Effects of obesity on occupant responses in frontal crashes: a simulation analysis using human body models

Abstract

The objective of this study is to investigate the effects of obesity on occupant responses in frontal crashes using whole-body human finite element (FE) models representing occupants with different obesity levels. In this study, the geometry of THUMS 4 midsize male model was varied using mesh morphing techniques with target geometries defined by statistical models of external body contour and exterior ribcage geometry. Models with different body mass indices (BMIs) were calibrated against cadaver test data under high-speed abdomen loading and frontal crash conditions. A parametric analysis was performed to investigate the effects of BMI on occupant injuries in frontal crashes based on the Taguchi method while controlling for several vehicle design parameters. Simulations of obese occupants predicted significantly higher risks of injuries to the thorax and lower extremities in frontal crashes compared with non-obese occupants, which is consistent with previous field data analyses. These higher injury risks are mainly due to the increased body mass and relatively poor belt fit caused by soft tissues for obese occupants. This study demonstrated the feasibility of using a parametric human FE model to investigate the obesity effects on occupant responses in frontal crashes.

A Simulation Study on the Efficacy of Advanced Belt Restraints to Mitigate the Effects of Obesity for Rear-Seat Occupant Protection in Frontal Crashes

“…In the study of Kent et al (2010), several tests were performed using 3-point belt-restrained obese cadavers (mean BMI value of 40.1 kg/m 2 ) and 5 non-obese cadavers (mean BMI value of 20.3 kg/m 2 ). In our previous work (Shi et al 2015), simulations using the human body models with BMI 20 and 40 kg/m 2 predicted very similar trends in body excursions as those in the cadaver tests reported by Kent et al (2010). …”

“…In our previous work (Shi et al 2015), different FE human body models representing occupants with different BMIs (20, 25, 30, 35, and 40 kg/m 2 ) and a stature of 175 cm were generated using mesh morphing techniques based on the THUMS 4 mid-size male model. The human models with different BMIs were validated against several sets of cadaver tests, including abdomen high-speed loading test (Foster et al 2006) and whole-body cadaver rear-seat sled tests (Forman et al 2009a).…”

“…By conducting cadaver tests, Forman et al (2009aForman et al ( , 2009b found that obese occupants experienced greater head, torso, and knee excursions; higher chest deflections; and higher submarining tendencies than lower BMI occupants. Computational studies by Turkovich (2011), Turkovich et al (2013), and Shi et al (2015) also showed that an increase in BMI may significantly increase the chest and lower extremity injury risks for front-seat occupants in frontal crashes. It was found that these increased injury risks are associated with greater mass-and body shape-induced poor belt fit for obese occupants.…”

Computational Modeling of Traffic Related Thoracic Injury of a 10-Year-Old Child Using Subject-Specific Modeling Technique

“…The radial-basisfunction method has been widely used for mesh morphing on different types of subjects and different body regions in the past, 14 including the pediatric head, 19,20 the adult rib cage, 39 the femur, 18 and even the wholebody. 38 Therefore, we believe that this method is suitable for this study.…”

“…This method has been used previously to generate parametric, human FE models. 19,38 Thin plate spline function (u r ð Þ ¼ r 2 log r) was used as the basic function for the RBF, because it generated a smooth geometry with good mesh quality. 20 To conduct mesh morphing, 2967 landmarks were selected from the baseline and target models to define the deformation field, and then a landmark-based RBF interpolation was conducted to calculate the new coordinates of all elements throughout the body, including the skeleton and soft tissues.…”