Post Mortem Human Surrogate Research Articles

Thoracic deformation response of pedestrians resulting from vehicle impact

Postmortem human surrogates were positioned in a mid-gait pedestrian stance and struck laterally by a vehicle buck traveling at a speed of 40 km/h. Three tests were performed with a midsize passenger car buck, and two tests were performed with a sport utility vehicle buck. Each subject was equipped with two chest bands positioned at the level of the 4th and 8th ribs to measure changes in cross- sectional shape of the upper and lower chest. Absolute and normalized deflection, deflection velocity, and the viscous criterion were calculated for frontal and lateral dimensions. Deformation-time histories were generated for the midsagittal and midcoronal chords passing through the chest centroid as well as for off-centroidal chords. Despite being positioned initially perpendicular to the impacting vehicle, the subjects exhibited maximal loading of the anterolateral thorax. Therefore, a polar coordinate system was centered at the initial chest centroid position and radial changes of chest deformation were recorded. Though similar in application to the standard frontal and lateral impact analyses, this radial technique appears better suited to the pedestrian environment in that it identifies a single position of maximum deformation rather than tracking only preselected locations. Maximum deformation levels and rates of deformation indicated that peak values were in the range of those resulting from traditional frontal and lateral sled tests as well as frontal and side dummy certification tests. Provided that consideration is given to the oblique nature of the loading, the results indicate that conventional injury criteria and biofidelity requirements used for occupant dummies could be reasonably applied to the pedestrian environment.

Investigation of an alleged mechanism of finger injury in an automobile crash

This investigation centers on the case of an adult male whose finger was allegedly amputated by the steering wheel of his car during a crash. The subject claimed to have been driving with his left index finger inserted through a hole in the spoke of his steering wheel and was subsequently involved in an offset frontal collision with a tree. The finger was found to be cleanly severed at the mid-shaft of the proximal phalanx after the crash. This injury was alleged to have been caused by inertial loading from the rotation of the steering wheel during the crash. To determine whether this injury mechanism was plausible, three laboratory tests representing distinct loading scenarios were carried out with postmortem human surrogates loaded dynamically by the subject's steering wheel. It was found that the inertial loads generated in this loading scenario are insufficient to amputate the finger. Additionally, artificially constraining the finger to force an amputation to occur revealed that a separation at the proximal interphalangeal joint occurs rather than a bony fracture of the proximal phalanx. Based on these biomechanical tests, it can be concluded that the subject's injury did not occur during the automobile crash in question. Furthermore, it can be shown that the injury was self-inflicted to fraudulently claim on an insurance policy.

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

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).

Limiting performance analysis of toepan padding for mitigating lower limb injuries

The potential application of using toepan padding for the prevention and reduction of lower limb injuries is investigated computationally in this paper. A two-mass lower limb injury model is developed on the basis of impact tests using post-mortem human surrogates. A limiting performance analysis is used to find the best possible physical performance and characteristics of passive and active padding for the minimization of peak tibia force. Computational results indicate that, for the prevention and reduction of lower limb injuries, the active padding is superior to the passive padding.

Finite element modelling and simulation of upper limb with radioss

The aim of this work is to understand the behaviour of the thoracic member (shoulder and arm) in case of side impact in motor vehicle accidents, and to identify tolerance criteria for this body region. In order to describe the dynamics involved in such impacts, and to focus on injuries mechanisms, a finite element model of the thoracic member was developed and validated with 3 Post Mortem Human Surrogates (PMHS). The geometry of the whole model was obtained from serial sections of a PMHS in driving position. It includes compact bones, ligaments, muscles and connective tissues, described with either shells, solids or spring elements. Concerning mechanical behaviour, bones and soft tissues are considered respectively as elastoplastic and viscoelastic materials. Numerical interfaces were also defined to model contacts between all components. The model was then integrated in a complete human model. Validation consisted of performing 6 subsystems tests (impactor) on instrumented PMHS placed in a car cockpit: a lateral load (37 kg at 7.55 ds) was applied directly on the shoulder. Displacements and acceleration of bones, as well as applied loads were measured. After each trial, a dissection was done to identify any injury on bones or ligaments.

Comparative evaluation of the THOR advanced frontal crash test dummy

Ten 48 km/h frontal sled tests were conducted to evaluate the biofidelity of the THOR dummy. Three replicate tests were conducted with THOR, three with a 50 th percentile male Hybrid III dummy, and four with post-mortem human surrogates (PMHS). The tests, conducted in a buck representing a mid-size US sedan, included a force-limited three-point belt system with buckle-side pretensioner and a driver side airbag. Following the tests, select parameters were used to compare THOR's responses with those of the Hybrid III dummy and the PMHS. The tesults were mass scaled in order to account for size differences between the subjects. Based on cadaveric response corridors, the sled test results provided evidence that THOR is more biofidelic than the Hybrid III dummy. THOR lap belt loads, head acceleration, and movement of the anterior chest wall were more similar to those of the PMHS than were those of the Hybrid III. However, THOR recorded less head forward movement and pelvic acceleration than did the PMHS.