Estimation of Impact Loads in a Hydraulic Breaker by Transfer Path Analysis

The aim of this study is to estimate the impact loads delivered to the housing of a hydraulic breaker quantitatively. Striking forces caused vibrations in the equipment housing, which were experimentally measured, and frequency response functions were also found through modal impact experiments. Transfer path analysis (TPA) method of the data quantified the impact loads delivered to the housing. TPA method can analyze the relationship between the vibration energy and the transfer path of an excitation source and so explore the way in which vibrations on each path contribute to the entire vibration profile. The impact loads of each part derived by TPA method were compared with the impact loads in the chisel derived from strain gauge measurements of the striking energy. This comparison validated the TPA approach. This study describes the basic concepts and components of TPA method and also reviews its applicability to mechanical equipment that experiences impact vibrations and impact loads.

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Identification of relevant acoustic transfer paths for WT drivetrains with an operational transfer path analysis

Forschung im Ingenieurwesen ◽

10.1007/s10010-021-00471-0 ◽

2021 ◽

Author(s):

W. Schünemann ◽

R. Schelenz ◽

G. Jacobs ◽

W. Vocaet

Keyword(s):

Path Analysis ◽

Wind Turbine ◽

Frequency Response ◽

Mechanical System ◽

Reference Point ◽

Response Functions ◽

Frequency Response Functions ◽

Transfer Path ◽

Transfer Path Analysis ◽

Turbine Model

AbstractThe aim of a transfer path analysis (TPA) is to view the transmission of vibrations in a mechanical system from the point of excitation over interface points to a reference point. For that matter, the Frequency Response Functions (FRF) of a system or the Transmissibility Matrix is determined and examined in conjunction with the interface forces at the transfer path. This paper will cover the application of an operational TPA for a wind turbine model. In doing so the path contribution of relevant transfer paths are made visible and can be optimized individually.

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Time-Domain Substructure Transient Vibration Transfer Path Analysis Based on Time-Varying Frequency Response Functions under Operational Excitations

Shock and Vibration ◽

10.1155/2019/2030326 ◽

2019 ◽

Vol 2019 ◽

pp. 1-16

Author(s):

Rong He ◽

Hong Zhou

Keyword(s):

Path Analysis ◽

Frequency Response ◽

Time Domain ◽

Time Varying ◽

Response Functions ◽

Transient Vibration ◽

Transfer Path ◽

Time Varying Systems ◽

Transfer Path Analysis ◽

The Time Domain

The time-domain substructure inverse matrix method has become a popular method to detect and diagnose problems regarding vehicle noise, vibration, and harshness, especially for those impulse excitations caused by roads. However, owning to its reliance on frequency response functions (FRFs), the approach is effective only for time-invariable linear or weak nonlinear systems. This limitation prevents this method from being applied to a typical vehicle suspension substructure, which shows different nonlinear characteristics under different wheel transient loads. In this study, operational excitation was considered as a key factor and applied to calculate dynamic time-varying FRFs to perform accurate time-domain transient vibration transfer path analysis (TPA). The core idea of this novel method is to divide whole coupled substructural relationships into two parts: one involved time-invariable components; normal FRFs could be obtained through tests directly. The other involved numerical computations of the time-domain operational loads matrix and FRFs matrix in static conditions. This method focused on determining dynamic FRFs affected by operational loads, especially the severe transient ones; these loads are difficult to be considered in other classical TPA approaches, such as operational path analysis with exogenous inputs (OPAX) and operational transfer path analysis (OTPA). Experimental results showed that this new approach could overcome the limitations of the traditional time-domain substructure TPA in terms of its strict requirements within time-invariable systems. This is because in the new method, time-varying FRFs were calculated and used, which could make the FRFs at the system level directly adapt to time-varying systems from time to time. In summary, the modified method extends TPA objects studied in time-invariable systems to time-varying systems and, thus, makes a methodology and application innovation compared to traditional the time-domain substructure TPA.

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Fixture for the High-Frequency Transfer Path Analysis for Relative Comparison of Fluids of an Electric Motor

Vibration ◽

10.3390/vibration4020026 ◽

2021 ◽

Vol 4 (2) ◽

pp. 406-413

Author(s):

Michael Schnell ◽

Nicole Wörz ◽

Frank Gauterin

Keyword(s):

Path Analysis ◽

Electric Motor ◽

High Frequency ◽

Incompressible Fluids ◽

Response Functions ◽

Electric Motors ◽

Transfer Path ◽

Transfer Path Analysis ◽

Temperature And Pressure ◽

Air Medium

In a previous paper, it was determined that coolant fluids can have a significant influence on the acoustic emission of an electric motor. There is no appliance that can investigate and compare the transfer path analysis of isolated fluids. For this case, a new fixture is introduced and its suitability is evaluated. Furthermore, the appliance is used to measure and compare different media and their frequency response functions. The results indicate that the fixture and its repeatability are suitable to measure and compare fluids and media. A comparison of different media shows how the air medium has the lowest amplitudes for the transfer path analysis, in relation to incompressible fluids. Furthermore, differences in the transfer path analysis between both considered gearbox oils are marginal. While the utilization of air as a coolant medium is not always possible, due to thermal issues, the presented fixture can help find an acoustically suitable coolant medium for future applications in electric motors. Additionally, it is possible to investigate the influence of temperature and pressure conditions on the transfer path analysis of fluids.

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Identification of partially coherent sound sources for centrifugal fan

Noise Control Engineering Journal ◽

10.3397/1/37696 ◽

2021 ◽

Vol 69 (1) ◽

pp. 66-76

Author(s):

Chenguang Wang ◽

Weikang Jiang

Keyword(s):

Path Analysis ◽

Mechanical Equipment ◽

Test Model ◽

Sound Sources ◽

Transfer Path ◽

Partially Coherent ◽

Contribution Analysis ◽

Coherent Sources ◽

Transfer Path Analysis ◽

Partially Coherent Sources

The signal model with multiple inputs and single output (MISO) is often used for investigating sound sources of vehicles and mechanical equipment, in which transfer path analysis (TPA) and operational transfer path analysis (OTPA) procedure are well known in industry. Sources are completely coherent, as well as completely incoherent in TPA and OTPA models. However, some mechanical devices like centrifugal fans contain not only structure-borne and air-borne sound but also vibrational source and acoustical source. The sources may be partially coherent and cannot be calculated using traditional method. In order to understand the origination of sound from the partially coherent sources of the fan, a MISO model with partially coherent inputs was developed, in which the partially coherent sources were identified by partial singular value decomposition (PSVD) method. Vibration, pressure pulsation and sound signals were measured, and partially coherent sources contribution analysis were used to calculate the contribution of sources quantitatively. A test model was built, and an experiment was conducted to verify that this method is feasible. This method is also suitable for the identification and contribution analysis of sources with partially coherent characteristics, such as automobile exhaust system. This method can calculate the contribution of partially coherent sources, which is not available in other noise source identification methods.

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