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Investigations were made on computational analyses of ejection seat cushions, which include the characterization of the impact properties of ejection seat cushions, computational modeling of an ejection seat cushion system using a rigid multi-body dynamics program, parametric optimization of the cushion impact properties, and global sensitivity analysis of the safety performance of a cushion to its impact properties. The results indicate that computational analyses can be used to effectively evaluate and improve the cushion performance in the prevention and reduction of spinal injuries.

The performance of inflatable toepan padding for mitigating lower limb injuries was investigated. A rigid multi-body model was used to describe the scenario of an occupant in an automobile frontal crash with toepan intrusion. The emphasis was placed on the lower limb responses during impact. The interaction between the lower limbs and the inflatable toepan padding was described by the contact between the feet and the load distribution plate of the padding. Computational simulations were performed to analyze the effects of the controlled motion of this plate on the lower limb impact responses.

This paper presents efforts made on the computational modeling and simulation of out-of-position occupant-airbag interaction. The airbag was modeled using the finite element method with LSDYNA. Static airbag deployment tests were performed to support and validate computational modeling efforts. A 50-segment rigid body model was developed for the 5th percentile Hybrid-III female dummy using the Articulated Total Body (ATB) model program. This occupant model allows for the detailed simulation of occupant responses in several body regions. The system that describes out-of-position occupant-airbag interaction in frontal crashes, including airbag, occupant, and major vehicle structures, was modeled through the integration of the rigid body occupant model with the finite element airbag model using the function provided by LSDYNA. The biodynamics of the occupant-airbag interaction were simulated for unbelted occupant sled impacts and two out-of-position static deployment impacts.

Critical in vehicle crash simulations, human body data sets include mass, moments of inertia (MOIs), and ellipsoid size for each body segment, and location and resistive torque properties for each joint. The Generator of Body Data (GEBOD) program generates these human data sets for use in multibody programs. The objective of this study was to validate GEBOD estimates by directly measuring whole-body inertial properties of 69 volunteers and comparing the results with values calculated by the Articulated Total Body (ATB) model using GEBOD data sets. While the predicted whole-body center of gravity (CG) averaged within 1 cm of the measured values in the horizontal direction, vertically the errors were much larger. The predicted principal MOI were consistently 5%-30% lower than the measured values.

To demonstrate the Articulated Total Body (ATB) model's capability to predict complex rollover accidents, a rollover accident was selected from the National Accident Sampling System (NASS) and simulated. This paper focuses on the simulation of the vehicle's dynamics which can in turn be used to specify the vehicle motion for occupant simulations. The selected accident case involved a pickup truck, crashing at high speed and completing three rolls. The pickup truck was modeled as a single rigid segment with fifteen contact hyperellipsoids rigidly attached to it. These hyperellipsoids were sized and positioned to approximate the exterior surfaces of the pickup truck. The force-deflection functions were defined based upon previous simulations of rollover tests. The initial conditions were defined to match the data in the NASS accident report as closely as possible.

The objective of this study was to mathematically model several proposed vehicle glazing materials using derived force-deflection characteristics, validate the models' dynamic behavior, and use the resulting glazing models in simulations of occupant dynamics during vehicle rollover. Simulations were performed with the three-dimensional, multibody dynamics program, the Articulated Total Body (ATB) model. The contact characteristics of side windows of tempered glass; polymethyl methacrylimide, also referred to as PMMI; and polycarbonate; as well as windshields from Ford Tempos and Jeeps, were developed from headform impact tests. These characteristics were first validated by performing simulations of the headform impact tests, and were then included in rollover simulations. Previously validated simulations of belted driver and unbelted passenger dynamics during an actual rollover accident were used as the baseline simulations.

Computer simulations of occupant dynamics are ideal for conducting parametric studies evaluating injury countermeasures. A rollover accident was selected from the National Accident Sampling System (NASS) for simulation to validate the Articulated Total Body (ATB) model's capability to predict occupant dynamics during rollover accidents and to gain insight into injury mechanisms. Simulations of both the driver and passenger occupants which may be used in future countermeasure studies are performed. In the selected accident, a pickup truck rolled multiple times, the belted driver had minor injuries and the unrestrained passenger was ejected with fatal injuries. The body properties for both occupants were obtained using the Generator of Body Data (GEBOD) program based on their weights, heights, and sexes. The interior configuration of the vehicle compartment was modeled based on measurements taken from another vehicle of the same model.

Sophisticated computer simulation of human response during various violent force exposure situations requires not only the validated programs, but also high quality databases, especially the data sets that characterize human body structures. Although anthropometric surveys and stereophotometric studies have been performed to create geometric and inertial property databases for the human body, there have been limited efforts on establishing the joint kinematics and resistive torque data sets. This paper presents the development, implementation, and validation of the human articulating joint model parameters for crash dynamics simulations. Measured human joint data on the voluntary range of motion and passive resistive torques were used to mathematically model the shoulder, elbow, hip, knee, and ankle joints.

In order to validate a Hybrid III dummy analytical simulation data set, a sled impact test was simulated in which both a Part 572 dummy and a Hybrid III dummy were used. Each dummy was restrained with a three-point belt system during the 32G sled test. The Crash Victim Simulator (CVS )/Articulated Total Body (ATB) model simulations were set up to reflect the same conditions as in the test and the previously developed standard Part 572 and the newly developed Hybrid III dummy body data sets were used. Graphics of the dummies' motion from the simulation are compared with films of the sled test. Accelerometer and load cell data from both the test and simulations are also used to demonstrate the validity of the CVS/ATB model for simulating the Hybrid III dummy dynamics.

In order to understand an occupant's often violent and complicated motion during rollover accidents, the motion of an anthropomorphic dummy was predicted dynamically using a human body gross motion simulation program. The accuracy of the predicted motion was established by its favorable comparison to that recorded on high speed film during a 60 mph crash in which the vehicle rolled over four times. This vehicle motion was then modified to six other rollover crash situations for computer simulation. Significant changes in the predicted occupant motion were readily observed. Differences were also observed in occupant accelerations and impact and belt forces.