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The advent of the Hybrid III crash test dummy marked the beginning of biofidelic anthropomorphic test devices. During the development of its critical components, notably the head, neck, knee, and thorax, biomechanical cadaver test results were incorporated into the design. The result was a dummy that represented the 50th percentile male during idealized impacts. In order to achieve a more biofidelic response from the components, many exotic materials and unique designs were utilized. The thorax, for instance, incorporates a spring steel rib design laminated with a viscoelastic polymeric composite material to damp the response. This combination results in the proper hysteretic losses necessary to model the human thorax under impact loading conditions. The disadvantage of this design is that the damping material properties are highly sensitive to temperature. A variation of more than 5 degrees Fahrenheit dramatically affects the response of the thorax.

This paper presents an overview of the evolution of computer simulations in vehicle collision and occupant kinematic reconstructions. The basic principles behind these simulations, the origin of these programs and the evolution of these programs from a basic analytical mathematical model to a sophisticated computer program are discussed. In addition, a brief computer development history is discussed to demonstrate how the evolution of computer assisted vehicle accident reconstruction becomes feasible for a reconstructionist. Possible future research in computer reconstruction is also discussed.

Accident reconstruction encompasses the evaluation of a crash situation from evidence and observations available after the accident. Such evidence includes vehicular damage, property damage, marks, and witness statements. The reconstructionist is responsible for transforming this information into a theory of the accident sequence. In addition to satisfying the evidence and statements, the theory must also agree with the laws of physics which dictate reactions to forces and torques. The computer program presented here assists in this analysis by providing a graphical depiction of the accident scenario. This program is called ANMATE and utilizes simulation results prepared by the CRASH or SMAC program for vehicle motions. A number of features assist in viewing the accident from different points of view, allow the user to stop action, and provide other data presentation formats. A real world example is given.

Objectives. Examination of head injuries in the Pedestrian Crash Data Study (PCDS) indicates that many pedestrian head injuries are induced by a combination of head translation and rotation. The Simulated Injury Monitor (SIMon) is a computer algorithm that calculates both translational and rotational motion parameters relatable head injury. The objective of this study is to examine how effectively HIC and three SIMon correlates predict the presence of either their associated head injury or any serious head injury in pedestrian collisions. Methods. Ten reconstructions of actual pedestrian crashes documented by the PCDS were conducted using a combination of MADYMO simulations and experimental headform impacts. Linear accelerations of the head corresponding to a nine-accelerometer array were calculated within the MADYMO model's head simulation.

During a motor-vehicle collision, an occupant may interact with a variety of interior structures. The material properties and construction of these structures can directly affect the occupant's kinetic response. Simulation tools such as MADYMO (Mathematical Dynamical Models) can be used to estimate the forces imparted to an occupant for injury mechanism and causation evaluation relative to a particular event. Depending on the impact event and the specific injury mechanism being evaluated, the selection of proper material characteristics can be quite important. A comprehensive literature review of MADYMO studies illustrates the prevalent use of generic material characteristics and the need for improved property estimation and implementation methods.

There have been a number of papers written about the dynamic effects of low speed front to rear impacts between motor vehicles during the last several years. This has been an important issue in the field of accident analysis and reconstruction because of the frequency with which the accidents occur and the costs of injuries allegedly associated with them. Several of these papers have discussed the importance of the coefficient of restitution in the accelerations and speed changes that the vehicles undergo in such impacts. These discussions often include data showing the measured restitution for impacts involving various bumper types and closing speeds. However, in most of these studies, the impacts are controlled so that direct bumper to bumper impacts occur. This paper will present the results of several rear impact tests with non-standard impact configurations.

Seat belt usage in the United States is increasing dramatically, due in part to legislative action. In addition, education programs have improved public awareness of the need for automotive restraints in achieving crash survival and injury reduction. The safety consciousness level of automobile passengers is particularly strong among pregnant women. It is reasonable to expect wider use of seat belts by expectant mothers due to this acute attention to safety. The literature demonstrates that incorrect usage of seat belts is a cause of injury. This can be especially applicable during pregnancy when changes in anatomy dictate a change in belt positioning, Review of the literature shows that the technical issues associated with the use of current production belt restraint systems by pregnant women has not been addressed.

This paper describes the development of a device to simulate the thorax of the fiftieth percentile six year old child in lateral blunt impact. The device is to be used to reconstruct actual vehicle/pedestrian collisions to determine the injury potential that various vehicles have towards pedestrians. The device is a modification of a fiftieth percentile six year old dummy thorax. Verification of the response is made by comparison with adult cadaver lateral impact data normalized and scaled to the child case. Performance evaluation of the device gave encouraging results although repeatability needs further verification.

The development of injury predictive models for pedestrian thoracic impact based on experimental data obtained in a previous study is presented. The data consists of ten cadaveric test subjects including eight side and two frontal impacts. A ten accelerometer array was mounted on the thorax to define thoracic kinematics. Three types of parameters, Q, B, and PSD, are developed to summarize each acceleration signal. A statistical regression is performed to generate empirical models for predicting the injury level (number of rib fractures) from these parameters. Coefficients of determination for these models range from 0.8 to 0.99 with the new PSD parameter showing exciting promise. Success of these parameters in predicting thoracic injury implies a relationship with frequency, particularly in the neighborhood of 60 Hz.

A technique has been developed to study the effects of the vehicle interior on the performance of child safety seats. Child safety seat sled tests are used to define the kinematics of the seat and child in a crash situation. Computer animation of this motion is superimposed on the motion of the actual vehicle crash tests giving an estimation of the kinematics of the child and child seat in a real crash situation. The significance of the vehicle interior and the interference of the vehicle interior with the child's kinematics is presented within the computer animation. The analysis is conducted using a single child restraint device in multiple seating conditions within a single vehicle.

Experimental reconstructions of pedestrian accidents involving head injury sustained primarily from hood impact were conducted to determine the relationship between HIC and injury severity. The purpose was to establish the capability of predicting pedestrian head injury severity in simple laboratory tests. The reconstruction test results were analyzed by a median ranking technique to provide a family of curves showing probability of injury of AIS 3, 4, and 5 severities as a function of HIC. This analysis method was used by Prasad and Mertz [1]1 to develop a head injury risk curve from cadaver head impact test data. Results of the two analyses were compared to determine the degree of agreement between the HIC/injury-risk relationship derived from controlled experiments with cadavers and that derived from uncontrolled accidents involving live people. The reconstruction test results also were used to derive a relationship between head injury risk (HIC) and vehicle impact speed.

Determining injury causation and/or developing injury thresholds is important, specifically in the lumbar spine during minor accidents. Much work has been done to study cervical spine behavior, however, there is a lack of data on injury thresholds of the lumbar spine and on lumbar exposure during these minor events. A MADYMO model was developed to quantify the lumbar loads and accelerations experienced when dropping down onto a surface into a seated position. The model was validated using data collected during tests involving an instrumented Hybrid III dummy. This work shows that MADYMO models can be used to predict the lumbar spine's exposure during common everyday activities.

The International Harmonization Research Activities Pedestrian Safety Working Group (IHRA PSWG) has proposed design requirements for two head-forms for vehicle hood (bonnet) impact testing. This paper discusses the development of MADYMO models representing the IHRA adult and child head-forms, validation of the models against laboratory drop tests, and assessment of the effect of IHRA geometric and mass constraints on the model response by conducting a parameter sensitivity analysis. The models consist of a multibody rigid sphere covered with a finite element modeled vinyl skin. The most important part in developing the MADYMO head-form models was to experimentally determine the material properties of the energy-absorbing portion of the head-form (vinyl skin) and incorporate these properties into MADYMO using a suitable material model. Three material models (linear isotropic, viscoelastic, hyperelastic) were examined.

Field literature in testing and experimentation on general human perception and reaction times, was reviewed to better address questions on the parameters of driving performance. Brake reaction time studies and driver visual search studies were reviewed with attendant material on the effects of aging, intoxication and fatigue. A short examination is made on the degree of increase in “surprise intrusion” event upper values from simple human basic reaction time testing to a real-time pedestrian crossing event in real-world urban driving. These upper range values began at 0.78 second in the laboratory environment and became 2.50 seconds on an urban street in real-time.

The use of vehicle damage measurements has been proven to be an effective technique in the determination of impact energy and pre-collision speeds. However, as with any analytical technique, the quality of the speed estimate is highly dependent on the accuracy of the measurements. This relationship suggests a need to employ intricate and exacting measurement schemes to obtain useable data. This approach is often difficult to implement in a routine accident investigation where a tape measure may be the only available measuring device. In the current study, vehicle damage resulting from collisions with a known speed is measured with techniques of increasing sophistication and the results are compared. These measurements are then used in conjunction with the CRASH III computer program to estimate the pre-impact vehicle speeds. The analysis technique used by CRASH III is also reviewed to provide a summary understanding of how the crush measurements are used in the program.

This paper presents a pedestrian head impact reconstruction methodology as an initial mitigating response to this need for pedestrian protection. This methodology which is based on preliminary testing results is illustrated with a real world case example from the Pedestrian Accident Investigation Data Support (PAIDS) Study. This PAIDS study provides documentation of medical reports, vehicle impact speeds, photographs and a dent profile of the vehicle damage. The pedestrian head impact damage from this real-world case is reproduced in a comparison vehicle with a rigid pneumatic impactor developed for the National Highway Traffic Safety Administration. The physical reconstruction results are then compared to the actual accident damage and conclusions are rendered.

Taillight lamp filaments provide valuable information on their illumination status during a collision. This information is contained in the shape of filament deformation, extent and nature of filament fracture, and filament oxidation. The degree of deformation of these filaments, a quantity which may be useful in determining velocities prior to impact, has been documented for headlights but has not been closely examined for taillights. In this paper, a study of the quantification of automobile taillight filament response when subjected to low speed impacts is presented. These studies include two different brands, five velocities up to approximately 19 miles per hour, three filament orientations, and two different deceleration pulses. Recommendations are given for further study in order to provide sufficient data for practical application and use in accident reconstruction.

In this research, cervical muscle behavior in rear impact accidents was investigated. Specifically, cervical muscle forces and muscle lengthening velocities were investigated with respect to cervical injuries. Variation of the onset time for muscle activation, variation of muscle activation level and variation of rear impact pulses were considered. The human body simulation computer program, MADYMO and anthropometric numerical human model were used to evaluate the neck. The factors mentioned above were examined with specific data being obtained from several different literature sources. Cervical muscles were separated into three groups, the sternocleidomastoideus, the flexor muscle group and the extensor muscle group. Longuscolli and spleniuscapitis were selected to represent the flexor muscle and extensor muscle groups respectively. The values and trends of the muscle forces and lengthening velocities are investigated in each muscle group.

It is commonly recommended to use infant/child restraints in the rear seat, and that until an infant reaches certain age, weight and height criteria, the infant restraint should be placed rear facing. This paper will describe the injuries suffered by an infant that was restrained in a forward-facing child seat placed in the front passenger seating position during a real world collision. Based on this collision, a full-scale vehicle to barrier impact test was performed. For this test, two 6-month-old CRABI dummies were used in identical child restraints. One of the restraints was placed in the front passenger seat in a forward facing configuration, and the other was placed in the right rear seating position in a rear-facing configuration. This paper provides a detailed discussion of the results of this test, including comparisons of the specific kinematics for both the restraint/child dummy configurations.