Gregory S. Klopp

Biomechanical Response and Physical Properties of the Leg, Foot, and Ankle

The anatomical dimensions, inertial properties, and mechanical responses of cadaver leg, foot, and ankle specimens were evaluated relative to those of human volunteers and current anthropometric test devices. Dummy designs tested included: (1) the Hybrid III; (2) the Hybrid III with soft joint stops; (3) the Advanced Lower Extremity prototype (ALEX 1); and (4) the General Motors Corporation (GM)/First Technology Safety Systems (FTSS) lower limbs. Static and dynamic tests of the leg, foot, and ankle were conducted. The inertial and geometric properties of the dummy lower limbs were measured and compared with cadaver properties and published volunteer values. Compression tests of the leg were performed using static and dynamic loading. Quasi-static rotational properties for dorsiflexion and inversion/eversion motion were obtained for the dummy, cadaver, and volunteer joints of the hindfoot. Dynamic and impact tests were conducted with dummy and cadaver limbs. The testing indicates that passive and active musculature of the leg strongly influences response of the leg, foot, and ankle. The testing suggests that future dummy designs should incorporate these effects. Synthesis of the volunteer and cadaver test results provides physical properties and response corridors of the foot, leg, and ankle for use in mathematical and mechanical models. For the covering abstract of the conference see IRRD 891635.

Thoracic trauma assessment formulations for restrained drivers in simulated frontal impacts

Using cadaveric specimens, sixty-three simulated frontal impacts were performed to examine and quantify the performance of various contemporary automotive restraint systems. To characterize the mechanical responses during the impact, test-specimens were instrumented with accelerometers and chest bands. The resulting thoracic injury severity was determined using detailed autopsy and was classified using the Abbreviated Injury Scale.

Research Program to Investigate Lower Extremity Injuries

Biomechanical response and injury tolerance of the lower extremities is being investigated at the University of Virginia. This paper presents the experimental and simulation work used to study the injury patterns and mechanisms of the ankle/foot complex. The simulation effort has developed a segmented lower limb and foot model for an occupant simulator program to study the interactions of the foot with intruding toepan and pedal components. The experimental procedures include static tests, pendulum impacts, and full-scale sled tests with the Advanced Anthropomorphic Test Device and human cadavers. In these tests, the response of the lower extremities is characterized with analogous dummy and cadaver instrumentation packages that include strain gauges, electrogoniometers, angular rate sensors, accelerometers, and load cells. An external apparatus is applied to the surrogates lower extremities to simulate the effects of muscle tensing. Sled tests are performed with a toepan device that subjects the lower extremities to rotational, longitudinal, and vertical intrusion pulses typical of offset vehicle crashes. Based upon data from the component and full-scale sled tests, a risk function which correlates observed cadaver injury with dummy responses is developed.

Reproducing the Structural Intrusion of Frontal Offset Crashes in the Laboratory Sled Test Environment

The response and risk of injury for occupants in frontal crashes are more severe when structural deformation occurs in the vehicle interior. The aim of this paper is to reproduce this impact environment in the laboratory. A sled system capable of producing structural intrusion in the footwell region was developed. The system couples the hydraulic decelerator of the sled to actuator pistons attached to the toepan and floorpan structure of the buck. Characterization of the footwell intrusion event is based on developing a toepan pulse analogous to the acceleration pulse used to characterize sled and vehicle decelerations. Preliminary sled tests with the system indicate that it is capable of simulating a complex sequence of toepan/floorpan translations and rotations. (A) For the covering abstract of the conference see IRRD 875833.

Angular Rate Sensor Joint Kinematics Applications

High speed rotary motion of complex joints were quantified with triaxial angular rate sensors. Angular rate sensors were mounted to rigid links on either side of a joint to measure angular velocities about three orthogonal sensor axes. After collecting the data, the angular velocity vector of each sensor was transformed to local link axes and integrated to obtain the incremental change in angular position for each time step. Using the angular position time histories, a transformation matrix between the reference frame of each link was calculated. Incremental Eulerian rotations from the transformation matrix were calculated using an axis system defined for the joint. Summation of the incremental Eulerian rotations produced the angular position of the joint in terms of the standard axes. This procedure is illustrated by applying it to joint motion of the ankle, the spine, and the neck of crash dummies during impact tests. The methodology exhibited an accuracy of less than 5% error, improved flexibility over photographic techniques, and the ability to examine 3-dimensional motion.