Rapid assessment method to predict the failure modes of laminated bamboo composites

Laminated bamboo is a promising material with mechanical properties comparable to structural timber. The lack of technologies available to assess its structural integrity limits the use of laminated bamboo as a reliable building material. Modelling failure is of specific importance to guarantee the structural preservation of any material. Currently, no methods are developed to assess the deformation and failure of laminated bamboo rapidly. Attempts have been made at modelling the mechanical behaviour of laminated bamboo using numerical methods. However, these methods require a considerable number of computational resources and time. Moreover, they do not acknowledge how the cellular structure of bamboo strips affects the material's behaviour. The use of geometric methods can help overcome these limitations. The present study focuses on developing a geometric-based method to assess and predict laminated bamboo composites' failure rapidly. A series of tensile, compressive and shear experiments were carried out on small-sized pieces to achieve this objective. The original configuration of the specimens, as well as their deformation and failure, were recorded with a High-Resolution Camera. Simultaneously, deformation fields were determined using Digital Image Correlation. The experiments suggest that the distribution of bamboo fibres and their geometric arrangement are the features that will determine the failure mechanisms of the composites. As such, a series of geometric relationships and algorithms were developed to predict the deformation and failure of laminated bamboo by acknowledging the physical features of the pieces before loading. The primary input of the algorithms is a picture of the un-deformed specimens where the areas with fewer bamboo fibres are highlighted. Then, an array of points is used to describe the original and deformed states of the pieces. Finally, a tracking algorithm determines the most likely fracture geometry. The mathematical parameters that define the displacement of points and the fracture geometry are based on a geometric analysis of the findings of the experimental program. The study results suggest that the proposed methodology does approximate the actual behaviour of laminated bamboo. Moreover, it strongly suggests that the application of geometric methods is a novel approach that could signal new avenues to understand and predict the behaviour of laminated bamboo as a structural element.