OxDEM: Discrete element method based on strain energy formulation

• Novel DEM derives both normal and tangential forces exclusively from strain energy. • Energy dissipation emerges naturally, no explicit friction coefficient required. • Benchmarks show consistent particle dynamics and emergent dissipation. • OxDEM bypasses parameter calibration, enhancing modelling reliability. • Framework supports future extensions to fluid-particle and non-spherical systems. This study introduces OxDEM, a novel strain-energy-based formulation of the Discrete Element Method, in which both normal and tangential contact forces are derived exclusively from strain energy. Unlike the widely used Hertz-Mindlin approach that relies on empirically calibrated stiffness and friction parameters, OxDEM eliminates the need for such inputs. Tangential interactions emerge naturally from relative velocities and shear strains, introducing an intrinsic dissipation mechanism without requiring empirical parameters. A series of benchmark simulations, ranging from single-particle impacts to multi-particle settling, demonstrate that OxDEM reproduces physically consistent dynamics, including energy transfer, emergent dissipation through tangential interactions, and collective particle rearrangements, while avoiding artefacts linked to parameter calibration. The present formulation deliberately omits explicit damping forces to isolate the core mechanics, leaving their incorporation for future development. By unifying normal and tangential responses under a common strain energy framework, OxDEM establishes a physically grounded and parameter-efficient pathway for predictive modelling of granular systems, with clear potential for extension to fluid-particle systems and non-spherical discrete element interactions.