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Nanoscale Materials for Macroscale Applications: Design of Superlubricants from 2D Materials
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
In previous sections, we reviewed some of the unique properties of 2D materials, including those that are of benefit for their tribological characteristics and that enable their use as solid lubricants. To minimize frictional energy losses, all possible mechanisms of energy dissipation should be minimized. Figure 21.9 highlights eight distinguished mechanisms of frictional energy dissipation, that can be controlled with the use of 2D materials.
Electronic Components
Published in Michael Pecht, Handbook of Electronic Package Design, 2018
Denise Burkus Harris, Michael Pecht, Pradeep Lall
Low power dissipation is desired in large systems because it increases reliability, lowers cooling costs and cooling distribution costs, and thus reduces mechanical design problems. As chips increase in complexity, the power dissipation has increased on a per gate basis. The complexity is then limited by heat dissipation requirements arising from system design and allowable semiconductor temperature.
Vibration damping by dry friction
Published in Zbigniew Osiński, Damping of Vibrations, 2018
In Fig. 3.21 we have a scheme of a simple system under an impact. It consists of two masses, m1 and m2. A considerable difference of their velocities is assumed for the impact. The process in this system can be characterized by a change of the forces present as well as a deformation of the absorber. During this deformation energy both accumulates and is dissipated. Potential energy is stored in elastic elements. The dissipation is due to friction.
Full-Scale Shake Table Tests of a Reinforced Concrete Building Equipped with a Novel Servo-Hydraulic Active Mass Damper
Published in Journal of Earthquake Engineering, 2023
G. Rebecchi, P. M. Calvi, Alberto Bussini, Filippo Dacarro, Davide Bolognini, Luca Grottoli, Matteo Rosti, Francesco Ripamonti, Stefano Cii
Examples of passive vibration control devices (Constantinou, Soong, and Dargush 1998) include base isolators (Calvi and Calvi 2018; Patil and Reddy 2012), viscous, hysteretic and friction dampers (Aiken 1996) and (Constantinou and Symans 1993), and tuned mass dampers (Mariantonieta and Hojjat 2013) such as the one installed on the Shangai Tower that proved to be effective at reducing wind-induced vibrations of the structure during Typhoons (Zhang et al. 2022). Passive devices enhance the seismic performance of a structure primarily by absorbing part of the input energy of the earthquake, thus reducing the seismic demand on the structural elements. The dissipation of energy occurs through a variety of mechanisms that depend on the nature of the damper utilized. Common energy dissipation mechanisms include yielding of mild steel, viscoelastic action in rubber-like materials, shearing of viscous fluid, sliding friction, etc. In addition to dissipating part of the input seismic energy, base isolators modify the period of vibration of the structure shifting its response such that the seismic demand on the system is reduced.
Seismic energy dissipation in reinforced concrete beam: investigating damping formulations
Published in European Journal of Environmental and Civil Engineering, 2022
Clotilde Chambreuil, Cédric Giry, Frédéric Ragueneau, Pierre Léger
Using a nonlinear constitutive model in dynamic computations reduces the viscous damping requirement. However, sufficient dissipative phenomena must be modelled to accurately represent the structure global responses. In particular, the frictional phenomenon appears to be the most dissipative phenomenon. Therefore, a constitutive model considering only the damage (cracking) phenomenon is not adequate. Then, if the signal amplitude increases, a larger viscous damping ratio must be considered to compensate for the lack of dissipations at the local level, demonstrating that improved damping actualizations should be considered to consider the development of nonlinearities. Indeed, the nonlinear evolution is strongly dependent on the damping formulation choice. Therefore, even if the beam global responses are accurately represented, the energy dissipations and nonlinearity developments (crack opening and friction) do not completely match the experimental observations.
Model reduction for discrete-time periodic systems with dissipativity
Published in International Journal of Systems Science, 2020
Liu Yang, Chengwei Wu, Yuxin Zhao, Ligang Wu
As an important performance, the dissipativity is widely addressed in the design process, which can guarantee that the considered system is dissipative. Many results have discussed the dissipative performance for different categories of systems. Here, the corresponding description for periodical system is provided.