In this paper we ultrasonic signals from array transducers are simulated using the Thompson and Gray measurement model. The measurement model consists of a beam model, a system efficiency factor which characterizes the response of the electro-mechanical and electrical components of the system, and a flaw scattering model. To inspect layered composite structures with complex geometries such as curvature, a beam model which is non-singular is required. Hence a multi Gaussian beam model for an ultrasonic array which includes the slowness surface parameters for unidirectional CFRP is investigated. The system functions of the ultrasonic array are modelled using a system efficiency model for a rectangular array. The Kirchoff approximation and separation of variables method for far field scattering in anisotropic materials is used to model the far field response of scatterers such as side drilled holes (SDH) in unidirectional CFRP. In summary the ultrasonic measurement model developed is able to predict the signals from scatterers such as side drilled holes (SDH) in transversely isotropic CFRP.

This paper presents results of material characterisation experiments on the hygrothermal viscoelastic behaviour of unidirectional laminates of continuous carbon-fibre reinforced polyamide 6. The material behaviour when subjected to the automotive painting process is of interest. Coefficients of thermal- and -moisture expansion were determined from dilatometer experiments and micrometer measurements together with weighing, respectively. Diffusion coefficients were generated from thermogravimetric analysis and fitted with the Arrhenius equation. Dynamic mechanical analysis and digital image correlation of quasi-static tensile tests were performed to obtain a relaxation curve and a major Poisson's ratio, respectively. The Williams-Landel-Ferry equation was fitted to the time shift factors.

Grid stiffened panels promise increased damage tolerance with reduced weight. Recent progress in automated manufacturing of composites has made it possible to produce such panels at low cost and thus has made them a competitive alternative to traditional skin-stiffened or sandwich panels. Fuselage skin panels typical of a 150 passenger aircraft were designed using an iterative process combining finite element models and local special purpose analysis methods. 40 cm by 30 cm panels, representing the final design, were fabricated using vacuum assisted resin transfer moulding. Pristine and impact damaged panels were tested in compression to failure. A progressive failure model was used to predict the extent and type of damage during impact. It was then combined with the global finite element model to obtain residual strength predictions. Analytical predictions were very close to test results. The fabrication method showed good quality and consistency and, when automated, can be used for production.