Modeling of Indentation on Wooden Surface in Drop Tower Impact

Wood is a lightweight material that finds applications in sports equipment and structural members despite the advent of many advanced synthetic composite structures. This paper investigates the inelastic percussion mechanics of wood in low-speed impact events like drop-tower impact experimentally, theoretically, and numerically. A 22 kg tup, mounted with a hemispherical punch, is dropped onto wooden plates from a specific height. Indentation followed by secondary cracking observed on the surface of the wood is analyzed from the Hunt-Crossley approach in formulating contact force model, phase diagrams and impact parameters. A simple elastoplastic numerical model aids in understanding indentation and damping, despite wood being an orthotropic material. The phase diagrams show that the damping effect due to indentation renders a coefficient of restitution (COR) less than or equal to 0.4. Additionally, the results reveal the vibromechanics effect (damping and kinematic restitution coefficient) on interaction forces between the tup and plate.