Analysis of the Equation of Motion on the Chest of Hybrid III 3YO Dummy in Dynamic Loads

To investigate the chest loadings of the 3-year-old child occupant in detail using a child restraint system (CRS), a finite element model of sled and energy absorption tubes were established by LS-DYNA. The Sled-CRS FE model in a frontal impact test simulation was conducted utilizing Hybrid III 3-year-old dummy. A method of reproducing crash pulse with the combination of thin-walled circular tubes was used to satisfy acceleration interval requirements of ECE R44 regulation. The equation of motion of chest was established by the internal forces (lower neck, shoulder joint, upper lumbar spine) and external forces (seatbelt force) that are exert on the chest. The simulation results showed that the chest acceleration is related to the external and internal forces. Based on this formula, the mechanism of the chest acceleration that was generated can be examined with time. According to the forces that applied the dummy chest, it is possible to known the load applied to the chest and to judge whether the forces is balanced.