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Spatial damping identification and control of mechanical systems
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Experimental and numerical mode shape tracing from components to whole motorbike chassis
No full textThis paper aims to analyse the most influent component mode shapes on the dynamic properties of a whole motorbike frame. Experimental and numerical modal analyses have been carried out on chassis, swingarm, engine, wheel and different subsystems of increasing complexity. The component global modes shapes are traced from component to assembly with both Modal Assurance Criterion. The most influent mode shapes of each component are highlighted and their effects on the global motorbike dynamics are
discussed. The component to assembly method results to be a preliminary tool to have an objective evaluation of the most important modes of components on which possible improvements can be suggested
Analysis of heavy commercial vehicle cornering behaviour through a multibody model
No full textThe evaluation of heavy commercial vehicles dynamics represents a significant and challenging task because of the increasing complexity of the vehicle subsystems. The methods commonly used to study vehicle dynamics are on-road test with the real vehicle or virtual tests based on simplified models. This paper focusses on the cornering behaviour virtual analysis of a heavy-duty commercial vehicle through a multibody model implemented in Adams/Car. Two layouts of the tractor, without and with a semitrailer, are studied during ramp steer and sweep steer manoeuvres for characterizing the steady-state and frequency responses. The frequency response functions of the tractor with the semitrailer is further evaluated when the vehicle longitudinal speed or the trailer mass distribution changes
Experimental evaluation of the influence of shock-absorbers on white-body chassis modal behaviour
No full textExperimental direct spatial damping identification by the Stabilised Layers Method
Get PDFA new method is developed for direct damping matrix identification using experimental receptance-matrix data together with physical connectivity constraints based on what are described as layers. A number of spectral lines are considered in symmetric frequency bands around the damped peaks of the receptances and the identification procedure is shown to be ill-conditioned (singular) when one of the spectral lines coincides with an undamped natural frequency. A test is developed that makes use of a stabilisation diagram to ensure not only that a solution exists, but also that it is stable when the number and frequency range of the spectral lines is changed. An experimental parametric three degrees of freedom lumped mass system connected by springs and air dampers is considered and the matrix of non-proportional viscous damping terms is identified under different damper configurations and levels
Parametric Experimental Modal Analysis of a Modern Violin Based on a Guarneri del Gesù Model
No full textMechanical effects and dynamic behaviour of a modern violin, built on a Guarneri del Gesù model, were examined via parametric experimental modal analysis. Among the few mobile components of a violin, the soundpost has a particular relevance for the final acoustic performance, even if its dimensions are extremely small. Therefore, the aim of this first research is to understand the violin sensitivity to the soundpost position considering its influence on the overall structural-vibrational behaviour. Experimental modal analysis was performed in six different configurations, related to different positions of the soundpost inside the violin, including both the outer possible locations and optimal position, generally defined by the violinist according only to the perceived best acoustic performance. Six “Signature” modes were identified and tracked in all configurations, comparing mode shapes, damping and natural frequencies of involved modes, in order to find a correlation between mechanical vibrations and acoustic performance of the instrument. The effects of the soundpost position on the modal properties of the “Signature” mode shapes are highlighted and discussed. Finally, the potential role of soundpost as a practical engineering tool to improve the signature and sound quality is discussed
An experimental procedure for the identification of the dynamic parameters for the rigid-ring tyre model
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