Full-Field Measurements for Determining Orthotropic Elastic Parameters of Woven Glass-Epoxy Composites Using Off-Axis Tensile Specimens

Abstract

Using theoretical formulations to describe the general response of an orthogonally woven glass‐epoxy composite subjected to off‐axis tension loading, a simple experimental methodology incorporating stereovision and 3D digital image correlation (3D‐DIC) into several optimization procedures is described that provides a direct approach for quantitatively determining all of the elastic properties. During each off‐axis tensile loading experiment, axial strains are determined using both mechanical extensometry and 3D‐DIC, with the 3D‐DIC measurements also used to extract both the in‐plane transverse normal strain and the shear strain fields. The effectiveness of various optimization procedures are then evaluated and compared by performing a series of off‐axis tensile loading experiments to determine the material engineering constants, including E1, E2, G12, and v12 for the nominally transversely isotropic material. Results indicate excellent agreement between the extensometer measurements and the average axial strain obtained by 3D‐DIC. Furthermore, direct comparison of the proposed optimization methods indicates that each method is robust and effective, especially when employing 3D‐DIC to extract additional information to complete the elastic property characterization procedure.

Metrological Performance of Hybrid Measurement Technique Applied for the Lamb Waves Phase Velocity Dispersion Evaluation

“…The semi-analytical finite element (SAFE) method [10], [32] has been used for the theoretical dispersion curves calculation. The elastic properties [33] of the investigated object are presented in Table 1, where the axis x, y, z are marked accordingly as 2, 3, 1. In this case, a generalized stiffness matrix was used to describe a GFRP laminate [34].…”

The effect of off-axis angles on the mesoscale deformation response and failure behavior of an orthotropic textile carbon-epoxy composite

“…Though the off-axis loading regime is uniaxial, multiaxial stress states will be generated due to the spatial variation of fiber orientation, leading to complex load-bearing mechanisms of textile composites from the interaction between the fibers and the matrix. The non-linear stress-strain response of textile composites is often observed in the global stress-strain curves under off-axis tensile loading [4,[14][15][16][17][18]. The mechanical behavior has a strong sensitivity to the alignment of the fibers relative to the external loading.…”

“…The mechanical behavior has a strong sensitivity to the alignment of the fibers relative to the external loading. The angle between the fiber orientation and the loading direction significantly affects the degree of non-linear response [18,19]. Penava et al [20] calculated the elastic constants of four woven fabrics for different fiber angles relative to the loading direction.…”

Comparative Study of Several Methods for the Calculation of Ultrasonic Guided Waves in Composites

“…m . For the modeling of the dispersion curves of Lamb modes, equivalent matrix method[24] was used to find the total stiffness matrix [C] of our material[26] …”