Low-velocity impact on carbon/epoxy tubes subjected to torque – Experimental results, analytical models and FEM analysis

This paper investigates the effect of torsional loads on the damage introduced by lateral impacts on cylindrical T300-carbon/epoxy specimens. A total of 16 specimens were subjected to a 7 J transverse impact under various torsional preloads. Four different lamination sequences were studied. A two-degree-of-freedom spring-mass model was developed to investigate the impact dynamics. To account for the damage propagation, a non-linear model of the tube flexural stiffness is proposed. Moreover, impact damage initiation was studied in detail by various FEM analyses. For each laminate, results show an invariant delamination threshold contact force, suggesting that the delamination initiation is not affected by the torsional preload. On the other hand, as evidenced by the variation in the contact duration and the tube maximum deflection, delamination propagation is highly affected by the torsional load.