Multi-scale stochastic dynamic analysis of a damaged pretwisted composite strip

This paper proposes a stochastic approach for estimating the natural frequencies of reducible composite strips. The framework accounts for multi-scale uncertainty at micro, meso, and component levels; additionally, it accounts for damages due to matrix cracking and delamination in a pretwisted composite strip. An asymptotically accurate Variational Asymptotic Method (VAM) based model for cross-sectional stiffness is coupled with a one-dimensional Finite Element Method (FEM) approach for the determination of natural frequencies of the pretwisted strips. The proposed model is validated by comparing the deterministic natural frequencies of composite strips with experimental and numerical results reported in the literature. The quantification of uncertainty is carried out by determining the probabilistic variations in the first three natural frequencies of the strips and analyzing the local and global sensitivity measures. The study identifies the uncertainties in material attributes, addressed at micro and macro levels, influencing the free vibration response of the strips.