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

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.

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

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.

Generalized Frequency Response Functions for Systems with Time-Varying Coefficients

1994 ◽  
Vol 208 (3) ◽  
pp. 145-153 ◽  
Author(s):  
M R Belmont
Keyword(s):  
Frequency Response ◽  
Time Domain ◽  
Illustrative Case ◽  
Time Varying ◽  
Response Functions ◽  
Governing Equations ◽  
Varying Coefficients ◽  
Wide Range ◽  
Time Varying Coefficients ◽  
The Time Domain

An extension of the concept of frequency response is introduced which can be applied to systems described by differential equations whose coefficients vary periodically or almost periodically with time. Such systems are not accessible to traditional frequency response function methods because while the governing equations may be linear in the time domain they are non-linear in frequency. The basic theory of the technique is introduced and results are obtained for a wide range of systems. Time domain solutions are also deduced to complement the spectral development. Numerical results are calculated for an illustrative case that deals with a photochemical problem driven by a solar daylight cycle.

Time-domain Transfer Path Analysis for Transient Phenomena Applied to Tip-in/Tip-out (Shock & amp; Jerk)

2012 ◽  
Author(s):  
Hirotaka Shiozaki ◽  
Theo Geluk ◽  
Frank Daenen ◽  
Yoshihisa Iwanaga ◽  
Joris Van Herbruggen
Keyword(s):  
Path Analysis ◽  
Time Domain ◽  
Transient Phenomena ◽  
Transfer Path ◽  
Transfer Path Analysis ◽  
Domain Transfer

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

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Changheon Song ◽  
Dae Ji Kim ◽  
Jintai Chung ◽  
Kang Won Lee ◽  
Sang Seuk Kweon ◽  
...  
Keyword(s):  
Path Analysis ◽  
Mechanical Equipment ◽  
Impact Loads ◽  
Response Functions ◽  
Transfer Path ◽  
Transfer Path Analysis ◽  
Strain Gauge Measurements ◽  
The Impact ◽  
Impact Experiments ◽  
The Relationship

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.

Time-domain transfer path analysis of multiple moving noise sources

2011 ◽  
Vol 59 (5) ◽  
pp. 541 ◽  
Author(s):  
Sifa Zheng ◽  
Peng Hao ◽  
Xiaomin Lian ◽  
Keqiang Li
Keyword(s):  
Path Analysis ◽  
Time Domain ◽  
Noise Sources ◽  
Transfer Path ◽  
Transfer Path Analysis ◽  
Domain Transfer

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

Vibration ◽  
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.

scholarly journals Unidirectional amplification with acoustic non-Hermitian space−time varying metamaterial

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Xinhua Wen ◽  
Xinghong Zhu ◽  
Alvin Fan ◽  
Wing Yim Tam ◽  
Jie Zhu ◽  
...  
Keyword(s):  
Time Domain ◽  
Frequency Conversion ◽  
Space Time ◽  
Time Varying ◽  
Impulse Responses ◽  
Experimental Realization ◽  
Material Gain ◽  
Time Varying Systems ◽  
Hermitian Space ◽  
The Time Domain

AbstractSpace−time modulated metamaterials support extraordinary rich applications, such as parametric amplification, frequency conversion, and non-reciprocal transmission. The non-Hermitian space−time varying systems combining non-Hermiticity and space−time varying capability, have been proposed to realize wave control like unidirectional amplification, while its experimental realization still remains a challenge. Here, based on metamaterials with software-defined impulse responses, we experimentally demonstrate non-Hermitian space−time varying metamaterials in which the material gain and loss can be dynamically controlled and balanced in the time domain instead of spatial domain, allowing us to suppress scattering at the incident frequency and to increase the efficiency of frequency conversion at the same time. An additional modulation phase delay between different meta-atoms results in unidirectional amplification in frequency conversion. The realization of non-Hermitian space−time varying metamaterials will offer further opportunities in studying non-Hermitian topological physics in dynamic and nonreciprocal systems.

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