Passive Restraint Systems Research Articles

Analysis of injury mechanism and thoracic response of elderly, small female PMHS in near-side impact scenarios

Objective In 2020, 17% of all crash fatalities were individuals aged 65 years or older. Crash data also revealed that for older occupants, thoracic related injuries are among the leading causes of fatality. Historically, the majority of near-side impact postmortem human subjects (PMHS) studies used a generic load wall to capture external loads that were applied to PMHS. While these data were helpful in documenting biofidelity, they did not represent a realistic response an occupant would undergo in a near-side crash. The objective of this research was to test small, elderly female PMHS in a repeatable, realistic near-side impact crash scenario to investigate current injury criteria as they relate to this vulnerable population. Method Ten small, elderly PMHS were subjected to a realistic near-side impact loading condition. The PMHS were targeted to be elderly females age 60+, approximately 5th percentile in height and weight, with osteopenic areal bone mineral density. Each subject was seated on a mass-production seat, equipped with a side airbag and standard three-point restraint with a pretensioner. Other boundary conditions included an intruding driver’s side door. PMHS instrumentation included strain gages on ribs 3-10 bilaterally to identify fracture timing. Two chestbands were used to measure chest deflection, one at the level of the axilla and one at the level of the xiphoid process. Results Injuries observed included rib fractures, particularly on the struck side, and in multiple cases a flail chest was observed. Eight of ten subjects resulted in AIS3+ thoracic injuries, despite previously tested ATDs predicting less than a 10% chance of AIS3+ injury. Subjects crossed the threshold for AIS3 injury in the range of only 1% − 9% chest compression. Additionally, mechanisms of injury varied, as some injuries were incurred by door interactions while others came during airbag interactions. Conclusions This research points to two areas of concern that likely require further analysis: (1) the appropriateness of potentially oversimplified PMHS testing to establish injury thresholds and define injury criteria for complicated crash scenarios; (2) the importance of identifying the precise timing of injuries to better understand the effect of current passive restraint systems.

Views of American and Australian mobility device users and ambulant bus users regarding occupant restraint systems on public buses

IntroductionWith an ageing population, increasing numbers of people are using mobility devices, such as wheelchairs or scooters, whilst travelling on public route buses. The regulations and availability of active (wheelchair tie down and occupant restraint systems or WTORS) and passive (rearward facing) mobility device restraint systems on buses varies between countries. To date few studies have investigated passenger feedback on the use of restraint systems. This study aimed to gather feedback about WTORS on buses from passengers where these are in use (United States) and not in routine use (Australia) to guide decisions on their introduction. MethodsA prospective study using a purpose-designed electronic survey. Participants, predominantly recruited by Qualtrics, comprised two groups; mobility device and ambulant bus users in two countries; Australia and the United States (US). ResultsThe 448 participants rated the top two most important factors when deciding if buses should have WTORS as safety and comfort. Ninety-two percent of respondents believed people using mobility devices should use a WTORS which was rated 7.66/10 (SD1.97) as effective to prevent injuries to self or others. Only a minority of participants (13.2%) had ever slid or fallen from their mobility device, or seen a person slide or fall (13.6%) while on a bus with no differences between countries despite WTORS not being in use in Australia. Respondents reported it was OK to delay a journey an average of 5.52 (SD 2.89) minutes to secure/release a restraint system, which compares favourably to literature-reported real time of one to 4 min. ConclusionsAlthough WTORS were widely perceived by participants as important for safety, questions concerning their effectiveness to prevent slide or tip remain. Prior to the introduction of any securement system in Australia, the effectiveness of passive occupant containment systems to prevent slide or tip also warrants investigation.

Improving collapsibility robustness of an EPS-CD by means of simulation and six sigma

Steering columns for column assist Electric Steering are one of the main elements of the passive safety restraint system in a passenger vehicle. It is designed to collapse applying an optimized ride down force to reduce chest and head injuries of the driver during a frontal crash event, making this requirement one of the most important ones for its development. The system crash response is generated by several elements and interfaces due to the fact of many other different product requirements that a steering column must fulfill. This could lead into a complex validation process throughout the development, as it is needed to integrate the product into the vehicle in order to meet the passive safety requirements. As part of ZF lean Validation approach a new method has been developed to improve the system robustness in ZF Active safety division by means of virtual simulation and six sigma disciplines. This resultant method is also applicable for a model based development process and also contributes to improve frontloading development techniques. An analysis of variance has been done using a correlated virtual model for crash simulation, where the main parameters of the system are known (normally the case when same product generation is reused in a new vehicle). Obtaining as a result of the analysis the regression equation of the system response. This equation defines and quantifies the importance of each factor, and consequently is defining the component contribution and how to develop a column from bottom to top. Moreover, as a second step, a Monte Carlo analysis has been applied using the equation obtained generating statistical results for a number of cases (based in the design tolerances) not manageable from the hardware testing perspective neither from the finite elements methods. In that project Monte Carlo analysis has been applied for 100,000 cases generating response confident intervals instead of the classic FEM deterministic response where only the nominal case is considered.

Numerical child restraint system analysis in 6 years old infant during a dolly rollover test

This research analyzes the head and chest injuries with a finite element model of Hybrid III six years old during the vehicle rollover, using a passive safety Child restraint system (CRS). Vehicle seats and passive safety systems were modeled in CAD software. Subsequently, all elements were analyzed using the finite element method in the LS-DYNA® software. The border conditions were established for each study, in accordance with the Federal Motor Vehicle Safety Standard (FMVSS), following the FMVSS 213 standard for the mounting and fastening of the infant, the FMVSS 208 for the dolly rollover test methodology with which the vehicle rollover was performed. The vehicle Toyota Yaris 2010 was considered in all the analyzes. The numerical simulations were performed during an interval of 1 s, and there were obtained values every 2 ms to analyze the efficiency of the system and the restriction performance of the CRS system. It was compared the behavior when the chair uses a 5-point seatbelt, with respect to using the 3-point seatbelt, and what happens when holding the chair with the single seatbelt and with the ISOFIX anchorage. Three cases of studies were analyzed: Study I; CRS Study II; CRS with ISOFIX anchorage; and Study III; CRS with a seatbelt of 5-points. The outcome shows that the best restriction efficiency is that of the CRS 5 points seatbelt because it presents the lowest level of chest injury. In conclusion, the main factor to reduce injuries during a rollover accident is the correct anchoring of CRS, this is achieved with ISOFIX system, on the other hand, a good quality of material and a correct thickness used for the headrest could reduce the risk of a head injury.

Current Topics in the Management of Acute Traumatic Spinal Cord Injury.

Acute traumatic spinal cord injury (SCI) affects more than 250,000 people in the USA, with approximately 17,000 new cases each year. It continues to be one of the most significant causes of trauma-related morbidity and mortality. Despite the introduction of primary injury prevention education and vehicle safety devices, such as airbags and passive restraint systems, traumatic SCI continues to have a substantial impact on the healthcare system. Over the last three decades, there have been considerable advancements in the management of patients with traumatic SCI. The advent of spinal instrumentation has improved the surgical treatment of spinal fractures and the ability to manage SCI patients with spinal mechanical instability. There has been a concomitant improvement in the nonsurgical care of these patients with particular focus on care delivered in the pre-hospital, emergency room, and intensive care unit (ICU) settings. This article represents an overview of the critical aspects of contemporary traumatic SCI care and notes areas where further research inquiries are needed. We review the pre-hospital management of a patient with an acute SCI, including triage, immobilization, and transportation. Upon arrival to the definitive treatment facility, we review initial evaluation and management steps, including initial neurological assessment, radiographic assessment, cervical collar clearance protocols, and closed reduction of cervical fracture/dislocation injuries. Finally, we review ICU issues including airway, hemodynamic, and pharmacological management, as well as future directions of care.

Chapter 15 - Management of acute traumatic spinal cord injuries

Acute traumatic spinal cord injury (SCI) is a devastating disease process affecting tens of thousands of people across the USA each year. Despite the increase in primary prevention measures, such as educational programs, motor vehicle speed limits, automobile running lights, and safety technology that includes automobile passive restraint systems and airbags, SCIs continue to carry substantial permanent morbidity and mortality. Medical measures implemented following the initial injury are designed to limit secondary insult to the spinal cord and to stabilize the spinal column in an attempt to decrease devastating sequelae. This chapter is an overview of the contemporary management of an acute traumatic SCI patient from the time of injury through the stay in the intensive care unit. We discuss initial triage, immobilization, and transportation of the patient by emergency medical services personnel to a definitive treatment facility. Upon arrival at the emergency department, we review initial trauma protocols and the evidence-based recommendations for radiographic evaluation of the patient's vertebral column. Finally, we outline closed cervical spine reduction and various aggressive medical therapies aimed at improving neurologic outcome.

Finite Element Approach to Identify the Potential of Improved Heavy-Truck Crashworthiness and Occupant Protection in Frontal Impacts

Interior crash protection has not yet received adequate attention for heavy trucks, as such protection did for automobiles. The goal of this pilot project was to determine the nature of truck crashes that would remain after full deployment of advanced collision avoidance technologies and to assess the crashes with respect to truck driver injury and prevention. Heavy-truck occupant safety was analyzed according to injury pattern and severity to help identify and characterize heavy-truck crashes to define opportunities for improved truck crashworthiness and reduce truck driver fatalities and injuries. A finite element (FE) model combining heavy-truck cabin structure, interior components, dummy, and passive restraint systems was developed to simulate a head-on crash into a rigid barrier at 35 mph, the impact conditions used with the NHTSA new car assessment program test. This crash also represented an impact condition that was overrepresented in real-world crash data and for which there was room for improvement in occupant safety. A full FE tractor semitrailer model was employed to collect the crash pulse resulting on the truck cab as outcome of the computer simulation, which was then applied to defined locations of the FE cab model. Acceleration data were collected from impact of different parts of the dummy with interior components of the occupant compartment to assist in the calculation of body injury levels. The researchers developed a comparative risk study to evaluate the effectiveness of passive safety restraints, which would lead to preliminary guidance on the effectiveness of the use of such occupant injury mitigation systems.

English

English

A numerical study of occupant responses and injuries in vehicular crashes into roadside barriers based on finite element simulations

Occupant responses and injuries are important considerations in the design and assessment of roadside safety devices such as barriers. Although incorporating occupant responses and injuries into the design of safety devices is highly recommended by the current safety regulations, there are limited studies that directly consider occupant responses and injuries. Crash test dummies are seldom equipped in the state-of-the-art crash testing of roadside barriers and thus occupant responses and injury risks are evaluated primarily based on vehicle responses. In the present work, occupant responses and injuries in automotive crash events were investigated by incorporating crash test dummies into the vehicle model that was used in the finite element (FE) simulations of roadside crashes. The FE models of a Ford F250 pickup truck and a Hybrid III 50th percentile crash test dummy were employed and a passive restraint system was developed in the FE model. The FE model was validated using existing experiments including a sled test and a full-frontal impact test. Simulations of the Ford F250 impacting a concrete barrier and a W-beam guardrail were conducted and the occupant responses were analyzed. Furthermore, occupant injuries were quantitatively estimated using occupant injury criteria based directly on dummy responses and compared to those based solely on vehicle responses. The correlations between vehicle responses and occupant injuries were studied.

DETERMINATION OF THE SIZE OF THE STORAGE CHAMBER AND THE CHARGING PRESSURE FOR AIR BAGS USED IN AUTOMOTIVE PASSIVE RESTRAINT SYSTEMS

This paper presents design and service charts that enable the size and pressure after inflation of an air bag in a passive restraint system to be predicted for a specified storage chamber size and charging pressure. It is shown that they are independent of the elastic properties of the bag and inflation dynamics, and that an equilibrium analysis leads to incorrect predictions.

Influence assessment of the passive restraint system devices of the passenger locomotive on its dynamic loading during accidenton the railroad

The purpose. To evaluate the work of passenger locomotive protective devices in the test scenarios of collisions adopted in the Russian requirements to the passive safety system. Methodology. Minimization of the effects of incident collisions is done by inclusion of the passive safety devices designed to absorb the kinetic energy of collision in the car bodies bearing constructions. To estimate the maximum accelerations of the train, as well as the compressing longitudinal forces arising in the intercar connection during collisions the discrete mass model of the train is used. Interaction of the train cars was simulated by introducing intercar connections. Findings. At collision of a locomotive at 20 km/h speed (both in separate and in standard train), which does not have a passive safety system, with a vehicle of 10 tones weight the plastic deformations in the locomotive structural elements are observed. At collision of a locomotive with a vehicle, which a mass is comparable to the mass of the loaded car, the plastic deformations in the locomotive structural elements occur at the 10 km/h speed of collision. Originality. It is shown that to decrease the maximum longitudinal force occurring between the locomotive and an obstacle like a freight car of 80 tons mass to the standard value it is necessary to equip the end parts of locomotive with safety devices, which deformation is about 1.5 m. Practical value. To preserve the car structures integrity and passengers, staff and locomotive brigade safety at the incident collisions, a new generation passenger locomotives have to be equipped with the passive safety system devices. On this basis, it is necessary to conduct further researches in the field of passive safety systems for carriages.

Anterior Knee Stiffness Changes in Laxity “Responders” Versus “Nonresponders” Across the Menstrual Cycle

Although changes in anterior knee laxity (AKL) across the menstrual cycle have been reported, the effects of cyclic knee laxity changes on the underlying characteristics of the load-displacement (stiffness) curve generated during anterior loading of the tibia relative to the femur are relatively unknown. To describe the anterior load-displacement curve during anterior loading of the tibia relative to the femur using incremental stiffnesses and to compare underlying stiffness measures between days of the cycle when AKL is at its minimum and maximum. Descriptive laboratory study. University laboratory. Fifty-seven recreationally active women. Anterior knee laxity and 6 incremental stiffness measures (N/mm) were obtained with an instrumented knee arthrometer on days 1-6 of menses and days 0-8 postovulation during 2 consecutive menstrual cycles. Participants were then classified in tertiles based on the maximum change (difference between maximum and minimum) in AKL, and incremental stiffness was compared on days of minimum versus maximum laxity between the lowest (<1.24 mm cyclic laxity change = laxity "nonresponders" [n = 19]) and highest (>1.75 mm cyclic laxity change = laxity "responders" [n = 19]) tertiles. All participants displayed decreasing stiffness initially (0-20 N > 20-40 N and 40-60 N), followed by incrementally increasing stiffness (40-60 N < 60-80 N < 80-100 N < 100-130 N) (P ≤ .05). Responders demonstrated decreased stiffness between the days of minimum and maximum AKL at the 10-130-N increment versus the 0-20-N and 20-40-N increments (P ≤ .05); nonresponders had no change in stiffness. Participants who experienced larger magnitudes of cyclic changes in AKL also experienced decreases in terminal (100-130 N) stiffness during anterior knee joint loading. Decreases in incremental stiffness at higher anterior directed loads may adversely affect passive restraint systems, resulting in altered arthrokinematics during functional activity.

Active and passive movement are encoded equally by head direction cells in the anterodorsal thalamus

The head direction (HD) system is composed of cells that represent the direction in which the animal's head is facing. Each HD cell responds optimally when the head is pointing in a particular, or preferred, direction. Although vestibular system input is necessary to generate the directional signal, motor/proprioceptive inputs can also influence HD cell responses. Previous studies comparing active and passive movement have reported significant suppression of the HD signal during passive restraint. However, in each of these studies there was considerable variability across cells, and the animal's head was never completely fixed. To address these issues, we developed a passive restraint system that more fully prevented head and body movement. HD cell responses in the anterodorsal thalamus (ADN) were evaluated during active and passive movement with this new system. Contrary to previous reports, HD cell responses were not affected by passive restraint. Both head-fixed and hand-held restraint failed to produce significant inhibition of the active HD cell response. Furthermore, direction-specific firing was maintained regardless of 1) the animal's previous experience with restraint, 2) whether it was tested in the light or dark, or 3) the position of the animal relative to the axis of rotation. The maintenance of a stable directional signal without appropriate motor, proprioceptive, or visual input indicates that vestibular input is necessary and sufficient for the generation of the HD signal. Motor and proprioceptive influences may therefore be important for the control of the preferred firing direction of HD cells, but not the generation of the signal itself.

Passive Restraint System for Floating Docks with Large Water-Level Excursions

Anchorage of a recreational two unit floating dock, a gangway-deck configuration, is achieved using a combination of a fixed pile and fixed-length mooring lines. Attached to the floating gangway is a guide that rides along the pile during fluctuations in water level. For a 15.2-m (50-ft) gangway and a pile inclined toward shore at a critical angle of 10.55° with the vertical direction, two symmetrically placed shore-anchored mooring lines attached to the deck corners and diverging at 45° remain at nearly constant length during extreme water-level excursions. Experiments employing a scale model of such a design, together with the observed behavior of a recently installed prototype system in a flood control reservoir, serve to validate the practicality of this passive restraint system for inland water applications.

Optimal Occupant Kinematics and Crash Pulse for Automobile Frontal Impact

Based on a lumped-parameter model of the occupant-vehicle system, optimal kinematics of the occupant in frontal impact are investigated. It is found that for the minimization of the peak occupant deceleration, the optimal kinematics move the occupant at a constant deceleration. Based on this the optimal vehicle crash pulse is investigated. The optimal crash pulse for passive restraint systems is found to be: a positive impulse at the onset, an immediate plunge followed by a gradual rebound, and finally a positive level period. The relation of the peak occupant deceleration to the impact speed, crash deformation, and vehicle interior rattlespace is established. The optimal crash pulse for active and pre-acting restraint systems is discussed.

Optimal Occupant Kinematics and Crash Pulse for Automobile Frontal Impact

Based on a lumped-parameter model of the occupant-vehicle system, optimal kinematics of the occupant in frontal impact are investigated. It is found that for the minimization of the peak occupant deceleration, the optimal kinematics move the occupant at a constant deceleration. Based on this the optimal vehicle crash pulse is investigated. The optimal crash pulse for passive restraint systems is found to be: a positive impulse at the onset, an immediate plunge followed by a gradual rebound, and finally a positive level period. The relation of the peak occupant deceleration to the impact speed, crash deformation, and vehicle interior rattlespace is established. The optimal crash pulse for active and pre-acting restraint systems is discussed.

Concept of a platform-based impact isolation system for protection of wheelchair occupants from injuries in vehicle crashes

To improve the protection of a wheelchair-seated person with disabilities traveling in a vehicle from injuries in a crash, it is proposed to attach the wheelchair to a movable platform separated from the vehicle body by means of a shock isolator. The control of the platform is designed to reduce the occupant's injury risk, as compared with the case of the attachment of the wheelchair directly to the vehicle. The isolator design is based on the minimization of the force transmitted to the wheelchair occupant, provided that the space allowed for the platform to move relative to the vehicle is constrained. The possibility of pre-acting control, when the isolator is engaged for a time prior to the crash, is discussed. Passive tiedown and restraint systems are studied, although it is recognized that active systems could provide even lower injury risks. A multibody model of the platform-based occupied wheelchair is utilized for full-scale simulation of the response of the system to a crash pulse. The simulation shows a noticeable reduction in the injury risk due to the platform and an even greater reduction of injury with pre-acting control.

Seaborne petrochemical spill analysis within the United States, 1992-1999.

Through discussion of causative factors and examination of historical data, petrochemical spill prevention in US waters is reviewed. Unintentional petrochemical outflow is analyzed in a comprehensive manner and presented as a hierarchical sequence of antecedent events to reveal the trends of causative factors leading to release. Specifically, a seaborne petrochemical spill is examined in terms of four basic, antecedent events: (1) an underway source, (2) a failure incident, (3) a marine accident capable of breaching the hull and cargo block, and (4) the onset of outflow. These events are further subdivided into underlying, contributing events to form a causative framework for spill prevention. While a hierarchical review is not necessary to uncover the elements of causation, it does provide a comprehensive and logical structure that clearly defines these elements in terms of occurrence frequency and contribution to resulting outflow. It is found that relatively small, frequent spills less than 40,000 liters (10,567 gallons), attributable to human operator failures, leading to grounding, and cargo transfer system failure accidents, dominate US seaborne petrochemical outflow from 1992 to 1999. Given the frequency of groundings, structural reinforcement regulations such as those contained in the Oil Pollution Act of 1990 (requiring double hulls) appear well justified. However, passive restraint systems are secondary to the need for vigilant training and licensing of tank vessel operators.

Biomechanics of Calcaneal Fractures

Changes in legislation, availability of passive or active restraint systems, or both, together with increased public awareness for safety and the need for use of restraint, have shifted the spectrum of trauma in motor vehicle crashes from the head and torso to other regions. Lower extremity trauma in motor vehicle crashes continues to be a significant problem. The objective of this study was to investigate the biomechanics of the human foot and ankle complex under impact loading and replicate calcaneal fractures routinely seen in motor vehicle crashes. Twenty-two unembalmed cadaver lower extremity specimens were subjected to dynamic loads using a minisled pendulum device. Input and output forces and results of pathologic analysis were obtained using load cell data, radiographs obtained before and after testing, and gross dissection. The intraarticular fracture patterns produced were similar to those seen clinically and described in the literature. Maximum forces ranged from 3.6 to 11.4 kN for the fracture, and 0.5 to 7.3 kN for the nonfracture groups. Logistic regression analysis revealed a 50% probability of calcaneal fracture at 5.5 kN and a 25% probability at 4.0 kN. These studies will lead to an understanding of the tolerance of the lower extremity in sustaining calcaneal fractures under impact. Implications of the work are in the design of crash test dummies, data acquisition, and modifications in motor vehicle design and safety.

Seat belts and trauma: Clinical clues for the surgeon

Since their introduction over 30 years ago, seat belts have reduced the overall mortality associated with motor vehicle accidents by as much as 50%. The position and adjustment of the seat belt appear to play an important role in preventing injury. The lap portion of the belt should be kept low on the abdomen at the level of the anterior superior iliac spine because the pelvis is structurally able to withstand impacts that would seriously damage the soft portions of the abdomen. The diagonal belt should be positioned in such a manner that the clavicle and the chest wall absorb a portion of the force load. The use of seat belts has been associated with a constellation of abdominal injuries, which has been termed “the seat belt syndrome.” The “seat belt syndrome” is most commonly associated with using a lap belt, but it has also been reported in occupants using 3-point restraints. The seat belt syndrome itself is characterized by injuries in the plane of the lap portion of the belt, particularly with laceration of the colon, small bowel, and occasionally the stomach, the liver and spleen, occasional injury of the pancreas, major vascular injuries, and also lumbar spine or spinal cord injury, ie, “chance fractures.” Some serious injuries may be present without early symptoms or physical signs, and neither CT scanning nor DPL is fully reliable or accurate in finding the injury. Prompt diagnosis may be difficult and requires a high index of suspicion as well as a determined approach that may include exploratory celiotomy. The management of patients with potential intra-abdominal injuries resulting from blunt trauma continues to challenge surgeons. Much work continues to be done in the design of automobiles that will ultimately negate the injury that results from the transfer of kinetic energy to the human body. Preemptory strategies may involve crash avoidance techniques, evolutions in highway design, and more intensive driver education as the environment becomes more technologically advanced. Until the time that all automobile passive and active restraint systems are able to abolish all injury, it is up to the surgeon to maintain an appropriate level of suspicion in determining the risk of significant intra-abdominal trauma. Although much has been published in the engineering literature on this subject, recent large population-based reports in the medical literature are few. These 4 articles provide useful direction about the relative risks of injury and the most logical approach to diagnostic evaluation. For the most part, injuries of this nature are relatively rare. Even so, the nemesis of the practicing clinical surgeon is the “negative” CT evaluation of the abdomen with the subsequent significant devascularized shear injury that seems to be specifically associated with seat belt injury. Yet to be determined is the role of newer modalities for diagnosing intra-abdominal injury, including the use of ultrasound. Perhaps we can look forward to newer applications of diagnostic studies that will help us solve the conundrum of the seat belt-injured abdomen unequivocally. Until then, it seems that the mainstay of diagnosis will be a high index of suspicion and external signs, when present, of the “seat belt syndrome.”