Shear forces at sitting interfaces are a major contributing factor in pressure injury formation. However, measuring shear forces throughout the sitting interface is not possible due to a lack of shear sensors for this application. This paper presents a finite element simulation model for an automated air cell smart seat cushion that can predict shear forces at the interface. The model was developed and validated by comparing static analyses to experimental data, with respect to interface pressure, internal air cell pressure, and interaction forces. The real-time experimental data in this study was generated from three different sources: 1) A commercial seating pressure mat yields an interface pressure map, 2) The smart seat cushion yields the internal pressure of air cells, and 3) The rigid cushion loading indenter yields the immersion into the cushion and the force applied on the cushion. The validated simulation model was used to evaluate shear force data at the sitting interface corresponding to different loading scenarios.