Hello, world! VIVA+: A human body model lineup to evaluate sex-differences in crash protection

Abstract

Finite element Human Body Models are increasingly becoming vital tools for injury assessment and are expected to play an important role in virtual vehicle safety testing. With the aim of realizing models to study sex-differences seen in the injury- and fatality-risks from epidemiology, we developed models that represent an average female and an average male. The models were developed with an objective to allow tissue-based skeletal injury assessment, and thus non-skeletal organs and joints were defined with simplified characterizations to enhance computational efficiency and robustness. The model lineup comprises female and male representations of (seated) vehicle occupants and (standing) vulnerable road users, enabling the safety assessment of broader segments of the road user population. In addition, a new workflow utilized in the model development is presented. In this workflow, one model (the seated female) served as the base model while all the other models were generated as closely-linked derivative models, differing only in terms of node coordinates and mass distribution. This approach opens new possibilities to develop and maintain further models as part of the model lineup, representing different types of road users to reflect the ongoing transitions in mobility patterns (like bicyclists and e-scooter users). In this paper, we evaluate the kinetic and kinematic responses of the occupant and standing models to blunt impacts, mainly on the torso, in different directions (front, lateral, and back). The front and lateral impacts to the thorax showed responses comparable to the experiments, while the back impact varied with the location of impact (T1 and T8). Abdomen bar impact showed a stiffer load-deflection response at higher intrusions beyond 40 mm, because of simplified representation of internal organs. The lateral shoulder impact responses were also slightly stiffer, presumably from the simplified shoulder joint definition. This paper is the first in a series describing the development and validation of the new Human Body Model lineup, VIVA+. With the inclusion of an average-sized female model as a standard model in the lineup, we seek to foster an equitable injury evaluation in future virtual safety assessments.

Dynamic human body models in vehicle safety: An overview

“…Vehicle safety has improved remarkably over the past century [83] due, in part, to lessons learned from studying simulated crashes using mechanical and computational models of the human body. The broad variety of design and safety considerations that are a part of modern car design have resulted in a correspondingly wide variety of digital models to represent the human form: kinematic models to assess ergonomics [5,97]; multibody models to both analyze recorded motions [12,115] and simulate responses through the phases of a crash [35]; and detailed finite element models to compute the stresses and strains of ATDs [129] and HBMs [10,49,51] throughout the crash phases. This broad array of models and simulation methods motivated us to write this review to help people working in the field both to see what is possible and to make more informed decisions when using simulation in the future.…”

“…Current state‐of‐the‐art HBMs in vehicle safety (Figure 10) include Toyota's Total HUman Model for Safety (THUMS) [51], the VIVA+ [49] models, and the GHBMC [10,30,114] models. Six THUMS model versions have been developed and evaluated [121] since 2000.…”

“…Addressing gender diversity, includes a detailed head-neck model [95] Virtual testing in vehicle safety assessment of (standing) vulnerable road users [49] Comments Open access, head and neck submodel for speedup available [102] Abbreviations: F: female; M: male; number corresponds to percentile; YO: year-old; O: occupant model; P: pedestrian model. class of HBMs are RAMSIS [5] and Jack [97] which are both connected to anthropometric databases to evaluate the ergonomics of a specific age, sex, or population.…”

“…A wide variety of models have been developed to balance detail against simulation time for the many crash scenarios that must be considered during the design phase. Current state-of-the-art HBMs in vehicle safety (Figure 10) include Toyota's Total HUman Model for Safety (THUMS) [51], the VIVA+ [49] models, and the GHBMC [10,30,114] models. Six THUMS model versions have been developed and evaluated [121] since 2000.…”

“…The default positions of most models are either standing postures of pedestrians or seated postures of car occupants. Three state-of-the-art models in the LS-Dyna software environment are used: the VIVA+ 50F and 50M [49,89], the THUMS [51], and the GHBMC [30] models (Figure 10). The posture of a motorcyclist is determined by their anthropometric measurements and the geometry of the motorcycle.…”