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The objective of this study is to compare the risk of injury to pedestrians involved in vehicle-pedestrian impacts as predicted by two different types of risk assessment tools: the pedestrian subsystem impactors recommended by the European Enhanced Vehicle-Safety Committee (EEVC) and post-mortem human surrogates (PMHS). Seven replicate full-scale vehicle-pedestrian impact tests were performed with PMHS and a mid-sized sedan travelling at 40 km/h. The PMHS were instrumented with six-degree-of-freedom sensor cubes and sensor data were transformed and translated to predict impact kinematics at the head center of gravity, proximal tibiae, and knee joints. Single EEVC WG 17/EuroNCAP adult headform, upper legform and lower legform impactor tests of the same vehicle were selected for comparison based on the proximity of their impact locations to that of the PMHS.

A recent study of U.S. crash data has shown that children 0-23 months of age in forward-facing child restraint systems (FFCRS) are 76% more likely to be seriously injured in comparison to children in rear-facing child restraint systems (RFCRS). Motivated by the epidemiological data, seven sled tests of dummies in child seats were performed at the University of Virginia using a crash pulse similar to FMVSS 213 test conditions. The tests showed an advantage for RFCRS; however, real-world crashes include a great deal of variability among factors that may affect the relative performance of FFCRS and RFCRS. Therefore, this research developed MADYMO computational models of these tests and varied several real-world parameters. These models used ellipsoid models of Q-series child dummies and facet surface models of American- and Swedish- style convertible child restraints (CRS).

Rupture of the thoracic aorta is a leading cause of rapid fatality in automobile crashes, but the mechanism of this injury remains unknown. One commonly postulated mechanism is a differential motion of the aortic arch relative to the heart and its neighboring vessels caused by high-magnitude acceleration of the thorax. Recent Indy car crash data show, however, that humans can withstand accelerations exceeding 100 g with no injury to the thoracic vasculature. This paper presents a method to investigate the efficacy of acceleration as an aortic injury mechanism using high-acceleration, low chest deflection sled tests. The repeatability and predictability of the test method was evaluated using two Hybrid III tests and two tests with cadaver subjects. The cadaver tests resulted in sustained mid-spine accelerations of up to 80 g for 20 ms with peak mid-spine accelerations of up to 175 g, and maximum chest deflections lower than 11% of the total chest depth.

This paper investigates the viscoelastic behavior of polyurethane foams. A three-dimensional single hereditary integral nonlinear viscoelastic model is developed using the results of stress relaxation experiments in compression, tension, and shear. The material behavior is characterized with the instantaneous dilatational and deviatoric elastic responses together with the normalized relaxation functions. The relaxation of the material is described using three different functions for high compression (above 7% strain), low compression/tension, and shear. The material model is implemented in the LS-DYNA3D program and is validated by comparing the numerical and experimental results.

This paper presents a technique for developing corridors from individual subject responses contained in experimental biomechanical data sets. Force-deflection response is used as an illustrative example. The technique begins with a method for averaging human subject force-deflection responses in which curve shape characteristics are maintained and discontinuities are avoided. Individual responses sharing a common characteristic shape are averaged based upon normalized deflection values. The normalized average response is then scaled to represent the given data set using the mean peak deflection value associated with the set of experimental data. Finally, a procedure for developing a corridor around the scaled normalized average response is presented using standard deviation calculations for both force and deflection.

The objective of this study was to investigate the use of a fiber optic based sensor, ShapeTape, as an instrument for measuring abdominal and chest deflection, and to compare it to the current instrument used in impact biomechanics applications, the chestband. Drift, pressure, and temperature tests were conducted for ShapeTape alone, whereas quasi-static and dynamic loading tests were conducted as comparison tests between the chestband and ShapeTape. The effects of drift and temperature on ShapeTape were very small, averaging 0.26% and 1.2% full scale changes respectively. During the pressure test at a load of 1000 N the ShapeTape sensor tested experience a 7.47% full scale voltage change. The average errors in reporting maximum deflection of the chest form during the quasi-static loading tests were 3.35% and 1.64% for ShapeTape and the chestband respectively.

Computer simulations, dummy experiments with a new enhanced upper extremity, and small female cadaver experiments were used to analyze the small female upper extremity response under side air bag loading. After establishing the initial position, three tests were performed with the 5th percentile female hybrid III dummy, and six experiments with small female cadaver subjects. A new 5th percentile female enhanced upper extremity was developed for the dummy experiments that included a two-axis wrist load cell in addition to the existing six-axis load cells in both the forearm and humerus. Forearm pronation was also included in the new dummy upper extremity to increase the biofidelity of the interaction with the handgrip. Instrumentation for both the cadaver and dummy tests included accelerometers and magnetohydrodynamic angular rate sensors on the forearm, humerus, upper and lower spine.

This paper considers an application of reference governor (RG) to automotive diesel aftertreatment temperature control. Recently, regulations on vehicle emissions have become more stringent, and engine hardware and software are expected to be more complicated. It is getting more difficult to guarantee constraints in control systems as well as good control performance. Among model-based control methods that can directly treat constraints, this paper focuses on the RG, which has recently attracted a lot of attention as one method of model prediction-based control. In the RG, references in tracking control are modified based on future prediction so that the predicted outputs in a closed-loop system satisfy the constraints. This paper proposes an online RG algorithm, taking account of the real-time implementation on engine embedded controllers.

This study investigates the performance of a 3-point restraint system incorporating an inflatable shoulder belt with a nominal 2.5-kN load limiter and a non-inflatable lap belt with a pretensioner (the “Airbelt”). Frontal impacts with PMHS in a rear seat environment are presented and the Airbelt system is contrasted with an earlier 3-point system with inflatable lap and shoulder belts but no load-limiter or pretensioners, which was evaluated with human volunteers in the 1970s but not fully reported in the open literature (the “Inflataband”). Key differences between the systems include downward pelvic motion and torso recline with the Inflataband, while the pelvis moved almost horizontally and the torso pitched forward with the Airbelt. One result of these kinematic differences was an overall more biomechanically favorable restraint loading but greater maximum forward head excursion with the Airbelt.

Conventional cruise control systems have been in use for many years. Their function is to maintain a preset vehicle speed thus improving the comfort for the driver during steady driving conditions. Most systems achieve this by having a small electronic control unit which monitors vehicle speed and driver interface controls and operates the throttle butterfly to control engine power. Figure 1. Various interlock features are fitted to prevent unwanted engine power increases in the event of a system failure. Cruise control is widely fitted in the North American market, but on the more crowded roads of Western Europe its use is somewhat restricted. The ability to maintain a fixed speed is of limited use when traffic conditions dictate the widely varying speeds that are commonplace in the UK and becoming more common in the rest of Western Europe and North America.

Experimental tests were performed on the modified Polar-II pedestrian dummy lower extremity components to evaluate their biofidelity in lateral impact loading corresponding to a 40 km/h pedestrian-car collision. The bending moment-angle response from a newly developed knee joint, dynamically loaded in four-point valgus bending, was compared against previously published postmortem human subject (PMHS) response corridors. In addition to the stiffness characteristics of the knee joint, individual ligament forces were also recorded during the bending tests. The evaluated force-relative elongation response of the medial collateral ligament (MCL) in the new knee was compared against PMHS data on MCL tensile stiffness. Lower extremity long bones developed for improved anthropometrical accuracy and deformability were dynamically loaded in latero-medial three-point bending.

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 the Hybrid III, Hybrid III with soft joint stops, ALEX I, and the GM/FTSS lower limbs. Static and dynamic tests of the leg, foot, and ankle were conducted at the laboratories of the Renault Biomedical Research Department and the University of Virginia. 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 to determine compliance of the foot and ankle. Quasi-static rotational properties for dorsiflexion and inversion/eversion motion were obtained for the dummy, cadaver, and volunteer joints of the hindfoot.

The abdomen is the second most commonly injured region in children using adult seat belts, but engineers are limited in their efforts to design systems that mitigate these injuries since no current pediatric dummy has the capability to quantify injury risk from loading to the abdomen. This paper develops a porcine (sus scrofa domestica) model of the 6-year-old human's abdomen, and then defines the biomechanical response of this abdominal model. First, a detailed abdominal necropsy study was undertaken, which involved collecting a series of anthropometric measurements and organ masses on 25 swine, ranging in age from 14 to 429 days (4-101 kg mass). These were then compared to the corresponding human quantities to identify the best porcine representation of a 6-year-old human's abdomen. This was determined to be a pig of age 77 days, and whole-body mass of 21.4 kg.

This paper describes the injuries generated during dynamic belt loading to a porcine model of the 6-year-old human abdomen, and correlates injury outcomes with measurable parameters. The test fixture produced transverse, dynamic belt loading on the abdomen of 47 immediately post-mortem juvenile swine at two locations (upper/lower), with penetration magnitudes ranging from 23% – 65% of the undeformed abdominal depth, with and without muscle tensing, and over a belt penetration rate range of 2.9 m/s – 7.8 m/s. All thoracoabdominal injuries were documented in detail and then coded according to the Abbreviated Injury Scale (AIS). Observed injuries ranged from AIS 1 to AIS 4. The injury distribution matched well the pattern of injuries observed in a large sample of children exposed to seatbelt loading in the field, with most of the injuries in the lower abdomen.

Traumatic aortic rupture (TAR) accounts for a significant mortality in automobile crashes. A numerical method by means of a mesh-based code coupling is employed to elucidate the injury mechanism of TAR. The aorta is modeled as a single-layered thick wall composed of two families of collagen fibers using an anisotropic strain energy function with consideration of viscoelasticity. A set of constitutive parameters is identified from experimental data of the human aorta, providing strict local convexity. An in vitro aorta model reconstructed from the Visible Human dataset is applied to the pulsatile blood flow to establish the references of mechanical quantities for physiological conditions. A series of simulations is performed using the parameterized impact pulses obtained from frontal sled tests.

Emergency situations rarely occur in a driver's experience and the braking and steering manoeuvres that are then required are usually outside the routine physical behaviour ranges. Immediate reactions are automatic and are therefore unlikely to include physical movements that go beyond these limits. It has always been difficult, however, to prove this because simulators could not create total realism, accident studies do not show brake pedal behaviour and realistic experiments are unethical and dangerous. This paper reviews what is known about driver braking behaviour together with accident studies. Experiments performed by Lucas are described in which pseudo-realistic accident situations are created and braking behaviour modelled.

Multiple series of frontal sled tests were performed to evaluate the new Thor-Lx/HIIIr lower extremity developed by the National Highway Traffic Safety Administration for retrofit use on the 50th percentile male Hybrid III. This study's objective was to compare the Thor-Lx/HIIIr to the existing Hybrid III dummy leg (HIII) from the standpoint of repeatability and effects on femur and upper body response values.\ The test-to-test repeatability of the dummy responses, as measured by the coefficient of variation (CV), was generally acceptable (CV < 10%) for all of the test conditions for both legs. Overall, tests with the Thor-Lx/HIIIr legs produced upper body movement and injury criteria values for the head and chest that were acceptably consistent and were generally indistinguishable from those produced with the HIII leg. Low right femur loads, which ranged from 4 to 25 percent of the injury assessment reference value, varied substantially test-to-test for tests with both types of legs.

This paper compares restrained Hybrid III and THOR thoracic kinematics and cadaver injury outcome in 30° oblique frontal and in full frontal sled tests. Peak shoulder belt tension, the primary source of chest loading, changed by less than four percent and peak chest resultant acceleration changed by less than 10% over the 30° range tested. Thoracic kinematics were likewise insensitive to the direction of the collision vector, though they were markedly different between the two dummies. Mid-sternal Hybrid III chest deflection, measured by the standard sternal potentiometer and by supplemental internal string potentiometers, was slightly lower (∼10%) in the oblique tests, but the oblique tests produced a negligible increase in lateral movement of the sternum. In an attempt to understand the biofidelity of these dummy responses, a series of 30-km/h human cadaver tests having several collision vectors (0°, 15°, 30°, 45°) was analyzed.

A biaxial test procedure is used to assess the constitutive properties of polymers in tension. The constitutive constants are derived for high strain rate applications such as those associated with crashworthiness studies. The test procedure is used in conjunction with a time- and strain-dependent quasi-linear viscoelastic constitutive law consisting of a Mooney-Rivlin formulation combined with Maxwell elements. The procedure is demonstrated by describing the stress vs. strain relationship of a rubber specimen subjected to a step-relaxation input. The constitutive equation is transformed from a nonlinear convolution integral to a set of first order differential equations. These equations, with the appropriate boundary conditions, are solved numerically to obtain transient stresses in two principal directions. Material constants for use in the explicit LS-Dyna non-linear finite element code are provided.

A finite element human model has been developed to simulate occupant behavior and to estimate injuries in real-world car crashes. The model represents an average adult male of the US population in a driving posture. Physical geometry, mechanical characteristics and joint structures were replicated as precise as possible. The total number of nodes and materials is around 67,000 and 1,000 respectively. Each part of the model was not only validated against human test data in the literature but also for realistic loading conditions. Additional tests were newly conducted to reproduce realistic loading to human subjects. A data set obtained in human volunteer tests was used for validating the neck part. The head-neck kinematics and responses in low-speed rear impacts were compared between the measured and calculated results. The validity of the lower extremity part was examined by comparing the tibia force in a foot impact between the test data and simulation results.