Modeling red blood cell deformation under high shear and extensional stresses

Studying red blood cells (RBCs) under high-stress conditions is essential for understanding their mechanical response and the onset of sub-hemolytic damage. In this work, we present a comprehensive computational investigation of RBC behavior under high shear and extensional flow conditions. We begin with a systematic evaluation of RBC membrane models through a series of mechanical tests to identify formulations capable of capturing large deformations. Both one-component and two-component models are then employed to simulate RBC dynamics in pure shear flow and hyperbolic nozzle configurations, with results validated against experimental measurements of cell deformation. The developed framework demonstrates strong quantitative and qualitative agreement with experimental observations across a wide range of loading conditions, establishing a robust platform for modeling RBC mechanics under high stress. As a secondary contribution, the two-component model is used to examine bilayer–cytoskeleton bond dissociation as a mechanistic indicator of sub-hemolytic damage. RBCs are subjected to a numerically generated pure extensional field, and dissociation events are analyzed within a reduced-time framework. The results show that increasing extensional stress promotes earlier onset of dissociation in a non-dimensional sense and reveal a threshold-like transition in dissociation behavior around approximately 15 Pa, where significantly greater exposure is required to initiate bond failure. Furthermore, extensional stresses exhibit a substantially higher propensity for damage initiation compared to shear stresses at equivalent magnitudes. These findings provide a mechanistic perspective on stress-dependent damage initiation while highlighting the importance of extensional loading in RBC integrity.