This study was motivated from field observation of severe and fatal injuries to abdominal solid organs in side impacts, and the necessity to assess these injuries when using a full-body human model in the development of restraint system devices. The goal of this work was to develop and validate model-based injury criteria for the spleen and kidneys in side impacts.

Takata’s existing in-house full-body human model was used to develop and validate the injury criteria for the spleen and kidneys. At the tissue and organ level, meshes of both the spleen and kidneys were refined, and the material models for these organs were validated against test data generated from multiple sources at different loading rates. At the whole body level, three series of post-mortem human subjects (PMHS) tests were selected for the model validations, which include Wayne State University PMHS linear side impact cases (Chung, et al. 1999), and Medical College of Wisconsin (MCW) PMHS side airbag (SAB) static and dynamic out-of-position (OOP) test cases (Hallman, et al. 2010). To quantify the SAB loading, a generic SAB model in MCW’s OOP tests was characterized according to the MCW setup (Hallman, et al. 2009) with the same level of deployment energy and the same airbag volume and dimensions. The PMHS test validation results showed very good correlation with the force-displacement corridors developed from the existing literature for the spleen and kidneys. Chest deformations at the Axilla, Xyphoid, and T10 level were validated against chest band measurements, as were accelerations at T1, T12, and the sacrum. Finally, forces from rigid loading plates at the thorax, abdomen, and pelvis regions were all validated against the tests.

To develop the injury criteria for the spleen and kidneys, different measures for the tissue injuries were evaluated against the selected PMHS test data, including:​ principal stress, principle strain, and strain energy density (SED). It was found that the tolerances of the stress and strain-based injury measures varied widely with the PMHS test set-up, loading conditions, and modeling methods. Comparatively, peak SED showed much less variability and therefore SED is proposed as the indicator of injury risk for both the spleen and kidney. The injury thresholds for the spleen and kidney are 35KJ/m³ and 27KJ/m³, respectively, for the current study, which are consistent with both the tissue-level material test data reported from the literature and the PMHS full body side impact tests.