Development and Validation of Subject-Specific Finite Element Models for Blunt Trauma Study

Abstract

This study developed and validated finite element (FE) models of swine and human thoraxes and abdomens that had subject-specific anatomies and could accurately and efficiently predict body responses to blunt impacts. Anatomies of the rib cage, torso walls, thoracic, and abdominal organs were reconstructed from X-ray computed tomography (CT) images and extracted into geometries to build FE meshes. The rib cage was modeled as an inhomogeneous beam structure with geometry and bone material parameters determined directly from CT images. Meshes of soft components were generated by mapping structured mesh templates representative of organ topologies onto the geometries. The swine models were developed from and validated by 30 animal tests in which blunt insults were applied to swine subjects and CT images, chest wall motions, lung pressures, and pathological data were acquired. A comparison of the FE calculations of animal responses and experimental measurements showed a good agreement. The errors in calculated response time traces were within 10% for most tests. Calculated peak responses showed strong correlations with the experimental values. The stress concentration inside the ribs, lungs, and livers produced by FE simulations also compared favorably to the injury locations. A human FE model was developed from CT images from the Visible Human project and was scaled to simulate historical frontal and side post mortem human subject (PMHS) impact tests. The calculated chest deformation also showed a good agreement with the measurements. The models developed in this study can be of great value for studying blunt thoracic and abdominal trauma and for designing injury prevention techniques, equipments, and devices.

Finite Element Modeling of Blast Lung Injury in Sheep

“…A solid hexahedral mesh was created using the outer surface of the thorax, and boundaries of the soft tissue and thoracic organ components were defined by the boundaries observed in the CT images. The outermost layer of hexahedral elements was designated as skin, and all hexahedral elements between the skin and ribcage were designated as soft tissue with the material properties of bulk muscle taken from [17]. A shared node model was used for the solid elements to eliminate contacts at the soft tissue boundaries that can lead to numerical instabilities during a dynamic simulation.…”

Promoting Innovation and Convergence in Military Medicine: Technology-Inspired Problem Solving

“…Previous and continuing efforts by Dr. James Stuhmiller (Jaycor, Inc. San Diego, CA) have developed a very important family of predictive models for developers of new military systems to ensure protection of human operators. These models include prediction of health and performance risks associated with blast overpressure of new high powered weapons systems [42,43], survivability in burning vehicles and aircraft [44], evaluation criteria for new lighter weight body armor systems [45], and improved helmet design to withstand forces acting on the head. These convergent modeling efforts by Dr. Reifman and Dr. Stuhmiller have advanced the analysis of years of discovery research data, substantially reduced the need for animal tests, and improved current protection of soldiers [46].…”

Human rib response to different restraint systems in frontal impacts: a study using a human body model

“…A straincontrolled fracture onset is supported by some researches [27,39]. Others have reported successfully predicting bone fractures using stress [15,36]. Furthermore, bone has different failure thresholds depending on the loading modes; it is weakest in tension or shear and strongest in compression [40].…”