Simulating brittle and ductile response of alumina ceramics under dynamic loading

• Published in: Engineering fracture mechanics Vol. 216; p. 106481
• Main Authors: Simons, E.C., Weerheijm, J., Sluys, L.J.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.07.2019; Elsevier BV
• Subjects: Aluminum oxide; Armor; Brittle; Brittleness; Ceramic; Ceramics; Computer simulation; Ductile; Ductile-brittle transition; Dynamic loads; Failure; Johnson-Holmquist; Projectiles; Simulation; Ductile; Ceramic; Johnson-Holmquist; Brittle; Failure
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2019.05.013

•A viscosity regularized Johnson-Holmquist-2 model is used to simulate ceramic.•Four experiments on ceramic are simulated, each with different loading conditions.•Either brittle or ductile response is captured by the original model.•A new failure strain formulation is given, separating tensile/compressive behaviour.•The model now predicts both brittle tensile failure and ductile compressive failure. Alumina ceramic is often used in armour systems. This material is known to have a brittle response under tensile loading, while a ductile response is found when sufficiently high pressures are reached. During projectile impact a ceramic material experiences both tensile loading and high pressures, hence fails in both a brittle and ductile way. Properly capturing the ceramic failure in a single material model remains challenging. A viscosity regularized Johnson-Holmquist-2 model has been used to simulate dynamic loading on alumina ceramic. The simulations show that the brittle and ductile nature of the material can not be captured simultaneously in the current material model. A new failure strain formulation is proposed where the behaviour under tensile and compressive loading can be controlled independently. This allows to properly capture both the brittle and ductile response of the material in a single constitutive framework, with a single set of model parameters.