Loss of Bifurcation in Thin Unsymmetric Composite Ribbons: Fid-Bau Portal

Loss of Bifurcation in Thin Unsymmetric Composite Ribbons

Gupta, Vijay Kumar / Kumar, Abhijeet / Haldar, Ayan

Thin strips or ribbons made of unsymmetric laminates exhibiting multistability have gained prominence in a diverse engineering application such as adaptive aero foils and flaps, deployable space structures, adaptive metamaterials, robots and vibrational energy harvesting designs. They can transform from one stable state to another via snap-through transition. A semi analytical model based on the Rayleigh–Ritz approach is developed to predict the out-of-plane displacements of the two stable shapes of flat unsymmetric composite laminates as they cool from their elevated cure temperature to room temperature. The developed semi-analytical model proved to be computationally efficient means to determine all the stable solutions with reasonable accuracy when compared to corresponding FE models. This study investigates the loss of bifurcation phenomenon in thin unsymmetric composite laminates. After a certain critical aspect ratio, a cross ply unsymmetric laminate plate no longer remained bistable. By using the developed theoretical model and a corresponding FE model, the critical aspect ratio of the plate is determined. The critical aspect ratio after which bistability is lost, depends on various factors such as material properties, dimensions of the laminate, and fiber orientation. The findings provide insights for designing and optimizing thin composite structures, enhancing stability, and improving structural performance. In this work, we investigate on how the critical aspect ratio changes with respect to different families of composite laminates such as cross-plies [90n/0n] as well as angle-plies [−θn/θn] and [(90−θ)n/θn]. By means of these models, we further investigate on how this critical aspect ratio depends on number of layups and the fiber orientation.