Chest Deflection Mapping between HBM-Connect® 50M and Virtual ATD Models

Human Body Models (HBMs) are increasingly recognized by consumer protection agencies as essential tools for evaluating vehicle safety, complementing the use of traditional Anthropomorphic Test Devices (ATDs). However, HBMs are new for product development and pose challenges in connecting them with the ATDs. These challenges can be overcome if a link is established for the injury metrics between HBMs and ATDs. The study aims to develop a chest deflection mapping function between the HBM Connect^® 50M and three ATD models: Hybrid III 50M, THOR-50M and World SID 50M for thoracic assessment in impact scenarios. Several frontal and lateral thorax loading scenarios were selected from the HBM4VT qualification catalogue (Euro NCAP technical bulletin CP 550), including hub impacts and table-top seatbelt loading tests. Matched-pair LS-DYNA simulations were conducted with HBM Connect^® 50M and the ATD models recording peak chest deflections for developing the mapping function. In the HBM Connect^® 50M model, deflection outputs were defined- analogous to the four IR-TRACCs in THOR-50M, one for sternum potentiometer in Hybrid III 50M and IR-TRACCs analogous to World SID. Three linear regression models were developed: one mapping chest deflections between HBM Connect^® 50M and THOR-50M, second between HBM Connect^® 50M and Hybrid III 50M and the third between HBM Connect^® 50M and World SID 50M. The mapping suggests that a 30mm chest deflection in THOR-50M, Hybrid III 50M and World SID 50M corresponds to approximately 47mm, 58mm and 55mm, in HBM Connect^® 50M suggesting that HBMs are softer and more compliant than ATDs for the torso region. Data points were selected to ensure a coefficient of determination (R²>0.9. Future work will include additional sled cases to further validate and improve these mappings for various impact load case applications. This study establishes chest deflection mapping functions to facilitate the interpretation of HBM Connect^® 50M outputs using established ATD-based chest deflection metrics. A strong correlation is observed with THOR-50M, and a moderate correlation is observed with Hybrid III 50M and World SID 50M.