operating conditions, and large loads. Therefore, the attenuation of fault signal characteristics and the complexity of operating conditions in gear transmission systems significantly affect the effectiveness of vibration signal-based fault diagnosis. This paper proposes a unified diagnostic framework based on vibration source inversion for two typical transmission component fault signal phenomena: meshing frequency modulation sidebands and equally spaced fault characteristic frequency interval harmonic clusters. This approach incorporates the vibration transfer path analysis of passive subsystems and identifies bearing dynamic forces, followed by their decomposition, reconstruction, and sensitive frequency band localization. It enables accurate diagnosis of complex gear transmission systems under non-stationary conditions with limited vibration testing. The effectiveness and advantages of this method over existing mainstream signal processing techniques are validated through actual cases of gear and weak bearing fault diagnosis on a complex planetary gear transmission system test bench.

Methods for separating the noise produced by the wheels and track during a train pass-by

AbstractRolling noise is produced by vibration of the wheels and track, induced by their combined surface roughness. It is important to know the relative contributions of the different sources, as this affects noise control strategies as well as acceptance testing of new rolling stock. Three different techniques are described that aim to use pass-by measurements to separate the wheel and track components of rolling noise. One is based on the TWINS model, which is tuned to measured track vibration. The second is based on the advanced transfer path analysis method, which provides an entirely experimental assessment. The third is based on the pass-by analysis method in combination with static vibroacoustic transfer functions which are obtained using a reciprocity method. The development of these methods is described and comparisons between them are presented using the results from three experimental measurement campaigns. These covered a metro train, a regional train and a high-speed train at a range of speeds. The various methods agree reasonably well in terms of overall trends, with moderate agreement in the mid-frequency region, and less consistent results at low and high frequency.

Fault tracing in multistage gearbox systems based on an improved transfer path analysis method

This study, has developed a novel structural dynamics decoupling method based on TPA. This approach effectively facilitates fault diagnosis and tracing in multistage gearbox systems. Initially, the research explores the relationship between the transfer function of systems with rigid link decoupling and the coupled system’s frequency response function. Compared with Huangfu et al. (2023) , the signal measurement points are reduced. The MWI (Yu et al., 2023) is employed to solve the inverse problem of bearing force identification. Subsequently, the decoupled frequency response and bearing forces are multiplied to calculate the path contribution, determining the dominant fault transfer path and thereby facilitating fault tracing in gearboxes. The effectiveness of this method is validated through numerical simulations and experimental studies, with fault characteristic enhancement exceeding 200%. To evaluate the method’s universality and robustness, experiments on diverse gearbox systems under varying conditions show enhanced fault characteristics across three fault types, confirming its generalizability.

Operational transfer path analysis with crosstalk cancellation based on least variance spectrum estimation

Operational transfer path analysis with crosstalk cancellation based on least variance spectrum estimation

Exploring the application of a Bayesian framework in transfer path analysis

Transfer path analysis (TPA) is a methodology widely used in transmission identification of vibration and noise. Among the TPA families, the two prevailing approaches are classical TPA with the matrix inversion method and operational transfer path analysis (OTPA). Both methods rely on measurements within costly and complicated overdetermined systems. These experiment-based methods are also limited by sufficient space for the sensor mounting, which can result in difficulty when analyzing the transfer path in small objects. In this paper, we use an experimental setup that mimics an engine mounted on a suspension with resilient connections. The severity of errors stemming from the application of underdetermined measurement systems is assessed, alongside an exploration of how the Bayesian framework can be integrated into the analysis to mitigate errors and enhance the performance of TPA.

A development on the interior noise prediction technology using active noise control algorithm

When developing NVH of a vehicle, identifying a noise transmission vulnerable path is a very important task. The traditional TPA(Transfer Path Analysis) is based on a physical theoretical equation and calculates the contribution of each path by multiplying the ATF(Acoustic Transfer Function) of each path by the driving load. In this case, it is often difficult to calculate the driving load, and M/H consumption is also high. OTPA(Operational Transfer Path Analysis) performs transfer path analysis only with driving signals for each route, but has a disadvantage of insufficient physical causality. In this study, we proposed an efficient indoor noise TPA method that modifies the ANC algorithm by combining the reference signals while driving with the secondary path of Filtered-X LMS. The proposed method uses the secondary transfer function of Fx-LMS as the ATF for each path. It is not necessary to obtain physical load by predicting target noise with the Ref signal for each route. Therefore, it is possible to predict indoor noise with low M/H. In this study, it can be confirmed that the proposed method shows similar results compared to the existing methods and efficiently identifies main noise path for interior noise.

Investigation of the vibro-acoustic signature of a heat pump through an experimental transfer path analysis

With the increasing interest on heat pumps due to their energy efficiency and environmentally favorable characteristics, concerns regarding their operational noise and vibration levels are becoming paramount, particularly in residential applications where occupant comfort is a priority. A heat pump consists of significantly distinct components regarding their physical properties, contributing to a complex dynamic system with respect to noise and vibration. To better understand its vibro-acoustic signature, this work presents an experimental transfer path analysis (TPA) of an outdoor unit of a heat pump system for residential applications. In this study, the main noise sources and the predominant vibration and noise paths are identified. Predictions of the total and partial responses at the receiver side is determined in order to quantify the contribution of each individual path. For the determination of the operational internal forces, the inversion matrix method is adopted. The findings of this study can contribute to the development of effective design guidelines and engineering solutions for minimizing the acoustic and vibrational footprint of residential heat pumps.

Operational transfer path analysis for the fixed shaft gear transmission system based on the simulation and experiment

Operational transfer path analysis for the fixed shaft gear transmission system based on the simulation and experiment

Sound source identification of a cylindrical shell by merging near-field acoustic holography with operational transfer path analysis

The purpose of this paper is to propose a new sound source identification method to identify and separate the sound sources generated by the cross-coupled vibration sources inside the cylindrical shell structure. Near-field acoustic holography (NAH) has fundamentally changed sound source identification in that it has enabled the identification of sound sources and the visualization of the 3-D sound field. Nevertheless, the NAH technique is still unable to identify the vibration sources inside a structure and also finds it difficult to identify the contribution of a single sound source to sound fields due to cross-coupling among the vibration sources. To overcome these limitations, a modified operational transfer path analysis (OPA) technique has also been proposed, which can address the cross-coupling between vibration sources. In practice, however, a single identification method often appears to be inadequate. Thus, in this paper, a novel method of merging the NAH technique and the modified OPA technique has been adopted and used to identify the structure-borne sound source of a cylindrical shell. Finally, the adaptability of the proposed method has been demonstrated by numerical simulations and experimentally and it has been shown that the novel method can not only compute the sound field distribution of a cylindrical surface, but also reconstruct other 3-D field distributions, and moreover, can locate a sound source and predict the sound field.

Investigation of noise characteristics of electric vibrator utilizing acoustic camera and transfer path analysis

Abstract Mechanical equipment operation frequently results in noise generation, which can raise concerns regarding quality and safety. This study focuses on electric vibrators, essential electromechanical systems, with the goal of identifying the source and transfer path of noise. To achieve this objective, an acoustic camera positioning analysis was performed to approximate the distribution and characteristics of the noise. Building upon this foundation, a thorough evaluation of the transfer path and noise contribution was conducted. Subsequently, targeted noise suppression methods were implemented based on the properties of the noise. Primary noise sources were observed to be classified into wind turbulence and mechanical vibration based on operating conditions. Time-frequency analysis revealed the presence of low-frequency signals (around 50 Hz) and intermediate-frequency signals (around the resonant frequency), corresponding to wind-induced and mechanical response noise, respectively. Leveraging the characteristics of the noise and its transfer path, passive methods (Sound-absorbing rubber and Soundproof cotton) and active method (FxLMS algorithm) were employed. The findings of this study contribute to a better understanding of noise mechanisms and provide insights for noise emission strategies.

Estimation of blocked forces for NVH source characterization of a beam axle using analytical methods

Component-Based Transfer Path Analysis (TPA) has been of growing interest recently because, unlike classical TPA, it enables source characterization independent of the receiver structure. The source energy in component TPA is typically characterized by blocked forces. As part of virtual prototyping, OEMs have interest in building a library of component/subsystem models that may be "plugged" into larger system models. For an OEM supplier, it is imperative to have the capability to provide subsystem models along with source energy characterized in component blocked force prior to availability of physical parts to support virtual validation and optimization efforts for seamless system integration. In this paper, three methods of blocked force calculation are considered: Direct, Free Velocity and In-situ. A Finite Element Analysis (FEA) model is used to Directly calculate the blocked forces exerted by a rear beam axle at the vehicle attachment points, then to simulate how they might be estimated in a dynamometer test stand using the Free Velocity or In-situ methods, with the aim of offering practical guidance for both scenarios. Assumptions regarding input and output boundary conditions, along with three versus six degree-of-freedom (DOF) attachment paths, affecting both the analytical and test-based estimation of blocked forces, are also scrutinized.

On the variability of blocked forces determined using an inverse approach

Mount force data of motors, fans, and pumps is rarely available from the suppliers. However, manufacturers are beginning to ask for and even require this information from their suppliers. In-situ estimation of these forces can be accomplished using blocked force transfer path analysis. Since these forces are difficult to measure directly, forces are calculated using an inverse approach. A simple case study is considered on a commercial air handler. Blocked forces are determined using different inlet locations and path selections. The consistency of the inversely calculated forces is evaluated.

Vibration source analysis and structural optimization design of rotary table based on OTPA.

Due to the influence of coal rock shape, hardness, working environment and other factors in the cutting process of cantilever roadheader, the cutting head will produce irregular and violent vibration. As the rotary table of key stress components, its operation process stability, dynamic reliability and life affect the cutting efficiency and cutting stability of cantilever roadheader. In order to study the vibration characteristics of the rotary table in the cutting process, firstly, based on the theory of spatial force analysis and calculation, the spatial mechanical model of the rotary table of the cantilever roadheader is established. By solving the balance equation of the rotary table force system, the variation law of the load at the hinge ear of the rotary table with the cutting pitch angle and the horizontal angle is obtained. Secondly, based on the path transfer analysis method of working condition, the vibration data of cutting head, cutting cantilever, cutting lifting and rotary hydraulic cylinder under stable cutting condition are taken as input signals. By constructing the transfer path analysis model of rotary table working condition, the synthetic vibration of rotary table in cutting process is simulated, and the main vibration source of rotary table is determined. Then, the vibration contribution and contribution degree of each vibration excitation point to the hinge ear of rotary table are studied. By building a cutting test bench, the vibration response of rotary table in cutting process is tested to verify the correctness of the theoretical model.Thirdly, based on the frequency domain analysis method of random vibration fatigue life, combined with the S-N curve of the rotary table, the PSD curve at the maximum stress of the rotary table is obtained by modal excitation method, and the load data is imported into ANSYS nCode software to obtain the life cloud diagram and damage cloud diagram of the rotary table, and then the fatigue life of the rotary table under symmetrical cyclic load is solved. Finally, based on the response surface optimization analysis method, the maximum stress and maximum deformation of the rotary table are taken as the optimization objectives, and the aperture of each hinge ear of the rotary table is taken as the optimization variable. Based on Design Expert, a second-order regression model is established to realize the multi-objective optimization design of the key stress parts of the rotary table in the cutting process. The simulation results show that under the same cutting conditions, the maximum stress of the optimized rotary table is reduced by 15.82% year-on-year, and the maximum deformation is reduced by 24.70% year-on-year. The optimized rotary table structure can better adapt to the cutting process, which is beneficial to improve the service life of the rotary table and enhance its operation stability. The research results are beneficial to enrich the relevant research theory in the field of rotary table vibration of cantilever roadheader, and are beneficial to improve the service life of the rotary table and the efficiency of tunneling and mining.

A study on active road noise control based on operational transfer path analysis and selective subband adaptive filtering

In the feedforward active road noise control (ARNC) system, the noise reduction performance relies on the correlation between the reference signals and the target noise signals. To achieve better noise reduction performance, the operational transfer path analysis (OTPA) model with singular value decomposition was proposed to separate the road noise component from the target noise. Combined with OTPA and multi-coherence sorting method (MCSM), simulation analysis and real vehicle tests under various speeds both showed that the system with optimized reference sensor set had better road noise reduction performance, especially at the peak frequencies. To further improve noise reduction performance and reduce computational load, a selective subband adaptive filtering (SSAF) algorithm was proposed to build an active road noise control model with optimized reference sensor set. Simulation results, employing real vehicle test data, showed that the proposed method further improved the noise reduction performance and effectively reduced the amount of computational load.

Damping Optimization Method of Combine Harvester Frame Undergoing Multi-Source Excitation

The complex mechanical system of a rice combine harvester not only has various excitation sources, but also, the vibration transmission path between each working device and the vibration contribution characteristics to the frame are not clear, so it is difficult to perform a reduction vibration design for the sharp vibration of the rice combine harvester frame. Therefore, based on the comparison and improvement of multiple classical transfer path analysis methods, this paper analyzed the vibration transfer characteristics and transfer characteristics of each harvester by the discrete time matrix method and operating path method. In the Experimental section, through the vibration characteristic experiment firstly, this paper obtained the power spectrum variation and the most needed optimized path in the transmission path of each device under each operating condition. Secondly, through frame simulation analysis under the exciting force, we obtained the vibration damping areas that needs to be optimized. Finally, the damping optimization experiment connected with the vibration characteristic experiment, and the excitation force simulation analysis was performed. The results of the damping optimization experiment displayed that the maximum change value of the vibration acceleration of the cutting table decreased from 7.862 m·s−2 to 3.522 m·s−2, decreasing by 55.2%, and the peak amplitude of the multipoint test in the cab was 5.4, 5.3, 1.7 and 2.0 μm, respectively, which was significantly reduced, so the optimization effect was significant. This study provides theoretical support for the vibration reduction optimization of a rice combine harvester frame.

Collaborative control method of cruise ships’ vibration and mass based on structural intensity weighted sum analysis

Focusing solely on a single objective during the ship structure optimization process may negatively impact the performance of other aspects, this study proposes a collaborative method for cruise ship optimization, which can achieve both vibration control and lightweight while maintaining the structure's original strength. In this method, transfer path analysis is performed before vibration control, and a concept of structural intensity weighted sum (SIWS) is proposed to overcome the limitation of traditional SI analysis, which can only identify the main transfer paths at a single frequency. This concept calculates the weighted sum of SI in coordinate directions at different frequencies, aiming to identify the transfer paths of the weighted root mean square (WRMS) of vibration acceleration (ACC) at different frequencies, with its effect validated through performing vibration sensitivity analysis on structures along these paths. Furthermore, in the optimization to control vibration with mass and maximum stress as constraints, the response surface method (RSM) is used to construct surrogate models for the maximum stress of the cabin section, and constraints are applied to the surrogate model's values to guarantee structural strength. The optimization results reveal that the proposed collaborative method for vibration control and lightweight successfully achieves both objectives without compromising structural strength. Additionally, optimizing the primary transfer paths identified through SIWS analysis is shown to enhance the vibration control effect.

Research on decoupled transfer path analysis method and its application in hybrid mechanical systems

As a key technique of vibration control, transfer path analysis (TPA) provides theoretical support for diagnosis, analysis, evaluation, and optimization of vibration in mechanical systems. The coupling phenomena often exists in the vibration transfer paths of complex mechanical systems, which makes most of the existing TPA methods unable to accurately analyze the transfer function of the coupled paths. The classical transfer path analysis (CTPA) is an effective method to solve the problem of path coupling, but it changes the inherent characteristics of the system, the results can not accurately reflect the vibration transfer characteristics of the system. In order to overcome the disadvantages of CTPA method, a decoupled transfer path analysis (DTPA) method is proposed in this paper, and the implementation process of this method is introduced by taking a hybrid mechanical system as an example. The results show that DTPA method can solve the path crosstalk problem and accurately calculate the transfer function of each path.

Influence of the vibrating source behavior and source side excitations on the Interface Completeness Criterion

In the framework of component-based transfer path analysis (CB-TPA), the Interface Completeness Criterion (ICC) is used to select the mobility completeness, i.e., the number of degrees of freedom (DoFs) at the interface between a vibrating source and a receiving structure. The calculation of the ICC is similar to a coherence function with values between 0 and 1. The higher the ICC, the better the completeness of the mobility. Although ICC has shown promising results, its application remains ambiguous. The influence of source side excitations and the behavior of the vibrating source have not been investigated. In this study, ICC is computed numerically in the case of a rigid vibrating source connected to a plate. Full completeness provides high ICC values, while completeness along a single DoF, normal to the structure, provides low ICC values, which may suggest a poor assessment of the on-board velocity. However, it is shown that the on-board velocity is perfectly estimated with the CB-TPA when the source behavior is simple. Discrepancies appear when the source behavior becomes more complex, but the link between these discrepancies and ICC is not obvious. The influence of source side excitations during ICC calculation is also investigated in the case of the Z completeness. It is shown that the number and orientation of the source side excitations govern ICC values and therefore should follow the source behavior, which is normally unknown. The numerical results are confirmed by the experimental study where similar results are obtained.

Operational transfer path analysis based on neural network

Noise, vibration, and harshness (NVH) issues induced by vibrating source to receivers are sensitive concerns in the automotive industry, significantly determining the product quality. Transfer path analysis (TPA) serves as a crucial tool in addressing these concerns. However, classical and component-based TPA methods necessitate the measurement of all transfer functions associated with the NVH phenomenon, causing high experimental costs; moreover, operational TPA (OTPA) involves matrix inversion processes that may result in the loss of important information. In this study, a neural network-based OTPA (NOTPA) method is proposed that eliminates the need for a matrix inversion process and utilizes only operational measurement. To derive the physical meaning of transmissibility obtained from the trained neural network model, the learning algorithm for NOTPA was developed, and appropriate learning rules were applied to the model. In the general neural network model, training was performed using real-valued parameters. However, the phase of the signal is crucial information in the theoretical formulation of TPA; thus, a complex-valued propagation algorithm was established. Furthermore, an appropriate activation function was chosen to derive the actual transfer mechanism from the trained complex-valued parameters. To experimentally verify the NOTPA method, a testbed resembling automotive vehicle structure was constructed. Estimation of sound pressure and noise contribution analysis were conducted using the NOTPA method and compared with conventional TPA methods. The proposed method demonstrated higher accuracy compared to the conventional OTPA method and successfully identified the main transfer path compared to the classical TPA. Furthermore, by comparing the estimated sound pressure according to the architecture of the model, the consistency of the proposed model was verified.