This study presents the dynamic analysis and experimental validation of a modular prosthetic foot designed for integration within an active transfemoral robotic prosthesis (SmartLeg). The work focuses on quantifying the time-dependent biomechanical response of the foot during gait and stair approach, with emphasis on load transfer, energy absorption, and propulsion. The proposed design features a segmented structure with an articulated forefoot, enabling controlled dorsiflexion and improved replication of physiological foot behavior. Dynamic performance was evaluated using finite element analysis (FEA) under representative loading conditions and experimental plantar pressure measurements obtained via a Zebris system. Ground reaction force profiles were normalized to body weight and analyzed across the stance phase. Statistical analysis using repeated-measures ANOVA indicated no significant difference in early stance loading between walking and stair approach (p > 0.05). However, late stance propulsion forces were significantly higher during stair initiation (p < 0.001), with a mean increase of 0.61 F/G (95% CI [0.52, 0.70]).The results demonstrate that the prosthetic foot exhibits stable dynamic behavior and sufficient structural reliability. Moreover, forefoot pressure patterns provide a robust indicator of locomotion intent, supporting the development of predictive, sensor-driven control strategies for adaptive prosthetic systems.