Forced vibration analysis of isogrid-stiffened composite plates using VAM-based equivalent plate model

Abstract

The dynamic behaviors of isogrid-stiffened composite plates (SCPs) exhibit new dynamic characteristics as a result of the introduction of composite materials. To accurately and quickly characterize the forced vibration characteristics of the isogrid SCP, its equivalent plate properties were determined by homogenizing over the unit cell and input to a two-dimensional equivalent model (2D-EPM) obtained from the framework of the variational asymptotic approach. Experiments of free and forced vibrations, as well as numerical examples of free vibration under various boundary conditions and frequency-/time-domain forced vibration under single-/multi-point excitation, were performed to validate the accuracy and efficiency of the proposed model. The effects of structural parameters and stiffening schemes on dynamic characteristics were also investigated. Compared to traditional finite element models, the novelty of cell tailoring is a very important feature that significantly facilitates the investigation of the effect of geometric parameters on the dynamic performance of isogrid SCPs. The results showed that the dynamic performance of the antisymmetric angle-ply SCP was significantly better than that of the unidirectional SCP. The stiffener height had a stronger impact on the forced vibration response, and the inclined stiffeners could significantly improve the dynamic performance of stiffened composite plates. The modeling method has high accuracy and efficiency in forced vibration analysis, which is helpful in predicting the fatigue life of an isogrid SCP under a periodic load.