Torsional vibration of a back-to-back gearbox rig Part 1: Frequency domain modal analysis

Proceedings of the Institution of Mechanical Engineers, Part K:

2005

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The coupled torsional and transverse vibration of a back-to-back gearbox system has been investigated experimentally and analytically. Receptance methods were used to model the system, and were shown to be effective. A detailed experimental modal analysis was performed using the swept-sine technique with an a.c. servomotor torsional exciter. Torsional excitation allowed for the dynamic response to be measured up to 1600 Hz. The model included a combination of lumped mass elements and continuous shafts with distributed inertia and damping. The bearings were modelled as having both radial and tilt stiffness and damping elements. The model simulated the experimental results well and predicted each of the first 11 natural frequencies to within 8 per cent. Of the 11 natural frequencies, 9 simulated deflected shapes matched very well, validating the modelling approach taken for the project together with the assumptions made in the derivation of the model. This paper presents the detailed results of a full torsional/transverse model analysis of the gearbox system.

Section: Introductionmentioning

confidence: 60%

Coupled Torsional and Transverse Vibration of a Back-to-Back Gearbox Rig

Sargeant

Proceedings of the Institution of Mechanical Engineers, Part K:

2005

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“…Optimum torsional excitation and signal processing were achieved by undertaking the measurements in several frequency ranges (bands). Previously [24], the rst nine torsional natural frequencies were identi ed (0-1600 Hz), and the corresponding torsional de ected shapes were plotted against the modelled results. Examples of predicted and measured torsional FRFs are shown in Fig.…”

Section: Experimental Torsional Damping Results Using Swept-sine Excimentioning

confidence: 99%

“…Reference [24] presented the torsional operating de ected shape of the ninth system natural frequency. The measured torsional response was a maximum at measurement positions 2 and 3, with a slightly smaller response at positions 5 and 6 and a very small response at positions 9 and 10.…”

Section: Assessment Of the Damping Calculation Methodsmentioning

confidence: 99%

“…In previous papers [24,25], experimental torsional modal analysis results were presented for a 'four-square' or 'backto-back' gearbox rig, driven by an a.c. servo drive as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…The MS was received on24 October 2001 and was accepted after revision for publication on 25 January 2002. *Corresponding author: Department of Mechanical and Materials Engineering, The University of Western Australia, Nedlands, Perth 6907, Australia.…”

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confidence: 99%

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Torsional damping of a back-to-back gearbox rig: Experimental measurements and frequency domain modelling

Proceedings of the Institution of Mechanical Engineers, Part K:

2002

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This paper is concerned with the experimental measurement and modelling of the torsional damping levels of a back-to-back gearbox rig. The aims of the investigation were to experimentally measure and analyse modal damping levels for the rst nine torsional natural frequencies; to optimize damping parameters for modelling and to assess any limitations of the models for future work. Standard signal processing methods were used to determine modal damping levels from measured torsional frequency responses, with good con dence in the results. A damping sensitivity analysis for the two frequency domain receptance (FDR) models was used to determine optimum damping parameter values. Damping levels for six of nine natural frequencies were well matched with the experimental data. Discrepancies at other frequencies were attributed mainly to torsional-transverse coupling, present in the rig but not the model. Analysis of results for the ninth natural frequency determined a very low level of damping for the gearbox. It was also concluded that the model parameters may be used with con dence in a time domain receptance model for future investigations related to the test gearbox damping.

Torsional vibration of a back-to-back gearbox rig Part 2: Time domain modelling and verification

Leishman

Proceedings of the Institution of Mechanical Engineers, Part K:

2000

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The torsional vibration of a back-to-back gearbox system has been simulated in the time domain, using time domain receptance theory. Receptance analysis in the time domain is an extension of the frequency domain method and allows the benefits of a systems approach for modelling complicated systems. Meshing spur gears represent a complicated dynamic system. The excitation from the variation in gear mesh stiffness has been considered in the present model. A gear mesh kinematic simulation was developed to simulate the contact pattern and mesh stiffness for a spur gear pair with a contact ratio of less than 2.0. The time domain receptance model was verified using a simulated white noise input to generate frequency response functions up to 1600 Hz. The simulated torsional natural frequencies were compared with the experimentally measured results in Part 1 [1]. After the adjustment of model parameters, the first eight torsional natural frequencies were accurately matched by the predictions of the time domain model. The simulated frequency response functions of the time domain model accurately matched the frequency response functions from the frequency domain receptance model presented in Part 1 [1].