Multiscale approach for identification of transverse isotropic carbon fibre properties and prediction of woven elastic properties using ultrasonic identification

Abstract

In this work the possibility to reverse engineer the transverse isotropic carbon fibre properties from the 3D homogenized elastic tensor of the UD ply for the prediction of woven ply properties is explored. Ultrasonic insonification is used to measure the propagation velocity of both the longitudinally and transversally polarized bulk waves at various symmetry planes of a unidirectional (UD) Carbon/Epoxy laminate. These velocities and the samples' dimensions and density are combined to obtain the full 3D orthotropic stiffness tensor of the ply. The properties are subsequently used to reverse engineer the stiffness tensor, assumed to be transversely isotropic, of the carbon fibres. To this end, four micro-scale homogenization methods are explored: 2 analytical models (Mori-Tanaka and Mori-Tanaka-Lielens), 1 semi-empirical (Chamis) and 1 finite-element (FE) homogenization (randomly distributed fibres in a Representative Volume Element). Next, the identified fibre properties are used to predict the elastic parameters of UD plies with multiple fibre volume fractions. These are then used to model the fibre bundles (yarns) in a meso-scale FE model of a plain woven carbon/epoxy material. Finally, the predicted elastic response of the woven carbon/epoxy is compared to the experimentally obtained elastic stiffness tensor. The predicted and measured properties are in good agreement. Some discrepancy exists between the ultrasonically measured value of the Poisson's ratio and the predicted value.Nonetheless, it is shown that virtual identification and prediction of mechanical properties for woven plies is feasible.

Characterization of the orthotropic viscoelastic tensor of composites using the Ultrasonic Polar Scan

“…The results following the second stage of the inversion are summarized in the fourth column of Table 3 and the match between the experimental polar plot and prediction based on the inversion parameters is visualized by a difference amplitude polar plot in Figure 12b. A comparison of the associated elastic engineering constants (in the notation E ii , ν ij and G ij ) with values obtained and estimated from literature [24][25][26] (last three columns of Table 3) reveals that the inverted elasticity constants are within the expected range for a unidirectional carbon-epoxy material. In the study of Degrieck [24], these engineering constants are obtained through tensile tests of a UD C/E plate with a similar fiber volume fraction V f of approximately 55% as used here.…”

“…A comparison of the associated elastic engineering constants (in the notation E ii , ν ij and G ij ) with values obtained and estimated from literature [24][25][26] (last three columns of Table 3) reveals that the inverted elasticity constants are within the expected range for a unidirectional carbon-epoxy material. In the study of Degrieck [24], these engineering constants are obtained through tensile tests of a UD C/E plate with a similar fiber volume fraction V f of approximately 55% as used here. Italic values represent estimations of parameters which cannot be determined by the experimental technique.…”

Improving the Deformability and Recovery Moment of Shape Memory Polymer Composites for Bending Actuators: Multiple Neutral Axis Skins and Deployable Core

“…This MNA effect plays an important role during the shape programming process where large deformation occurs under a temperature of 70 °C. For this reason, the axial direction elastic modulus was measured from the tensile test at the elevated temperature of 70 °C, and the other material properties of SMPC were referred and estimated by previous studies − as shown in Table S2. The boundary condition of the bending test is shown in Figure S5.…”

Comparative study of ultrasonic techniques for reconstructing the multilayer structure of composites

“…When defining the effective mass density of the ply, the rule of mixture is applied, assuming a density of the carbon fibers of 1800 ∕ 3 . The stiffness matrix for each ply is calculated by the Chamis model [57] from the properties of carbon fiber [58] and epoxy matrix. The longitudinal wave velocity propagating in the thickness direction is then calculated from the stiffness matrix.…”