Energy-absorbing wood composite for improved damage tolerance inspired by mollusc shells

The crossed lamellar structure (CLS) found in mollusc shells is an excellent example for nature's ability to form complex hierarchical microstructures with a remarkable balance between strength and toughness. The CLS has become the subject of numerous studies focusing on the replication of the unique microstructure using synthetic composites. The present study proposes a wood composite replicating the CLS' middle layer microstructure and investigates the mechanical properties using three-point bending tests. The morphology of the failure mechanisms is recorded using digital microscopy and the experimental data are compared to those from ply- and solid woods. The results show a successful replication of the dominating failure mechanisms of crack deflection and crack bridging. While strength decreased significantly by similar to 60%, toughness increased remarkable by similar to 70% compared to plywood and was in the range of solid wood. The small data scattering from the wooden CLS samples compared to solid wood further hints on a stable failure mechanism and uniform energy-absorption. The results document that wood can be used to design an energy-absorbing composite based on the CLS-inspired ductile microstructure.