Pseudo-elastic Hysteresis Damping Characteristics of SMA Hybrid Composite Lamina

The longitudinal mechanical behavior of shape memory alloy （SMA） composite lamina subjected to longitudinally strain or stress controlled cyclic loading is investigated. The SMA is under pseudoelastic condition and the fibers are embedded （bonded） to the host material. The influences of temperature, volume fraction of SMA and longitudinal modulus of the host material on the stress-strain relation and energy dissipation of the SMA hybrid composite lamina are discussed. The results indicate that the stress-strain curve of the lamina per cycle shows a hysteresis loop. The hysteresis damping decreases with increasing temperature and with decreasing volume fractions of SMA. In addition, the hysteresis damping is nearly independent of the longitudinal modulus of the host material under strain controlled loading. However, it depends dramatically on the longitudinal modulus of the host material under stress controlled loading, which shows the SMA composite lamina has high pseudo-elastic hysteresis damping when the longitudinal modulus of the host material is low.

High damping in Fe-Ga-La alloys:Phenomenological model for magneto-mechanical hysteresis damping and experiment

Ferromagnetic high damping(FHA)alloys with a wide temperature range from-150℃to 300℃have unique application value in extreme environments.In the present work,the damping behaviors of Fe-21 Ga-xLa(x=0.12 wt.%,0.24 wt.%,0.47 wt.%,1.18 wt.%,and 2.33 wt.%La)alloys have been studied in detail,and a new phenomenological model has been proposed.With the increase of La content,the Laves phase(LaGa_(2))in the matrix increases gradually,and the resistance opposing the domain movement increases as well.Combined with the results of synchrotron radiation X-ray diffraction,neutron diffraction,and magnetic domain observation,the resistance mainly comes from three parts:the average stress related to the lattice distortion of the matrix,the average stress related to the increasing area energy of domain walls(DWs),and the ave rage stress related to the increasing demagnetization energy induced by the Laves phase.Different from the traditional method of reducing internal stress through annealing to improve the damping capacity,the proper internal stress barriers are necessary to Barkhausen jumps to dissipate energy.Therefore,proper doping to balance resistance and mobility of DWs is a reliable way to improve damping capacity.Meanwhile,for Fe-Al and Fe-Cr based Alloys,the new model also has a good fitting effect.This study provides a theoretical and experimental reference for improving the functional properties of ferromagnetic alloys.

Random response of an oscillator with hysteresis damping

The response behaviour of an oscillator with Reid hysteresis damping under stationary Gauss white excitation is studied. By means of numerical simulation conducted on computer, the mean square response, probability density function and power spectral density function for the response are given. These response characteristics are compared with those predicted by equivalent linearization treatment.

Dry friction damping mechanism of flexible microporous metal rubber based on cell group energy dissipation mechanism

Flexible microporous metal rubber (FMP-MR) is a high-damping material that dissipates energy by dry friction through internal spiral metal wires in contact with each other. However, the FMP-MR energy dissipation mechanism is not fully understood owing to its disordered grid interpenetrating structure. In this work, computer-aided preparation technology is used to accurately reconstruct the complex spiral network structure of FMP-MR multipoint random contact, and a cell group model with an energy dissipation mechanism is proposed to obtain the dynamic energy distribution of the contact friction in both space and time dimensions. By judging the effective contact point, a global displacement ablation phenomenon of hooked staggered porous materials is induced. The macro- and micro-equivalent frictions are introduced to effectively explain the characteristics of the strong energy dissipation in FMP-MR under fretting excitation. A real and effective damping hysteresis constitutive model is then constructed to dynamically capture the mapping relationship between the complex nonlinear topological structure effect of the materials and spatial random contact dry friction in real time. The results indicate that the contact behavior between turns of the FMP-MR wire follows a clear quasi-Gaussian distribution under an external load, forcing the topological results to change. The energy dissipation of the materials revealed peak energy consumption lagging behind the loading limit for a certain distance, which can be determined by the effective contact point and contact dry friction slip. The consistency between the quasi-static compression tests and constitutive curves of the model was quantitatively verified through residual analysis. The data demonstrated the differential behavior of the FMP-MR meso-structure to follow a phased growth law during loading with different action mechanisms in the guiding, main growth, and relaxation stages of the energy consumption displacement curve. In summary, these findings provide an acceptable theoretical basis for the damping energy consumption mechanism and lifetime prediction of FMP-MR.