Mechanism of transverse mechanical property evolution in bamboo induced by flattening

This study explores how flattening transforms transverse mechanical properties of bamboo through the redistribution of vascular bundles and residual stresses. Using dual-scale characterization and mechanical testing, we reveal that: (1) Flattening enhances transverse strength, with non-notched flattened bamboo achieving peak compression strength (23.3 MPa) and tension strength (9.4 MPa), while notched flattened bamboo excels in the small-size tension test (10.8 MPa); (2) Size effects arise from structural reorganization rather than stochastic defects; (3) Specific strength analysis demonstrates the lightweight advantage of notched flattened bamboo, confirming flattening improves the intrinsic mechanical efficiency beyond densification. These mechanistic insights address critical gaps in engineered bamboo design, enabling tailored applications.