Showing papers by "Jason R. Kerrigan published in 2004"

Tolerance of the human leg and thigh in dynamic latero-medial bending

Abstract: The goal of the current study was to perform dynamic bending experiments on legs and thighs from post mortem human surrogates (PMHS) and combine the failure data with that of previous applicable studies to perform an injury risk analysis. Four leg and 12 thigh specimens were loaded dynamically (∼1.5 m/s) in latero-medial 3-point bending. The four leg specimens and six of the thigh specimens were loaded at the mid-diaphysis and the other 6 thigh specimens were loaded at a third of the length from the distal end. Data from four other studies were used with data from the current study to develop injury risk functions for the human thigh loaded at the distal third (50% probability of femur fracture = 372 Nm), and at the mid shaft (50% probability of femur fracture = 447 Nm) and for the human leg loaded at the mid shaft (50% probability of tibia fracture = 312 Nm).

Dynamic Response Corridors and Injury Thresholds of the Pedestrian Lower Extremities

Abstract: Current standards and test devices for pedestrian safety were developed using results from impact tests where inertial considerations have dominated and the vehicle pedestrian loading environment has not been properly replicated. When controlled tests have been conducted to evaluate injury criteria and the biofidelity of anthropometric test devices, current designs have faired poorly. The present study uses recently published results from controlled tests to develop force-deformation and moment-deformation response corridors with localized injury thresholds for the 50th percentile adult male thigh, leg, and knee subjected to latero-medial bending at rates characteristic of the vehicle pedestrian loading environment. The response corridors provide necessary information for development of biofidelic ATDs [anthropometric test devices] for evaluation of countermeasures for pedestrian lower extremity protection. For the covering abstract see ITRD E141807.

Dynamic bending tolerance and elastic-plastic material properties of the human femur

Abstract: The objective of this study was to provide data on the structural tolerance and material properties of the human femur in dynamic bending. Fifteen (15) isolated femurs from eight (8) males were tested in either posterior-to-anterior or lateral-to-medial three-point bending. The failure moment was 458 +/- 95 Nm and did not differ significantly with loading direction. A method was developed to estimate the elastic-plastic material properties of the bone using both force-deflection data and strain gauge measurements. The bone material appeared to yield at about one third of the ultimate strain level prior to fracture. It is hoped that these data will aid in the development of injury criteria and finite element models for predicting injuries to pedestrians and vehicle occupants.

Non-contact strain measurement of biological tissue.

Abstract: Strain measurement in biological material is frequently problematic due to material in-homogeneity, high strain to failure, and the relatively low stiffness of most biological tissue. As an alternative to conventional strain measurement techniques, this study investigates the potential of a non-contact optical system capable of measuring three dimensional surface strain maps. The technique makes use of two CCD cameras and pattern recognition algorithms to track the motion of a random speckle pattern on the specimen and compute the displacement and strain fields. The application of this system on biological material is demonstrated on two tissue types that differ widely in material and surface characteristics (cortical bone and ligamentous tissue). A human tibia was loaded in quasi-static three-point bending and the medial collateral ligament from a human knee joint was loaded in tension. The strain field was computed and analyzed in each case. On the relatively stiff cortical bone, accurate results were obtained wherever high resolution imaging of the speckle pattern was possible. Since wicking and seepage from blood vessels during the test affect the speckle pattern, countermeasures are proposed. On the other hand, stretching of ligaments produced large surface strain discontinuities from tissue unfolding, which caused automated pattern recognition algorithms to fail.

Full scale pedestrian impact testing with PMHS: A pilot study

Abstract: The complexity of vehicle-pedestrian collisions necessitates extensive validation of pedestrian computational models. While body components can be individually simulated, overall validation of human pedestrian models requires full-scale testing with post mortem human surrogates (PMHS). This paper presents the development of a full-scale pedestrian impact test plan and experimental design, and some results from a pilot experiment. The test plan and experimental design are developed based on the analysis of a combination of literature review, multi-body modeling, and epidemiologic studies. The proposed system has proven effective in testing an anthropometrically correct rescue dummy in multiple instances, and in one test with a PMHS.