Residual stress measurements in CFRE and GFRE composite missile shells

The present paper presents the work developed utilizing a simple, sensitive, non-contact, quantitative technique for evaluating residual stresses in composite missile components. The proposed technique is a combination of the slitting technique accompanied with image processing analysis to measure displacements caused by relieving residual stresses. The technique has been applied to two types of composites: filament wound carbon/epoxy and filament wound glass/epoxy. The results for radial and tangential residual stresses along the thickness have been obtained. The tangential (hoop) stresses are at least one order of magnitude higher than those in the radial direction. The maximum tangential residual stresses occur at the boundaries, while the maximum radial residual stresses are near the mean radius. The statistical analysis shows that the scatter in the glass/epoxy results is higher than the other sampled materials.