On the behavior of composite shells under transverse impact and quasi-static loading

Abstract

The impact and quasi-static response of various composite shell structures to transverse loading was studied experimentally. In particular, the effect of varying structural parameters (radius, span, and thickness) on the loading response, including damage resistance, is explored. The AS4/3501-6 graphite/epoxy composite structures considered have a [±45 n /0 n 1s layup configuration (n = 1, 2, 3) and include convex and concave shell sections, plates, and full cylinders. All structural parameters are found to affect the response, particularly characteristics of the instability associated with the convex shell behavior and the structural stiffness. Trends with regard to peak force and structural stiffness with the structural parameters are established and discussed. Specimen thickness is noted to have the greatest effect of all the parameters, but shell radius is clearly important due to the instability that it introduces. Damage resistance trends with structural parameters are established and linked to peak force. Although linked to peak force, these damage trends are also found to be dependent upon whether the peak force occurs before or after the shell instability. The results of this work establish the effects of structural parameters on the general response characteristics, including damage resistance, of composite shells under transverse loading with application to low-velocity impact. Thus, these results provide benchmark data for comparison with analytical and numerical, e.g., finite element, studies. Suggestions for areas of further work are provided.