Contour Based Repositioning of Specific Joints of the GHBMC Human Body FE Model

The generation of anatomically correct postures of finite element based Human Body Models (HBM) is indispensable for injury prediction in passive safety analysis. HBMs are often underutilized in industrial R&D since these are typically available only in one posture and do not represent the variability in the human postures in an actual vehicle environment. The work presented in the paper is part of a number of tools being developed for this purpose under a European Union project - Piper. It uses a computer graphic based method for positioning an HBM in the desired posture. In the past the technique has been used for repositioning the knee and pelvic joints of the HBM. The technique has been extended to other joints of the HBM. It ensures that the result is anatomically correct while maintaining its mesh quality. Further, the method needs minimal subjective intervention. In the method, a set of contours are first defined on the given model surface. The space between the contours and outer surface of the bones is discretized into tetrahedrons using the Delaunay Triangulation. The soft tissue nodes are mapped into these tetrahedrons. The bones and contours are given desired affine transformation and later the soft tissue nodes are transformed automatically using the tetrahedron mappings. The methodology has been implemented in a software library and the results have been tested for various mesh quality measures such as Jacobian and Negative Volumes. Overall, the methodology gives anatomically correct postures of HBM with mesh quality comparable to the initially provided mesh. The technique has been implemented on the Piper platform which is a platform being developed for personalization and repositioning of HBMs, and shall be demonstrated on the GHBMC Human Body FE model. Using the Piper application, the final positioned model can be exported into solvers like LS-DYNA and PAMCrash for further analysis.