Fundamentals, processes and applications of high-permittivity polymer–matrix composites

Recent advances in nonlinear passive vibration isolators

The present state-of-the-art article is devoted to the analysis of new trends and recent results carried out during the last 10 years in the field of fractional calculus application to dynamic problems of solid mechanics. This review involves the papers dealing with study of dynamic behavior of linear and nonlinear 1DOF systems, systems with two and more DOFs, as well as linear and nonlinear systems with an infinite number of degrees of freedom: vibrations of rods, beams, plates, shells, suspension combined systems, and multilayered systems. Impact response of viscoelastic rods and plates is considered as well. The results obtained in the field are critically estimated in the light of the present view of the place and role of the fractional calculus in engineering problems and practice. This articles reviews 337 papers and involves 27 figures. DOI: 10.1115/1.4000563

Application of Fractional Calculus for Dynamic Problems of Solid Mechanics: Novel Trends and Recent Results

Interfacial damping characteristics of carbon nanotube-based composites

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Formulas For Natural Frequency And Mode Shape

A nonlinear constitutive audio frequency magneto-sensitive rubber model including amplitude, frequency and magnetic field dependence

Compaction of polymer powders and polymer-based nanocomposites by uniaxial high-velocity cold compaction (HVC), by high-energy ball milling (HEBM) and using a novel technique, relaxation assists, was investigated with a focus on the process parameters, the compactibility characteristics, surface morphology and friction. The basic phenomena associated with HVC are explained and the general energy principle is introduced to explain the pull-out phenomenon, springback gradient, delay time, relative time of the pressure wave, and stick-slip phenomenon during the compaction process. Experimental results for different compaction profiles, different particle size distributions and different milling system for polymer-based nanocomposite are presented, showing the effect of varying the process parameters on the compacted material; the compactibility in the compacted bed, the uniformity of the compacted surface, the pull-out phenomenon, the springback gradient, the stick-slip phenomenon and the homogeneity of the dispersions of nanoparticles in the polymer powders in the solid state. It was found that the high-velocity compaction process is an interruption process and that the opposite velocity and pressure loss during the compaction process have a major influence on the quality of the compacted material. The relaxation assist device is a novel technique that has been successfully developed to improve the compaction process. The relaxation assists are parts of the piston and they are regarded as projectile supports. They are constructed of the same material as the piston, and the diameters are the same but the lengths are different. The relaxation assist device leads to an improvement in the compaction of powders, polymer powders and polymer-based nanocomposites by giving a more homogeneous opposite velocity and a better locking of the powder bed in the compacted form during the compaction process with less change in dimensions in the case of both homogeneous and heterogeneous materials. If the movement of the particles is restricted the powder bed attains a higher density and the total elastic springback is minimized. In addition, there is a more homogeneous dispersion of nanoparticles in the case of a heterogeneous material. A much better transfer of the pressure through the powder bed and a smaller loss of pressure lead to a more homogenous stick-slip of the particles and a higher sliding coefficient due to the overall friction during the compaction process.

Polymer–nanofiller prepared by high‐energy ball milling and high velocity cold compaction

On the waveguide modelling of dynamic stiffness of cylindrical vibration isolators. part i: the model, solution and experimental comparison

The preload dependence of magnetosensitive rubber is experimentally studied along with the influence of frequency, vibrational amplitude and magnetic field strength. The material studied is an iron particle filled natural rubber with a volume particle fraction of 33%, which is close to the optimal particle concentration. The results of the measurements show that an increased preload decreases the influence of magnetic field strength and they also suggest that an increase in the magnetic field reduces the influence of the preload. Measurements of the magnitude of the dynamic shear modulus also display a preload dependence. These results imply that in a description of these materials, the preload should be taken into account, especially since magnetosensitive elastomers are used in applications where they are often exposed to preloads.

Preload, frequency, vibrational amplitude and magnetic field strength dependence of magnetosensitive rubber

An engineering design formula for the torsion stiffness of a filled rubber bushing in the frequency domain, including the amplitude dependence, is presented. It is developed by applying a novel sep ...

Leif Kari

Papers

A nonlinear constitutive audio frequency magneto-sensitive rubber model including amplitude, frequency and magnetic field dependence

Polymer–nanofiller prepared by high‐energy ball milling and high velocity cold compaction

On the waveguide modelling of dynamic stiffness of cylindrical vibration isolators. part i: the model, solution and experimental comparison

Preload, frequency, vibrational amplitude and magnetic field strength dependence of magnetosensitive rubber

Torsion stiffness of a rubber bushing : a simple engineering design formula including amplitude dependence