On the vibro-acoustical operational modal analysis of a helicopter cabin

Pierro, Elena; Mucchi, Emiliano; Soria, Leonardo; Vecchio, Antonio Del

doi:10.1016/j.ymssp.2008.10.009

Cited by 30 publications

(11 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Using the FRFs, the equations can be solved for the parameter estimation of the coupled modes such as the modal shapes and the modal frequencies. More detailed information about the theory of the vibro-acoustical modal analysis can be found in [17][18][19]. For solving the equations, we used the software Siemens Simcenter Testlab with the PolyMax method [20].…”

Section: Vibro-acoustical Modal Analysis Of a Vehiclementioning

confidence: 99%

Importance of Vehicle Body Elements and Rear Axle Elements for Describing Road Booming Noise

Herrmann

Jöst²,

Kehl³

et al. 2020

Vehicles

View full text Add to dashboard Cite

For investigating influences of vehicle components on the acoustic comfort at low frequencies, e.g., the booming noise behavior of a vehicle, building a whole car simulation model is useful. To reduce the model’s complexity and to save resources in the validation process, we first identify relevant components before building the model. Based on previous studies, we focus on the vehicle’s body and the rear axle. In this paper, we analyze which axle and body elements are crucial for describing road booming noise. For this purpose, we use impact measurements to examine noise transfer functions of the body and a vibro-acoustical modal analysis to identify coupled modes between the body’s structure and the interior cavity. For investigating relevant force paths from the rear axle to the body, we used a chassis test bench. We identify the main transmission paths of road booming noise and highlight which axle and body components have an influence on them. Mainly the rear axle in its upright direction in combination with a rigid body movement of the rear tailgate coupled with the first longitudinal mode of the airborne cavity causes road booming noise. Furthermore, the rear axle steering, the active roll stabilization and the trim elements of the vehicle’s body are essential to describe road booming noise. The results can be used to set priorities in the validation of individual axle and body components for future simulation models. We found that the ventilation openings, the front seats, the headliner, and the cockpit of a vehicle have little influence on its noise transfer functions from the rear axle connection points to the driver’s ear between 20 and 60 Hz.

show abstract

Section: Vibro-acoustical Modal Analysis Of a Vehiclementioning

confidence: 99%

Importance of Vehicle Body Elements and Rear Axle Elements for Describing Road Booming Noise

Herrmann

Jöst²,

Kehl³

et al. 2020

Vehicles

View full text Add to dashboard Cite

show abstract

“…7 OMA developed from civil engineering works quite efficiently in modal parameters estimation of structure in operation. 8,9 For example, studies have extracts structure modal parameters of a flying helicopter cabin, 10 using modal decomposition formulation for a vibro-acoustical OMA. Pintelon presents three methods for suppressing the influence of harmonic disturbances with unknown varying frequencies in OMA.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation on dynamic parameters of broaching machine

Ying

Wang

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

Dynamic properties of the whole broaching machine structure greatly contribute to the broaching quality and efficiency. However, it is hard to measure the dynamic parameters because they will change during operation compared with the static results from classic experimental modal analysis. This study is to examine the dynamic parameters of broaching machine LG7120KT using both the numerical finite element (FE) method and the experimental operational modal analysis (OMA). Firstly, FE analysis model of the broaching machine with the real dimension is constructed and calculated. Second, experimental results are obtained from OMA in practical broaching process, which can be used to identify steady-state modes. Modal parameters including mode shapes, damping ratio, and natural frequencies are examined, using both LMS SCADAS III-305 system and PolyMAX method in OMA. The numerical and experimental results show high agreement in their calculated natural frequencies. From the modal analysis results, it is also found the vibration normal to cutting direction can be greatly reduced by adjusting broaching speed. From the topology optimization result based on the already correlated FE model, we redesigned a lightweight machine structure with a better dynamic performance, due to its lower displacement of broaching machine at force point and its higher first-order natural frequency. The experimental and numerical results in this paper help to design the structural parameters of broaching machine and propose a better broaching process.

show abstract

“…It is interesting to note that although the presented methodologies concern particular helicopters, they have a general meaning, since they can be applied in a large variety of fields, as in aircraft fuselage, car or track interiors , etc. This work has to be intended as an analytical review of the authors' research 2010;Pierro et al, 2009). Due to confidentiality reasons, several vibro-acoustical quantities reported in this chapter are presented without numerical values.…”

Section: Introductionmentioning

confidence: 99%