Improvement of structures vibroacoustics by widespread embodiment of viscoelastic materials

Ghiringhelli, G.L.; Terraneo, Mauro; Vigoni, Edoardo

doi:10.1016/j.ast.2012.11.003

Cited by 36 publications

(19 citation statements)

References 17 publications

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“…There is considerable literature predicting and proposing technologies for the mitigation of aircraft noise [33,34]. Some strategies act inside the fairing by using dampers, [35,36,37] or by using active materials [38,39]] with the main objective of reducing the structure borne noise in the rocket [40,41,42,43,44,45]. Others act externally, at the level of the launch pad, in order to reduce both the direct and the reflected components of the airborne sound.…”

Section: Discussion For Aerospace Applicationsmentioning

confidence: 99%

Broadband reduction of the specular reflections by using sonic crystals: A proof of concept for noise mitigation in aerospace applications

Garcı́a-Raffi

Salmerón-Contreras

Herrero-Durá

et al. 2018

Aerospace Science and Technology

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The broadband reduction of the specular reflections by sonic crystals (SCs) is theoretically and experimentally reported in this work. The analysed system consists of a sound source radiating a SC made of acoustically rigid scatterers embedded in water partially covering an open cavity. By comparison with a reference flat reflector, we observe that reflected waves spread in space as a consequence of the spatially modulated properties of the SC. Moreover, due to the different working frequency ranges of the SC a significant noise reduction is produced in a broadband region. Therefore, due to the spreading of the reflected waves, the system produces a broadband noise reduction in the area of the source. In particular, the noise reduction is close to 2 dB for the two octaves emitted by our source, which represents a decrease of 37% of the acoustic energy. The results shown in this work constitute a proof of concept for the use of SCs as broadband-noise reduction systems at the launch pad. An approach to the geometry of the Vega launch vehicle the European Space Agency is proposed and the limitations of the study are discussed.

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Section: Discussion For Aerospace Applicationsmentioning

confidence: 99%

Broadband reduction of the specular reflections by using sonic crystals: A proof of concept for noise mitigation in aerospace applications

Garcı́a-Raffi

Salmerón-Contreras

Herrero-Durá

et al. 2018

Aerospace Science and Technology

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“…Today several applications in the aviation and automotive industry benefit from this type of damping mechanism [12,13]. The mechanism was also investigated for CFRP or metal laminates with elastomeric interlayers by Ghiringhelli et al [14]. They showed that a fine distribution of the elastomer layers over the thickness leads to a better damping capacity than a single thick layer in the middle.…”

Section: Introductionmentioning

confidence: 99%

Damping Characterization of Hybrid Carbon Fiber Elastomer Metal Laminates using Experimental and Numerical Dynamic Mechanical Analysis

et al. 2019

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Lightweight structures which consist to a large extent of carbon fiber reinforced plastics (CFRP), often lack sufficient damping behavior. This also applies to hybrid laminates such as fiber metal laminates made of CFRP and aluminum. Since they are usually prone to vibrations due to their high stiffness and low mass, additional damping material is required to meet noise, vibration and harshness comfort demands in automotive or aviation industry. In the present study, hybrid carbon fiber elastomer metal laminates (HyCEML) are investigated which are intended to influence the damping behavior of the laminates by an elastomer interlayer between the CFRP ply and the aluminum sheets. The damping behavior is based on the principle of constrained layer damping. To characterize the damping behavior, dynamic mechanical analyses (DMA) are performed under tension on the elastomer and the CFRP, and under three point bending on the hybrid laminate. Different laminate lay-ups, with and without elastomer, and two different elastomer types are examined. The temperature and frequency dependent damping behavior is related to the bending stiffness and master curves are generated by using the time temperature superposition to analyze the damping behavior at higher frequencies. A numerical model is built up on the basis of DMA experiments on the constituents and micro mechanical studies. Subsequently, three point bending DMA experiments on hybrids are simulated and the results are compared with the experimental investigations. In addition, a parameter study on different lay-ups is done numerically. Increasing vibration damping is correlated to increasing elastomer content and decreasing elastomer modulus in the laminate. A rule of mixture is used to estimate the laminate loss factor for varying elastomer content.

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“…Coupled rotation and vibration tests: an A109MKII ironbird was used, i.e. a highly representative rotating rig, available at Politecnico di Milano laboratories [42], to validate the measuring devices considering realistic conditions in terms of centrifugal acceleration and gearbox-generated vibrations. 3.…”

Section: System Based On Stereo Camerasmentioning

confidence: 99%

Laser and vision-based measurements of helicopter blade angles

et al. 2018

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Improvement of structures vibroacoustics by widespread embodiment of viscoelastic materials

Cited by 36 publications

References 17 publications

Broadband reduction of the specular reflections by using sonic crystals: A proof of concept for noise mitigation in aerospace applications

Broadband reduction of the specular reflections by using sonic crystals: A proof of concept for noise mitigation in aerospace applications

Damping Characterization of Hybrid Carbon Fiber Elastomer Metal Laminates using Experimental and Numerical Dynamic Mechanical Analysis

Laser and vision-based measurements of helicopter blade angles

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