Structural response and strain patterns of isolated ribs under lateral loading

Efforts to mitigate thoracic injury under lateral impact require an understanding of the structural and fracture characteristics of individual ribs under lateral loading. While a number of studies have loaded segments of rib under three-point bending, this study is the first to investigate lateral loading onto entire ribs. Fifteen individual ribs were extracted, positioned upright and a lateral displacement at 1 m/sec was applied. Displacements at the time of fracture were relatively constant across rib levels at 18.3 ± 3.7 mm. Fracture forces ranged from 27 N to 270 N at the anterior extremity and 103 N to 326 N at the posterior extremity; this was also insensitive to rib number. The strain gages indicated that the point immediately opposite the loader on the rib's internal surface experienced the highest tensile strains, while elsewhere the internal surface was in compression and the external surface was in tension. This structural-level rib characterisation can help to better understand the mechanisms of thoracic injury under lateral impact.