Influence of fibre orientation and stacking sequence on petalling of glass/polyester composite cylindrical shells under axial compression

The energy absorbing capability of FRP composite cylindrical tubes used as energy absorbers, by destroying itself progressively, depends on the way in which the tube material is crushed i.e., trend of petalling. This paper investigates the influence of fibre orientation and stacking sequence on the petal formation and specific energy absorption (SEA) of four and six-ply, 0°/90° glass/polyester composite cylindrical shells under axial compression. Number of petals formed and the trend of petalling are changed with proportion of axial (0°) and circumferential (90°) fibre content and stacking sequence in the tubes. In the tubes undergo petalling, presence of axial fibres close to inner surface and the proper proportion of circumferential fibres close to outer surface of the tube wall lead to higher energy dissipation. The axial fibres placed nearer to outer surface leads to more number of petal formation, leading to a stable crushing mechanism. The contribution of mode I strain energy release rate (GIc) to the energy dissipation in the form of circumferential delamination is also studied with double cantilever beam (DCB) tests. Analytical model which considers petalling is developed, and used to predict the mean crush load and SEA of cylindrical composite shells under axial compression. Results from the analytical model agree well with experimental results and are presented.