Design of damping properties of hybrid laminates through a global optimisation strategy

2012 ◽  
Vol 94 (11) ◽  
pp. 3309-3320 ◽  
Author(s):  
Marco Montemurro ◽  
Yao Koutsawa ◽  
Salim Belouettar ◽  
Angela Vincenti ◽  
Paolo Vannucci
Keyword(s):  
Global Optimisation ◽  
Damping Properties ◽  
Hybrid Laminates

Damping Analysis of Unidirectional Carbon/Flax Fiber Hybrid Composites

2018 ◽  
Vol 10 (05) ◽  
pp. 1850050 ◽  
Author(s):  
Mariem Ben Ameur ◽  
Abderrahim El Mahi ◽  
Jean-Luc Rebiere ◽  
Moez Abdennadher ◽  
Mohamed Haddar
Keyword(s):  
Fiber Orientation ◽  
Close Agreement ◽  
Hybrid Composites ◽  
Flax Fiber ◽  
Epoxy Composites ◽  
Damping Properties ◽  
Element Analysis ◽  
Damping Coefficients ◽  
Hybrid Laminates ◽  
Vibration Tests

The purpose of the present paper is to study the effect of hybridation, stacking sequences and fiber orientation on the damping properties of unidirectional carbon/flax fiber reinforced epoxy composites. Non-hybrid and hybrid laminates with different stacking sequences were produced by molding vacuum process. Free vibration tests with an impulse technique were performed on test specimens to investigate the dynamic behavior. Finite element analysis was used to model damping to evaluate the different energies dissipated in the material layer directions of the carbon/flax composites. Close agreement was found between the experimentally measured values and those derived from the numerical simulation for the damping coefficients. The results obtained show that flax layers had a significant effect on damping properties.

scholarly journals Interlayer Hybridization of Virgin Carbon, Recycled Carbon and Natural Fiber Laminates

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4955
Author(s):  
Peter Wilson ◽  
Alon Ratner ◽  
Gary Stocker ◽  
Frank Syred ◽  
Kerry Kirwan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibers ◽  
Natural Fiber ◽  
Damping Ratio ◽  
Transport Sector ◽  
Damping Properties ◽  
Minimal Impact ◽  
Alternative Materials ◽  
Hybrid Laminates ◽  
The Mean

To meet sustainability objectives in the transport sector, natural fiber (NF) and recycled carbon fiber (RCF) have been developed, although they have been typically limited to low to medium performance components. This work has considered the effect of interlayer hybridization of woven NF and non-woven RCF with woven virgin carbon fibers (VCF) on the mechanical and damping performance of hybrid laminates, produced using double bag vacuum infusion (DBVI). The mean damping ratio of the pure laminates showed a trend of NF>RCF>VCF, which was inversely proportional to their modulus. The tensile, flexural and damping properties of hybrid laminates were dominated by the outermost ply. The VCF-RCF and VCF-NF hybrid laminates showed a comparatively greater mean damping ratio. The results of this work demonstrate a method for the uptake of alternative materials with a minimal impact on the mechanical properties and improved damping performance.

Updating structural dynamic models with emphasis on the damping properties

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 1094-1099
Author(s):  
Amar T. Chouaki ◽  
Pierre Ladeveze ◽  
Laurent Proslier
Keyword(s):  
Dynamic Models ◽  
Damping Properties ◽  
Structural Dynamic

DAMPING PROPERTIES OF SEISMIC PROTECTIVE SYSTEMS

2019 ◽  
pp. 96-98
Author(s):  
B. T. Ibragimov ◽  
S. V. Mirzaev ◽  
D. R. Raupov ◽  
A. R. Raupov ◽  
Z. Ilashov
Keyword(s):  
Damping Properties ◽  
Protective Systems

scholarly journals Machine-Learning Assisted Optimisation of Free-Parameters of a Dual-Input Power Amplifier for Wideband Applications

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2831
Author(s):  
Teng Wang ◽  
Wantao Li ◽  
Roberto Quaglia ◽  
Pere L. Gilabert
Keyword(s):  
Power Amplifier ◽  
Power Efficiency ◽  
Average Power ◽  
Long Term Evolution ◽  
Input Power ◽  
Global Optimisation ◽  
Power Ratio ◽  
Term Evolution ◽  
Free Parameters

This paper presents an auto-tuning approach for dual-input power amplifiers using a combination of global optimisation search algorithms and adaptive linearisation in the optimisation of a multiple-input power amplifier. The objective is to exploit the extra degrees of freedom provided by dual-input topologies to enhance the power efficiency figures along wide signal bandwidths and high peak-to-average power ratio values, while being compliant with the linearity requirements. By using heuristic search global optimisation algorithms, such as the simulated annealing or the adaptive Lipschitz Optimisation, it is possible to find the best parameter configuration for PA biasing, signal calibration, and digital predistortion linearisation to help mitigating the inherent trade-off between linearity and power efficiency. Experimental results using a load-modulated balanced amplifier as device-under-test showed that after properly tuning the selected free-parameters it was possible to maximise the power efficiency when considering long-term evolution signals with different bandwidths. For example, a carrier aggregated a long-term evolution signal with up to 200 MHz instantaneous bandwidth and a peak-to-average power ratio greater than 10 dB, and was amplified with a mean output power around 33 dBm and 22.2% of mean power efficiency while meeting the in-band (error vector magnitude lower than 1%) and out-of-band (adjacent channel leakage ratio lower than −45 dBc) linearity requirements.

scholarly journals Effect of Bottom Geometry on the Natural Sloshing Motion of Water Inside Tanks: An Experimental Analysis

2021 ◽  
Vol 11 (2) ◽  
pp. 605
Author(s):  
Antonio Agresta ◽  
Nicola Cavalagli ◽  
Chiara Biscarini ◽  
Filippo Ubertini
Keyword(s):  
Energy Dissipation ◽  
Water Depth ◽  
Shear Force ◽  
Experimental Tests ◽  
Shear Load ◽  
Damping Properties ◽  
Base Shear ◽  
Structure Interaction ◽  
Sloshing Phenomenon ◽  
Key Aspects

The present work aims at understanding and modelling some key aspects of the sloshing phenomenon, related to the motion of water inside a container and its effects on the substructure. In particular, the attention is focused on the effects of bottom shapes (flat, sloped and circular) and water depth ratio on the natural sloshing frequencies and damping properties of the inner fluid. To this aim, a series of experimental tests has been carried out on tanks characterised by different bottom shapes installed over a sliding table equipped with a shear load cell for the measurement of the dynamic base shear force. The results are useful for optimising the geometric characteristics of the tank and the fluid mass in order to obtain enhanced energy dissipation performances by exploiting fluid–structure interaction effects.

A novel method of global optimisation for wavefront shaping based on the differential evolution algorithm

2021 ◽  
Vol 481 ◽  
pp. 126541
Author(s):  
Yingzi Hua ◽  
Xiubao Sui ◽  
Shenghang Zhou ◽  
Qian Chen ◽  
Guohua Gu ◽  
...  
Keyword(s):  
Differential Evolution ◽  
Differential Evolution Algorithm ◽  
Global Optimisation ◽  
Novel Method ◽  
Wavefront Shaping ◽  
Evolution Algorithm
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