Search Results

High speed craft are used by civilian agencies and the military for rescue, for interdiction, and for rapid insertion and extraction of forces. Ensign et al. (2000) found evidence of a significant injury problem in a study of self-reported injuries of boat operators of high speed craft. Though repeated vertical spinal impacts with greater than 10 g peak accelerations may occur in such craft, there is currently no completely suitable injury criterion to predict the likelihood of spinal injuries from high speed craft operations. A new low-order dynamics metamodel for predicting vertical impact to the human spine has been developed using a Madymo (TNO, Inc) simulation of a seated occupant under predominantly vertical impact. This model has been validated using experimental high speed craft operations for impacts with vertical accelerations greater than 10 g.

Traumatic aortic rupture is a significant cause of fatalities in frontal automobile crashes. However, such ruptures are difficult to reproduce experimentally in cadaveric surrogates, and it is difficult to observe dynamic aortic response in situ. So, the aortic injury mechanism or mechanisms remains in dispute. This study is a staged investigation of the physical parameters and mechanisms of human aortic rupture. The investigation includes both experimental study of local and global viscoelastic properties and failure properties of aortas using aortic tissue samples, excised aortas in vitro, and whole human aortas in situ in cadaver thoraxes. This study is the first phase in a staged programme to develop a finite element computer model of aorta injury to examine the mechanisms of aorta injury in automobile crashes.

Curvature-based contour measurement devices with discrete curvature measurement gauges are widely used for the measurement of dynamic thoracic contours in both dummy and cadaveric automobile sled testing. Such devices include the chestband used to determine local thoracic contours at several rib levels for evaluation of injury parameters in dummy and cadaveric subjects. The use of these devices involves integration of local curvatures to obtain position data, and often incorporates several approximations, including a quasi-continuous approximation of discrete measured curvatures. By comparing a reference and a calculated position profile, this study analyzes the error in local positions induced from several sources. The first source of error is the measurement of curvatures at discrete locations, typically with 2.5 - 5.0 cm curvature gauge spacing.

The air bag has proven effective in reducing fatalities in frontal crashes with estimated decreases ranging from 11% to 30% depending on the size of the vehicle [IIHS-1995, Kahane-1996]. At the same time, some air bag designs have caused fatalities when front-seat passengers have been in close proximity to the deploying air bag [Kleinberger-1997]. The objective of this study was to develop an accurate and repeatable out-of-position test fixture to study the deployment of air bags into out-of-position occupants. Tests were performed with a 5th percentile female Hybrid III dummy and studied air bag loading on the thorax using draft ISO-2 out-of-position (OOP) occupant positioning. Two different interpretations of the ISO-2 positioning were used in this study. The first, termed Nominal ISO-2, placed the chin on the steering wheel with the spine parallel to the steering wheel.

A series of eight sled tests was conducted using Hybrid III dummies and cadavers in order to examine the influence of foot placement on the brake pedal in frontal collisions. The brake pedal in the sled runs was fixed in a fully depressed position and the occupants' muscles were not tensed. The cadaver limbs and the Hybrid III lower extremities with 45° ankle and soft joint-stop were extensively instrumented to determine response during the crash event. Brake pedal reaction forces were measured using a six-axis load cell and high speed film was used for kinematic analysis of the crashes. Four right foot positions were identified from previous simulation studies as those orientations most likely to induce injury. In each test, the left foot was positioned on a simulated footrest, acting as a control variable that produced repeatable results in all dummy tests. Each of the different right foot orientations resulted in different loads and motions of the right leg and foot.

Originally designed for measuring closed-loop contours such as those around a human thorax, the External Peripheral Instrument for Deformation Measurement (EPIDM), or chestband, was developed to improve the measurement of dummy and cadaver thoracic response during impact. In the closed-loop configuration, the chestband wraps around on itself forming a closed contour. This study investigates the use of the chestband for dynamic deformation measurements in an open-loop configuration. In the open-loop configuration, the chestband does not generally form a closed contour. This work includes enhanced procedures and algorithms for the calculation of chestband deformation contours including the determination of static and dynamic chestband contours under several boundary conditions.

Recently there has been a greater awareness of the increased risk of certain injuries associated with air bag deployment, especially the risks to small occupants, often women. These injuries include serious eye and upper extremity injuries and even fatalities. This study investigates the interaction of a deploying air bag with cadaveric upper extremities in a typical driving posture; testing concentrates on female occupants. The goals of this investigation are to determine the risk of upper extremity injury caused by primary contact with a deploying air bag and to elucidate the mechanisms of these upper extremity injuries. Five air bags were used that are representative of a wide range of air bag ‘aggressivities’ in the current automobile fleet. This air bag ‘aggressivity’ was quantified using the response of a dummy forearm under air bag deployment.

Three-dimensional simulation models of a driver's right upper extremity interacting with a deploying airbag have been set up and run with the Articulated Total Body program. The goal of this study is to examine the significance of various occupant and airbag parameters during deployment, such as grip strength, upper extremity position, shoulder compliance, flap position, flap aggressivity, and deployment speed. Given a range of 250 N to 650 N, the grip strength did not affect the resultant loads. Also, the contact force and torque at the e.g. of the forearm are not sensitive to shoulder joint compliance. The flap aggressivity and the position of the airbag module relative to the upper extremity are most important in affecting the interaction. This study is used to justify cadaveric experiments involving disarticulated upper extremities.

This work studies the effect of padding on the force levels in impulsively loaded dummy lower extremities. Tests include the effect of padding incorporated into the soles of shoes and an examination of the potential of shoe padding for mitigating impact loading on the lower extremities. Three different shoes and three paddings were studied using a pendulum impactor; two different padding levels were studied in an impact sled test with simulated translational structural intrusion. The tests indicate a greater than 20% variation in peak axial force imparted to the lower tibia between shoes, and a greater than 50% variation in peak axial force across the paddings tested. From sled tests with simulated structural intruaion, we see a decrease of approximately 15% in peak axial load and a decrease of over 20% in peak anterior/posterior moment.