Publication of: Society of Automotive Engineers 

About: Publication of: Society of Automotive Engineers is an academic journal. The journal publishes majorly in the area(s): Rollover & Crashworthiness. Over the lifetime, 404 publications have been published receiving 3410 citations.

Finite element modeling approaches for predicting injury in an experimental model of severe diffuse axonal injury

Abstract: Traumatic brain injury (TBI) finite element (FE) analyses have evolved from crude geometric representations of the skull and brain system into sophisticated models which take into account distinct anatomical features. Two distinct FE modeling approaches have evolved to account for the relative motion that occurs between the skull and cerebral cortex during TBI. The first approach assumes that the relative motion can be estimated by representing the cerebrospinal fluid inside the subarachnoid space as a low shear modulus, virtually incompressible solid. The second approach assumes that the relative motion can be approximated by defining a frictional interface between the cerebral cortex and dura mater. This study presents data from an experimental model of TBI coupled with FE analyses to evaluate the modeling approach's ability to predict specific forms of TBI. Axial plane rotational accelerations produced prolonged traumatic coma in the miniature pig, axonal injury throughout regions of the white matter, and macroscopic hemorrhagic cortical contusions. Results from 2-dimensional FE analyses of the miniature pig showed that the manner in which the modeling approach accounts for the relative motions occurring between the skull and cerebral cortex can dramatically influence the outcome of an analysis. This study clearly demonstrated that the modeling approach which represented the relative motion between the skull and cerebral cortex as a frictional interface best predicted the resulting injury pattern in a 5th axial plane animal experiment.

Development of a finite element model of the human neck

Abstract: A 3-dimensional finite element model of a human neck was developed to study the mechanics of cervical spine while subjected to impacts. The neck geometry was obtained from MRI scans of a 50th percentile male volunteer. This model consisting of vertebrae C1-T1 was constructed primarily of 8-node brick elements. Vertebrae were modeled using linear elastic-plastic materials and the intervertebral discs were modeled using linear viscoelastic materials. Sliding interfaces were defined to simulate the motion of synovial facet joints. A previously developed head and brain model was also incorporated. Only the passive effects of the head and neck muscles were considered. Data from head drop tests performed at Duke University and data from 3, 24 km/hr cadaver rear-end impact sled tests were used to validate the model. The validated model was integrated into a skeleton torso model previously developed to simulate a 50th percentile male driver in a 48 km/hr impact with a pre-deployed airbag. This simulation was similar to that reported by Cheng et al. In this application, the kinematics and airbag pressure predicted by the model compared with experimental data. None of the airbags used in the simulations or experiments represent any currently in production. Further research is still needed to fully validate the model before it can be used to study neck loads during head-airbag or other serious injury interactions.

Rollover crash tests - the influence of roof strength on injury mechanics. in: occupant and vehicle responses in rollovers

Abstract: There has been ongoing research and discussion regarding the effect of roof strength on rollover protection since the 1950s. This chapter on the influence of roof strength on injury mechanics is from a comprehensive text on occupant and vehicle responses in rollovers. In this chapter, the authors report on a series of eight lateral dolly rollover tests that were conducted on 1983 Chevrolet Malibus at a speed of 32 mi/h (51.5 km/h). Four of the vehicles had rollcages; four had standard production roofs. Numerous cameras documented the vehicle and Hybrid III dummy movements during the tests. Results showed that, for both roof structures, the dummies moved upward and outward from their seats due to rotation and acceleration of the vehicle. High head/neck loads were measured when the head contacted a part of the car experiencing a large change in velocity (often that part of the car that struck the ground). The authors conclude that roof strength is not an important factor in head/neck injuries in rollover accidents for unstrained occupants. In addition, there was no significant difference in the occupant kinematics between standard and rollcaged vehicles. However, the vehicles with rollcages had less glass breakage. The chapter includes extensive appendices that reproduce photographs from each of the 8 tests.

Development of a 3d finite element model of the human body

Abstract: Even though computational techniques are now very common in automotive safety engineering, there is still a need for further development of biofidelic tools for assessing human responses in crash situations. The authors of this paper designed a 3D finite element model of the human body and constituted a large experimental database for the purpose of validation. The geometry of the seated 50th percentile adult male was chosen for the model. The number of elements used to represent the anatomy was limited to 10,000. Material laws come from existing literature and when necessary, parameter identification processes were used. Special attention was paid to the constitution of the validation database. Boundary conditions and results from most of the available cadaver and volunteer experiments were analyzed. More than 30 test configurations were selected, including sled, impactor, and belt compression tests with a wide range of energy levels and in frontal, lateral, and oblique directions. 120+ corridors were derived and integrated into the development of the validation phase. The model behavior was evaluated in the light of a set of impacts in a vehicle environment. The validation database is described in detail and correlation obtained between model responses and experimental results is shown. Uses of the model are discussed.

Rollover stability index including effects of suspension design. in: occupant and vehicle responses in rollovers

Abstract: With the growing popularity of vehicles with high centers of gravity, the evaluation of rollover propensity of these vehicles becomes an issue of increasing importance. This chapter on a rollover stability index is from a comprehensive textbook on occupant and vehicle responses in rollovers. The author proposes a simple model to predict vehicle propensity to rollover; the model includes the effects of suspension and tire compliance. The model uses only a few parameters, most of which are known at the design stage. The author compares the lateral accelerations at the rollover threshold that are predicted by the model to the results of simulations. In the simulations, vehicles with the same static stability factor, but with different suspension characteristics and payloads, are subjected to roll-inducing handling maneuvers. The results of simulations correlate well with the predictions based on the proposed model. An analytical expression for the optimal roll center height from the viewpoint of rollover resistance was developed.