Measurement Location Optimization of Component Transfer Path Analysis Method for Road Noise

In recent years, various transfer path analysis (TPA) methods have been proposed to separate contribution from multiple input points to the response point. In general, TPA methods require transfer function from input to the response points by hammering tests. However, obtaining accurate contribution becomes difficult in case the transfer function varies according to the operating condition or the complexity of the transfer path. In this study, we then considered input force contribution separation method for the difficult condition by combining operational TPA and blocked force used in component TPA. In the method, blocked force in the operational condition is obtained by component TPA at first, and operational TPA is applied between the obtained blocked force and the response point acceleration signals to obtain the transfer function without hammering tests. The contribution is calculated by multiplying the blocked force and the transfer function at the condition. As the verification, the proposed method was applied to a simple vehicle model equipped with a motor. And the response point vibration could be decreased well by measuring the high contributing part according to the contribution separation result. Through the verification test, the effectiveness of the proposed procedure was confirmed.

This paper presents a practical real approach for predicting the interior noise caused by the vibration of the powertrain by using the hybrid transfer path analysis (TPA) method. The traditional TPA has been used for the identification of powertrain noise sources. However, with only experimental data for the identification of vibration and noise, it is difficult to determine the effects of modifications to the structure of a powertrain. In order to solve this problem, the vibration of the powertrain in a vehicle is numerically analyzed by using the finite element method (FEM). The vibration of other parts in a vehicle is investigated by using the experimental method based on vibro-acoustic transfer function (VATF) analysis. These two methods are combined for the prediction of interior noise caused by a powertrain.

<div class="section abstract"><div class="htmlview paragraph">Due to stringent emission norms, all OEMs are shifting focus from Internal combustion engine (ICE) to Electric vehicle (EV). NVH refinement of EVs is challenging due to less background noise in EVs in comparison with ICE vehicles.</div><div class="htmlview paragraph">Motor whine noise is perceived inside cabin till the speed of 20 kmph. Vehicle is powered by electric powertrain (EPT). Electric powertrain is connected to the subframe with the help of three powertrain mounts. Subframe is connected to the body with the help of four mounts. With the help of Transfer Path Analysis (TPA), it is identified that the noise is structure borne and the dominant path is identified. By optimizing the stiffness of the EPT mounts, the structure borne noise levels are reduced. But reducing the stiffness of EPT mount deteriorated the road noise levels. The reason behind deterioration of road noise is investigated. The performance of double isolation of EPT is compared with single isolation of EPT with respect to both road and motor noise. Modal criteria which needs to be considered for EPT and subframe mount development in design stage with respect to road noise and structure borne motor noise is also discussed.</div></div>

Transfer Path Analysis (TPA) is a useful tool for the reduction of automotive noise and vibration. TPA offers the information about the contribution of the transfer paths and analysts would take effective measures with this information. However it could not seem easy to apply to the automotive body structure itself. One of the reasons is complexity of the vibration transmission in the body structure that is assembled by many members and that should be analyzed by manifold vibration transfer paths. This means there are a lot of transmitted forces an transfer functions defined in the assembled structure. This paper presents two proposals in TPA using finite element model: 1) technique in contribution analysis to the structure with manifold and continuous transfer paths, 2) visualization technique of the influence degree for the reduction of the response of the structure. In the contribution analysis, the transmitted force at every node is accurately calculated with the proposed element force calculation, and the element plays a part of a transfer path. The influence degree is newly defined by the result of the contribution analysis and assists analysts to obtain measures more efficiently. These two techniques let the analysts easy to understand the vibration transfer characteristics by the visualization. The application to an automotive body structure validates the effectiveness and usefulness of the proposed approach.

Electric vehicles (EV) are considerably quieter than internal combustion engine (ICE) powered vehicles, because noise of ICE is eliminated. However, the interior noise of an EV usually contains significant high-frequency noise components caused by electrical motor, which can be subjectively perceived as annoying and unpleasant. This paper describes a numerical model to predict interior acoustic noise caused by electromagnetic forces in permanent magnet synchronous motor (PMSM) for electric vehicles. Firstly, the principle of the multiphysics method is to establish a complete 3Dstructural finite element model (FEM) of motor. Based on FEM, natural frequency and modal shape were calculated by modal analysis. Secondly, using an electromagnetic finite element solver, the excitation due to electromagnetic phenomena is obtained. This excitation is then projected onto the structure mesh of motor in order to calculate the dynamic response. Thirdly, radiated electromagnetic vibration acceleration on the surface of the motor is calculated with modal superposition method. Compared with experimental test results, the creditability of motor electromagnetic vibration simulation is proved. Finally, by combining with transfer path analysis (TPA) techniques, interior electromagnetic noise of electric vehicles is accurately predicted. According to contribution analysis, motor surface zones and transfer paths contributing largely to the interior motor electromagnetic noise are identified. The results play a significant guiding role in both electric vehicle and permanent magnet synchronous motor for noise control and analysis.

The complex vibration field in agricultural equipment during field operations not only predisposes key mechanical components to fatigue failure, but also leads to crop losses. This study introduces the Operating Transfer Path Analysis (OTPA) method to identify the vibration sources in the pickup header of a straw forage harvester. Finite element modal analysis, vibration testing, and operating transfer path analysis were conducted on the header frame. The findings indicate that excitation sources, including the hammer claw device, transmission, and dust box on the pickup header, are prone to resonant coupling with the header frame. The analysis reveals that the right transmission output shaft contributes 18.3% to the vertical vibrations on the right side panel of the frame. Meanwhile, the left transmission output shaft accounts for 29.4% of the horizontal vibrations on the left side panel. Additionally, the transmission input end is responsible for 54.8% of the horizontal vibrations on the front beam, while the dust box end contributes 45% to the forward vibrations on the rear beam. By identifying the primary transmission paths, the most effective strategies for the vibration reduction and optimization design of the pickup header can be developed. Furthermore, this study offers a theoretical foundation and experimental references for the vibration reduction optimization of other agricultural machinery.

<div class="section abstract"><div class="htmlview paragraph">In general, in-cabin booming noise is low frequency (20 Hz∼300 Hz) phenomenon which excites the cabin structure mainly due to excitations from the powertrain, exhaust system, road loads, etc. When a vehicle drives over road seams or a bumpy surface, low-frequency drumming noise is generated, causing driver discomfort. The generation of drumming noise is due to road irregularities, transferred and amplified through the vibration characteristics of the suspension, body frame, and body panels, as well as the acoustic characteristics of the vehicle interior. It is therefore difficult to take measures to get rid of drumming, after the basic vehicle construction has been finalized. The regular practice in vehicle development is finite element method (FEM) to obtain acoustical transfer functions of the body, and multi body simulation to get suspension load characteristics. The full vehicle simulation needs more time for analysis and extracting data. So traditional computational aided engineering (CAE) will not support development timeline. Market has become very dynamic, benchmark changes very often, so getting complete data is difficult for very accurate analysis in ‘early to market’ project timeline. Most of the automotive companies are using computational tools for predicting road noise in simulation phase. But with the help of method, we developed can predict road noise at early design stage itself. It is a novel hybrid tool which can give strong directional results in comparatively lesser time.</div><div class="htmlview paragraph">This user-friendly hybrid tool is developed for predicting and improving road noise at early stage with limited data, especially for new age battery electric vehicle. The inputs used during the initial stage of the program are vibration data of benchmark vehicle at body attachment points, targets, or simulation data (DPDS, NTF), etc. By the proposed methodology, overall trend of road noise can be predicted. In addition to that critical paths can be identified by using transfer path analysis. Once the project/program matures, we can use physically measured data (DPDS & NTF) of the trimmed body and perform the robust root cause analysis to identify the critical paths. Based upon the analysis, modifications to be made on actual body structure for effective drumming reduction. Hence new hybrid approach is proposed, which consists of mathematical model and design philosophy for better in cabin noise. It is worth to note that there are some limitations in the tool and results from the calculations such as granularity of benchmark test data availability, accurate trimmed body level test or simulation data.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Customers are expecting higher level of refinement in electric vehicle. Since the background noise is less in electric vehicle in comparison with ICE, it is challenging for NVH engineers to address even minor noise concerns without cost and mass addition.</div><div class="htmlview paragraph">Higher boom noise is perceived in the test vehicle when driven on the coarse road at a speed of 50 kmph. The test vehicle is rear wheel driven vehicle powered by electric motor. Multi reference Transfer Path Analysis (TPA) is conducted on the vehicle to identify the path through which maximum forces are entering the body. Based on the findings from TPA, solutions like reduction in the dynamic stiffness of the suspension bushes are optimized which resulted in reduction of noise. To reduce the noise further, Operational Deflection Shape (ODS) analysis is conducted on the entire vehicle to identify the deflection shapes of all the suspension components and all the body panels like floor, roof, tailgate, dash panel, quarter panel and doors at the problematic frequency. Based on ODS, the components having higher deflections at the problematic frequency is identified. Modifications are proposed to improve the dynamic stiffness of the structure at the problematic frequency and the contribution of each modification for cabin noise reduction is discussed. Solutions like tuned mass dampers (TMD) on suspension components are explored and the critical parameter which should be considered to get maximum reduction in noise with TMD is also discussed. With all the modifications, the noise levels are reduced by 5 dB (A) at problematic frequency. NVH criteria which should be considered related to suspension system to avoid boom noise concern in electric vehicle is also discussed.</div></div>

The complete transfer path pays attention to the synergy among medical institutions, the result of treatment and the temporal sequence. However, the patient’s visiting behavior usually spans many medical institutions. It is not only difficult for inter-agency medical records, examination results and treatment process to be transmitted comprehensively and efficiently, but also difficult to trace the origin of the complete transfer path. This paper proposes a blockchain medical asset model to support the analysis of transfer paths across medical institutions. Firstly, this method establishes a sharing mechanism based on blockchain across medical institutions, and proposes a mapping algorithm between visiting data and blockchain assets. To solve the problem of lack of traceability and reduce the cost of using medical assets, the blockchain is used to transfer the status and inspect structure of diagnosis and treatment process among institutions. Then, aiming at the problem of lack of referral for patient transfer paths, a blockchain based full-chain transfer path analysis method is designed to find the optimal transfer paths for local medical institutions and overcome the bottleneck of the lack of referral for medical institutions transfer paths. Experiments show that the blockchain medical asset model proposed in this paper can cover the whole chain data of transfer, and can meet the needs of cross-medical institutions tracing the complete transfer path. The prediction algorithm used in this model has better performance than other prediction algorithms in mining the optimal path.

Active control of road noise considering the vibro-acoustic transfer path of a passenger car

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.

<div class="section abstract"><div class="htmlview paragraph">Transfer path analysis is a powerful tool to support the vehicle NVH development. On the one hand it is a fast method to gain an overview of the complex interplay in the vehicle noise generation process. On the other hand it can be used to identify critical noise paths and vehicle components responsible for specific noise phenomena.</div><div class="htmlview paragraph">FEV has developed several tools, which are adapted to the considered noise phenomena: Powertrain induced interior noise and vibration is analyzed by VINS (Vehicle Interior Noise Simulation), which allows the deduction of improvement measures fast enough for application in the accelerated vehicle development process. Further on vehicle/powertrain combinations not realized in hardware can be evaluated by virtual installation of the powertrain in the vehicle, which is especially interesting in the context of engine downsizing from four to three or six to four cylinders. Road induced interior noise is investigated by “Chassis-VINS” or “Fast-VINS”, depending on the required level of detailing and project timing. With the upcoming change of pass-by noise legislation VENS (Vehicle Exterior Noise Simulation) supports the target oriented component development to fulfill the legal limits.</div><div class="htmlview paragraph">The application of these methods on more than one hundred vehicles - from microcar to heavy duty truck - in the last decade allows for rating vehicle noise shares relative to the state of the art. Selected examples of different vehicles show possible distributions of several airborne and structure borne noise paths.</div></div>

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.

This research was aimed to analyze the behaviors of Brawijaya University’s stakeholders through the intention in managing waste. Considering that campus is a place of education, the analysis of the intention associated with the educational theory in cognitive, affective and psychomotor domains. Thus, this research implementation was supported by intention model. The objects of this research were the stakeholders of Brawijaya University consisting of students, lecturers, and staffs. This research was done using survey method with a total of 120 respondents. The analysis was conducted using a path analysis method with trimming. Given that the number of variables used was quite a lot, the data were first analyzed using a factor analysis method and then followed with a path analysis method. The results of the path analysis on Model 1 showed that the significant variables to the intention of managing waste were cognitive and behavioral control variables. The indicators of cognitive variable as knowing the types of waste and the economic benefits of waste. As for Model 2, the intention of managing waste significantly influenced the realization of the green campus varibles. The indicators of managing waste intention as intention to help manage waste in Brawijaya University, and then the indicators of green campus varible as the emerge of wise thoughts. As the suggestion, rules or policies on waste management are highly required to be established in Brawijaya University so that the stakeholders are willing to manage and process waste. Keywords: Affective and psychomotor domains, Brawijaya University’s stakeholders, Cognitive, Green campus, Waste management intention model

Vibration is a common issue in the automobile system, especially in an old car. Several causes that may generate vibration are vibration at idle and engine RPM. Vibration can decrease the ride comfort and become one of the contributing factors that cause an accident or emergency condition. Therefore, vibration evaluation to know the vibration characteristics of the classic car must be conducted to diagnose when and under what condition the vibration occurs. This paper aims to know the vibration level and vibration characterization of the classic car from car engine as the vibration source to some selected positions at low-frequency engine idle speed by using Transfer Path Analysis (TPA). This research used a 1991-manufactured car. Finite element calculation, simulation, and experimental modal analysis were used to determine the dynamic characteristics of the car for the natural frequencies. The natural frequencies that generated from the experimental modal analysis are convoluted by operational acceleration when the car engine was turning on which equal to operational force as transfer path analysis. In conclusion, TPA can be used to know the vibration characteristics in Noise Vibration and Harshness (NVH) issues by tracing the flow of vibration using operational force.