Fred H. Carlin

Biomechanics of Side Impact Injuries: Evaluation of Seat Belt Restraint System, Occupant Kinematics and Injury Potential

Side impact crashes are the second most severe motor vehicle accidents resulting in serious and fatal injuries. One of the occupant restraint systems in the vehicle is the three point lap/shoulder harness. However, the lap/shoulder restraint is not effective in a far-side crash (impact is opposite to the occupant location) since the occupant may slip out of the shoulder harness. The present comprehensive study was designed to delineate the biomechanics of far-side planar crashes. The first part of the study involves a car-to-car crash to study the crash dynamics and occupant kinematics; the second part involves an epidemiological analysis of NASS/CDS 1988-2003 database to study the distribution of serious injury; the third part includes the mathematical MADYMO analysis to study the occupant kinematics in detail; and the fourth part includes an in-depth analysis of a real world far-side accident to delineate the injury mechanism and occupant kinematics. Results indicate that the shoulder harness is ineffective in far-side crashes. The upper torso of the belted driver dummy slips out of the shoulder harness and interacted with the opposite vehicle interior such as the door panel. The unbelted occupants had a similar head injury severity pattern compared to belted occupants. The present study is another step to advance towards better understanding of the prevention, treatment and rehabilitation of side impact injuries

Biomechanical Injury Evaluation of Laminated Glass During Rollover Conditions

Each year, on average, about 7,300 people are killed and about 7,800 people are seriously injured because of partial or complete ejection through glazing (the windows of a vehicle). Of the fatalities, more than 4,400 are associated with vehicle rollovers and the majority of these rollover victims were not using safety belts. In this chapter, from a comprehensive text about occupant and vehicle responses in rollovers, the authors report on a study conducted to determine the occupant retention and head-neck injury potential aspects of laminated glass in rollover accidents. The head injury and neck parameters used in the study were obtained from Hybrid III 50% male dummy test device impacting on various types of side windows with laminated glass. Results indicate that the glass contained the dummy assembly and the head-neck biomechanical parameters were below the critical value injury tolerance limits in simulated rollover accidents. The head injury criteria, peak angular acceleration, and neck bending moments were also well below the critical value limits. The authors conclude that head-neck injury in rollover accidents is unlikely due to laminated glass contact used in production vehicles.

Fork lift overturns and head injury

Phase I, Phase II, Caterpillar, Allis-Chalmers, Clark, Hyster, Toyota and Entwistle fork lift upset studies have been conducted with Hybrid II dummies, Side Impact Dummies, and stunt men. The investigations concluded that the dummy lacks the ability to brace itself, hold on, and does not have adequate biofidelity to represent the human in a fork lift upset. Crushing injuries and death typically occur when the operator is thrown or jumps from the overturning forklift and is pinned by the overhead guard or canopy. The dummy studies demonstrated a wide range of Head Injury Criteria (HIC) values that were not reproducible. Furthermore, other injury producing variables such as angular acceleration, angular velocity or induced brain stress were not investigated. The injury level of 1000 for the HIC for the mid-sized male, small female, and 6 year-old has been recommended by the National Highway Transportation Safety Administration (NHTSA). The fork lift studies showed that HIC values were typically lower when the dummy stayed within the fork lift. Stunt-man experiments demonstrated that humans can brace themselves and hold on to prevent ejection and injury if they are lap-belted and have either a winged seat or hip restraint. The winged seat and lap belt was adopted by Clark in 1983 and the lap belt and hip restraints by Hyster in 1986 even though field acceptance levels were low.

Biomechanical Quantification of Flexion Movement (Ducking) of the Human Head-Neck and Rollover Accidents

Rollover accidents are one of the major types of crashes contributing to the serious or fatal injuries to occupants [1]. The roof crush in rollover accidents is associated with serious injuries to head and neck system [2]. The roof crush intrudes into the occupant survival space and imparts force to the head. The excessive force on the head subjects the cervical spine to injurious level. A commonly observed cervical spine injury in rollover accidents is locked facets with no major bony fractures that are often associated with the flexion-distraction type of loading [3]. Although numerous studies addressed the mechanism of locked facet injuries and the survival space issues [4–9], limited comprehensive efforts have been advanced so far. It is noted that humans tend to duck their head while startled due to sudden fear [10,11]. It is hypothesized that the occupants inside the vehicle tend to duck their heads as a protective mechanism to avoid impact on the head. Although range of motion of the cervical spine is well reported [12], the change in downward movement of the head-neck system (ducking) is not studied well. The present study quantifies the downward movement of the head-neck system of volunteers while seated erect.Copyright

Biomechanical study of traumatic asphyxia due to thoracic load

The purpose of the study was to determine the force-deflection characteristics of the chest of the human surrogate dummy during the loading typical of traumatic asphyxia conditions. The 5th percentile female Hybrid III and 50th percentile male Hybrid III anthropomorphic dummies were used. The vehicle rear bumper impacted the chest of the dummy at idle speed and was allowed to remain in contact with the chest. A total of 14 tests were conducted. The chest force was measured using the load cell and chest deflection was measured using the potentiometer. High-speed photography was used to collect the kinematics data of the dummy. The measured peak deflection was above the proposed injury assessment reference value for chest compression. The peak force was found to be injurious.