Dynamic Pulsebuckling Analysis of FRP Composite Laminated Beams Using LS-DYNA

Buckling and post-buckling of composite structures have been important research topics since composite materials became widely used in engineering. As a result, significant volume of research has been done on their static stability, while relatively less has been devoted on characterizing their dynamic buckling and post-buckling response. The literature became particularly scares when considering the dynamic pulsebuckling and post buckling of axial components subjected to axial impact. This paper, therefore, presents the findings of our finite element analysis of dynamic pulsebuckling response of slender laminated fiber reinforced plastic (FRP) composite beams, with initial geometric imperfection, subject to axial impulse using LS-DYNA. Dynamic pulsebuckling, as an instability form, or in the form of excessive growth of lateral or out of plane displacements, is resulted from a transient loading function of a single pulse with a magnitude greater than the static Euler buckling load. The FRP laminated composite beam with initial geometric imperfection, subject to axial impact of a moving object, is modeled by the Belytschko-Tsay shell element. The moving object is defined as a rigid wall with a mass and initial velocity. Dynamic pulsebuckling of an imperfect beam is characterized by the sudden and drastic increase in the lateral deflection while the axial load bearing capacity remains unchanged relatively when the impact momentum reaches a critical value. Numerical results show that momentum of the moving object may be considered as a viable parameter for predicting the dynamic pulsebuckling limit of the beam. In this investigation, the effect of initial geometric imperfection used to promote instability was investigated and was shown to be a significant factor in promoting pulsebuckling. The effect of boundary conditions was also investigated and the significances of the axial and rotational restraints were demonstrated with numerical examples. A predictive criterion for the onset of pulse buckling was also presented.