Determination of the elastic properties of woven composite panels for Lamb wave studies

Abstract

Typically, numerical simulations of Lamb wave propagation are done using material properties which originate from tensile testing. This approach is well established in relation to isotropic homogenous structures such as aluminium plates. However if this approach is used for woven composites such as carbon fibre reinforced plastics (CFRP), inaccuracies can arise that stem from vastly different stress distributions, strain rates and amplitudes during Lamb wave propagation. In order to account for this, an approach is presented where the elastic properties in a numerical Lamb wave model are optimised to achieve good correlation between model predictions and experimental observations. Since the material properties are determined under a Lamb wave propagation regime, the strain rates and amplitudes are consistent with the intended modelling application. The approach is validated with an experimental case study involving a M18/G939 carbon-epoxy system. The methodology is shown to yield property estimates that furnish simulations that closely match observed behaviours. The optimised properties were significantly different to those supplied by the manufacturer, as much as 52% for the in-plane stiffness. The findings demonstrate that large errors are possible if elastic properties determined using conventional quasi-static testing are used in Lamb wave simulations pertaining to woven composite materials.

Damage Evaluation in Woven Glass Reinforced Polyamide 6.6/6 Composites Using Ultrasound Phase-Shift Analysis and X-ray Tomography

“…sample orientations) and therefore can provide all the components of the stiffness tensor and accordingly a complete anisotropic damage evaluation of the tested sample. This method was also extended for use with guided waves in several studies because of their established advantages [11,12]. In the industry one normally do not require full understanding of all physical phenomena involved but rather seek practical and workable techniques that are reliable.…”

Adhesive material property evaluation for improved Lamb wave simulation

“…A Particle Swarm Optimisation (PSO) [32] technique was used to optimise the material properties of the adhesive. The PSO used here is similar to that reported by Ong et al [22] which was used to determine material properties in a woven composite. The optimisation method is presented in a simplified form in Figure 11.…”

“…Similarly, Ambroszinski et al [12] and Ong et al [22] have presented frequency domain methods which iteratively optimise material properties in a model until the output dispersion curves match their experimental target. The present paper follows in the footsteps of these publications and examines three ultrasonics based methodologies for estimating the stiffness of structural epoxy adhesive.…”

Direct-write piezoelectric coating transducers in combination with discrete ceramic transducer and laser pulse excitation for ultrasonic impact damage detection on composite plates

“…The estimated experimental phase velocity was determined from the wavelength, λ, and the corresponding frequency f. In Figure 1, experimental values of S 0 mode are lower than theoretical values because of mechanical data provided for static mechanical test (with differences from dynamic ultrasonic test) and other assumptions in calculation, such as plies isotropy. 27,28 The differences are mainly observed for the S 0 mode. 27 The difference in elastic properties may be as much as 52% and is attributed to the fibre waviness in woven composites.…”