Модифицированные параметры приема 1-3-композитов на основе сегнетоэлектрических кристаллов

A system of modified figures of merit is studied for fibrous piezo-active composites ‘system of aligned ferroelectric crystal rods – polymer matrix’ with 1–3 connectivity in a wide volume-fraction range of the crystal component. The modified figures of merit are important to estimate an effectiveness of harvesting, accumulating and transducing energy in a piezo-element at a constant mechanical stress or constant strain. Polydomain [001]-poled (1 – x)Pb(Mg1/3Nb2/3)O3 – xPbTiO3 (0.28  x  0.33) and [Liv(K1-yNay)1-v](Nb1-zTaz)O3:Mn (v = 0.06, y = 0.1 … 0.3, z = 0.07 … 0.17) crystals serve as piezoelectric components. Comparison of parameters evaluated for the 1–3 composites by means of the matrix method and effective field method is made. Analysed is the role of electromechanical properties of the crystal component in forming the modified figures of merit of the composite. Based on results on modeling the effective properties and related modified figures of merit, advantages of the lead-free 1–3 composite over its analogs based on (1 – x)Pb(Mg1/3Nb2/3)O3 – xPbTiO3 crystals are shown.

Investigation of the mechanical properties of nanocomposite SWCNTS/epoxy by micromechanics methods and experimental works

In the present paper, the stiffening effect of carbon nanotubes is quantitatively investigated by micromechanics methods. The Mori-Tanaka effective-field method is employed to calculate the effective elastic moduli of composites with aligned or randomly oriented straight nanotubes. In addition, the epoxy resin is modified experimentally by adding SWCNT with different ratio i.e 0, 0.1, 0.3, 0.5 and 0.7 wt.-%. A comparison between the results for SWCNT/epoxy nanocomposite which obtained analytically and experimentally is done.In the experimental work the epoxy resin is modified by adding SWCNT with different ratio i.e 0, 0.1, 0.3, 0.5 and 0.7 wt.-%. The materials are characterized in tension to obtain the mechanical properties of SWCNT/epoxy nanocomposite experimentally. The results of micromechanics methods indicated that the CNTs are highly anisotropic, with Young’s modulus in the tube direction two orders of magnitude higher than that normal to the tube. The results shows a nanotube volume fraction of 0.3%of SWCNT improve all mechanical properties such as the tensile strength, modulus of elasticity and the toughness. Avoid the volume fraction greater than 0.5% SWCNT. The optimal value achieved experimentally, (at 0.3% SWCNT) lies between the analytical values (that achieved parallel to the CNT and the randomly orientated straight CNTs).