Unlike car occupants, pedestrian crashes occur in a variety of postures (like stationary, walking, running or jogging etc). Muscle contraction, required to maintain the initial posture, modifies the load at the knee joint in rapid loading conditions. This study investigates the effect of muscle active forces on lower extremity injuries for various impact locations and impact angles for a freely standing pedestrian. Three different pre-impact conditions of a freely standing pedestrian, representing a cadaver, an unaware and an aware braced pedestrian, have been simulated for each impact orientation. Stretch based reflexive action was included in the simulations for an unaware pedestrian. It is concluded that strain in knee ligaments is dependent on impact locations and angles and the MCL is the most vulnerable ligament. Further, due to muscle effects, except when the impact is on the knee, peak strain values in all the ligaments are lower for an unaware pedestrian than either for a cadaver or for a fully braced pedestrian.
Keywords:
Muscle Contraction; Hill Muscle Model; Pedestrian Safety; Knee Injury; Finite Element Modeling