A new HBM simulation based approach for improved thorax dummy injury criteria

Abstract

To assess occupant safety in a crash test, dummy criteria relating the dummy measurement to injury risk are needed. The development of these criteria and functions are usually based on matched dummy and Post Mortem Human Surrogate (PMHS) tests by relating the observed PMHS injuries to dummy measurements. The limitation with this approach is that there are few matched PMHS and dummy tests available and the new tests are complicated to perform. To overcome the limitations with this approach and extend the data set, within the EC funded project SENIORS a computer model simulation based approach was applied.

Matched frontal impact sled simulations were conducted with a model representing the latest THOR-M version and matching simulations with a human body model (HBM) representing an elderly car occupant. The HBM that was used for this study is THUMS-TUC, with modified rib cage, which was developed within the SENIORS project. Details of the modifications including material and geometry changes will be explained in detail.

A key part of the methodology was based on rib fracture risk predicted by a probabilistic method. With this method for each load case an injury probability to sustain a certain number of fractured ribs was predicted by comparing local strain values to the distribution of cortical rib ultimate strain adjusted by age. By relating this probability to multi-point dummy injury criteria like PCA or Rmax a risk curve was calculated by statistical methods.

This presentation will show and discuss first results of this new approach. Furthermore, a focus will be to discuss requirements towards the applied human body model regarding the necessary level of biofidelity and injury prediction capability to be used for this approach. This will be done based on comparison to literature PMHS data and new PMHS data from SENIORS tests.