A Finite Element Model of the Lower Limb for Simulating Automotive Impacts

Abstract

A finite element (FE) model of a vehicle occupant's lower limb was developed in this study to improve understanding of injury mechanisms during traffic crashes. The reconstructed geometry of a male volunteer close to the anthropometry of a 50th percentile male was meshed using mostly hexahedral and quadrilateral elements to enhance the computational efficiency of the model. The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The models of the femur, tibia, and leg were validated against Post-Mortem Human Surrogate (PMHS) data in various loading conditions which generates the bone fractures observed in traffic accidents. The model was then used to investigate the tolerances of femur and tibia under axial compression and bending. It was shown that the bending moment induced by the axial force reduced the bone tolerance significantly more under posterior-anterior (PA) loading than under anterior-posterior (AP) loading. It is believed that the current lower limb models could be used in defining advanced injury criteria of the lower limb and in various applications as an alternative to physical testing, which may require complex setups and high cost.

Constant strain rate compression of bovine cortical bone on the Split-Hopkinson Pressure Bar

“…The computational simulation of the complex, dynamic interactions of the human body is becoming a useful and cost-effective research and development tool [2]. This is especially true in hazardous environments such as impact, ballistic and blast loading situations where designs are evaluated for their ability to mitigate injury or improve survivability [3].…”

Development of a lower extremity model for high strain rate impact loading

“…The complete anatomical model is shown and labelled in Figure 1. Material models for anatomical components were determined based on literature (Cox et al, 2007;Glozman and Azhari, 2010;Krone and Schuster, 2006;Untaroiu et al, 2005). Elastic-plastic material models are typical of bone modelling (Gabler et al, 2014;Suresh and Zhu, 2012;Untaroiu and Shin, 2013), thus the plastic-kinematic material model was chosen in the finite element software to capture this material behaviour.…”

“…One limitation of the current finite element model is the exclusion of viscoelasticity in the constitutive description of soft tissue, which is included in some soft tissue formulations (Gabler et al, 2014;Untaroiu et al, 2005). To model the progression of damage, it may be more accurate for the constitutive model to be extended to account for the strain-rate dependent behaviour of soft tissue.…”

“…A variety of extremity poses were also considered in studying the full extremity response. A sensitivity study was undertaken to compare the effect of different hyperelastic material constants in soft tissue, since there is a wide range reported in literature (Kraft et al, 2012;Untaroiu et al, 2005). The sole of a combat boot was incorporated into the model, as in a real world UBB scenario this personal protective equipment would be worn.…”

Development of a Computationally Efficient Full Human Body Finite Element Model

“…A new cortical thickness mapping technique was applied to the coxal bone from CT images and the effects of posture on hip injury tolerance were analyzed (Kim et al 2012;Yue et al 2014). The lower limbs were also tested under complex loading resulting from blunt impacts Shin et al 2012;Untaroiu et al 2013). The fullbody M50-O was validated by mass distribution and in a variety of hub and lateral impacts Park et al 2013;Vavalle et al 2015;Vavalle et al 2012).…”